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-rw-r--r--ssh-ecdsa.c200
1 files changed, 200 insertions, 0 deletions
diff --git a/ssh-ecdsa.c b/ssh-ecdsa.c
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+/* $OpenBSD: ssh-ecdsa.c,v 1.16 2019/01/21 09:54:11 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"
+
+/* ARGSUSED */
+int
+ssh_ecdsa_sign(const struct sshkey *key, u_char **sigp, size_t *lenp,
+ const u_char *data, size_t datalen, u_int compat)
+{
+ ECDSA_SIG *sig = NULL;
+ const BIGNUM *sig_r, *sig_s;
+ int hash_alg;
+ u_char digest[SSH_DIGEST_MAX_LENGTH];
+ size_t len, dlen;
+ 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 ||
+ (dlen = ssh_digest_bytes(hash_alg)) == 0)
+ return SSH_ERR_INTERNAL_ERROR;
+ if ((ret = ssh_digest_memory(hash_alg, data, datalen,
+ digest, sizeof(digest))) != 0)
+ goto out;
+
+ if ((sig = ECDSA_do_sign(digest, dlen, 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(sig, &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(sig);
+ return ret;
+}
+
+/* ARGSUSED */
+int
+ssh_ecdsa_verify(const struct sshkey *key,
+ const u_char *signature, size_t signaturelen,
+ const u_char *data, size_t datalen, u_int compat)
+{
+ ECDSA_SIG *sig = NULL;
+ BIGNUM *sig_r = NULL, *sig_s = NULL;
+ int hash_alg;
+ u_char digest[SSH_DIGEST_MAX_LENGTH];
+ size_t dlen;
+ 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 ||
+ signature == NULL || signaturelen == 0)
+ return SSH_ERR_INVALID_ARGUMENT;
+
+ if ((hash_alg = sshkey_ec_nid_to_hash_alg(key->ecdsa_nid)) == -1 ||
+ (dlen = ssh_digest_bytes(hash_alg)) == 0)
+ return SSH_ERR_INTERNAL_ERROR;
+
+ /* fetch signature */
+ if ((b = sshbuf_from(signature, signaturelen)) == 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 ((sig = ECDSA_SIG_new()) == NULL) {
+ ret = SSH_ERR_ALLOC_FAIL;
+ goto out;
+ }
+ if (!ECDSA_SIG_set0(sig, 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, datalen,
+ digest, sizeof(digest))) != 0)
+ goto out;
+
+ switch (ECDSA_do_verify(digest, dlen, sig, 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(sig);
+ BN_clear_free(sig_r);
+ BN_clear_free(sig_s);
+ free(ktype);
+ return ret;
+}
+
+#endif /* WITH_OPENSSL && OPENSSL_HAS_ECC */