1 files changed, 470 insertions, 0 deletions

diff --git a/ssh-ecdsa.c b/ssh-ecdsa.c
new file mode 100644
index 0000000..4bcb89b
--- /dev/null
+++ b/ssh-ecdsa.c
@@ -0,0 +1,470 @@
+/* $OpenBSD: ssh-ecdsa.c,v 1.25 2022/10/28 00:44:44 djm Exp $ */
+/*
+ * Copyright (c) 2000 Markus Friedl.  All rights reserved.
+ * Copyright (c) 2010 Damien Miller.  All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "includes.h"
+
+#if defined(WITH_OPENSSL) && defined(OPENSSL_HAS_ECC)
+
+#include <sys/types.h>
+
+#include <openssl/bn.h>
+#include <openssl/ec.h>
+#include <openssl/ecdsa.h>
+#include <openssl/evp.h>
+
+#include <string.h>
+
+#include "sshbuf.h"
+#include "ssherr.h"
+#include "digest.h"
+#define SSHKEY_INTERNAL
+#include "sshkey.h"
+
+#include "openbsd-compat/openssl-compat.h"
+
+static u_int
+ssh_ecdsa_size(const struct sshkey *key)
+{
+	switch (key->ecdsa_nid) {
+	case NID_X9_62_prime256v1:
+		return 256;
+	case NID_secp384r1:
+		return 384;
+#ifdef OPENSSL_HAS_NISTP521
+	case NID_secp521r1:
+		return 521;
+#endif
+	default:
+		return 0;
+	}
+}
+
+static void
+ssh_ecdsa_cleanup(struct sshkey *k)
+{
+	EC_KEY_free(k->ecdsa);
+	k->ecdsa = NULL;
+}
+
+static int
+ssh_ecdsa_equal(const struct sshkey *a, const struct sshkey *b)
+{
+	const EC_GROUP *grp_a, *grp_b;
+	const EC_POINT *pub_a, *pub_b;
+
+	if (a->ecdsa == NULL || b->ecdsa == NULL)
+		return 0;
+	if ((grp_a = EC_KEY_get0_group(a->ecdsa)) == NULL ||
+	    (grp_b = EC_KEY_get0_group(b->ecdsa)) == NULL)
+		return 0;
+	if ((pub_a = EC_KEY_get0_public_key(a->ecdsa)) == NULL ||
+	    (pub_b = EC_KEY_get0_public_key(b->ecdsa)) == NULL)
+		return 0;
+	if (EC_GROUP_cmp(grp_a, grp_b, NULL) != 0)
+		return 0;
+	if (EC_POINT_cmp(grp_a, pub_a, pub_b, NULL) != 0)
+		return 0;
+
+	return 1;
+}
+
+static int
+ssh_ecdsa_serialize_public(const struct sshkey *key, struct sshbuf *b,
+    enum sshkey_serialize_rep opts)
+{
+	int r;
+
+	if (key->ecdsa == NULL)
+		return SSH_ERR_INVALID_ARGUMENT;
+	if ((r = sshbuf_put_cstring(b,
+	    sshkey_curve_nid_to_name(key->ecdsa_nid))) != 0 ||
+	    (r = sshbuf_put_eckey(b, key->ecdsa)) != 0)
+		return r;
+
+	return 0;
+}
+
+static int
+ssh_ecdsa_serialize_private(const struct sshkey *key, struct sshbuf *b,
+    enum sshkey_serialize_rep opts)
+{
+	int r;
+
+	if (!sshkey_is_cert(key)) {
+		if ((r = ssh_ecdsa_serialize_public(key, b, opts)) != 0)
+			return r;
+	}
+	if ((r = sshbuf_put_bignum2(b,
+	    EC_KEY_get0_private_key(key->ecdsa))) != 0)
+		return r;
+	return 0;
+}
+
+static int
+ssh_ecdsa_generate(struct sshkey *k, int bits)
+{
+	EC_KEY *private;
+
+	if ((k->ecdsa_nid = sshkey_ecdsa_bits_to_nid(bits)) == -1)
+		return SSH_ERR_KEY_LENGTH;
+	if ((private = EC_KEY_new_by_curve_name(k->ecdsa_nid)) == NULL)
+		return SSH_ERR_ALLOC_FAIL;
+	if (EC_KEY_generate_key(private) != 1) {
+		EC_KEY_free(private);
+		return SSH_ERR_LIBCRYPTO_ERROR;
+	}
+	EC_KEY_set_asn1_flag(private, OPENSSL_EC_NAMED_CURVE);
+	k->ecdsa = private;
+	return 0;
+}
+
+static int
+ssh_ecdsa_copy_public(const struct sshkey *from, struct sshkey *to)
+{
+	to->ecdsa_nid = from->ecdsa_nid;
+	if ((to->ecdsa = EC_KEY_new_by_curve_name(from->ecdsa_nid)) == NULL)
+		return SSH_ERR_ALLOC_FAIL;
+	if (EC_KEY_set_public_key(to->ecdsa,
+	    EC_KEY_get0_public_key(from->ecdsa)) != 1)
+		return SSH_ERR_LIBCRYPTO_ERROR; /* caller will free k->ecdsa */
+	return 0;
+}
+
+static int
+ssh_ecdsa_deserialize_public(const char *ktype, struct sshbuf *b,
+    struct sshkey *key)
+{
+	int r;
+	char *curve = NULL;
+
+	if ((key->ecdsa_nid = sshkey_ecdsa_nid_from_name(ktype)) == -1)
+		return SSH_ERR_INVALID_ARGUMENT;
+	if ((r = sshbuf_get_cstring(b, &curve, NULL)) != 0)
+		goto out;
+	if (key->ecdsa_nid != sshkey_curve_name_to_nid(curve)) {
+		r = SSH_ERR_EC_CURVE_MISMATCH;
+		goto out;
+	}
+	EC_KEY_free(key->ecdsa);
+	key->ecdsa = NULL;
+	if ((key->ecdsa = EC_KEY_new_by_curve_name(key->ecdsa_nid)) == NULL) {
+		r = SSH_ERR_LIBCRYPTO_ERROR;
+		goto out;
+	}
+	if ((r = sshbuf_get_eckey(b, key->ecdsa)) != 0)
+		goto out;
+	if (sshkey_ec_validate_public(EC_KEY_get0_group(key->ecdsa),
+	    EC_KEY_get0_public_key(key->ecdsa)) != 0) {
+		r = SSH_ERR_KEY_INVALID_EC_VALUE;
+		goto out;
+	}
+	/* success */
+	r = 0;
+#ifdef DEBUG_PK
+	sshkey_dump_ec_point(EC_KEY_get0_group(key->ecdsa),
+	    EC_KEY_get0_public_key(key->ecdsa));
+#endif
+ out:
+	free(curve);
+	if (r != 0) {
+		EC_KEY_free(key->ecdsa);
+		key->ecdsa = NULL;
+	}
+	return r;
+}
+
+static int
+ssh_ecdsa_deserialize_private(const char *ktype, struct sshbuf *b,
+    struct sshkey *key)
+{
+	int r;
+	BIGNUM *exponent = NULL;
+
+	if (!sshkey_is_cert(key)) {
+		if ((r = ssh_ecdsa_deserialize_public(ktype, b, key)) != 0)
+			return r;
+	}
+	if ((r = sshbuf_get_bignum2(b, &exponent)) != 0)
+		goto out;
+	if (EC_KEY_set_private_key(key->ecdsa, exponent) != 1) {
+		r = SSH_ERR_LIBCRYPTO_ERROR;
+		goto out;
+	}
+	if ((r = sshkey_ec_validate_private(key->ecdsa)) != 0)
+		goto out;
+	/* success */
+	r = 0;
+ out:
+	BN_clear_free(exponent);
+	return r;
+}
+
+/* ARGSUSED */
+static int
+ssh_ecdsa_sign(struct sshkey *key,
+    u_char **sigp, size_t *lenp,
+    const u_char *data, size_t dlen,
+    const char *alg, const char *sk_provider, const char *sk_pin, u_int compat)
+{
+	ECDSA_SIG *esig = NULL;
+	const BIGNUM *sig_r, *sig_s;
+	int hash_alg;
+	u_char digest[SSH_DIGEST_MAX_LENGTH];
+	size_t len, hlen;
+	struct sshbuf *b = NULL, *bb = NULL;
+	int ret = SSH_ERR_INTERNAL_ERROR;
+
+	if (lenp != NULL)
+		*lenp = 0;
+	if (sigp != NULL)
+		*sigp = NULL;
+
+	if (key == NULL || key->ecdsa == NULL ||
+	    sshkey_type_plain(key->type) != KEY_ECDSA)
+		return SSH_ERR_INVALID_ARGUMENT;
+
+	if ((hash_alg = sshkey_ec_nid_to_hash_alg(key->ecdsa_nid)) == -1 ||
+	    (hlen = ssh_digest_bytes(hash_alg)) == 0)
+		return SSH_ERR_INTERNAL_ERROR;
+	if ((ret = ssh_digest_memory(hash_alg, data, dlen,
+	    digest, sizeof(digest))) != 0)
+		goto out;
+
+	if ((esig = ECDSA_do_sign(digest, hlen, key->ecdsa)) == NULL) {
+		ret = SSH_ERR_LIBCRYPTO_ERROR;
+		goto out;
+	}
+
+	if ((bb = sshbuf_new()) == NULL || (b = sshbuf_new()) == NULL) {
+		ret = SSH_ERR_ALLOC_FAIL;
+		goto out;
+	}
+	ECDSA_SIG_get0(esig, &sig_r, &sig_s);
+	if ((ret = sshbuf_put_bignum2(bb, sig_r)) != 0 ||
+	    (ret = sshbuf_put_bignum2(bb, sig_s)) != 0)
+		goto out;
+	if ((ret = sshbuf_put_cstring(b, sshkey_ssh_name_plain(key))) != 0 ||
+	    (ret = sshbuf_put_stringb(b, bb)) != 0)
+		goto out;
+	len = sshbuf_len(b);
+	if (sigp != NULL) {
+		if ((*sigp = malloc(len)) == NULL) {
+			ret = SSH_ERR_ALLOC_FAIL;
+			goto out;
+		}
+		memcpy(*sigp, sshbuf_ptr(b), len);
+	}
+	if (lenp != NULL)
+		*lenp = len;
+	ret = 0;
+ out:
+	explicit_bzero(digest, sizeof(digest));
+	sshbuf_free(b);
+	sshbuf_free(bb);
+	ECDSA_SIG_free(esig);
+	return ret;
+}
+
+/* ARGSUSED */
+static int
+ssh_ecdsa_verify(const struct sshkey *key,
+    const u_char *sig, size_t siglen,
+    const u_char *data, size_t dlen, const char *alg, u_int compat,
+    struct sshkey_sig_details **detailsp)
+{
+	ECDSA_SIG *esig = NULL;
+	BIGNUM *sig_r = NULL, *sig_s = NULL;
+	int hash_alg;
+	u_char digest[SSH_DIGEST_MAX_LENGTH];
+	size_t hlen;
+	int ret = SSH_ERR_INTERNAL_ERROR;
+	struct sshbuf *b = NULL, *sigbuf = NULL;
+	char *ktype = NULL;
+
+	if (key == NULL || key->ecdsa == NULL ||
+	    sshkey_type_plain(key->type) != KEY_ECDSA ||
+	    sig == NULL || siglen == 0)
+		return SSH_ERR_INVALID_ARGUMENT;
+
+	if ((hash_alg = sshkey_ec_nid_to_hash_alg(key->ecdsa_nid)) == -1 ||
+	    (hlen = ssh_digest_bytes(hash_alg)) == 0)
+		return SSH_ERR_INTERNAL_ERROR;
+
+	/* fetch signature */
+	if ((b = sshbuf_from(sig, siglen)) == NULL)
+		return SSH_ERR_ALLOC_FAIL;
+	if (sshbuf_get_cstring(b, &ktype, NULL) != 0 ||
+	    sshbuf_froms(b, &sigbuf) != 0) {
+		ret = SSH_ERR_INVALID_FORMAT;
+		goto out;
+	}
+	if (strcmp(sshkey_ssh_name_plain(key), ktype) != 0) {
+		ret = SSH_ERR_KEY_TYPE_MISMATCH;
+		goto out;
+	}
+	if (sshbuf_len(b) != 0) {
+		ret = SSH_ERR_UNEXPECTED_TRAILING_DATA;
+		goto out;
+	}
+
+	/* parse signature */
+	if (sshbuf_get_bignum2(sigbuf, &sig_r) != 0 ||
+	    sshbuf_get_bignum2(sigbuf, &sig_s) != 0) {
+		ret = SSH_ERR_INVALID_FORMAT;
+		goto out;
+	}
+	if ((esig = ECDSA_SIG_new()) == NULL) {
+		ret = SSH_ERR_ALLOC_FAIL;
+		goto out;
+	}
+	if (!ECDSA_SIG_set0(esig, sig_r, sig_s)) {
+		ret = SSH_ERR_LIBCRYPTO_ERROR;
+		goto out;
+	}
+	sig_r = sig_s = NULL; /* transferred */
+
+	if (sshbuf_len(sigbuf) != 0) {
+		ret = SSH_ERR_UNEXPECTED_TRAILING_DATA;
+		goto out;
+	}
+	if ((ret = ssh_digest_memory(hash_alg, data, dlen,
+	    digest, sizeof(digest))) != 0)
+		goto out;
+
+	switch (ECDSA_do_verify(digest, hlen, esig, key->ecdsa)) {
+	case 1:
+		ret = 0;
+		break;
+	case 0:
+		ret = SSH_ERR_SIGNATURE_INVALID;
+		goto out;
+	default:
+		ret = SSH_ERR_LIBCRYPTO_ERROR;
+		goto out;
+	}
+
+ out:
+	explicit_bzero(digest, sizeof(digest));
+	sshbuf_free(sigbuf);
+	sshbuf_free(b);
+	ECDSA_SIG_free(esig);
+	BN_clear_free(sig_r);
+	BN_clear_free(sig_s);
+	free(ktype);
+	return ret;
+}
+
+/* NB. not static; used by ECDSA-SK */
+const struct sshkey_impl_funcs sshkey_ecdsa_funcs = {
+	/* .size = */		ssh_ecdsa_size,
+	/* .alloc = */		NULL,
+	/* .cleanup = */	ssh_ecdsa_cleanup,
+	/* .equal = */		ssh_ecdsa_equal,
+	/* .ssh_serialize_public = */ ssh_ecdsa_serialize_public,
+	/* .ssh_deserialize_public = */ ssh_ecdsa_deserialize_public,
+	/* .ssh_serialize_private = */ ssh_ecdsa_serialize_private,
+	/* .ssh_deserialize_private = */ ssh_ecdsa_deserialize_private,
+	/* .generate = */	ssh_ecdsa_generate,
+	/* .copy_public = */	ssh_ecdsa_copy_public,
+	/* .sign = */		ssh_ecdsa_sign,
+	/* .verify = */		ssh_ecdsa_verify,
+};
+
+const struct sshkey_impl sshkey_ecdsa_nistp256_impl = {
+	/* .name = */		"ecdsa-sha2-nistp256",
+	/* .shortname = */	"ECDSA",
+	/* .sigalg = */		NULL,
+	/* .type = */		KEY_ECDSA,
+	/* .nid = */		NID_X9_62_prime256v1,
+	/* .cert = */		0,
+	/* .sigonly = */	0,
+	/* .keybits = */	0,
+	/* .funcs = */		&sshkey_ecdsa_funcs,
+};
+
+const struct sshkey_impl sshkey_ecdsa_nistp256_cert_impl = {
+	/* .name = */		"ecdsa-sha2-nistp256-cert-v01@openssh.com",
+	/* .shortname = */	"ECDSA-CERT",
+	/* .sigalg = */		NULL,
+	/* .type = */		KEY_ECDSA_CERT,
+	/* .nid = */		NID_X9_62_prime256v1,
+	/* .cert = */		1,
+	/* .sigonly = */	0,
+	/* .keybits = */	0,
+	/* .funcs = */		&sshkey_ecdsa_funcs,
+};
+
+const struct sshkey_impl sshkey_ecdsa_nistp384_impl = {
+	/* .name = */		"ecdsa-sha2-nistp384",
+	/* .shortname = */	"ECDSA",
+	/* .sigalg = */		NULL,
+	/* .type = */		KEY_ECDSA,
+	/* .nid = */		NID_secp384r1,
+	/* .cert = */		0,
+	/* .sigonly = */	0,
+	/* .keybits = */	0,
+	/* .funcs = */		&sshkey_ecdsa_funcs,
+};
+
+const struct sshkey_impl sshkey_ecdsa_nistp384_cert_impl = {
+	/* .name = */		"ecdsa-sha2-nistp384-cert-v01@openssh.com",
+	/* .shortname = */	"ECDSA-CERT",
+	/* .sigalg = */		NULL,
+	/* .type = */		KEY_ECDSA_CERT,
+	/* .nid = */		NID_secp384r1,
+	/* .cert = */		1,
+	/* .sigonly = */	0,
+	/* .keybits = */	0,
+	/* .funcs = */		&sshkey_ecdsa_funcs,
+};
+
+#ifdef OPENSSL_HAS_NISTP521
+const struct sshkey_impl sshkey_ecdsa_nistp521_impl = {
+	/* .name = */		"ecdsa-sha2-nistp521",
+	/* .shortname = */	"ECDSA",
+	/* .sigalg = */		NULL,
+	/* .type = */		KEY_ECDSA,
+	/* .nid = */		NID_secp521r1,
+	/* .cert = */		0,
+	/* .sigonly = */	0,
+	/* .keybits = */	0,
+	/* .funcs = */		&sshkey_ecdsa_funcs,
+};
+
+const struct sshkey_impl sshkey_ecdsa_nistp521_cert_impl = {
+	/* .name = */		"ecdsa-sha2-nistp521-cert-v01@openssh.com",
+	/* .shortname = */	"ECDSA-CERT",
+	/* .sigalg = */		NULL,
+	/* .type = */		KEY_ECDSA_CERT,
+	/* .nid = */		NID_secp521r1,
+	/* .cert = */		1,
+	/* .sigonly = */	0,
+	/* .keybits = */	0,
+	/* .funcs = */		&sshkey_ecdsa_funcs,
+};
+#endif
+
+#endif /* WITH_OPENSSL && OPENSSL_HAS_ECC */