Adding upstream version 1:9.2p1.upstream/1%9.2p1upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 3931 insertions, 0 deletions

diff --git a/ssh-keygen.c b/ssh-keygen.c
new file mode 100644
index 0000000..ae05440
--- /dev/null
+++ b/ssh-keygen.c
@@ -0,0 +1,3931 @@
+/* $OpenBSD: ssh-keygen.c,v 1.461 2022/12/04 23:50:49 cheloha Exp $ */
+/*
+ * Author: Tatu Ylonen <ylo@cs.hut.fi>
+ * Copyright (c) 1994 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
+ *                    All rights reserved
+ * Identity and host key generation and maintenance.
+ *
+ * As far as I am concerned, the code I have written for this software
+ * can be used freely for any purpose.  Any derived versions of this
+ * software must be clearly marked as such, and if the derived work is
+ * incompatible with the protocol description in the RFC file, it must be
+ * called by a name other than "ssh" or "Secure Shell".
+ */
+
+#include "includes.h"
+
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <sys/stat.h>
+
+#ifdef WITH_OPENSSL
+#include <openssl/evp.h>
+#include <openssl/pem.h>
+#include "openbsd-compat/openssl-compat.h"
+#endif
+
+#ifdef HAVE_STDINT_H
+# include <stdint.h>
+#endif
+#include <errno.h>
+#include <fcntl.h>
+#include <netdb.h>
+#ifdef HAVE_PATHS_H
+# include <paths.h>
+#endif
+#include <pwd.h>
+#include <stdarg.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <limits.h>
+#include <locale.h>
+#include <time.h>
+
+#include "xmalloc.h"
+#include "sshkey.h"
+#include "authfile.h"
+#include "sshbuf.h"
+#include "pathnames.h"
+#include "log.h"
+#include "misc.h"
+#include "match.h"
+#include "hostfile.h"
+#include "dns.h"
+#include "ssh.h"
+#include "ssh2.h"
+#include "ssherr.h"
+#include "ssh-pkcs11.h"
+#include "atomicio.h"
+#include "krl.h"
+#include "digest.h"
+#include "utf8.h"
+#include "authfd.h"
+#include "sshsig.h"
+#include "ssh-sk.h"
+#include "sk-api.h" /* XXX for SSH_SK_USER_PRESENCE_REQD; remove */
+#include "cipher.h"
+
+#ifdef WITH_OPENSSL
+# define DEFAULT_KEY_TYPE_NAME "rsa"
+#else
+# define DEFAULT_KEY_TYPE_NAME "ed25519"
+#endif
+
+/*
+ * Default number of bits in the RSA, DSA and ECDSA keys.  These value can be
+ * overridden on the command line.
+ *
+ * These values, with the exception of DSA, provide security equivalent to at
+ * least 128 bits of security according to NIST Special Publication 800-57:
+ * Recommendation for Key Management Part 1 rev 4 section 5.6.1.
+ * For DSA it (and FIPS-186-4 section 4.2) specifies that the only size for
+ * which a 160bit hash is acceptable is 1kbit, and since ssh-dss specifies only
+ * SHA1 we limit the DSA key size 1k bits.
+ */
+#define DEFAULT_BITS		3072
+#define DEFAULT_BITS_DSA	1024
+#define DEFAULT_BITS_ECDSA	256
+
+static int quiet = 0;
+
+/* Flag indicating that we just want to see the key fingerprint */
+static int print_fingerprint = 0;
+static int print_bubblebabble = 0;
+
+/* Hash algorithm to use for fingerprints. */
+static int fingerprint_hash = SSH_FP_HASH_DEFAULT;
+
+/* The identity file name, given on the command line or entered by the user. */
+static char identity_file[PATH_MAX];
+static int have_identity = 0;
+
+/* This is set to the passphrase if given on the command line. */
+static char *identity_passphrase = NULL;
+
+/* This is set to the new passphrase if given on the command line. */
+static char *identity_new_passphrase = NULL;
+
+/* Key type when certifying */
+static u_int cert_key_type = SSH2_CERT_TYPE_USER;
+
+/* "key ID" of signed key */
+static char *cert_key_id = NULL;
+
+/* Comma-separated list of principal names for certifying keys */
+static char *cert_principals = NULL;
+
+/* Validity period for certificates */
+static u_int64_t cert_valid_from = 0;
+static u_int64_t cert_valid_to = ~0ULL;
+
+/* Certificate options */
+#define CERTOPT_X_FWD				(1)
+#define CERTOPT_AGENT_FWD			(1<<1)
+#define CERTOPT_PORT_FWD			(1<<2)
+#define CERTOPT_PTY				(1<<3)
+#define CERTOPT_USER_RC				(1<<4)
+#define CERTOPT_NO_REQUIRE_USER_PRESENCE	(1<<5)
+#define CERTOPT_REQUIRE_VERIFY			(1<<6)
+#define CERTOPT_DEFAULT	(CERTOPT_X_FWD|CERTOPT_AGENT_FWD| \
+			 CERTOPT_PORT_FWD|CERTOPT_PTY|CERTOPT_USER_RC)
+static u_int32_t certflags_flags = CERTOPT_DEFAULT;
+static char *certflags_command = NULL;
+static char *certflags_src_addr = NULL;
+
+/* Arbitrary extensions specified by user */
+struct cert_ext {
+	char *key;
+	char *val;
+	int crit;
+};
+static struct cert_ext *cert_ext;
+static size_t ncert_ext;
+
+/* Conversion to/from various formats */
+enum {
+	FMT_RFC4716,
+	FMT_PKCS8,
+	FMT_PEM
+} convert_format = FMT_RFC4716;
+
+static char *key_type_name = NULL;
+
+/* Load key from this PKCS#11 provider */
+static char *pkcs11provider = NULL;
+
+/* FIDO/U2F provider to use */
+static char *sk_provider = NULL;
+
+/* Format for writing private keys */
+static int private_key_format = SSHKEY_PRIVATE_OPENSSH;
+
+/* Cipher for new-format private keys */
+static char *openssh_format_cipher = NULL;
+
+/* Number of KDF rounds to derive new format keys. */
+static int rounds = 0;
+
+/* argv0 */
+extern char *__progname;
+
+static char hostname[NI_MAXHOST];
+
+#ifdef WITH_OPENSSL
+/* moduli.c */
+int gen_candidates(FILE *, u_int32_t, u_int32_t, BIGNUM *);
+int prime_test(FILE *, FILE *, u_int32_t, u_int32_t, char *, unsigned long,
+    unsigned long);
+#endif
+
+static void
+type_bits_valid(int type, const char *name, u_int32_t *bitsp)
+{
+	if (type == KEY_UNSPEC)
+		fatal("unknown key type %s", key_type_name);
+	if (*bitsp == 0) {
+#ifdef WITH_OPENSSL
+		int nid;
+
+		switch(type) {
+		case KEY_DSA:
+			*bitsp = DEFAULT_BITS_DSA;
+			break;
+		case KEY_ECDSA:
+			if (name != NULL &&
+			    (nid = sshkey_ecdsa_nid_from_name(name)) > 0)
+				*bitsp = sshkey_curve_nid_to_bits(nid);
+			if (*bitsp == 0)
+				*bitsp = DEFAULT_BITS_ECDSA;
+			break;
+		case KEY_RSA:
+			*bitsp = DEFAULT_BITS;
+			break;
+		}
+#endif
+	}
+#ifdef WITH_OPENSSL
+	switch (type) {
+	case KEY_DSA:
+		if (*bitsp != 1024)
+			fatal("Invalid DSA key length: must be 1024 bits");
+		break;
+	case KEY_RSA:
+		if (*bitsp < SSH_RSA_MINIMUM_MODULUS_SIZE)
+			fatal("Invalid RSA key length: minimum is %d bits",
+			    SSH_RSA_MINIMUM_MODULUS_SIZE);
+		else if (*bitsp > OPENSSL_RSA_MAX_MODULUS_BITS)
+			fatal("Invalid RSA key length: maximum is %d bits",
+			    OPENSSL_RSA_MAX_MODULUS_BITS);
+		break;
+	case KEY_ECDSA:
+		if (sshkey_ecdsa_bits_to_nid(*bitsp) == -1)
+#ifdef OPENSSL_HAS_NISTP521
+			fatal("Invalid ECDSA key length: valid lengths are "
+			    "256, 384 or 521 bits");
+#else
+			fatal("Invalid ECDSA key length: valid lengths are "
+			    "256 or 384 bits");
+#endif
+	}
+#endif
+}
+
+/*
+ * Checks whether a file exists and, if so, asks the user whether they wish
+ * to overwrite it.
+ * Returns nonzero if the file does not already exist or if the user agrees to
+ * overwrite, or zero otherwise.
+ */
+static int
+confirm_overwrite(const char *filename)
+{
+	char yesno[3];
+	struct stat st;
+
+	if (stat(filename, &st) != 0)
+		return 1;
+	printf("%s already exists.\n", filename);
+	printf("Overwrite (y/n)? ");
+	fflush(stdout);
+	if (fgets(yesno, sizeof(yesno), stdin) == NULL)
+		return 0;
+	if (yesno[0] != 'y' && yesno[0] != 'Y')
+		return 0;
+	return 1;
+}
+
+static void
+ask_filename(struct passwd *pw, const char *prompt)
+{
+	char buf[1024];
+	char *name = NULL;
+
+	if (key_type_name == NULL)
+		name = _PATH_SSH_CLIENT_ID_RSA;
+	else {
+		switch (sshkey_type_from_name(key_type_name)) {
+		case KEY_DSA_CERT:
+		case KEY_DSA:
+			name = _PATH_SSH_CLIENT_ID_DSA;
+			break;
+#ifdef OPENSSL_HAS_ECC
+		case KEY_ECDSA_CERT:
+		case KEY_ECDSA:
+			name = _PATH_SSH_CLIENT_ID_ECDSA;
+			break;
+		case KEY_ECDSA_SK_CERT:
+		case KEY_ECDSA_SK:
+			name = _PATH_SSH_CLIENT_ID_ECDSA_SK;
+			break;
+#endif
+		case KEY_RSA_CERT:
+		case KEY_RSA:
+			name = _PATH_SSH_CLIENT_ID_RSA;
+			break;
+		case KEY_ED25519:
+		case KEY_ED25519_CERT:
+			name = _PATH_SSH_CLIENT_ID_ED25519;
+			break;
+		case KEY_ED25519_SK:
+		case KEY_ED25519_SK_CERT:
+			name = _PATH_SSH_CLIENT_ID_ED25519_SK;
+			break;
+		case KEY_XMSS:
+		case KEY_XMSS_CERT:
+			name = _PATH_SSH_CLIENT_ID_XMSS;
+			break;
+		default:
+			fatal("bad key type");
+		}
+	}
+	snprintf(identity_file, sizeof(identity_file),
+	    "%s/%s", pw->pw_dir, name);
+	printf("%s (%s): ", prompt, identity_file);
+	fflush(stdout);
+	if (fgets(buf, sizeof(buf), stdin) == NULL)
+		exit(1);
+	buf[strcspn(buf, "\n")] = '\0';
+	if (strcmp(buf, "") != 0)
+		strlcpy(identity_file, buf, sizeof(identity_file));
+	have_identity = 1;
+}
+
+static struct sshkey *
+load_identity(const char *filename, char **commentp)
+{
+	char *pass;
+	struct sshkey *prv;
+	int r;
+
+	if (commentp != NULL)
+		*commentp = NULL;
+	if ((r = sshkey_load_private(filename, "", &prv, commentp)) == 0)
+		return prv;
+	if (r != SSH_ERR_KEY_WRONG_PASSPHRASE)
+		fatal_r(r, "Load key \"%s\"", filename);
+	if (identity_passphrase)
+		pass = xstrdup(identity_passphrase);
+	else
+		pass = read_passphrase("Enter passphrase: ", RP_ALLOW_STDIN);
+	r = sshkey_load_private(filename, pass, &prv, commentp);
+	freezero(pass, strlen(pass));
+	if (r != 0)
+		fatal_r(r, "Load key \"%s\"", filename);
+	return prv;
+}
+
+#define SSH_COM_PUBLIC_BEGIN		"---- BEGIN SSH2 PUBLIC KEY ----"
+#define SSH_COM_PUBLIC_END		"---- END SSH2 PUBLIC KEY ----"
+#define SSH_COM_PRIVATE_BEGIN		"---- BEGIN SSH2 ENCRYPTED PRIVATE KEY ----"
+#define	SSH_COM_PRIVATE_KEY_MAGIC	0x3f6ff9eb
+
+#ifdef WITH_OPENSSL
+static void
+do_convert_to_ssh2(struct passwd *pw, struct sshkey *k)
+{
+	struct sshbuf *b;
+	char comment[61], *b64;
+	int r;
+
+	if ((b = sshbuf_new()) == NULL)
+		fatal_f("sshbuf_new failed");
+	if ((r = sshkey_putb(k, b)) != 0)
+		fatal_fr(r, "put key");
+	if ((b64 = sshbuf_dtob64_string(b, 1)) == NULL)
+		fatal_f("sshbuf_dtob64_string failed");
+
+	/* Comment + surrounds must fit into 72 chars (RFC 4716 sec 3.3) */
+	snprintf(comment, sizeof(comment),
+	    "%u-bit %s, converted by %s@%s from OpenSSH",
+	    sshkey_size(k), sshkey_type(k),
+	    pw->pw_name, hostname);
+
+	sshkey_free(k);
+	sshbuf_free(b);
+
+	fprintf(stdout, "%s\n", SSH_COM_PUBLIC_BEGIN);
+	fprintf(stdout, "Comment: \"%s\"\n%s", comment, b64);
+	fprintf(stdout, "%s\n", SSH_COM_PUBLIC_END);
+	free(b64);
+	exit(0);
+}
+
+static void
+do_convert_to_pkcs8(struct sshkey *k)
+{
+	switch (sshkey_type_plain(k->type)) {
+	case KEY_RSA:
+		if (!PEM_write_RSA_PUBKEY(stdout, k->rsa))
+			fatal("PEM_write_RSA_PUBKEY failed");
+		break;
+	case KEY_DSA:
+		if (!PEM_write_DSA_PUBKEY(stdout, k->dsa))
+			fatal("PEM_write_DSA_PUBKEY failed");
+		break;
+#ifdef OPENSSL_HAS_ECC
+	case KEY_ECDSA:
+		if (!PEM_write_EC_PUBKEY(stdout, k->ecdsa))
+			fatal("PEM_write_EC_PUBKEY failed");
+		break;
+#endif
+	default:
+		fatal_f("unsupported key type %s", sshkey_type(k));
+	}
+	exit(0);
+}
+
+static void
+do_convert_to_pem(struct sshkey *k)
+{
+	switch (sshkey_type_plain(k->type)) {
+	case KEY_RSA:
+		if (!PEM_write_RSAPublicKey(stdout, k->rsa))
+			fatal("PEM_write_RSAPublicKey failed");
+		break;
+	case KEY_DSA:
+		if (!PEM_write_DSA_PUBKEY(stdout, k->dsa))
+			fatal("PEM_write_DSA_PUBKEY failed");
+		break;
+#ifdef OPENSSL_HAS_ECC
+	case KEY_ECDSA:
+		if (!PEM_write_EC_PUBKEY(stdout, k->ecdsa))
+			fatal("PEM_write_EC_PUBKEY failed");
+		break;
+#endif
+	default:
+		fatal_f("unsupported key type %s", sshkey_type(k));
+	}
+	exit(0);
+}
+
+static void
+do_convert_to(struct passwd *pw)
+{
+	struct sshkey *k;
+	struct stat st;
+	int r;
+
+	if (!have_identity)
+		ask_filename(pw, "Enter file in which the key is");
+	if (stat(identity_file, &st) == -1)
+		fatal("%s: %s: %s", __progname, identity_file, strerror(errno));
+	if ((r = sshkey_load_public(identity_file, &k, NULL)) != 0)
+		k = load_identity(identity_file, NULL);
+	switch (convert_format) {
+	case FMT_RFC4716:
+		do_convert_to_ssh2(pw, k);
+		break;
+	case FMT_PKCS8:
+		do_convert_to_pkcs8(k);
+		break;
+	case FMT_PEM:
+		do_convert_to_pem(k);
+		break;
+	default:
+		fatal_f("unknown key format %d", convert_format);
+	}
+	exit(0);
+}
+
+/*
+ * This is almost exactly the bignum1 encoding, but with 32 bit for length
+ * instead of 16.
+ */
+static void
+buffer_get_bignum_bits(struct sshbuf *b, BIGNUM *value)
+{
+	u_int bytes, bignum_bits;
+	int r;
+
+	if ((r = sshbuf_get_u32(b, &bignum_bits)) != 0)
+		fatal_fr(r, "parse");
+	bytes = (bignum_bits + 7) / 8;
+	if (sshbuf_len(b) < bytes)
+		fatal_f("input buffer too small: need %d have %zu",
+		    bytes, sshbuf_len(b));
+	if (BN_bin2bn(sshbuf_ptr(b), bytes, value) == NULL)
+		fatal_f("BN_bin2bn failed");
+	if ((r = sshbuf_consume(b, bytes)) != 0)
+		fatal_fr(r, "consume");
+}
+
+static struct sshkey *
+do_convert_private_ssh2(struct sshbuf *b)
+{
+	struct sshkey *key = NULL;
+	char *type, *cipher;
+	u_char e1, e2, e3, *sig = NULL, data[] = "abcde12345";
+	int r, rlen, ktype;
+	u_int magic, i1, i2, i3, i4;
+	size_t slen;
+	u_long e;
+	BIGNUM *dsa_p = NULL, *dsa_q = NULL, *dsa_g = NULL;
+	BIGNUM *dsa_pub_key = NULL, *dsa_priv_key = NULL;
+	BIGNUM *rsa_n = NULL, *rsa_e = NULL, *rsa_d = NULL;
+	BIGNUM *rsa_p = NULL, *rsa_q = NULL, *rsa_iqmp = NULL;
+
+	if ((r = sshbuf_get_u32(b, &magic)) != 0)
+		fatal_fr(r, "parse magic");
+
+	if (magic != SSH_COM_PRIVATE_KEY_MAGIC) {
+		error("bad magic 0x%x != 0x%x", magic,
+		    SSH_COM_PRIVATE_KEY_MAGIC);
+		return NULL;
+	}
+	if ((r = sshbuf_get_u32(b, &i1)) != 0 ||
+	    (r = sshbuf_get_cstring(b, &type, NULL)) != 0 ||
+	    (r = sshbuf_get_cstring(b, &cipher, NULL)) != 0 ||
+	    (r = sshbuf_get_u32(b, &i2)) != 0 ||
+	    (r = sshbuf_get_u32(b, &i3)) != 0 ||
+	    (r = sshbuf_get_u32(b, &i4)) != 0)
+		fatal_fr(r, "parse");
+	debug("ignore (%d %d %d %d)", i1, i2, i3, i4);
+	if (strcmp(cipher, "none") != 0) {
+		error("unsupported cipher %s", cipher);
+		free(cipher);
+		free(type);
+		return NULL;
+	}
+	free(cipher);
+
+	if (strstr(type, "dsa")) {
+		ktype = KEY_DSA;
+	} else if (strstr(type, "rsa")) {
+		ktype = KEY_RSA;
+	} else {
+		free(type);
+		return NULL;
+	}
+	if ((key = sshkey_new(ktype)) == NULL)
+		fatal("sshkey_new failed");
+	free(type);
+
+	switch (key->type) {
+	case KEY_DSA:
+		if ((dsa_p = BN_new()) == NULL ||
+		    (dsa_q = BN_new()) == NULL ||
+		    (dsa_g = BN_new()) == NULL ||
+		    (dsa_pub_key = BN_new()) == NULL ||
+		    (dsa_priv_key = BN_new()) == NULL)
+			fatal_f("BN_new");
+		buffer_get_bignum_bits(b, dsa_p);
+		buffer_get_bignum_bits(b, dsa_g);
+		buffer_get_bignum_bits(b, dsa_q);
+		buffer_get_bignum_bits(b, dsa_pub_key);
+		buffer_get_bignum_bits(b, dsa_priv_key);
+		if (!DSA_set0_pqg(key->dsa, dsa_p, dsa_q, dsa_g))
+			fatal_f("DSA_set0_pqg failed");
+		dsa_p = dsa_q = dsa_g = NULL; /* transferred */
+		if (!DSA_set0_key(key->dsa, dsa_pub_key, dsa_priv_key))
+			fatal_f("DSA_set0_key failed");
+		dsa_pub_key = dsa_priv_key = NULL; /* transferred */
+		break;
+	case KEY_RSA:
+		if ((r = sshbuf_get_u8(b, &e1)) != 0 ||
+		    (e1 < 30 && (r = sshbuf_get_u8(b, &e2)) != 0) ||
+		    (e1 < 30 && (r = sshbuf_get_u8(b, &e3)) != 0))
+			fatal_fr(r, "parse RSA");
+		e = e1;
+		debug("e %lx", e);
+		if (e < 30) {
+			e <<= 8;
+			e += e2;
+			debug("e %lx", e);
+			e <<= 8;
+			e += e3;
+			debug("e %lx", e);
+		}
+		if ((rsa_e = BN_new()) == NULL)
+			fatal_f("BN_new");
+		if (!BN_set_word(rsa_e, e)) {
+			BN_clear_free(rsa_e);
+			sshkey_free(key);
+			return NULL;
+		}
+		if ((rsa_n = BN_new()) == NULL ||
+		    (rsa_d = BN_new()) == NULL ||
+		    (rsa_p = BN_new()) == NULL ||
+		    (rsa_q = BN_new()) == NULL ||
+		    (rsa_iqmp = BN_new()) == NULL)
+			fatal_f("BN_new");
+		buffer_get_bignum_bits(b, rsa_d);
+		buffer_get_bignum_bits(b, rsa_n);
+		buffer_get_bignum_bits(b, rsa_iqmp);
+		buffer_get_bignum_bits(b, rsa_q);
+		buffer_get_bignum_bits(b, rsa_p);
+		if (!RSA_set0_key(key->rsa, rsa_n, rsa_e, rsa_d))
+			fatal_f("RSA_set0_key failed");
+		rsa_n = rsa_e = rsa_d = NULL; /* transferred */
+		if (!RSA_set0_factors(key->rsa, rsa_p, rsa_q))
+			fatal_f("RSA_set0_factors failed");
+		rsa_p = rsa_q = NULL; /* transferred */
+		if ((r = ssh_rsa_complete_crt_parameters(key, rsa_iqmp)) != 0)
+			fatal_fr(r, "generate RSA parameters");
+		BN_clear_free(rsa_iqmp);
+		break;
+	}
+	rlen = sshbuf_len(b);
+	if (rlen != 0)
+		error_f("remaining bytes in key blob %d", rlen);
+
+	/* try the key */
+	if ((r = sshkey_sign(key, &sig, &slen, data, sizeof(data),
+	    NULL, NULL, NULL, 0)) != 0)
+		error_fr(r, "signing with converted key failed");
+	else if ((r = sshkey_verify(key, sig, slen, data, sizeof(data),
+	    NULL, 0, NULL)) != 0)
+		error_fr(r, "verification with converted key failed");
+	if (r != 0) {
+		sshkey_free(key);
+		free(sig);
+		return NULL;
+	}
+	free(sig);
+	return key;
+}
+
+static int
+get_line(FILE *fp, char *line, size_t len)
+{
+	int c;
+	size_t pos = 0;
+
+	line[0] = '\0';
+	while ((c = fgetc(fp)) != EOF) {
+		if (pos >= len - 1)
+			fatal("input line too long.");
+		switch (c) {
+		case '\r':
+			c = fgetc(fp);
+			if (c != EOF && c != '\n' && ungetc(c, fp) == EOF)
+				fatal("unget: %s", strerror(errno));
+			return pos;
+		case '\n':
+			return pos;
+		}
+		line[pos++] = c;
+		line[pos] = '\0';
+	}
+	/* We reached EOF */
+	return -1;
+}
+
+static void
+do_convert_from_ssh2(struct passwd *pw, struct sshkey **k, int *private)
+{
+	int r, blen, escaped = 0;
+	u_int len;
+	char line[1024];
+	struct sshbuf *buf;
+	char encoded[8096];
+	FILE *fp;
+
+	if ((buf = sshbuf_new()) == NULL)
+		fatal("sshbuf_new failed");
+	if ((fp = fopen(identity_file, "r")) == NULL)
+		fatal("%s: %s: %s", __progname, identity_file, strerror(errno));
+	encoded[0] = '\0';
+	while ((blen = get_line(fp, line, sizeof(line))) != -1) {
+		if (blen > 0 && line[blen - 1] == '\\')
+			escaped++;
+		if (strncmp(line, "----", 4) == 0 ||
+		    strstr(line, ": ") != NULL) {
+			if (strstr(line, SSH_COM_PRIVATE_BEGIN) != NULL)
+				*private = 1;
+			if (strstr(line, " END ") != NULL) {
+				break;
+			}
+			/* fprintf(stderr, "ignore: %s", line); */
+			continue;
+		}
+		if (escaped) {
+			escaped--;
+			/* fprintf(stderr, "escaped: %s", line); */
+			continue;
+		}
+		strlcat(encoded, line, sizeof(encoded));
+	}
+	len = strlen(encoded);
+	if (((len % 4) == 3) &&
+	    (encoded[len-1] == '=') &&
+	    (encoded[len-2] == '=') &&
+	    (encoded[len-3] == '='))
+		encoded[len-3] = '\0';
+	if ((r = sshbuf_b64tod(buf, encoded)) != 0)
+		fatal_fr(r, "base64 decode");
+	if (*private) {
+		if ((*k = do_convert_private_ssh2(buf)) == NULL)
+			fatal_f("private key conversion failed");
+	} else if ((r = sshkey_fromb(buf, k)) != 0)
+		fatal_fr(r, "parse key");
+	sshbuf_free(buf);
+	fclose(fp);
+}
+
+static void
+do_convert_from_pkcs8(struct sshkey **k, int *private)
+{
+	EVP_PKEY *pubkey;
+	FILE *fp;
+
+	if ((fp = fopen(identity_file, "r")) == NULL)
+		fatal("%s: %s: %s", __progname, identity_file, strerror(errno));
+	if ((pubkey = PEM_read_PUBKEY(fp, NULL, NULL, NULL)) == NULL) {
+		fatal_f("%s is not a recognised public key format",
+		    identity_file);
+	}
+	fclose(fp);
+	switch (EVP_PKEY_base_id(pubkey)) {
+	case EVP_PKEY_RSA:
+		if ((*k = sshkey_new(KEY_UNSPEC)) == NULL)
+			fatal("sshkey_new failed");
+		(*k)->type = KEY_RSA;
+		(*k)->rsa = EVP_PKEY_get1_RSA(pubkey);
+		break;
+	case EVP_PKEY_DSA:
+		if ((*k = sshkey_new(KEY_UNSPEC)) == NULL)
+			fatal("sshkey_new failed");
+		(*k)->type = KEY_DSA;
+		(*k)->dsa = EVP_PKEY_get1_DSA(pubkey);
+		break;
+#ifdef OPENSSL_HAS_ECC
+	case EVP_PKEY_EC:
+		if ((*k = sshkey_new(KEY_UNSPEC)) == NULL)
+			fatal("sshkey_new failed");
+		(*k)->type = KEY_ECDSA;
+		(*k)->ecdsa = EVP_PKEY_get1_EC_KEY(pubkey);
+		(*k)->ecdsa_nid = sshkey_ecdsa_key_to_nid((*k)->ecdsa);
+		break;
+#endif
+	default:
+		fatal_f("unsupported pubkey type %d",
+		    EVP_PKEY_base_id(pubkey));
+	}
+	EVP_PKEY_free(pubkey);
+	return;
+}
+
+static void
+do_convert_from_pem(struct sshkey **k, int *private)
+{
+	FILE *fp;
+	RSA *rsa;
+
+	if ((fp = fopen(identity_file, "r")) == NULL)
+		fatal("%s: %s: %s", __progname, identity_file, strerror(errno));
+	if ((rsa = PEM_read_RSAPublicKey(fp, NULL, NULL, NULL)) != NULL) {
+		if ((*k = sshkey_new(KEY_UNSPEC)) == NULL)
+			fatal("sshkey_new failed");
+		(*k)->type = KEY_RSA;
+		(*k)->rsa = rsa;
+		fclose(fp);
+		return;
+	}
+	fatal_f("unrecognised raw private key format");
+}
+
+static void
+do_convert_from(struct passwd *pw)
+{
+	struct sshkey *k = NULL;
+	int r, private = 0, ok = 0;
+	struct stat st;
+
+	if (!have_identity)
+		ask_filename(pw, "Enter file in which the key is");
+	if (stat(identity_file, &st) == -1)
+		fatal("%s: %s: %s", __progname, identity_file, strerror(errno));
+
+	switch (convert_format) {
+	case FMT_RFC4716:
+		do_convert_from_ssh2(pw, &k, &private);
+		break;
+	case FMT_PKCS8:
+		do_convert_from_pkcs8(&k, &private);
+		break;
+	case FMT_PEM:
+		do_convert_from_pem(&k, &private);
+		break;
+	default:
+		fatal_f("unknown key format %d", convert_format);
+	}
+
+	if (!private) {
+		if ((r = sshkey_write(k, stdout)) == 0)
+			ok = 1;
+		if (ok)
+			fprintf(stdout, "\n");
+	} else {
+		switch (k->type) {
+		case KEY_DSA:
+			ok = PEM_write_DSAPrivateKey(stdout, k->dsa, NULL,
+			    NULL, 0, NULL, NULL);
+			break;
+#ifdef OPENSSL_HAS_ECC
+		case KEY_ECDSA:
+			ok = PEM_write_ECPrivateKey(stdout, k->ecdsa, NULL,
+			    NULL, 0, NULL, NULL);
+			break;
+#endif
+		case KEY_RSA:
+			ok = PEM_write_RSAPrivateKey(stdout, k->rsa, NULL,
+			    NULL, 0, NULL, NULL);
+			break;
+		default:
+			fatal_f("unsupported key type %s", sshkey_type(k));
+		}
+	}
+
+	if (!ok)
+		fatal("key write failed");
+	sshkey_free(k);
+	exit(0);
+}
+#endif
+
+static void
+do_print_public(struct passwd *pw)
+{
+	struct sshkey *prv;
+	struct stat st;
+	int r;
+	char *comment = NULL;
+
+	if (!have_identity)
+		ask_filename(pw, "Enter file in which the key is");
+	if (stat(identity_file, &st) == -1)
+		fatal("%s: %s", identity_file, strerror(errno));
+	prv = load_identity(identity_file, &comment);
+	if ((r = sshkey_write(prv, stdout)) != 0)
+		fatal_fr(r, "write key");
+	if (comment != NULL && *comment != '\0')
+		fprintf(stdout, " %s", comment);
+	fprintf(stdout, "\n");
+	if (sshkey_is_sk(prv)) {
+		debug("sk_application: \"%s\", sk_flags 0x%02x",
+			prv->sk_application, prv->sk_flags);
+	}
+	sshkey_free(prv);
+	free(comment);
+	exit(0);
+}
+
+static void
+do_download(struct passwd *pw)
+{
+#ifdef ENABLE_PKCS11
+	struct sshkey **keys = NULL;
+	int i, nkeys;
+	enum sshkey_fp_rep rep;
+	int fptype;
+	char *fp, *ra, **comments = NULL;
+
+	fptype = print_bubblebabble ? SSH_DIGEST_SHA1 : fingerprint_hash;
+	rep =    print_bubblebabble ? SSH_FP_BUBBLEBABBLE : SSH_FP_DEFAULT;
+
+	pkcs11_init(1);
+	nkeys = pkcs11_add_provider(pkcs11provider, NULL, &keys, &comments);
+	if (nkeys <= 0)
+		fatal("cannot read public key from pkcs11");
+	for (i = 0; i < nkeys; i++) {
+		if (print_fingerprint) {
+			fp = sshkey_fingerprint(keys[i], fptype, rep);
+			ra = sshkey_fingerprint(keys[i], fingerprint_hash,
+			    SSH_FP_RANDOMART);
+			if (fp == NULL || ra == NULL)
+				fatal_f("sshkey_fingerprint fail");
+			printf("%u %s %s (PKCS11 key)\n", sshkey_size(keys[i]),
+			    fp, sshkey_type(keys[i]));
+			if (log_level_get() >= SYSLOG_LEVEL_VERBOSE)
+				printf("%s\n", ra);
+			free(ra);
+			free(fp);
+		} else {
+			(void) sshkey_write(keys[i], stdout); /* XXX check */
+			fprintf(stdout, "%s%s\n",
+			    *(comments[i]) == '\0' ? "" : " ", comments[i]);
+		}
+		free(comments[i]);
+		sshkey_free(keys[i]);
+	}
+	free(comments);
+	free(keys);
+	pkcs11_terminate();
+	exit(0);
+#else
+	fatal("no pkcs11 support");
+#endif /* ENABLE_PKCS11 */
+}
+
+static struct sshkey *
+try_read_key(char **cpp)
+{
+	struct sshkey *ret;
+	int r;
+
+	if ((ret = sshkey_new(KEY_UNSPEC)) == NULL)
+		fatal("sshkey_new failed");
+	if ((r = sshkey_read(ret, cpp)) == 0)
+		return ret;
+	/* Not a key */
+	sshkey_free(ret);
+	return NULL;
+}
+
+static void
+fingerprint_one_key(const struct sshkey *public, const char *comment)
+{
+	char *fp = NULL, *ra = NULL;
+	enum sshkey_fp_rep rep;
+	int fptype;
+
+	fptype = print_bubblebabble ? SSH_DIGEST_SHA1 : fingerprint_hash;
+	rep =    print_bubblebabble ? SSH_FP_BUBBLEBABBLE : SSH_FP_DEFAULT;
+	fp = sshkey_fingerprint(public, fptype, rep);
+	ra = sshkey_fingerprint(public, fingerprint_hash, SSH_FP_RANDOMART);
+	if (fp == NULL || ra == NULL)
+		fatal_f("sshkey_fingerprint failed");
+	mprintf("%u %s %s (%s)\n", sshkey_size(public), fp,
+	    comment ? comment : "no comment", sshkey_type(public));
+	if (log_level_get() >= SYSLOG_LEVEL_VERBOSE)
+		printf("%s\n", ra);
+	free(ra);
+	free(fp);
+}
+
+static void
+fingerprint_private(const char *path)
+{
+	struct stat st;
+	char *comment = NULL;
+	struct sshkey *privkey = NULL, *pubkey = NULL;
+	int r;
+
+	if (stat(identity_file, &st) == -1)
+		fatal("%s: %s", path, strerror(errno));
+	if ((r = sshkey_load_public(path, &pubkey, &comment)) != 0)
+		debug_r(r, "load public \"%s\"", path);
+	if (pubkey == NULL || comment == NULL || *comment == '\0') {
+		free(comment);
+		if ((r = sshkey_load_private(path, NULL,
+		    &privkey, &comment)) != 0)
+			debug_r(r, "load private \"%s\"", path);
+	}
+	if (pubkey == NULL && privkey == NULL)
+		fatal("%s is not a key file.", path);
+
+	fingerprint_one_key(pubkey == NULL ? privkey : pubkey, comment);
+	sshkey_free(pubkey);
+	sshkey_free(privkey);
+	free(comment);
+}
+
+static void
+do_fingerprint(struct passwd *pw)
+{
+	FILE *f;
+	struct sshkey *public = NULL;
+	char *comment = NULL, *cp, *ep, *line = NULL;
+	size_t linesize = 0;
+	int i, invalid = 1;
+	const char *path;
+	u_long lnum = 0;
+
+	if (!have_identity)
+		ask_filename(pw, "Enter file in which the key is");
+	path = identity_file;
+
+	if (strcmp(identity_file, "-") == 0) {
+		f = stdin;
+		path = "(stdin)";
+	} else if ((f = fopen(path, "r")) == NULL)
+		fatal("%s: %s: %s", __progname, path, strerror(errno));
+
+	while (getline(&line, &linesize, f) != -1) {
+		lnum++;
+		cp = line;
+		cp[strcspn(cp, "\n")] = '\0';
+		/* Trim leading space and comments */
+		cp = line + strspn(line, " \t");
+		if (*cp == '#' || *cp == '\0')
+			continue;
+
+		/*
+		 * Input may be plain keys, private keys, authorized_keys
+		 * or known_hosts.
+		 */
+
+		/*
+		 * Try private keys first. Assume a key is private if
+		 * "SSH PRIVATE KEY" appears on the first line and we're
+		 * not reading from stdin (XXX support private keys on stdin).
+		 */
+		if (lnum == 1 && strcmp(identity_file, "-") != 0 &&
+		    strstr(cp, "PRIVATE KEY") != NULL) {
+			free(line);
+			fclose(f);
+			fingerprint_private(path);
+			exit(0);
+		}
+
+		/*
+		 * If it's not a private key, then this must be prepared to
+		 * accept a public key prefixed with a hostname or options.
+		 * Try a bare key first, otherwise skip the leading stuff.
+		 */
+		if ((public = try_read_key(&cp)) == NULL) {
+			i = strtol(cp, &ep, 10);
+			if (i == 0 || ep == NULL ||
+			    (*ep != ' ' && *ep != '\t')) {
+				int quoted = 0;
+
+				comment = cp;
+				for (; *cp && (quoted || (*cp != ' ' &&
+				    *cp != '\t')); cp++) {
+					if (*cp == '\\' && cp[1] == '"')
+						cp++;	/* Skip both */
+					else if (*cp == '"')
+						quoted = !quoted;
+				}
+				if (!*cp)
+					continue;
+				*cp++ = '\0';
+			}
+		}
+		/* Retry after parsing leading hostname/key options */
+		if (public == NULL && (public = try_read_key(&cp)) == NULL) {
+			debug("%s:%lu: not a public key", path, lnum);
+			continue;
+		}
+
+		/* Find trailing comment, if any */
+		for (; *cp == ' ' || *cp == '\t'; cp++)
+			;
+		if (*cp != '\0' && *cp != '#')
+			comment = cp;
+
+		fingerprint_one_key(public, comment);
+		sshkey_free(public);
+		invalid = 0; /* One good key in the file is sufficient */
+	}
+	fclose(f);
+	free(line);
+
+	if (invalid)
+		fatal("%s is not a public key file.", path);
+	exit(0);
+}
+
+static void
+do_gen_all_hostkeys(struct passwd *pw)
+{
+	struct {
+		char *key_type;
+		char *key_type_display;
+		char *path;
+	} key_types[] = {
+#ifdef WITH_OPENSSL
+		{ "rsa", "RSA" ,_PATH_HOST_RSA_KEY_FILE },
+#ifdef OPENSSL_HAS_ECC
+		{ "ecdsa", "ECDSA",_PATH_HOST_ECDSA_KEY_FILE },
+#endif /* OPENSSL_HAS_ECC */
+#endif /* WITH_OPENSSL */
+		{ "ed25519", "ED25519",_PATH_HOST_ED25519_KEY_FILE },
+#ifdef WITH_XMSS
+		{ "xmss", "XMSS",_PATH_HOST_XMSS_KEY_FILE },
+#endif /* WITH_XMSS */
+		{ NULL, NULL, NULL }
+	};
+
+	u_int32_t bits = 0;
+	int first = 0;
+	struct stat st;
+	struct sshkey *private, *public;
+	char comment[1024], *prv_tmp, *pub_tmp, *prv_file, *pub_file;
+	int i, type, fd, r;
+
+	for (i = 0; key_types[i].key_type; i++) {
+		public = private = NULL;
+		prv_tmp = pub_tmp = prv_file = pub_file = NULL;
+
+		xasprintf(&prv_file, "%s%s",
+		    identity_file, key_types[i].path);
+
+		/* Check whether private key exists and is not zero-length */
+		if (stat(prv_file, &st) == 0) {
+			if (st.st_size != 0)
+				goto next;
+		} else if (errno != ENOENT) {
+			error("Could not stat %s: %s", key_types[i].path,
+			    strerror(errno));
+			goto failnext;
+		}
+
+		/*
+		 * Private key doesn't exist or is invalid; proceed with
+		 * key generation.
+		 */
+		xasprintf(&prv_tmp, "%s%s.XXXXXXXXXX",
+		    identity_file, key_types[i].path);
+		xasprintf(&pub_tmp, "%s%s.pub.XXXXXXXXXX",
+		    identity_file, key_types[i].path);
+		xasprintf(&pub_file, "%s%s.pub",
+		    identity_file, key_types[i].path);
+
+		if (first == 0) {
+			first = 1;
+			printf("%s: generating new host keys: ", __progname);
+		}
+		printf("%s ", key_types[i].key_type_display);
+		fflush(stdout);
+		type = sshkey_type_from_name(key_types[i].key_type);
+		if ((fd = mkstemp(prv_tmp)) == -1) {
+			error("Could not save your private key in %s: %s",
+			    prv_tmp, strerror(errno));
+			goto failnext;
+		}
+		(void)close(fd); /* just using mkstemp() to reserve a name */
+		bits = 0;
+		type_bits_valid(type, NULL, &bits);
+		if ((r = sshkey_generate(type, bits, &private)) != 0) {
+			error_r(r, "sshkey_generate failed");
+			goto failnext;
+		}
+		if ((r = sshkey_from_private(private, &public)) != 0)
+			fatal_fr(r, "sshkey_from_private");
+		snprintf(comment, sizeof comment, "%s@%s", pw->pw_name,
+		    hostname);
+		if ((r = sshkey_save_private(private, prv_tmp, "",
+		    comment, private_key_format, openssh_format_cipher,
+		    rounds)) != 0) {
+			error_r(r, "Saving key \"%s\" failed", prv_tmp);
+			goto failnext;
+		}
+		if ((fd = mkstemp(pub_tmp)) == -1) {
+			error("Could not save your public key in %s: %s",
+			    pub_tmp, strerror(errno));
+			goto failnext;
+		}
+		(void)fchmod(fd, 0644);
+		(void)close(fd);
+		if ((r = sshkey_save_public(public, pub_tmp, comment)) != 0) {
+			error_r(r, "Unable to save public key to %s",
+			    identity_file);
+			goto failnext;
+		}
+
+		/* Rename temporary files to their permanent locations. */
+		if (rename(pub_tmp, pub_file) != 0) {
+			error("Unable to move %s into position: %s",
+			    pub_file, strerror(errno));
+			goto failnext;
+		}
+		if (rename(prv_tmp, prv_file) != 0) {
+			error("Unable to move %s into position: %s",
+			    key_types[i].path, strerror(errno));
+ failnext:
+			first = 0;
+			goto next;
+		}
+ next:
+		sshkey_free(private);
+		sshkey_free(public);
+		free(prv_tmp);
+		free(pub_tmp);
+		free(prv_file);
+		free(pub_file);
+	}
+	if (first != 0)
+		printf("\n");
+}
+
+struct known_hosts_ctx {
+	const char *host;	/* Hostname searched for in find/delete case */
+	FILE *out;		/* Output file, stdout for find_hosts case */
+	int has_unhashed;	/* When hashing, original had unhashed hosts */
+	int found_key;		/* For find/delete, host was found */
+	int invalid;		/* File contained invalid items; don't delete */
+	int hash_hosts;		/* Hash hostnames as we go */
+	int find_host;		/* Search for specific hostname */
+	int delete_host;	/* Delete host from known_hosts */
+};
+
+static int
+known_hosts_hash(struct hostkey_foreach_line *l, void *_ctx)
+{
+	struct known_hosts_ctx *ctx = (struct known_hosts_ctx *)_ctx;
+	char *hashed, *cp, *hosts, *ohosts;
+	int has_wild = l->hosts && strcspn(l->hosts, "*?!") != strlen(l->hosts);
+	int was_hashed = l->hosts && l->hosts[0] == HASH_DELIM;
+
+	switch (l->status) {
+	case HKF_STATUS_OK:
+	case HKF_STATUS_MATCHED:
+		/*
+		 * Don't hash hosts already already hashed, with wildcard
+		 * characters or a CA/revocation marker.
+		 */
+		if (was_hashed || has_wild || l->marker != MRK_NONE) {
+			fprintf(ctx->out, "%s\n", l->line);
+			if (has_wild && !ctx->find_host) {
+				logit("%s:%lu: ignoring host name "
+				    "with wildcard: %.64s", l->path,
+				    l->linenum, l->hosts);
+			}
+			return 0;
+		}
+		/*
+		 * Split any comma-separated hostnames from the host list,
+		 * hash and store separately.
+		 */
+		ohosts = hosts = xstrdup(l->hosts);
+		while ((cp = strsep(&hosts, ",")) != NULL && *cp != '\0') {
+			lowercase(cp);
+			if ((hashed = host_hash(cp, NULL, 0)) == NULL)
+				fatal("hash_host failed");
+			fprintf(ctx->out, "%s %s\n", hashed, l->rawkey);
+			free(hashed);
+			ctx->has_unhashed = 1;
+		}
+		free(ohosts);
+		return 0;
+	case HKF_STATUS_INVALID:
+		/* Retain invalid lines, but mark file as invalid. */
+		ctx->invalid = 1;
+		logit("%s:%lu: invalid line", l->path, l->linenum);
+		/* FALLTHROUGH */
+	default:
+		fprintf(ctx->out, "%s\n", l->line);
+		return 0;
+	}
+	/* NOTREACHED */
+	return -1;
+}
+
+static int
+known_hosts_find_delete(struct hostkey_foreach_line *l, void *_ctx)
+{
+	struct known_hosts_ctx *ctx = (struct known_hosts_ctx *)_ctx;
+	enum sshkey_fp_rep rep;
+	int fptype;
+	char *fp = NULL, *ra = NULL;
+
+	fptype = print_bubblebabble ? SSH_DIGEST_SHA1 : fingerprint_hash;
+	rep =    print_bubblebabble ? SSH_FP_BUBBLEBABBLE : SSH_FP_DEFAULT;
+
+	if (l->status == HKF_STATUS_MATCHED) {
+		if (ctx->delete_host) {
+			if (l->marker != MRK_NONE) {
+				/* Don't remove CA and revocation lines */
+				fprintf(ctx->out, "%s\n", l->line);
+			} else {
+				/*
+				 * Hostname matches and has no CA/revoke
+				 * marker, delete it by *not* writing the
+				 * line to ctx->out.
+				 */
+				ctx->found_key = 1;
+				if (!quiet)
+					printf("# Host %s found: line %lu\n",
+					    ctx->host, l->linenum);
+			}
+			return 0;
+		} else if (ctx->find_host) {
+			ctx->found_key = 1;
+			if (!quiet) {
+				printf("# Host %s found: line %lu %s\n",
+				    ctx->host,
+				    l->linenum, l->marker == MRK_CA ? "CA" :
+				    (l->marker == MRK_REVOKE ? "REVOKED" : ""));
+			}
+			if (ctx->hash_hosts)
+				known_hosts_hash(l, ctx);
+			else if (print_fingerprint) {
+				fp = sshkey_fingerprint(l->key, fptype, rep);
+				ra = sshkey_fingerprint(l->key,
+				    fingerprint_hash, SSH_FP_RANDOMART);
+				if (fp == NULL || ra == NULL)
+					fatal_f("sshkey_fingerprint failed");
+				mprintf("%s %s %s%s%s\n", ctx->host,
+				    sshkey_type(l->key), fp,
+				    l->comment[0] ? " " : "",
+				    l->comment);
+				if (log_level_get() >= SYSLOG_LEVEL_VERBOSE)
+					printf("%s\n", ra);
+				free(ra);
+				free(fp);
+			} else
+				fprintf(ctx->out, "%s\n", l->line);
+			return 0;
+		}
+	} else if (ctx->delete_host) {
+		/* Retain non-matching hosts when deleting */
+		if (l->status == HKF_STATUS_INVALID) {
+			ctx->invalid = 1;
+			logit("%s:%lu: invalid line", l->path, l->linenum);
+		}
+		fprintf(ctx->out, "%s\n", l->line);
+	}
+	return 0;
+}
+
+static void
+do_known_hosts(struct passwd *pw, const char *name, int find_host,
+    int delete_host, int hash_hosts)
+{
+	char *cp, tmp[PATH_MAX], old[PATH_MAX];
+	int r, fd, oerrno, inplace = 0;
+	struct known_hosts_ctx ctx;
+	u_int foreach_options;
+	struct stat sb;
+
+	if (!have_identity) {
+		cp = tilde_expand_filename(_PATH_SSH_USER_HOSTFILE, pw->pw_uid);
+		if (strlcpy(identity_file, cp, sizeof(identity_file)) >=
+		    sizeof(identity_file))
+			fatal("Specified known hosts path too long");
+		free(cp);
+		have_identity = 1;
+	}
+	if (stat(identity_file, &sb) != 0)
+		fatal("Cannot stat %s: %s", identity_file, strerror(errno));
+
+	memset(&ctx, 0, sizeof(ctx));
+	ctx.out = stdout;
+	ctx.host = name;
+	ctx.hash_hosts = hash_hosts;
+	ctx.find_host = find_host;
+	ctx.delete_host = delete_host;
+
+	/*
+	 * Find hosts goes to stdout, hash and deletions happen in-place
+	 * A corner case is ssh-keygen -HF foo, which should go to stdout
+	 */
+	if (!find_host && (hash_hosts || delete_host)) {
+		if (strlcpy(tmp, identity_file, sizeof(tmp)) >= sizeof(tmp) ||
+		    strlcat(tmp, ".XXXXXXXXXX", sizeof(tmp)) >= sizeof(tmp) ||
+		    strlcpy(old, identity_file, sizeof(old)) >= sizeof(old) ||
+		    strlcat(old, ".old", sizeof(old)) >= sizeof(old))
+			fatal("known_hosts path too long");
+		umask(077);
+		if ((fd = mkstemp(tmp)) == -1)
+			fatal("mkstemp: %s", strerror(errno));
+		if ((ctx.out = fdopen(fd, "w")) == NULL) {
+			oerrno = errno;
+			unlink(tmp);
+			fatal("fdopen: %s", strerror(oerrno));
+		}
+		fchmod(fd, sb.st_mode & 0644);
+		inplace = 1;
+	}
+	/* XXX support identity_file == "-" for stdin */
+	foreach_options = find_host ? HKF_WANT_MATCH : 0;
+	foreach_options |= print_fingerprint ? HKF_WANT_PARSE_KEY : 0;
+	if ((r = hostkeys_foreach(identity_file, (find_host || !hash_hosts) ?
+	    known_hosts_find_delete : known_hosts_hash, &ctx, name, NULL,
+	    foreach_options, 0)) != 0) {
+		if (inplace)
+			unlink(tmp);
+		fatal_fr(r, "hostkeys_foreach");
+	}
+
+	if (inplace)
+		fclose(ctx.out);
+
+	if (ctx.invalid) {
+		error("%s is not a valid known_hosts file.", identity_file);
+		if (inplace) {
+			error("Not replacing existing known_hosts "
+			    "file because of errors");
+			unlink(tmp);
+		}
+		exit(1);
+	} else if (delete_host && !ctx.found_key) {
+		logit("Host %s not found in %s", name, identity_file);
+		if (inplace)
+			unlink(tmp);
+	} else if (inplace) {
+		/* Backup existing file */
+		if (unlink(old) == -1 && errno != ENOENT)
+			fatal("unlink %.100s: %s", old, strerror(errno));
+		if (link(identity_file, old) == -1)
+			fatal("link %.100s to %.100s: %s", identity_file, old,
+			    strerror(errno));
+		/* Move new one into place */
+		if (rename(tmp, identity_file) == -1) {
+			error("rename\"%s\" to \"%s\": %s", tmp, identity_file,
+			    strerror(errno));
+			unlink(tmp);
+			unlink(old);
+			exit(1);
+		}
+
+		printf("%s updated.\n", identity_file);
+		printf("Original contents retained as %s\n", old);
+		if (ctx.has_unhashed) {
+			logit("WARNING: %s contains unhashed entries", old);
+			logit("Delete this file to ensure privacy "
+			    "of hostnames");
+		}
+	}
+
+	exit (find_host && !ctx.found_key);
+}
+
+/*
+ * Perform changing a passphrase.  The argument is the passwd structure
+ * for the current user.
+ */
+static void
+do_change_passphrase(struct passwd *pw)
+{
+	char *comment;
+	char *old_passphrase, *passphrase1, *passphrase2;
+	struct stat st;
+	struct sshkey *private;
+	int r;
+
+	if (!have_identity)
+		ask_filename(pw, "Enter file in which the key is");
+	if (stat(identity_file, &st) == -1)
+		fatal("%s: %s", identity_file, strerror(errno));
+	/* Try to load the file with empty passphrase. */
+	r = sshkey_load_private(identity_file, "", &private, &comment);
+	if (r == SSH_ERR_KEY_WRONG_PASSPHRASE) {
+		if (identity_passphrase)
+			old_passphrase = xstrdup(identity_passphrase);
+		else
+			old_passphrase =
+			    read_passphrase("Enter old passphrase: ",
+			    RP_ALLOW_STDIN);
+		r = sshkey_load_private(identity_file, old_passphrase,
+		    &private, &comment);
+		freezero(old_passphrase, strlen(old_passphrase));
+		if (r != 0)
+			goto badkey;
+	} else if (r != 0) {
+ badkey:
+		fatal_r(r, "Failed to load key %s", identity_file);
+	}
+	if (comment)
+		mprintf("Key has comment '%s'\n", comment);
+
+	/* Ask the new passphrase (twice). */
+	if (identity_new_passphrase) {
+		passphrase1 = xstrdup(identity_new_passphrase);
+		passphrase2 = NULL;
+	} else {
+		passphrase1 =
+			read_passphrase("Enter new passphrase (empty for no "
+			    "passphrase): ", RP_ALLOW_STDIN);
+		passphrase2 = read_passphrase("Enter same passphrase again: ",
+		    RP_ALLOW_STDIN);
+
+		/* Verify that they are the same. */
+		if (strcmp(passphrase1, passphrase2) != 0) {
+			explicit_bzero(passphrase1, strlen(passphrase1));
+			explicit_bzero(passphrase2, strlen(passphrase2));
+			free(passphrase1);
+			free(passphrase2);
+			printf("Pass phrases do not match.  Try again.\n");
+			exit(1);
+		}
+		/* Destroy the other copy. */
+		freezero(passphrase2, strlen(passphrase2));
+	}
+
+	/* Save the file using the new passphrase. */
+	if ((r = sshkey_save_private(private, identity_file, passphrase1,
+	    comment, private_key_format, openssh_format_cipher, rounds)) != 0) {
+		error_r(r, "Saving key \"%s\" failed", identity_file);
+		freezero(passphrase1, strlen(passphrase1));
+		sshkey_free(private);
+		free(comment);
+		exit(1);
+	}
+	/* Destroy the passphrase and the copy of the key in memory. */
+	freezero(passphrase1, strlen(passphrase1));
+	sshkey_free(private);		 /* Destroys contents */
+	free(comment);
+
+	printf("Your identification has been saved with the new passphrase.\n");
+	exit(0);
+}
+
+/*
+ * Print the SSHFP RR.
+ */
+static int
+do_print_resource_record(struct passwd *pw, char *fname, char *hname,
+    int print_generic)
+{
+	struct sshkey *public;
+	char *comment = NULL;
+	struct stat st;
+	int r;
+
+	if (fname == NULL)
+		fatal_f("no filename");
+	if (stat(fname, &st) == -1) {
+		if (errno == ENOENT)
+			return 0;
+		fatal("%s: %s", fname, strerror(errno));
+	}
+	if ((r = sshkey_load_public(fname, &public, &comment)) != 0)
+		fatal_r(r, "Failed to read v2 public key from \"%s\"", fname);
+	export_dns_rr(hname, public, stdout, print_generic);
+	sshkey_free(public);
+	free(comment);
+	return 1;
+}
+
+/*
+ * Change the comment of a private key file.
+ */
+static void
+do_change_comment(struct passwd *pw, const char *identity_comment)
+{
+	char new_comment[1024], *comment, *passphrase;
+	struct sshkey *private;
+	struct sshkey *public;
+	struct stat st;
+	int r;
+
+	if (!have_identity)
+		ask_filename(pw, "Enter file in which the key is");
+	if (stat(identity_file, &st) == -1)
+		fatal("%s: %s", identity_file, strerror(errno));
+	if ((r = sshkey_load_private(identity_file, "",
+	    &private, &comment)) == 0)
+		passphrase = xstrdup("");
+	else if (r != SSH_ERR_KEY_WRONG_PASSPHRASE)
+		fatal_r(r, "Cannot load private key \"%s\"", identity_file);
+	else {
+		if (identity_passphrase)
+			passphrase = xstrdup(identity_passphrase);
+		else if (identity_new_passphrase)
+			passphrase = xstrdup(identity_new_passphrase);
+		else
+			passphrase = read_passphrase("Enter passphrase: ",
+			    RP_ALLOW_STDIN);
+		/* Try to load using the passphrase. */
+		if ((r = sshkey_load_private(identity_file, passphrase,
+		    &private, &comment)) != 0) {
+			freezero(passphrase, strlen(passphrase));
+			fatal_r(r, "Cannot load private key \"%s\"",
+			    identity_file);
+		}
+	}
+
+	if (private->type != KEY_ED25519 && private->type != KEY_XMSS &&
+	    private_key_format != SSHKEY_PRIVATE_OPENSSH) {
+		error("Comments are only supported for keys stored in "
+		    "the new format (-o).");
+		explicit_bzero(passphrase, strlen(passphrase));
+		sshkey_free(private);
+		exit(1);
+	}
+	if (comment)
+		printf("Old comment: %s\n", comment);
+	else
+		printf("No existing comment\n");
+
+	if (identity_comment) {
+		strlcpy(new_comment, identity_comment, sizeof(new_comment));
+	} else {
+		printf("New comment: ");
+		fflush(stdout);
+		if (!fgets(new_comment, sizeof(new_comment), stdin)) {
+			explicit_bzero(passphrase, strlen(passphrase));
+			sshkey_free(private);
+			exit(1);
+		}
+		new_comment[strcspn(new_comment, "\n")] = '\0';
+	}
+	if (comment != NULL && strcmp(comment, new_comment) == 0) {
+		printf("No change to comment\n");
+		free(passphrase);
+		sshkey_free(private);
+		free(comment);
+		exit(0);
+	}
+
+	/* Save the file using the new passphrase. */
+	if ((r = sshkey_save_private(private, identity_file, passphrase,
+	    new_comment, private_key_format, openssh_format_cipher,
+	    rounds)) != 0) {
+		error_r(r, "Saving key \"%s\" failed", identity_file);
+		freezero(passphrase, strlen(passphrase));
+		sshkey_free(private);
+		free(comment);
+		exit(1);
+	}
+	freezero(passphrase, strlen(passphrase));
+	if ((r = sshkey_from_private(private, &public)) != 0)
+		fatal_fr(r, "sshkey_from_private");
+	sshkey_free(private);
+
+	strlcat(identity_file, ".pub", sizeof(identity_file));
+	if ((r = sshkey_save_public(public, identity_file, new_comment)) != 0)
+		fatal_r(r, "Unable to save public key to %s", identity_file);
+	sshkey_free(public);
+	free(comment);
+
+	if (strlen(new_comment) > 0)
+		printf("Comment '%s' applied\n", new_comment);
+	else
+		printf("Comment removed\n");
+
+	exit(0);
+}
+
+static void
+cert_ext_add(const char *key, const char *value, int iscrit)
+{
+	cert_ext = xreallocarray(cert_ext, ncert_ext + 1, sizeof(*cert_ext));
+	cert_ext[ncert_ext].key = xstrdup(key);
+	cert_ext[ncert_ext].val = value == NULL ? NULL : xstrdup(value);
+	cert_ext[ncert_ext].crit = iscrit;
+	ncert_ext++;
+}
+
+/* qsort(3) comparison function for certificate extensions */
+static int
+cert_ext_cmp(const void *_a, const void *_b)
+{
+	const struct cert_ext *a = (const struct cert_ext *)_a;
+	const struct cert_ext *b = (const struct cert_ext *)_b;
+	int r;
+
+	if (a->crit != b->crit)
+		return (a->crit < b->crit) ? -1 : 1;
+	if ((r = strcmp(a->key, b->key)) != 0)
+		return r;
+	if ((a->val == NULL) != (b->val == NULL))
+		return (a->val == NULL) ? -1 : 1;
+	if (a->val != NULL && (r = strcmp(a->val, b->val)) != 0)
+		return r;
+	return 0;
+}
+
+#define OPTIONS_CRITICAL	1
+#define OPTIONS_EXTENSIONS	2
+static void
+prepare_options_buf(struct sshbuf *c, int which)
+{
+	struct sshbuf *b;
+	size_t i;
+	int r;
+	const struct cert_ext *ext;
+
+	if ((b = sshbuf_new()) == NULL)
+		fatal_f("sshbuf_new failed");
+	sshbuf_reset(c);
+	for (i = 0; i < ncert_ext; i++) {
+		ext = &cert_ext[i];
+		if ((ext->crit && (which & OPTIONS_EXTENSIONS)) ||
+		    (!ext->crit && (which & OPTIONS_CRITICAL)))
+			continue;
+		if (ext->val == NULL) {
+			/* flag option */
+			debug3_f("%s", ext->key);
+			if ((r = sshbuf_put_cstring(c, ext->key)) != 0 ||
+			    (r = sshbuf_put_string(c, NULL, 0)) != 0)
+				fatal_fr(r, "prepare flag");
+		} else {
+			/* key/value option */
+			debug3_f("%s=%s", ext->key, ext->val);
+			sshbuf_reset(b);
+			if ((r = sshbuf_put_cstring(c, ext->key)) != 0 ||
+			    (r = sshbuf_put_cstring(b, ext->val)) != 0 ||
+			    (r = sshbuf_put_stringb(c, b)) != 0)
+				fatal_fr(r, "prepare k/v");
+		}
+	}
+	sshbuf_free(b);
+}
+
+static void
+finalise_cert_exts(void)
+{
+	/* critical options */
+	if (certflags_command != NULL)
+		cert_ext_add("force-command", certflags_command, 1);
+	if (certflags_src_addr != NULL)
+		cert_ext_add("source-address", certflags_src_addr, 1);
+	if ((certflags_flags & CERTOPT_REQUIRE_VERIFY) != 0)
+		cert_ext_add("verify-required", NULL, 1);
+	/* extensions */
+	if ((certflags_flags & CERTOPT_X_FWD) != 0)
+		cert_ext_add("permit-X11-forwarding", NULL, 0);
+	if ((certflags_flags & CERTOPT_AGENT_FWD) != 0)
+		cert_ext_add("permit-agent-forwarding", NULL, 0);
+	if ((certflags_flags & CERTOPT_PORT_FWD) != 0)
+		cert_ext_add("permit-port-forwarding", NULL, 0);
+	if ((certflags_flags & CERTOPT_PTY) != 0)
+		cert_ext_add("permit-pty", NULL, 0);
+	if ((certflags_flags & CERTOPT_USER_RC) != 0)
+		cert_ext_add("permit-user-rc", NULL, 0);
+	if ((certflags_flags & CERTOPT_NO_REQUIRE_USER_PRESENCE) != 0)
+		cert_ext_add("no-touch-required", NULL, 0);
+	/* order lexically by key */
+	if (ncert_ext > 0)
+		qsort(cert_ext, ncert_ext, sizeof(*cert_ext), cert_ext_cmp);
+}
+
+static struct sshkey *
+load_pkcs11_key(char *path)
+{
+#ifdef ENABLE_PKCS11
+	struct sshkey **keys = NULL, *public, *private = NULL;
+	int r, i, nkeys;
+
+	if ((r = sshkey_load_public(path, &public, NULL)) != 0)
+		fatal_r(r, "Couldn't load CA public key \"%s\"", path);
+
+	nkeys = pkcs11_add_provider(pkcs11provider, identity_passphrase,
+	    &keys, NULL);
+	debug3_f("%d keys", nkeys);
+	if (nkeys <= 0)
+		fatal("cannot read public key from pkcs11");
+	for (i = 0; i < nkeys; i++) {
+		if (sshkey_equal_public(public, keys[i])) {
+			private = keys[i];
+			continue;
+		}
+		sshkey_free(keys[i]);
+	}
+	free(keys);
+	sshkey_free(public);
+	return private;
+#else
+	fatal("no pkcs11 support");
+#endif /* ENABLE_PKCS11 */
+}
+
+/* Signer for sshkey_certify_custom that uses the agent */
+static int
+agent_signer(struct sshkey *key, u_char **sigp, size_t *lenp,
+    const u_char *data, size_t datalen,
+    const char *alg, const char *provider, const char *pin,
+    u_int compat, void *ctx)
+{
+	int *agent_fdp = (int *)ctx;
+
+	return ssh_agent_sign(*agent_fdp, key, sigp, lenp,
+	    data, datalen, alg, compat);
+}
+
+static void
+do_ca_sign(struct passwd *pw, const char *ca_key_path, int prefer_agent,
+    unsigned long long cert_serial, int cert_serial_autoinc,
+    int argc, char **argv)
+{
+	int r, i, found, agent_fd = -1;
+	u_int n;
+	struct sshkey *ca, *public;
+	char valid[64], *otmp, *tmp, *cp, *out, *comment;
+	char *ca_fp = NULL, **plist = NULL, *pin = NULL;
+	struct ssh_identitylist *agent_ids;
+	size_t j;
+	struct notifier_ctx *notifier = NULL;
+
+#ifdef ENABLE_PKCS11
+	pkcs11_init(1);
+#endif
+	tmp = tilde_expand_filename(ca_key_path, pw->pw_uid);
+	if (pkcs11provider != NULL) {
+		/* If a PKCS#11 token was specified then try to use it */
+		if ((ca = load_pkcs11_key(tmp)) == NULL)
+			fatal("No PKCS#11 key matching %s found", ca_key_path);
+	} else if (prefer_agent) {
+		/*
+		 * Agent signature requested. Try to use agent after making
+		 * sure the public key specified is actually present in the
+		 * agent.
+		 */
+		if ((r = sshkey_load_public(tmp, &ca, NULL)) != 0)
+			fatal_r(r, "Cannot load CA public key %s", tmp);
+		if ((r = ssh_get_authentication_socket(&agent_fd)) != 0)
+			fatal_r(r, "Cannot use public key for CA signature");
+		if ((r = ssh_fetch_identitylist(agent_fd, &agent_ids)) != 0)
+			fatal_r(r, "Retrieve agent key list");
+		found = 0;
+		for (j = 0; j < agent_ids->nkeys; j++) {
+			if (sshkey_equal(ca, agent_ids->keys[j])) {
+				found = 1;
+				break;
+			}
+		}
+		if (!found)
+			fatal("CA key %s not found in agent", tmp);
+		ssh_free_identitylist(agent_ids);
+		ca->flags |= SSHKEY_FLAG_EXT;
+	} else {
+		/* CA key is assumed to be a private key on the filesystem */
+		ca = load_identity(tmp, NULL);
+		if (sshkey_is_sk(ca) &&
+		    (ca->sk_flags & SSH_SK_USER_VERIFICATION_REQD)) {
+			if ((pin = read_passphrase("Enter PIN for CA key: ",
+			    RP_ALLOW_STDIN)) == NULL)
+				fatal_f("couldn't read PIN");
+		}
+	}
+	free(tmp);
+
+	if (key_type_name != NULL) {
+		if (sshkey_type_from_name(key_type_name) != ca->type) {
+			fatal("CA key type %s doesn't match specified %s",
+			    sshkey_ssh_name(ca), key_type_name);
+		}
+	} else if (ca->type == KEY_RSA) {
+		/* Default to a good signature algorithm */
+		key_type_name = "rsa-sha2-512";
+	}
+	ca_fp = sshkey_fingerprint(ca, fingerprint_hash, SSH_FP_DEFAULT);
+
+	finalise_cert_exts();
+	for (i = 0; i < argc; i++) {
+		/* Split list of principals */
+		n = 0;
+		if (cert_principals != NULL) {
+			otmp = tmp = xstrdup(cert_principals);
+			plist = NULL;
+			for (; (cp = strsep(&tmp, ",")) != NULL; n++) {
+				plist = xreallocarray(plist, n + 1, sizeof(*plist));
+				if (*(plist[n] = xstrdup(cp)) == '\0')
+					fatal("Empty principal name");
+			}
+			free(otmp);
+		}
+		if (n > SSHKEY_CERT_MAX_PRINCIPALS)
+			fatal("Too many certificate principals specified");
+
+		tmp = tilde_expand_filename(argv[i], pw->pw_uid);
+		if ((r = sshkey_load_public(tmp, &public, &comment)) != 0)
+			fatal_r(r, "load pubkey \"%s\"", tmp);
+		if (sshkey_is_cert(public))
+			fatal_f("key \"%s\" type %s cannot be certified",
+			    tmp, sshkey_type(public));
+
+		/* Prepare certificate to sign */
+		if ((r = sshkey_to_certified(public)) != 0)
+			fatal_r(r, "Could not upgrade key %s to certificate", tmp);
+		public->cert->type = cert_key_type;
+		public->cert->serial = (u_int64_t)cert_serial;
+		public->cert->key_id = xstrdup(cert_key_id);
+		public->cert->nprincipals = n;
+		public->cert->principals = plist;
+		public->cert->valid_after = cert_valid_from;
+		public->cert->valid_before = cert_valid_to;
+		prepare_options_buf(public->cert->critical, OPTIONS_CRITICAL);
+		prepare_options_buf(public->cert->extensions,
+		    OPTIONS_EXTENSIONS);
+		if ((r = sshkey_from_private(ca,
+		    &public->cert->signature_key)) != 0)
+			fatal_r(r, "sshkey_from_private (ca key)");
+
+		if (agent_fd != -1 && (ca->flags & SSHKEY_FLAG_EXT) != 0) {
+			if ((r = sshkey_certify_custom(public, ca,
+			    key_type_name, sk_provider, NULL, agent_signer,
+			    &agent_fd)) != 0)
+				fatal_r(r, "Couldn't certify %s via agent", tmp);
+		} else {
+			if (sshkey_is_sk(ca) &&
+			    (ca->sk_flags & SSH_SK_USER_PRESENCE_REQD)) {
+				notifier = notify_start(0,
+				    "Confirm user presence for key %s %s",
+				    sshkey_type(ca), ca_fp);
+			}
+			r = sshkey_certify(public, ca, key_type_name,
+			    sk_provider, pin);
+			notify_complete(notifier, "User presence confirmed");
+			if (r != 0)
+				fatal_r(r, "Couldn't certify key %s", tmp);
+		}
+
+		if ((cp = strrchr(tmp, '.')) != NULL && strcmp(cp, ".pub") == 0)
+			*cp = '\0';
+		xasprintf(&out, "%s-cert.pub", tmp);
+		free(tmp);
+
+		if ((r = sshkey_save_public(public, out, comment)) != 0) {
+			fatal_r(r, "Unable to save public key to %s",
+			    identity_file);
+		}
+
+		if (!quiet) {
+			sshkey_format_cert_validity(public->cert,
+			    valid, sizeof(valid));
+			logit("Signed %s key %s: id \"%s\" serial %llu%s%s "
+			    "valid %s", sshkey_cert_type(public),
+			    out, public->cert->key_id,
+			    (unsigned long long)public->cert->serial,
+			    cert_principals != NULL ? " for " : "",
+			    cert_principals != NULL ? cert_principals : "",
+			    valid);
+		}
+
+		sshkey_free(public);
+		free(out);
+		if (cert_serial_autoinc)
+			cert_serial++;
+	}
+	if (pin != NULL)
+		freezero(pin, strlen(pin));
+	free(ca_fp);
+#ifdef ENABLE_PKCS11
+	pkcs11_terminate();
+#endif
+	exit(0);
+}
+
+static u_int64_t
+parse_relative_time(const char *s, time_t now)
+{
+	int64_t mul, secs;
+
+	mul = *s == '-' ? -1 : 1;
+
+	if ((secs = convtime(s + 1)) == -1)
+		fatal("Invalid relative certificate time %s", s);
+	if (mul == -1 && secs > now)
+		fatal("Certificate time %s cannot be represented", s);
+	return now + (u_int64_t)(secs * mul);
+}
+
+static void
+parse_hex_u64(const char *s, uint64_t *up)
+{
+	char *ep;
+	unsigned long long ull;
+
+	errno = 0;
+	ull = strtoull(s, &ep, 16);
+	if (*s == '\0' || *ep != '\0')
+		fatal("Invalid certificate time: not a number");
+	if (errno == ERANGE && ull == ULONG_MAX)
+		fatal_fr(SSH_ERR_SYSTEM_ERROR, "Invalid certificate time");
+	*up = (uint64_t)ull;
+}
+
+static void
+parse_cert_times(char *timespec)
+{
+	char *from, *to;
+	time_t now = time(NULL);
+	int64_t secs;
+
+	/* +timespec relative to now */
+	if (*timespec == '+' && strchr(timespec, ':') == NULL) {
+		if ((secs = convtime(timespec + 1)) == -1)
+			fatal("Invalid relative certificate life %s", timespec);
+		cert_valid_to = now + secs;
+		/*
+		 * Backdate certificate one minute to avoid problems on hosts
+		 * with poorly-synchronised clocks.
+		 */
+		cert_valid_from = ((now - 59)/ 60) * 60;
+		return;
+	}
+
+	/*
+	 * from:to, where
+	 * from := [+-]timespec | YYYYMMDD | YYYYMMDDHHMMSS | 0x... | "always"
+	 *   to := [+-]timespec | YYYYMMDD | YYYYMMDDHHMMSS | 0x... | "forever"
+	 */
+	from = xstrdup(timespec);
+	to = strchr(from, ':');
+	if (to == NULL || from == to || *(to + 1) == '\0')
+		fatal("Invalid certificate life specification %s", timespec);
+	*to++ = '\0';
+
+	if (*from == '-' || *from == '+')
+		cert_valid_from = parse_relative_time(from, now);
+	else if (strcmp(from, "always") == 0)
+		cert_valid_from = 0;
+	else if (strncmp(from, "0x", 2) == 0)
+		parse_hex_u64(from, &cert_valid_from);
+	else if (parse_absolute_time(from, &cert_valid_from) != 0)
+		fatal("Invalid from time \"%s\"", from);
+
+	if (*to == '-' || *to == '+')
+		cert_valid_to = parse_relative_time(to, now);
+	else if (strcmp(to, "forever") == 0)
+		cert_valid_to = ~(u_int64_t)0;
+	else if (strncmp(to, "0x", 2) == 0)
+		parse_hex_u64(to, &cert_valid_to);
+	else if (parse_absolute_time(to, &cert_valid_to) != 0)
+		fatal("Invalid to time \"%s\"", to);
+
+	if (cert_valid_to <= cert_valid_from)
+		fatal("Empty certificate validity interval");
+	free(from);
+}
+
+static void
+add_cert_option(char *opt)
+{
+	char *val, *cp;
+	int iscrit = 0;
+
+	if (strcasecmp(opt, "clear") == 0)
+		certflags_flags = 0;
+	else if (strcasecmp(opt, "no-x11-forwarding") == 0)
+		certflags_flags &= ~CERTOPT_X_FWD;
+	else if (strcasecmp(opt, "permit-x11-forwarding") == 0)
+		certflags_flags |= CERTOPT_X_FWD;
+	else if (strcasecmp(opt, "no-agent-forwarding") == 0)
+		certflags_flags &= ~CERTOPT_AGENT_FWD;
+	else if (strcasecmp(opt, "permit-agent-forwarding") == 0)
+		certflags_flags |= CERTOPT_AGENT_FWD;
+	else if (strcasecmp(opt, "no-port-forwarding") == 0)
+		certflags_flags &= ~CERTOPT_PORT_FWD;
+	else if (strcasecmp(opt, "permit-port-forwarding") == 0)
+		certflags_flags |= CERTOPT_PORT_FWD;
+	else if (strcasecmp(opt, "no-pty") == 0)
+		certflags_flags &= ~CERTOPT_PTY;
+	else if (strcasecmp(opt, "permit-pty") == 0)
+		certflags_flags |= CERTOPT_PTY;
+	else if (strcasecmp(opt, "no-user-rc") == 0)
+		certflags_flags &= ~CERTOPT_USER_RC;
+	else if (strcasecmp(opt, "permit-user-rc") == 0)
+		certflags_flags |= CERTOPT_USER_RC;
+	else if (strcasecmp(opt, "touch-required") == 0)
+		certflags_flags &= ~CERTOPT_NO_REQUIRE_USER_PRESENCE;
+	else if (strcasecmp(opt, "no-touch-required") == 0)
+		certflags_flags |= CERTOPT_NO_REQUIRE_USER_PRESENCE;
+	else if (strcasecmp(opt, "no-verify-required") == 0)
+		certflags_flags &= ~CERTOPT_REQUIRE_VERIFY;
+	else if (strcasecmp(opt, "verify-required") == 0)
+		certflags_flags |= CERTOPT_REQUIRE_VERIFY;
+	else if (strncasecmp(opt, "force-command=", 14) == 0) {
+		val = opt + 14;
+		if (*val == '\0')
+			fatal("Empty force-command option");
+		if (certflags_command != NULL)
+			fatal("force-command already specified");
+		certflags_command = xstrdup(val);
+	} else if (strncasecmp(opt, "source-address=", 15) == 0) {
+		val = opt + 15;
+		if (*val == '\0')
+			fatal("Empty source-address option");
+		if (certflags_src_addr != NULL)
+			fatal("source-address already specified");
+		if (addr_match_cidr_list(NULL, val) != 0)
+			fatal("Invalid source-address list");
+		certflags_src_addr = xstrdup(val);
+	} else if (strncasecmp(opt, "extension:", 10) == 0 ||
+		    (iscrit = (strncasecmp(opt, "critical:", 9) == 0))) {
+		val = xstrdup(strchr(opt, ':') + 1);
+		if ((cp = strchr(val, '=')) != NULL)
+			*cp++ = '\0';
+		cert_ext_add(val, cp, iscrit);
+		free(val);
+	} else
+		fatal("Unsupported certificate option \"%s\"", opt);
+}
+
+static void
+show_options(struct sshbuf *optbuf, int in_critical)
+{
+	char *name, *arg, *hex;
+	struct sshbuf *options, *option = NULL;
+	int r;
+
+	if ((options = sshbuf_fromb(optbuf)) == NULL)
+		fatal_f("sshbuf_fromb failed");
+	while (sshbuf_len(options) != 0) {
+		sshbuf_free(option);
+		option = NULL;
+		if ((r = sshbuf_get_cstring(options, &name, NULL)) != 0 ||
+		    (r = sshbuf_froms(options, &option)) != 0)
+			fatal_fr(r, "parse option");
+		printf("                %s", name);
+		if (!in_critical &&
+		    (strcmp(name, "permit-X11-forwarding") == 0 ||
+		    strcmp(name, "permit-agent-forwarding") == 0 ||
+		    strcmp(name, "permit-port-forwarding") == 0 ||
+		    strcmp(name, "permit-pty") == 0 ||
+		    strcmp(name, "permit-user-rc") == 0 ||
+		    strcmp(name, "no-touch-required") == 0)) {
+			printf("\n");
+		} else if (in_critical &&
+		    (strcmp(name, "force-command") == 0 ||
+		    strcmp(name, "source-address") == 0)) {
+			if ((r = sshbuf_get_cstring(option, &arg, NULL)) != 0)
+				fatal_fr(r, "parse critical");
+			printf(" %s\n", arg);
+			free(arg);
+		} else if (in_critical &&
+		    strcmp(name, "verify-required") == 0) {
+			printf("\n");
+		} else if (sshbuf_len(option) > 0) {
+			hex = sshbuf_dtob16(option);
+			printf(" UNKNOWN OPTION: %s (len %zu)\n",
+			    hex, sshbuf_len(option));
+			sshbuf_reset(option);
+			free(hex);
+		} else
+			printf(" UNKNOWN FLAG OPTION\n");
+		free(name);
+		if (sshbuf_len(option) != 0)
+			fatal("Option corrupt: extra data at end");
+	}
+	sshbuf_free(option);
+	sshbuf_free(options);
+}
+
+static void
+print_cert(struct sshkey *key)
+{
+	char valid[64], *key_fp, *ca_fp;
+	u_int i;
+
+	key_fp = sshkey_fingerprint(key, fingerprint_hash, SSH_FP_DEFAULT);
+	ca_fp = sshkey_fingerprint(key->cert->signature_key,
+	    fingerprint_hash, SSH_FP_DEFAULT);
+	if (key_fp == NULL || ca_fp == NULL)
+		fatal_f("sshkey_fingerprint fail");
+	sshkey_format_cert_validity(key->cert, valid, sizeof(valid));
+
+	printf("        Type: %s %s certificate\n", sshkey_ssh_name(key),
+	    sshkey_cert_type(key));
+	printf("        Public key: %s %s\n", sshkey_type(key), key_fp);
+	printf("        Signing CA: %s %s (using %s)\n",
+	    sshkey_type(key->cert->signature_key), ca_fp,
+	    key->cert->signature_type);
+	printf("        Key ID: \"%s\"\n", key->cert->key_id);
+	printf("        Serial: %llu\n", (unsigned long long)key->cert->serial);
+	printf("        Valid: %s\n", valid);
+	printf("        Principals: ");
+	if (key->cert->nprincipals == 0)
+		printf("(none)\n");
+	else {
+		for (i = 0; i < key->cert->nprincipals; i++)
+			printf("\n                %s",
+			    key->cert->principals[i]);
+		printf("\n");
+	}
+	printf("        Critical Options: ");
+	if (sshbuf_len(key->cert->critical) == 0)
+		printf("(none)\n");
+	else {
+		printf("\n");
+		show_options(key->cert->critical, 1);
+	}
+	printf("        Extensions: ");
+	if (sshbuf_len(key->cert->extensions) == 0)
+		printf("(none)\n");
+	else {
+		printf("\n");
+		show_options(key->cert->extensions, 0);
+	}
+}
+
+static void
+do_show_cert(struct passwd *pw)
+{
+	struct sshkey *key = NULL;
+	struct stat st;
+	int r, is_stdin = 0, ok = 0;
+	FILE *f;
+	char *cp, *line = NULL;
+	const char *path;
+	size_t linesize = 0;
+	u_long lnum = 0;
+
+	if (!have_identity)
+		ask_filename(pw, "Enter file in which the key is");
+	if (strcmp(identity_file, "-") != 0 && stat(identity_file, &st) == -1)
+		fatal("%s: %s: %s", __progname, identity_file, strerror(errno));
+
+	path = identity_file;
+	if (strcmp(path, "-") == 0) {
+		f = stdin;
+		path = "(stdin)";
+		is_stdin = 1;
+	} else if ((f = fopen(identity_file, "r")) == NULL)
+		fatal("fopen %s: %s", identity_file, strerror(errno));
+
+	while (getline(&line, &linesize, f) != -1) {
+		lnum++;
+		sshkey_free(key);
+		key = NULL;
+		/* Trim leading space and comments */
+		cp = line + strspn(line, " \t");
+		if (*cp == '#' || *cp == '\0')
+			continue;
+		if ((key = sshkey_new(KEY_UNSPEC)) == NULL)
+			fatal("sshkey_new");
+		if ((r = sshkey_read(key, &cp)) != 0) {
+			error_r(r, "%s:%lu: invalid key", path, lnum);
+			continue;
+		}
+		if (!sshkey_is_cert(key)) {
+			error("%s:%lu is not a certificate", path, lnum);
+			continue;
+		}
+		ok = 1;
+		if (!is_stdin && lnum == 1)
+			printf("%s:\n", path);
+		else
+			printf("%s:%lu:\n", path, lnum);
+		print_cert(key);
+	}
+	free(line);
+	sshkey_free(key);
+	fclose(f);
+	exit(ok ? 0 : 1);
+}
+
+static void
+load_krl(const char *path, struct ssh_krl **krlp)
+{
+	struct sshbuf *krlbuf;
+	int r;
+
+	if ((r = sshbuf_load_file(path, &krlbuf)) != 0)
+		fatal_r(r, "Unable to load KRL %s", path);
+	/* XXX check sigs */
+	if ((r = ssh_krl_from_blob(krlbuf, krlp, NULL, 0)) != 0 ||
+	    *krlp == NULL)
+		fatal_r(r, "Invalid KRL file %s", path);
+	sshbuf_free(krlbuf);
+}
+
+static void
+hash_to_blob(const char *cp, u_char **blobp, size_t *lenp,
+    const char *file, u_long lnum)
+{
+	char *tmp;
+	size_t tlen;
+	struct sshbuf *b;
+	int r;
+
+	if (strncmp(cp, "SHA256:", 7) != 0)
+		fatal("%s:%lu: unsupported hash algorithm", file, lnum);
+	cp += 7;
+
+	/*
+	 * OpenSSH base64 hashes omit trailing '='
+	 * characters; put them back for decode.
+	 */
+	tlen = strlen(cp);
+	tmp = xmalloc(tlen + 4 + 1);
+	strlcpy(tmp, cp, tlen + 1);
+	while ((tlen % 4) != 0) {
+		tmp[tlen++] = '=';
+		tmp[tlen] = '\0';
+	}
+	if ((b = sshbuf_new()) == NULL)
+		fatal_f("sshbuf_new failed");
+	if ((r = sshbuf_b64tod(b, tmp)) != 0)
+		fatal_r(r, "%s:%lu: decode hash failed", file, lnum);
+	free(tmp);
+	*lenp = sshbuf_len(b);
+	*blobp = xmalloc(*lenp);
+	memcpy(*blobp, sshbuf_ptr(b), *lenp);
+	sshbuf_free(b);
+}
+
+static void
+update_krl_from_file(struct passwd *pw, const char *file, int wild_ca,
+    const struct sshkey *ca, struct ssh_krl *krl)
+{
+	struct sshkey *key = NULL;
+	u_long lnum = 0;
+	char *path, *cp, *ep, *line = NULL;
+	u_char *blob = NULL;
+	size_t blen = 0, linesize = 0;
+	unsigned long long serial, serial2;
+	int i, was_explicit_key, was_sha1, was_sha256, was_hash, r;
+	FILE *krl_spec;
+
+	path = tilde_expand_filename(file, pw->pw_uid);
+	if (strcmp(path, "-") == 0) {
+		krl_spec = stdin;
+		free(path);
+		path = xstrdup("(standard input)");
+	} else if ((krl_spec = fopen(path, "r")) == NULL)
+		fatal("fopen %s: %s", path, strerror(errno));
+
+	if (!quiet)
+		printf("Revoking from %s\n", path);
+	while (getline(&line, &linesize, krl_spec) != -1) {
+		lnum++;
+		was_explicit_key = was_sha1 = was_sha256 = was_hash = 0;
+		cp = line + strspn(line, " \t");
+		/* Trim trailing space, comments and strip \n */
+		for (i = 0, r = -1; cp[i] != '\0'; i++) {
+			if (cp[i] == '#' || cp[i] == '\n') {
+				cp[i] = '\0';
+				break;
+			}
+			if (cp[i] == ' ' || cp[i] == '\t') {
+				/* Remember the start of a span of whitespace */
+				if (r == -1)
+					r = i;
+			} else
+				r = -1;
+		}
+		if (r != -1)
+			cp[r] = '\0';
+		if (*cp == '\0')
+			continue;
+		if (strncasecmp(cp, "serial:", 7) == 0) {
+			if (ca == NULL && !wild_ca) {
+				fatal("revoking certificates by serial number "
+				    "requires specification of a CA key");
+			}
+			cp += 7;
+			cp = cp + strspn(cp, " \t");
+			errno = 0;
+			serial = strtoull(cp, &ep, 0);
+			if (*cp == '\0' || (*ep != '\0' && *ep != '-'))
+				fatal("%s:%lu: invalid serial \"%s\"",
+				    path, lnum, cp);
+			if (errno == ERANGE && serial == ULLONG_MAX)
+				fatal("%s:%lu: serial out of range",
+				    path, lnum);
+			serial2 = serial;
+			if (*ep == '-') {
+				cp = ep + 1;
+				errno = 0;
+				serial2 = strtoull(cp, &ep, 0);
+				if (*cp == '\0' || *ep != '\0')
+					fatal("%s:%lu: invalid serial \"%s\"",
+					    path, lnum, cp);
+				if (errno == ERANGE && serial2 == ULLONG_MAX)
+					fatal("%s:%lu: serial out of range",
+					    path, lnum);
+				if (serial2 <= serial)
+					fatal("%s:%lu: invalid serial range "
+					    "%llu:%llu", path, lnum,
+					    (unsigned long long)serial,
+					    (unsigned long long)serial2);
+			}
+			if (ssh_krl_revoke_cert_by_serial_range(krl,
+			    ca, serial, serial2) != 0) {
+				fatal_f("revoke serial failed");
+			}
+		} else if (strncasecmp(cp, "id:", 3) == 0) {
+			if (ca == NULL && !wild_ca) {
+				fatal("revoking certificates by key ID "
+				    "requires specification of a CA key");
+			}
+			cp += 3;
+			cp = cp + strspn(cp, " \t");
+			if (ssh_krl_revoke_cert_by_key_id(krl, ca, cp) != 0)
+				fatal_f("revoke key ID failed");
+		} else if (strncasecmp(cp, "hash:", 5) == 0) {
+			cp += 5;
+			cp = cp + strspn(cp, " \t");
+			hash_to_blob(cp, &blob, &blen, file, lnum);
+			r = ssh_krl_revoke_key_sha256(krl, blob, blen);
+			if (r != 0)
+				fatal_fr(r, "revoke key failed");
+		} else {
+			if (strncasecmp(cp, "key:", 4) == 0) {
+				cp += 4;
+				cp = cp + strspn(cp, " \t");
+				was_explicit_key = 1;
+			} else if (strncasecmp(cp, "sha1:", 5) == 0) {
+				cp += 5;
+				cp = cp + strspn(cp, " \t");
+				was_sha1 = 1;
+			} else if (strncasecmp(cp, "sha256:", 7) == 0) {
+				cp += 7;
+				cp = cp + strspn(cp, " \t");
+				was_sha256 = 1;
+				/*
+				 * Just try to process the line as a key.
+				 * Parsing will fail if it isn't.
+				 */
+			}
+			if ((key = sshkey_new(KEY_UNSPEC)) == NULL)
+				fatal("sshkey_new");
+			if ((r = sshkey_read(key, &cp)) != 0)
+				fatal_r(r, "%s:%lu: invalid key", path, lnum);
+			if (was_explicit_key)
+				r = ssh_krl_revoke_key_explicit(krl, key);
+			else if (was_sha1) {
+				if (sshkey_fingerprint_raw(key,
+				    SSH_DIGEST_SHA1, &blob, &blen) != 0) {
+					fatal("%s:%lu: fingerprint failed",
+					    file, lnum);
+				}
+				r = ssh_krl_revoke_key_sha1(krl, blob, blen);
+			} else if (was_sha256) {
+				if (sshkey_fingerprint_raw(key,
+				    SSH_DIGEST_SHA256, &blob, &blen) != 0) {
+					fatal("%s:%lu: fingerprint failed",
+					    file, lnum);
+				}
+				r = ssh_krl_revoke_key_sha256(krl, blob, blen);
+			} else
+				r = ssh_krl_revoke_key(krl, key);
+			if (r != 0)
+				fatal_fr(r, "revoke key failed");
+			freezero(blob, blen);
+			blob = NULL;
+			blen = 0;
+			sshkey_free(key);
+		}
+	}
+	if (strcmp(path, "-") != 0)
+		fclose(krl_spec);
+	free(line);
+	free(path);
+}
+
+static void
+do_gen_krl(struct passwd *pw, int updating, const char *ca_key_path,
+    unsigned long long krl_version, const char *krl_comment,
+    int argc, char **argv)
+{
+	struct ssh_krl *krl;
+	struct stat sb;
+	struct sshkey *ca = NULL;
+	int i, r, wild_ca = 0;
+	char *tmp;
+	struct sshbuf *kbuf;
+
+	if (*identity_file == '\0')
+		fatal("KRL generation requires an output file");
+	if (stat(identity_file, &sb) == -1) {
+		if (errno != ENOENT)
+			fatal("Cannot access KRL \"%s\": %s",
+			    identity_file, strerror(errno));
+		if (updating)
+			fatal("KRL \"%s\" does not exist", identity_file);
+	}
+	if (ca_key_path != NULL) {
+		if (strcasecmp(ca_key_path, "none") == 0)
+			wild_ca = 1;
+		else {
+			tmp = tilde_expand_filename(ca_key_path, pw->pw_uid);
+			if ((r = sshkey_load_public(tmp, &ca, NULL)) != 0)
+				fatal_r(r, "Cannot load CA public key %s", tmp);
+			free(tmp);
+		}
+	}
+
+	if (updating)
+		load_krl(identity_file, &krl);
+	else if ((krl = ssh_krl_init()) == NULL)
+		fatal("couldn't create KRL");
+
+	if (krl_version != 0)
+		ssh_krl_set_version(krl, krl_version);
+	if (krl_comment != NULL)
+		ssh_krl_set_comment(krl, krl_comment);
+
+	for (i = 0; i < argc; i++)
+		update_krl_from_file(pw, argv[i], wild_ca, ca, krl);
+
+	if ((kbuf = sshbuf_new()) == NULL)
+		fatal("sshbuf_new failed");
+	if (ssh_krl_to_blob(krl, kbuf, NULL, 0) != 0)
+		fatal("Couldn't generate KRL");
+	if ((r = sshbuf_write_file(identity_file, kbuf)) != 0)
+		fatal("write %s: %s", identity_file, strerror(errno));
+	sshbuf_free(kbuf);
+	ssh_krl_free(krl);
+	sshkey_free(ca);
+}
+
+static void
+do_check_krl(struct passwd *pw, int print_krl, int argc, char **argv)
+{
+	int i, r, ret = 0;
+	char *comment;
+	struct ssh_krl *krl;
+	struct sshkey *k;
+
+	if (*identity_file == '\0')
+		fatal("KRL checking requires an input file");
+	load_krl(identity_file, &krl);
+	if (print_krl)
+		krl_dump(krl, stdout);
+	for (i = 0; i < argc; i++) {
+		if ((r = sshkey_load_public(argv[i], &k, &comment)) != 0)
+			fatal_r(r, "Cannot load public key %s", argv[i]);
+		r = ssh_krl_check_key(krl, k);
+		printf("%s%s%s%s: %s\n", argv[i],
+		    *comment ? " (" : "", comment, *comment ? ")" : "",
+		    r == 0 ? "ok" : "REVOKED");
+		if (r != 0)
+			ret = 1;
+		sshkey_free(k);
+		free(comment);
+	}
+	ssh_krl_free(krl);
+	exit(ret);
+}
+
+static struct sshkey *
+load_sign_key(const char *keypath, const struct sshkey *pubkey)
+{
+	size_t i, slen, plen = strlen(keypath);
+	char *privpath = xstrdup(keypath);
+	static const char * const suffixes[] = { "-cert.pub", ".pub", NULL };
+	struct sshkey *ret = NULL, *privkey = NULL;
+	int r, waspub = 0;
+	struct stat st;
+
+	/*
+	 * If passed a public key filename, then try to locate the corresponding
+	 * private key. This lets us specify certificates on the command-line
+	 * and have ssh-keygen find the appropriate private key.
+	 */
+	for (i = 0; suffixes[i]; i++) {
+		slen = strlen(suffixes[i]);
+		if (plen <= slen ||
+		    strcmp(privpath + plen - slen, suffixes[i]) != 0)
+			continue;
+		privpath[plen - slen] = '\0';
+		debug_f("%s looks like a public key, using private key "
+		    "path %s instead", keypath, privpath);
+		waspub = 1;
+	}
+	if (waspub && stat(privpath, &st) != 0 && errno == ENOENT)
+		fatal("No private key found for public key \"%s\"", keypath);
+	if ((r = sshkey_load_private(privpath, "", &privkey, NULL)) != 0 &&
+	    (r != SSH_ERR_KEY_WRONG_PASSPHRASE)) {
+		debug_fr(r, "load private key \"%s\"", privpath);
+		fatal("No private key found for \"%s\"", privpath);
+	} else if (privkey == NULL)
+		privkey = load_identity(privpath, NULL);
+
+	if (!sshkey_equal_public(pubkey, privkey)) {
+		error("Public key %s doesn't match private %s",
+		    keypath, privpath);
+		goto done;
+	}
+	if (sshkey_is_cert(pubkey) && !sshkey_is_cert(privkey)) {
+		/*
+		 * Graft the certificate onto the private key to make
+		 * it capable of signing.
+		 */
+		if ((r = sshkey_to_certified(privkey)) != 0) {
+			error_fr(r, "sshkey_to_certified");
+			goto done;
+		}
+		if ((r = sshkey_cert_copy(pubkey, privkey)) != 0) {
+			error_fr(r, "sshkey_cert_copy");
+			goto done;
+		}
+	}
+	/* success */
+	ret = privkey;
+	privkey = NULL;
+ done:
+	sshkey_free(privkey);
+	free(privpath);
+	return ret;
+}
+
+static int
+sign_one(struct sshkey *signkey, const char *filename, int fd,
+    const char *sig_namespace, const char *hashalg, sshsig_signer *signer,
+    void *signer_ctx)
+{
+	struct sshbuf *sigbuf = NULL, *abuf = NULL;
+	int r = SSH_ERR_INTERNAL_ERROR, wfd = -1, oerrno;
+	char *wfile = NULL, *asig = NULL, *fp = NULL;
+	char *pin = NULL, *prompt = NULL;
+
+	if (!quiet) {
+		if (fd == STDIN_FILENO)
+			fprintf(stderr, "Signing data on standard input\n");
+		else
+			fprintf(stderr, "Signing file %s\n", filename);
+	}
+	if (signer == NULL && sshkey_is_sk(signkey)) {
+		if ((signkey->sk_flags & SSH_SK_USER_VERIFICATION_REQD)) {
+			xasprintf(&prompt, "Enter PIN for %s key: ",
+			    sshkey_type(signkey));
+			if ((pin = read_passphrase(prompt,
+			    RP_ALLOW_STDIN)) == NULL)
+				fatal_f("couldn't read PIN");
+		}
+		if ((signkey->sk_flags & SSH_SK_USER_PRESENCE_REQD)) {
+			if ((fp = sshkey_fingerprint(signkey, fingerprint_hash,
+			    SSH_FP_DEFAULT)) == NULL)
+				fatal_f("fingerprint failed");
+			fprintf(stderr, "Confirm user presence for key %s %s\n",
+			    sshkey_type(signkey), fp);
+			free(fp);
+		}
+	}
+	if ((r = sshsig_sign_fd(signkey, hashalg, sk_provider, pin,
+	    fd, sig_namespace, &sigbuf, signer, signer_ctx)) != 0) {
+		error_r(r, "Signing %s failed", filename);
+		goto out;
+	}
+	if ((r = sshsig_armor(sigbuf, &abuf)) != 0) {
+		error_fr(r, "sshsig_armor");
+		goto out;
+	}
+	if ((asig = sshbuf_dup_string(abuf)) == NULL) {
+		error_f("buffer error");
+		r = SSH_ERR_ALLOC_FAIL;
+		goto out;
+	}
+
+	if (fd == STDIN_FILENO) {
+		fputs(asig, stdout);
+		fflush(stdout);
+	} else {
+		xasprintf(&wfile, "%s.sig", filename);
+		if (confirm_overwrite(wfile)) {
+			if ((wfd = open(wfile, O_WRONLY|O_CREAT|O_TRUNC,
+			    0666)) == -1) {
+				oerrno = errno;
+				error("Cannot open %s: %s",
+				    wfile, strerror(errno));
+				errno = oerrno;
+				r = SSH_ERR_SYSTEM_ERROR;
+				goto out;
+			}
+			if (atomicio(vwrite, wfd, asig,
+			    strlen(asig)) != strlen(asig)) {
+				oerrno = errno;
+				error("Cannot write to %s: %s",
+				    wfile, strerror(errno));
+				errno = oerrno;
+				r = SSH_ERR_SYSTEM_ERROR;
+				goto out;
+			}
+			if (!quiet) {
+				fprintf(stderr, "Write signature to %s\n",
+				    wfile);
+			}
+		}
+	}
+	/* success */
+	r = 0;
+ out:
+	free(wfile);
+	free(prompt);
+	free(asig);
+	if (pin != NULL)
+		freezero(pin, strlen(pin));
+	sshbuf_free(abuf);
+	sshbuf_free(sigbuf);
+	if (wfd != -1)
+		close(wfd);
+	return r;
+}
+
+static int
+sig_process_opts(char * const *opts, size_t nopts, char **hashalgp,
+    uint64_t *verify_timep, int *print_pubkey)
+{
+	size_t i;
+	time_t now;
+
+	if (verify_timep != NULL)
+		*verify_timep = 0;
+	if (print_pubkey != NULL)
+		*print_pubkey = 0;
+	if (hashalgp != NULL)
+		*hashalgp = NULL;
+	for (i = 0; i < nopts; i++) {
+		if (hashalgp != NULL &&
+		    strncasecmp(opts[i], "hashalg=", 8) == 0) {
+			*hashalgp = xstrdup(opts[i] + 8);
+		} else if (verify_timep &&
+		    strncasecmp(opts[i], "verify-time=", 12) == 0) {
+			if (parse_absolute_time(opts[i] + 12,
+			    verify_timep) != 0 || *verify_timep == 0) {
+				error("Invalid \"verify-time\" option");
+				return SSH_ERR_INVALID_ARGUMENT;
+			}
+		} else if (print_pubkey &&
+		    strcasecmp(opts[i], "print-pubkey") == 0) {
+			*print_pubkey = 1;
+		} else {
+			error("Invalid option \"%s\"", opts[i]);
+			return SSH_ERR_INVALID_ARGUMENT;
+		}
+	}
+	if (verify_timep && *verify_timep == 0) {
+		if ((now = time(NULL)) < 0) {
+			error("Time is before epoch");
+			return SSH_ERR_INVALID_ARGUMENT;
+		}
+		*verify_timep = (uint64_t)now;
+	}
+	return 0;
+}
+
+
+static int
+sig_sign(const char *keypath, const char *sig_namespace, int require_agent,
+    int argc, char **argv, char * const *opts, size_t nopts)
+{
+	int i, fd = -1, r, ret = -1;
+	int agent_fd = -1;
+	struct sshkey *pubkey = NULL, *privkey = NULL, *signkey = NULL;
+	sshsig_signer *signer = NULL;
+	char *hashalg = NULL;
+
+	/* Check file arguments. */
+	for (i = 0; i < argc; i++) {
+		if (strcmp(argv[i], "-") != 0)
+			continue;
+		if (i > 0 || argc > 1)
+			fatal("Cannot sign mix of paths and standard input");
+	}
+
+	if (sig_process_opts(opts, nopts, &hashalg, NULL, NULL) != 0)
+		goto done; /* error already logged */
+
+	if ((r = sshkey_load_public(keypath, &pubkey, NULL)) != 0) {
+		error_r(r, "Couldn't load public key %s", keypath);
+		goto done;
+	}
+
+	if ((r = ssh_get_authentication_socket(&agent_fd)) != 0) {
+		if (require_agent)
+			fatal("Couldn't get agent socket");
+		debug_r(r, "Couldn't get agent socket");
+	} else {
+		if ((r = ssh_agent_has_key(agent_fd, pubkey)) == 0)
+			signer = agent_signer;
+		else {
+			if (require_agent)
+				fatal("Couldn't find key in agent");
+			debug_r(r, "Couldn't find key in agent");
+		}
+	}
+
+	if (signer == NULL) {
+		/* Not using agent - try to load private key */
+		if ((privkey = load_sign_key(keypath, pubkey)) == NULL)
+			goto done;
+		signkey = privkey;
+	} else {
+		/* Will use key in agent */
+		signkey = pubkey;
+	}
+
+	if (argc == 0) {
+		if ((r = sign_one(signkey, "(stdin)", STDIN_FILENO,
+		    sig_namespace, hashalg, signer, &agent_fd)) != 0)
+			goto done;
+	} else {
+		for (i = 0; i < argc; i++) {
+			if (strcmp(argv[i], "-") == 0)
+				fd = STDIN_FILENO;
+			else if ((fd = open(argv[i], O_RDONLY)) == -1) {
+				error("Cannot open %s for signing: %s",
+				    argv[i], strerror(errno));
+				goto done;
+			}
+			if ((r = sign_one(signkey, argv[i], fd, sig_namespace,
+			    hashalg, signer, &agent_fd)) != 0)
+				goto done;
+			if (fd != STDIN_FILENO)
+				close(fd);
+			fd = -1;
+		}
+	}
+
+	ret = 0;
+done:
+	if (fd != -1 && fd != STDIN_FILENO)
+		close(fd);
+	sshkey_free(pubkey);
+	sshkey_free(privkey);
+	free(hashalg);
+	return ret;
+}
+
+static int
+sig_verify(const char *signature, const char *sig_namespace,
+    const char *principal, const char *allowed_keys, const char *revoked_keys,
+    char * const *opts, size_t nopts)
+{
+	int r, ret = -1;
+	int print_pubkey = 0;
+	struct sshbuf *sigbuf = NULL, *abuf = NULL;
+	struct sshkey *sign_key = NULL;
+	char *fp = NULL;
+	struct sshkey_sig_details *sig_details = NULL;
+	uint64_t verify_time = 0;
+
+	if (sig_process_opts(opts, nopts, NULL, &verify_time,
+	    &print_pubkey) != 0)
+		goto done; /* error already logged */
+
+	memset(&sig_details, 0, sizeof(sig_details));
+	if ((r = sshbuf_load_file(signature, &abuf)) != 0) {
+		error_r(r, "Couldn't read signature file");
+		goto done;
+	}
+
+	if ((r = sshsig_dearmor(abuf, &sigbuf)) != 0) {
+		error_fr(r, "sshsig_armor");
+		goto done;
+	}
+	if ((r = sshsig_verify_fd(sigbuf, STDIN_FILENO, sig_namespace,
+	    &sign_key, &sig_details)) != 0)
+		goto done; /* sshsig_verify() prints error */
+
+	if ((fp = sshkey_fingerprint(sign_key, fingerprint_hash,
+	    SSH_FP_DEFAULT)) == NULL)
+		fatal_f("sshkey_fingerprint failed");
+	debug("Valid (unverified) signature from key %s", fp);
+	if (sig_details != NULL) {
+		debug2_f("signature details: counter = %u, flags = 0x%02x",
+		    sig_details->sk_counter, sig_details->sk_flags);
+	}
+	free(fp);
+	fp = NULL;
+
+	if (revoked_keys != NULL) {
+		if ((r = sshkey_check_revoked(sign_key, revoked_keys)) != 0) {
+			debug3_fr(r, "sshkey_check_revoked");
+			goto done;
+		}
+	}
+
+	if (allowed_keys != NULL && (r = sshsig_check_allowed_keys(allowed_keys,
+	    sign_key, principal, sig_namespace, verify_time)) != 0) {
+		debug3_fr(r, "sshsig_check_allowed_keys");
+		goto done;
+	}
+	/* success */
+	ret = 0;
+done:
+	if (!quiet) {
+		if (ret == 0) {
+			if ((fp = sshkey_fingerprint(sign_key, fingerprint_hash,
+			    SSH_FP_DEFAULT)) == NULL)
+				fatal_f("sshkey_fingerprint failed");
+			if (principal == NULL) {
+				printf("Good \"%s\" signature with %s key %s\n",
+				    sig_namespace, sshkey_type(sign_key), fp);
+
+			} else {
+				printf("Good \"%s\" signature for %s with %s key %s\n",
+				    sig_namespace, principal,
+				    sshkey_type(sign_key), fp);
+			}
+		} else {
+			printf("Could not verify signature.\n");
+		}
+	}
+	/* Print the signature key if requested */
+	if (ret == 0 && print_pubkey && sign_key != NULL) {
+		if ((r = sshkey_write(sign_key, stdout)) == 0)
+			fputc('\n', stdout);
+		else {
+			error_r(r, "Could not print public key.\n");
+			ret = -1;
+		}
+	}
+	sshbuf_free(sigbuf);
+	sshbuf_free(abuf);
+	sshkey_free(sign_key);
+	sshkey_sig_details_free(sig_details);
+	free(fp);
+	return ret;
+}
+
+static int
+sig_find_principals(const char *signature, const char *allowed_keys,
+    char * const *opts, size_t nopts)
+{
+	int r, ret = -1;
+	struct sshbuf *sigbuf = NULL, *abuf = NULL;
+	struct sshkey *sign_key = NULL;
+	char *principals = NULL, *cp, *tmp;
+	uint64_t verify_time = 0;
+
+	if (sig_process_opts(opts, nopts, NULL, &verify_time, NULL) != 0)
+		goto done; /* error already logged */
+
+	if ((r = sshbuf_load_file(signature, &abuf)) != 0) {
+		error_r(r, "Couldn't read signature file");
+		goto done;
+	}
+	if ((r = sshsig_dearmor(abuf, &sigbuf)) != 0) {
+		error_fr(r, "sshsig_armor");
+		goto done;
+	}
+	if ((r = sshsig_get_pubkey(sigbuf, &sign_key)) != 0) {
+		error_fr(r, "sshsig_get_pubkey");
+		goto done;
+	}
+	if ((r = sshsig_find_principals(allowed_keys, sign_key,
+	    verify_time, &principals)) != 0) {
+		if (r != SSH_ERR_KEY_NOT_FOUND)
+			error_fr(r, "sshsig_find_principal");
+		goto done;
+	}
+	ret = 0;
+done:
+	if (ret == 0 ) {
+		/* Emit matching principals one per line */
+		tmp = principals;
+		while ((cp = strsep(&tmp, ",")) != NULL && *cp != '\0')
+			puts(cp);
+	} else {
+		fprintf(stderr, "No principal matched.\n");
+	}
+	sshbuf_free(sigbuf);
+	sshbuf_free(abuf);
+	sshkey_free(sign_key);
+	free(principals);
+	return ret;
+}
+
+static int
+sig_match_principals(const char *allowed_keys, char *principal,
+	char * const *opts, size_t nopts)
+{
+	int r;
+	char **principals = NULL;
+	size_t i, nprincipals = 0;
+
+	if ((r = sig_process_opts(opts, nopts, NULL, NULL, NULL)) != 0)
+		return r; /* error already logged */
+
+	if ((r = sshsig_match_principals(allowed_keys, principal,
+	    &principals, &nprincipals)) != 0) {
+		debug_f("match: %s", ssh_err(r));
+		fprintf(stderr, "No principal matched.\n");
+		return r;
+	}
+	for (i = 0; i < nprincipals; i++) {
+		printf("%s\n", principals[i]);
+		free(principals[i]);
+	}
+	free(principals);
+
+	return 0;
+}
+
+static void
+do_moduli_gen(const char *out_file, char **opts, size_t nopts)
+{
+#ifdef WITH_OPENSSL
+	/* Moduli generation/screening */
+	u_int32_t memory = 0;
+	BIGNUM *start = NULL;
+	int moduli_bits = 0;
+	FILE *out;
+	size_t i;
+	const char *errstr;
+
+	/* Parse options */
+	for (i = 0; i < nopts; i++) {
+		if (strncmp(opts[i], "memory=", 7) == 0) {
+			memory = (u_int32_t)strtonum(opts[i]+7, 1,
+			    UINT_MAX, &errstr);
+			if (errstr) {
+				fatal("Memory limit is %s: %s",
+				    errstr, opts[i]+7);
+			}
+		} else if (strncmp(opts[i], "start=", 6) == 0) {
+			/* XXX - also compare length against bits */
+			if (BN_hex2bn(&start, opts[i]+6) == 0)
+				fatal("Invalid start point.");
+		} else if (strncmp(opts[i], "bits=", 5) == 0) {
+			moduli_bits = (int)strtonum(opts[i]+5, 1,
+			    INT_MAX, &errstr);
+			if (errstr) {
+				fatal("Invalid number: %s (%s)",
+					opts[i]+12, errstr);
+			}
+		} else {
+			fatal("Option \"%s\" is unsupported for moduli "
+			    "generation", opts[i]);
+		}
+	}
+
+	if ((out = fopen(out_file, "w")) == NULL) {
+		fatal("Couldn't open modulus candidate file \"%s\": %s",
+		    out_file, strerror(errno));
+	}
+	setvbuf(out, NULL, _IOLBF, 0);
+
+	if (moduli_bits == 0)
+		moduli_bits = DEFAULT_BITS;
+	if (gen_candidates(out, memory, moduli_bits, start) != 0)
+		fatal("modulus candidate generation failed");
+#else /* WITH_OPENSSL */
+	fatal("Moduli generation is not supported");
+#endif /* WITH_OPENSSL */
+}
+
+static void
+do_moduli_screen(const char *out_file, char **opts, size_t nopts)
+{
+#ifdef WITH_OPENSSL
+	/* Moduli generation/screening */
+	char *checkpoint = NULL;
+	u_int32_t generator_wanted = 0;
+	unsigned long start_lineno = 0, lines_to_process = 0;
+	int prime_tests = 0;
+	FILE *out, *in = stdin;
+	size_t i;
+	const char *errstr;
+
+	/* Parse options */
+	for (i = 0; i < nopts; i++) {
+		if (strncmp(opts[i], "lines=", 6) == 0) {
+			lines_to_process = strtoul(opts[i]+6, NULL, 10);
+		} else if (strncmp(opts[i], "start-line=", 11) == 0) {
+			start_lineno = strtoul(opts[i]+11, NULL, 10);
+		} else if (strncmp(opts[i], "checkpoint=", 11) == 0) {
+			checkpoint = xstrdup(opts[i]+11);
+		} else if (strncmp(opts[i], "generator=", 10) == 0) {
+			generator_wanted = (u_int32_t)strtonum(
+			    opts[i]+10, 1, UINT_MAX, &errstr);
+			if (errstr != NULL) {
+				fatal("Generator invalid: %s (%s)",
+				    opts[i]+10, errstr);
+			}
+		} else if (strncmp(opts[i], "prime-tests=", 12) == 0) {
+			prime_tests = (int)strtonum(opts[i]+12, 1,
+			    INT_MAX, &errstr);
+			if (errstr) {
+				fatal("Invalid number: %s (%s)",
+					opts[i]+12, errstr);
+			}
+		} else {
+			fatal("Option \"%s\" is unsupported for moduli "
+			    "screening", opts[i]);
+		}
+	}
+
+	if (have_identity && strcmp(identity_file, "-") != 0) {
+		if ((in = fopen(identity_file, "r")) == NULL) {
+			fatal("Couldn't open modulus candidate "
+			    "file \"%s\": %s", identity_file,
+			    strerror(errno));
+		}
+	}
+
+	if ((out = fopen(out_file, "a")) == NULL) {
+		fatal("Couldn't open moduli file \"%s\": %s",
+		    out_file, strerror(errno));
+	}
+	setvbuf(out, NULL, _IOLBF, 0);
+	if (prime_test(in, out, prime_tests == 0 ? 100 : prime_tests,
+	    generator_wanted, checkpoint,
+	    start_lineno, lines_to_process) != 0)
+		fatal("modulus screening failed");
+#else /* WITH_OPENSSL */
+	fatal("Moduli screening is not supported");
+#endif /* WITH_OPENSSL */
+}
+
+/* Read and confirm a passphrase */
+static char *
+read_check_passphrase(const char *prompt1, const char *prompt2,
+    const char *retry_prompt)
+{
+	char *passphrase1, *passphrase2;
+
+	for (;;) {
+		passphrase1 = read_passphrase(prompt1, RP_ALLOW_STDIN);
+		passphrase2 = read_passphrase(prompt2, RP_ALLOW_STDIN);
+		if (strcmp(passphrase1, passphrase2) == 0) {
+			freezero(passphrase2, strlen(passphrase2));
+			return passphrase1;
+		}
+		/* The passphrases do not match. Clear them and retry. */
+		freezero(passphrase1, strlen(passphrase1));
+		freezero(passphrase2, strlen(passphrase2));
+		fputs(retry_prompt, stdout);
+		fputc('\n', stdout);
+		fflush(stdout);
+	}
+	/* NOTREACHED */
+	return NULL;
+}
+
+static char *
+private_key_passphrase(void)
+{
+	if (identity_passphrase)
+		return xstrdup(identity_passphrase);
+	if (identity_new_passphrase)
+		return xstrdup(identity_new_passphrase);
+
+	return read_check_passphrase(
+	    "Enter passphrase (empty for no passphrase): ",
+	    "Enter same passphrase again: ",
+	    "Passphrases do not match.  Try again.");
+}
+
+static char *
+sk_suffix(const char *application, const uint8_t *user, size_t userlen)
+{
+	char *ret, *cp;
+	size_t slen, i;
+
+	/* Trim off URL-like preamble */
+	if (strncmp(application, "ssh://", 6) == 0)
+		ret =  xstrdup(application + 6);
+	else if (strncmp(application, "ssh:", 4) == 0)
+		ret =  xstrdup(application + 4);
+	else
+		ret = xstrdup(application);
+
+	/* Count trailing zeros in user */
+	for (i = 0; i < userlen; i++) {
+		if (user[userlen - i - 1] != 0)
+			break;
+	}
+	if (i >= userlen)
+		return ret; /* user-id was default all-zeros */
+
+	/* Append user-id, escaping non-UTF-8 characters */
+	slen = userlen - i;
+	if (asmprintf(&cp, INT_MAX, NULL, "%.*s", (int)slen, user) == -1)
+		fatal_f("asmprintf failed");
+	/* Don't emit a user-id that contains path or control characters */
+	if (strchr(cp, '/') != NULL || strstr(cp, "..") != NULL ||
+	    strchr(cp, '\\') != NULL) {
+		free(cp);
+		cp = tohex(user, slen);
+	}
+	xextendf(&ret, "_", "%s", cp);
+	free(cp);
+	return ret;
+}
+
+static int
+do_download_sk(const char *skprovider, const char *device)
+{
+	struct sshsk_resident_key **srks;
+	size_t nsrks, i;
+	int r, ret = -1;
+	char *fp, *pin = NULL, *pass = NULL, *path, *pubpath;
+	const char *ext;
+	struct sshkey *key;
+
+	if (skprovider == NULL)
+		fatal("Cannot download keys without provider");
+
+	pin = read_passphrase("Enter PIN for authenticator: ", RP_ALLOW_STDIN);
+	if (!quiet) {
+		printf("You may need to touch your authenticator "
+		    "to authorize key download.\n");
+	}
+	if ((r = sshsk_load_resident(skprovider, device, pin, 0,
+	    &srks, &nsrks)) != 0) {
+		if (pin != NULL)
+			freezero(pin, strlen(pin));
+		error_r(r, "Unable to load resident keys");
+		return -1;
+	}
+	if (nsrks == 0)
+		logit("No keys to download");
+	if (pin != NULL)
+		freezero(pin, strlen(pin));
+
+	for (i = 0; i < nsrks; i++) {
+		key = srks[i]->key;
+		if (key->type != KEY_ECDSA_SK && key->type != KEY_ED25519_SK) {
+			error("Unsupported key type %s (%d)",
+			    sshkey_type(key), key->type);
+			continue;
+		}
+		if ((fp = sshkey_fingerprint(key, fingerprint_hash,
+		    SSH_FP_DEFAULT)) == NULL)
+			fatal_f("sshkey_fingerprint failed");
+		debug_f("key %zu: %s %s %s (flags 0x%02x)", i,
+		    sshkey_type(key), fp, key->sk_application, key->sk_flags);
+		ext = sk_suffix(key->sk_application,
+		    srks[i]->user_id, srks[i]->user_id_len);
+		xasprintf(&path, "id_%s_rk%s%s",
+		    key->type == KEY_ECDSA_SK ? "ecdsa_sk" : "ed25519_sk",
+		    *ext == '\0' ? "" : "_", ext);
+
+		/* If the file already exists, ask the user to confirm. */
+		if (!confirm_overwrite(path)) {
+			free(path);
+			break;
+		}
+
+		/* Save the key with the application string as the comment */
+		if (pass == NULL)
+			pass = private_key_passphrase();
+		if ((r = sshkey_save_private(key, path, pass,
+		    key->sk_application, private_key_format,
+		    openssh_format_cipher, rounds)) != 0) {
+			error_r(r, "Saving key \"%s\" failed", path);
+			free(path);
+			break;
+		}
+		if (!quiet) {
+			printf("Saved %s key%s%s to %s\n", sshkey_type(key),
+			    *ext != '\0' ? " " : "",
+			    *ext != '\0' ? key->sk_application : "",
+			    path);
+		}
+
+		/* Save public key too */
+		xasprintf(&pubpath, "%s.pub", path);
+		free(path);
+		if ((r = sshkey_save_public(key, pubpath,
+		    key->sk_application)) != 0) {
+			error_r(r, "Saving public key \"%s\" failed", pubpath);
+			free(pubpath);
+			break;
+		}
+		free(pubpath);
+	}
+
+	if (i >= nsrks)
+		ret = 0; /* success */
+	if (pass != NULL)
+		freezero(pass, strlen(pass));
+	sshsk_free_resident_keys(srks, nsrks);
+	return ret;
+}
+
+static void
+save_attestation(struct sshbuf *attest, const char *path)
+{
+	mode_t omask;
+	int r;
+
+	if (path == NULL)
+		return; /* nothing to do */
+	if (attest == NULL || sshbuf_len(attest) == 0)
+		fatal("Enrollment did not return attestation data");
+	omask = umask(077);
+	r = sshbuf_write_file(path, attest);
+	umask(omask);
+	if (r != 0)
+		fatal_r(r, "Unable to write attestation data \"%s\"", path);
+	if (!quiet)
+		printf("Your FIDO attestation certificate has been saved in "
+		    "%s\n", path);
+}
+
+static int
+confirm_sk_overwrite(const char *application, const char *user)
+{
+	char yesno[3];
+
+	printf("A resident key scoped to '%s' with user id '%s' already "
+	    "exists.\n", application == NULL ? "ssh:" : application,
+	    user == NULL ? "null" : user);
+	printf("Overwrite key in token (y/n)? ");
+	fflush(stdout);
+	if (fgets(yesno, sizeof(yesno), stdin) == NULL)
+		return 0;
+	if (yesno[0] != 'y' && yesno[0] != 'Y')
+		return 0;
+	return 1;
+}
+
+static void
+usage(void)
+{
+	fprintf(stderr,
+	    "usage: ssh-keygen [-q] [-a rounds] [-b bits] [-C comment] [-f output_keyfile]\n"
+	    "                  [-m format] [-N new_passphrase] [-O option]\n"
+	    "                  [-t dsa | ecdsa | ecdsa-sk | ed25519 | ed25519-sk | rsa]\n"
+	    "                  [-w provider] [-Z cipher]\n"
+	    "       ssh-keygen -p [-a rounds] [-f keyfile] [-m format] [-N new_passphrase]\n"
+	    "                   [-P old_passphrase] [-Z cipher]\n"
+#ifdef WITH_OPENSSL
+	    "       ssh-keygen -i [-f input_keyfile] [-m key_format]\n"
+	    "       ssh-keygen -e [-f input_keyfile] [-m key_format]\n"
+#endif
+	    "       ssh-keygen -y [-f input_keyfile]\n"
+	    "       ssh-keygen -c [-a rounds] [-C comment] [-f keyfile] [-P passphrase]\n"
+	    "       ssh-keygen -l [-v] [-E fingerprint_hash] [-f input_keyfile]\n"
+	    "       ssh-keygen -B [-f input_keyfile]\n");
+#ifdef ENABLE_PKCS11
+	fprintf(stderr,
+	    "       ssh-keygen -D pkcs11\n");
+#endif
+	fprintf(stderr,
+	    "       ssh-keygen -F hostname [-lv] [-f known_hosts_file]\n"
+	    "       ssh-keygen -H [-f known_hosts_file]\n"
+	    "       ssh-keygen -K [-a rounds] [-w provider]\n"
+	    "       ssh-keygen -R hostname [-f known_hosts_file]\n"
+	    "       ssh-keygen -r hostname [-g] [-f input_keyfile]\n"
+#ifdef WITH_OPENSSL
+	    "       ssh-keygen -M generate [-O option] output_file\n"
+	    "       ssh-keygen -M screen [-f input_file] [-O option] output_file\n"
+#endif
+	    "       ssh-keygen -I certificate_identity -s ca_key [-hU] [-D pkcs11_provider]\n"
+	    "                  [-n principals] [-O option] [-V validity_interval]\n"
+	    "                  [-z serial_number] file ...\n"
+	    "       ssh-keygen -L [-f input_keyfile]\n"
+	    "       ssh-keygen -A [-a rounds] [-f prefix_path]\n"
+	    "       ssh-keygen -k -f krl_file [-u] [-s ca_public] [-z version_number]\n"
+	    "                  file ...\n"
+	    "       ssh-keygen -Q [-l] -f krl_file [file ...]\n"
+	    "       ssh-keygen -Y find-principals -s signature_file -f allowed_signers_file\n"
+	    "       ssh-keygen -Y match-principals -I signer_identity -f allowed_signers_file\n"
+	    "       ssh-keygen -Y check-novalidate -n namespace -s signature_file\n"
+	    "       ssh-keygen -Y sign -f key_file -n namespace file [-O option] ...\n"
+	    "       ssh-keygen -Y verify -f allowed_signers_file -I signer_identity\n"
+	    "                  -n namespace -s signature_file [-r krl_file] [-O option]\n");
+	exit(1);
+}
+
+/*
+ * Main program for key management.
+ */
+int
+main(int argc, char **argv)
+{
+	char comment[1024], *passphrase = NULL;
+	char *rr_hostname = NULL, *ep, *fp, *ra;
+	struct sshkey *private, *public;
+	struct passwd *pw;
+	int r, opt, type;
+	int change_passphrase = 0, change_comment = 0, show_cert = 0;
+	int find_host = 0, delete_host = 0, hash_hosts = 0;
+	int gen_all_hostkeys = 0, gen_krl = 0, update_krl = 0, check_krl = 0;
+	int prefer_agent = 0, convert_to = 0, convert_from = 0;
+	int print_public = 0, print_generic = 0, cert_serial_autoinc = 0;
+	int do_gen_candidates = 0, do_screen_candidates = 0, download_sk = 0;
+	unsigned long long cert_serial = 0;
+	char *identity_comment = NULL, *ca_key_path = NULL, **opts = NULL;
+	char *sk_application = NULL, *sk_device = NULL, *sk_user = NULL;
+	char *sk_attestation_path = NULL;
+	struct sshbuf *challenge = NULL, *attest = NULL;
+	size_t i, nopts = 0;
+	u_int32_t bits = 0;
+	uint8_t sk_flags = SSH_SK_USER_PRESENCE_REQD;
+	const char *errstr;
+	int log_level = SYSLOG_LEVEL_INFO;
+	char *sign_op = NULL;
+
+	extern int optind;
+	extern char *optarg;
+
+	/* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
+	sanitise_stdfd();
+
+	__progname = ssh_get_progname(argv[0]);
+
+	seed_rng();
+
+	log_init(argv[0], SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_USER, 1);
+
+	msetlocale();
+
+	/* we need this for the home * directory.  */
+	pw = getpwuid(getuid());
+	if (!pw)
+		fatal("No user exists for uid %lu", (u_long)getuid());
+	pw = pwcopy(pw);
+	if (gethostname(hostname, sizeof(hostname)) == -1)
+		fatal("gethostname: %s", strerror(errno));
+
+	sk_provider = getenv("SSH_SK_PROVIDER");
+
+	/* Remaining characters: dGjJSTWx */
+	while ((opt = getopt(argc, argv, "ABHKLQUXceghiklopquvy"
+	    "C:D:E:F:I:M:N:O:P:R:V:Y:Z:"
+	    "a:b:f:g:m:n:r:s:t:w:z:")) != -1) {
+		switch (opt) {
+		case 'A':
+			gen_all_hostkeys = 1;
+			break;
+		case 'b':
+			bits = (u_int32_t)strtonum(optarg, 1, UINT32_MAX,
+			    &errstr);
+			if (errstr)
+				fatal("Bits has bad value %s (%s)",
+					optarg, errstr);
+			break;
+		case 'E':
+			fingerprint_hash = ssh_digest_alg_by_name(optarg);
+			if (fingerprint_hash == -1)
+				fatal("Invalid hash algorithm \"%s\"", optarg);
+			break;
+		case 'F':
+			find_host = 1;
+			rr_hostname = optarg;
+			break;
+		case 'H':
+			hash_hosts = 1;
+			break;
+		case 'I':
+			cert_key_id = optarg;
+			break;
+		case 'R':
+			delete_host = 1;
+			rr_hostname = optarg;
+			break;
+		case 'L':
+			show_cert = 1;
+			break;
+		case 'l':
+			print_fingerprint = 1;
+			break;
+		case 'B':
+			print_bubblebabble = 1;
+			break;
+		case 'm':
+			if (strcasecmp(optarg, "RFC4716") == 0 ||
+			    strcasecmp(optarg, "ssh2") == 0) {
+				convert_format = FMT_RFC4716;
+				break;
+			}
+			if (strcasecmp(optarg, "PKCS8") == 0) {
+				convert_format = FMT_PKCS8;
+				private_key_format = SSHKEY_PRIVATE_PKCS8;
+				break;
+			}
+			if (strcasecmp(optarg, "PEM") == 0) {
+				convert_format = FMT_PEM;
+				private_key_format = SSHKEY_PRIVATE_PEM;
+				break;
+			}
+			fatal("Unsupported conversion format \"%s\"", optarg);
+		case 'n':
+			cert_principals = optarg;
+			break;
+		case 'o':
+			/* no-op; new format is already the default */
+			break;
+		case 'p':
+			change_passphrase = 1;
+			break;
+		case 'c':
+			change_comment = 1;
+			break;
+		case 'f':
+			if (strlcpy(identity_file, optarg,
+			    sizeof(identity_file)) >= sizeof(identity_file))
+				fatal("Identity filename too long");
+			have_identity = 1;
+			break;
+		case 'g':
+			print_generic = 1;
+			break;
+		case 'K':
+			download_sk = 1;
+			break;
+		case 'P':
+			identity_passphrase = optarg;
+			break;
+		case 'N':
+			identity_new_passphrase = optarg;
+			break;
+		case 'Q':
+			check_krl = 1;
+			break;
+		case 'O':
+			opts = xrecallocarray(opts, nopts, nopts + 1,
+			    sizeof(*opts));
+			opts[nopts++] = xstrdup(optarg);
+			break;
+		case 'Z':
+			openssh_format_cipher = optarg;
+			if (cipher_by_name(openssh_format_cipher) == NULL)
+				fatal("Invalid OpenSSH-format cipher '%s'",
+				    openssh_format_cipher);
+			break;
+		case 'C':
+			identity_comment = optarg;
+			break;
+		case 'q':
+			quiet = 1;
+			break;
+		case 'e':
+			/* export key */
+			convert_to = 1;
+			break;
+		case 'h':
+			cert_key_type = SSH2_CERT_TYPE_HOST;
+			certflags_flags = 0;
+			break;
+		case 'k':
+			gen_krl = 1;
+			break;
+		case 'i':
+		case 'X':
+			/* import key */
+			convert_from = 1;
+			break;
+		case 'y':
+			print_public = 1;
+			break;
+		case 's':
+			ca_key_path = optarg;
+			break;
+		case 't':
+			key_type_name = optarg;
+			break;
+		case 'D':
+			pkcs11provider = optarg;
+			break;
+		case 'U':
+			prefer_agent = 1;
+			break;
+		case 'u':
+			update_krl = 1;
+			break;
+		case 'v':
+			if (log_level == SYSLOG_LEVEL_INFO)
+				log_level = SYSLOG_LEVEL_DEBUG1;
+			else {
+				if (log_level >= SYSLOG_LEVEL_DEBUG1 &&
+				    log_level < SYSLOG_LEVEL_DEBUG3)
+					log_level++;
+			}
+			break;
+		case 'r':
+			rr_hostname = optarg;
+			break;
+		case 'a':
+			rounds = (int)strtonum(optarg, 1, INT_MAX, &errstr);
+			if (errstr)
+				fatal("Invalid number: %s (%s)",
+					optarg, errstr);
+			break;
+		case 'V':
+			parse_cert_times(optarg);
+			break;
+		case 'Y':
+			sign_op = optarg;
+			break;
+		case 'w':
+			sk_provider = optarg;
+			break;
+		case 'z':
+			errno = 0;
+			if (*optarg == '+') {
+				cert_serial_autoinc = 1;
+				optarg++;
+			}
+			cert_serial = strtoull(optarg, &ep, 10);
+			if (*optarg < '0' || *optarg > '9' || *ep != '\0' ||
+			    (errno == ERANGE && cert_serial == ULLONG_MAX))
+				fatal("Invalid serial number \"%s\"", optarg);
+			break;
+		case 'M':
+			if (strcmp(optarg, "generate") == 0)
+				do_gen_candidates = 1;
+			else if (strcmp(optarg, "screen") == 0)
+				do_screen_candidates = 1;
+			else
+				fatal("Unsupported moduli option %s", optarg);
+			break;
+		default:
+			usage();
+		}
+	}
+
+#ifdef ENABLE_SK_INTERNAL
+	if (sk_provider == NULL)
+		sk_provider = "internal";
+#endif
+
+	/* reinit */
+	log_init(argv[0], log_level, SYSLOG_FACILITY_USER, 1);
+
+	argv += optind;
+	argc -= optind;
+
+	if (sign_op != NULL) {
+		if (strncmp(sign_op, "find-principals", 15) == 0) {
+			if (ca_key_path == NULL) {
+				error("Too few arguments for find-principals:"
+				    "missing signature file");
+				exit(1);
+			}
+			if (!have_identity) {
+				error("Too few arguments for find-principals:"
+				    "missing allowed keys file");
+				exit(1);
+			}
+			return sig_find_principals(ca_key_path, identity_file,
+			    opts, nopts);
+		} else if (strncmp(sign_op, "match-principals", 16) == 0) {
+			if (!have_identity) {
+				error("Too few arguments for match-principals:"
+				    "missing allowed keys file");
+				exit(1);
+			}
+			if (cert_key_id == NULL) {
+				error("Too few arguments for match-principals: "
+				    "missing principal ID");
+				exit(1);
+			}
+			return sig_match_principals(identity_file, cert_key_id,
+			    opts, nopts);
+		} else if (strncmp(sign_op, "sign", 4) == 0) {
+			/* NB. cert_principals is actually namespace, via -n */
+			if (cert_principals == NULL ||
+			    *cert_principals == '\0') {
+				error("Too few arguments for sign: "
+				    "missing namespace");
+				exit(1);
+			}
+			if (!have_identity) {
+				error("Too few arguments for sign: "
+				    "missing key");
+				exit(1);
+			}
+			return sig_sign(identity_file, cert_principals,
+			    prefer_agent, argc, argv, opts, nopts);
+		} else if (strncmp(sign_op, "check-novalidate", 16) == 0) {
+			/* NB. cert_principals is actually namespace, via -n */
+			if (cert_principals == NULL ||
+			    *cert_principals == '\0') {
+				error("Too few arguments for check-novalidate: "
+				    "missing namespace");
+				exit(1);
+			}
+			if (ca_key_path == NULL) {
+				error("Too few arguments for check-novalidate: "
+				    "missing signature file");
+				exit(1);
+			}
+			return sig_verify(ca_key_path, cert_principals,
+			    NULL, NULL, NULL, opts, nopts);
+		} else if (strncmp(sign_op, "verify", 6) == 0) {
+			/* NB. cert_principals is actually namespace, via -n */
+			if (cert_principals == NULL ||
+			    *cert_principals == '\0') {
+				error("Too few arguments for verify: "
+				    "missing namespace");
+				exit(1);
+			}
+			if (ca_key_path == NULL) {
+				error("Too few arguments for verify: "
+				    "missing signature file");
+				exit(1);
+			}
+			if (!have_identity) {
+				error("Too few arguments for sign: "
+				    "missing allowed keys file");
+				exit(1);
+			}
+			if (cert_key_id == NULL) {
+				error("Too few arguments for verify: "
+				    "missing principal identity");
+				exit(1);
+			}
+			return sig_verify(ca_key_path, cert_principals,
+			    cert_key_id, identity_file, rr_hostname,
+			    opts, nopts);
+		}
+		error("Unsupported operation for -Y: \"%s\"", sign_op);
+		usage();
+		/* NOTREACHED */
+	}
+
+	if (ca_key_path != NULL) {
+		if (argc < 1 && !gen_krl) {
+			error("Too few arguments.");
+			usage();
+		}
+	} else if (argc > 0 && !gen_krl && !check_krl &&
+	    !do_gen_candidates && !do_screen_candidates) {
+		error("Too many arguments.");
+		usage();
+	}
+	if (change_passphrase && change_comment) {
+		error("Can only have one of -p and -c.");
+		usage();
+	}
+	if (print_fingerprint && (delete_host || hash_hosts)) {
+		error("Cannot use -l with -H or -R.");
+		usage();
+	}
+	if (gen_krl) {
+		do_gen_krl(pw, update_krl, ca_key_path,
+		    cert_serial, identity_comment, argc, argv);
+		return (0);
+	}
+	if (check_krl) {
+		do_check_krl(pw, print_fingerprint, argc, argv);
+		return (0);
+	}
+	if (ca_key_path != NULL) {
+		if (cert_key_id == NULL)
+			fatal("Must specify key id (-I) when certifying");
+		for (i = 0; i < nopts; i++)
+			add_cert_option(opts[i]);
+		do_ca_sign(pw, ca_key_path, prefer_agent,
+		    cert_serial, cert_serial_autoinc, argc, argv);
+	}
+	if (show_cert)
+		do_show_cert(pw);
+	if (delete_host || hash_hosts || find_host) {
+		do_known_hosts(pw, rr_hostname, find_host,
+		    delete_host, hash_hosts);
+	}
+	if (pkcs11provider != NULL)
+		do_download(pw);
+	if (download_sk) {
+		for (i = 0; i < nopts; i++) {
+			if (strncasecmp(opts[i], "device=", 7) == 0) {
+				sk_device = xstrdup(opts[i] + 7);
+			} else {
+				fatal("Option \"%s\" is unsupported for "
+				    "FIDO authenticator download", opts[i]);
+			}
+		}
+		return do_download_sk(sk_provider, sk_device);
+	}
+	if (print_fingerprint || print_bubblebabble)
+		do_fingerprint(pw);
+	if (change_passphrase)
+		do_change_passphrase(pw);
+	if (change_comment)
+		do_change_comment(pw, identity_comment);
+#ifdef WITH_OPENSSL
+	if (convert_to)
+		do_convert_to(pw);
+	if (convert_from)
+		do_convert_from(pw);
+#else /* WITH_OPENSSL */
+	if (convert_to || convert_from)
+		fatal("key conversion disabled at compile time");
+#endif /* WITH_OPENSSL */
+	if (print_public)
+		do_print_public(pw);
+	if (rr_hostname != NULL) {
+		unsigned int n = 0;
+
+		if (have_identity) {
+			n = do_print_resource_record(pw, identity_file,
+			    rr_hostname, print_generic);
+			if (n == 0)
+				fatal("%s: %s", identity_file, strerror(errno));
+			exit(0);
+		} else {
+
+			n += do_print_resource_record(pw,
+			    _PATH_HOST_RSA_KEY_FILE, rr_hostname,
+			    print_generic);
+			n += do_print_resource_record(pw,
+			    _PATH_HOST_DSA_KEY_FILE, rr_hostname,
+			    print_generic);
+			n += do_print_resource_record(pw,
+			    _PATH_HOST_ECDSA_KEY_FILE, rr_hostname,
+			    print_generic);
+			n += do_print_resource_record(pw,
+			    _PATH_HOST_ED25519_KEY_FILE, rr_hostname,
+			    print_generic);
+			n += do_print_resource_record(pw,
+			    _PATH_HOST_XMSS_KEY_FILE, rr_hostname,
+			    print_generic);
+			if (n == 0)
+				fatal("no keys found.");
+			exit(0);
+		}
+	}
+
+	if (do_gen_candidates || do_screen_candidates) {
+		if (argc <= 0)
+			fatal("No output file specified");
+		else if (argc > 1)
+			fatal("Too many output files specified");
+	}
+	if (do_gen_candidates) {
+		do_moduli_gen(argv[0], opts, nopts);
+		return 0;
+	}
+	if (do_screen_candidates) {
+		do_moduli_screen(argv[0], opts, nopts);
+		return 0;
+	}
+
+	if (gen_all_hostkeys) {
+		do_gen_all_hostkeys(pw);
+		return (0);
+	}
+
+	if (key_type_name == NULL)
+		key_type_name = DEFAULT_KEY_TYPE_NAME;
+
+	type = sshkey_type_from_name(key_type_name);
+	type_bits_valid(type, key_type_name, &bits);
+
+	if (!quiet)
+		printf("Generating public/private %s key pair.\n",
+		    key_type_name);
+	switch (type) {
+	case KEY_ECDSA_SK:
+	case KEY_ED25519_SK:
+		for (i = 0; i < nopts; i++) {
+			if (strcasecmp(opts[i], "no-touch-required") == 0) {
+				sk_flags &= ~SSH_SK_USER_PRESENCE_REQD;
+			} else if (strcasecmp(opts[i], "verify-required") == 0) {
+				sk_flags |= SSH_SK_USER_VERIFICATION_REQD;
+			} else if (strcasecmp(opts[i], "resident") == 0) {
+				sk_flags |= SSH_SK_RESIDENT_KEY;
+			} else if (strncasecmp(opts[i], "device=", 7) == 0) {
+				sk_device = xstrdup(opts[i] + 7);
+			} else if (strncasecmp(opts[i], "user=", 5) == 0) {
+				sk_user = xstrdup(opts[i] + 5);
+			} else if (strncasecmp(opts[i], "challenge=", 10) == 0) {
+				if ((r = sshbuf_load_file(opts[i] + 10,
+				    &challenge)) != 0) {
+					fatal_r(r, "Unable to load FIDO "
+					    "enrollment challenge \"%s\"",
+					    opts[i] + 10);
+				}
+			} else if (strncasecmp(opts[i],
+			    "write-attestation=", 18) == 0) {
+				sk_attestation_path = opts[i] + 18;
+			} else if (strncasecmp(opts[i],
+			    "application=", 12) == 0) {
+				sk_application = xstrdup(opts[i] + 12);
+				if (strncmp(sk_application, "ssh:", 4) != 0) {
+					fatal("FIDO application string must "
+					    "begin with \"ssh:\"");
+				}
+			} else {
+				fatal("Option \"%s\" is unsupported for "
+				    "FIDO authenticator enrollment", opts[i]);
+			}
+		}
+		if ((attest = sshbuf_new()) == NULL)
+			fatal("sshbuf_new failed");
+		r = 0;
+		for (i = 0 ;;) {
+			if (!quiet) {
+				printf("You may need to touch your "
+				    "authenticator%s to authorize key "
+				    "generation.\n",
+				    r == 0 ? "" : " again");
+			}
+			fflush(stdout);
+			r = sshsk_enroll(type, sk_provider, sk_device,
+			    sk_application == NULL ? "ssh:" : sk_application,
+			    sk_user, sk_flags, passphrase, challenge,
+			    &private, attest);
+			if (r == 0)
+				break;
+			if (r == SSH_ERR_KEY_BAD_PERMISSIONS &&
+			    (sk_flags & SSH_SK_RESIDENT_KEY) != 0 &&
+			    (sk_flags & SSH_SK_FORCE_OPERATION) == 0 &&
+			    confirm_sk_overwrite(sk_application, sk_user)) {
+				sk_flags |= SSH_SK_FORCE_OPERATION;
+				continue;
+			}
+			if (r != SSH_ERR_KEY_WRONG_PASSPHRASE)
+				fatal_r(r, "Key enrollment failed");
+			else if (passphrase != NULL) {
+				error("PIN incorrect");
+				freezero(passphrase, strlen(passphrase));
+				passphrase = NULL;
+			}
+			if (++i >= 3)
+				fatal("Too many incorrect PINs");
+			passphrase = read_passphrase("Enter PIN for "
+			    "authenticator: ", RP_ALLOW_STDIN);
+		}
+		if (passphrase != NULL) {
+			freezero(passphrase, strlen(passphrase));
+			passphrase = NULL;
+		}
+		break;
+	default:
+		if ((r = sshkey_generate(type, bits, &private)) != 0)
+			fatal("sshkey_generate failed");
+		break;
+	}
+	if ((r = sshkey_from_private(private, &public)) != 0)
+		fatal_r(r, "sshkey_from_private");
+
+	if (!have_identity)
+		ask_filename(pw, "Enter file in which to save the key");
+
+	/* Create ~/.ssh directory if it doesn't already exist. */
+	hostfile_create_user_ssh_dir(identity_file, !quiet);
+
+	/* If the file already exists, ask the user to confirm. */
+	if (!confirm_overwrite(identity_file))
+		exit(1);
+
+	/* Determine the passphrase for the private key */
+	passphrase = private_key_passphrase();
+	if (identity_comment) {
+		strlcpy(comment, identity_comment, sizeof(comment));
+	} else {
+		/* Create default comment field for the passphrase. */
+		snprintf(comment, sizeof comment, "%s@%s", pw->pw_name, hostname);
+	}
+
+	/* Save the key with the given passphrase and comment. */
+	if ((r = sshkey_save_private(private, identity_file, passphrase,
+	    comment, private_key_format, openssh_format_cipher, rounds)) != 0) {
+		error_r(r, "Saving key \"%s\" failed", identity_file);
+		freezero(passphrase, strlen(passphrase));
+		exit(1);
+	}
+	freezero(passphrase, strlen(passphrase));
+	sshkey_free(private);
+
+	if (!quiet) {
+		printf("Your identification has been saved in %s\n",
+		    identity_file);
+	}
+
+	strlcat(identity_file, ".pub", sizeof(identity_file));
+	if ((r = sshkey_save_public(public, identity_file, comment)) != 0)
+		fatal_r(r, "Unable to save public key to %s", identity_file);
+
+	if (!quiet) {
+		fp = sshkey_fingerprint(public, fingerprint_hash,
+		    SSH_FP_DEFAULT);
+		ra = sshkey_fingerprint(public, fingerprint_hash,
+		    SSH_FP_RANDOMART);
+		if (fp == NULL || ra == NULL)
+			fatal("sshkey_fingerprint failed");
+		printf("Your public key has been saved in %s\n",
+		    identity_file);
+		printf("The key fingerprint is:\n");
+		printf("%s %s\n", fp, comment);
+		printf("The key's randomart image is:\n");
+		printf("%s\n", ra);
+		free(ra);
+		free(fp);
+	}
+
+	if (sk_attestation_path != NULL)
+		save_attestation(attest, sk_attestation_path);
+
+	sshbuf_free(attest);
+	sshkey_free(public);
+
+	exit(0);
+}