Annotation of src/usr.bin/ssh/ssh-ecdsa.c, Revision 1.13
1.13 ! djm 1: /* $OpenBSD: ssh-ecdsa.c,v 1.12 2015/12/11 04:21:12 mmcc Exp $ */
1.1 djm 2: /*
3: * Copyright (c) 2000 Markus Friedl. All rights reserved.
4: * Copyright (c) 2010 Damien Miller. All rights reserved.
5: *
6: * Redistribution and use in source and binary forms, with or without
7: * modification, are permitted provided that the following conditions
8: * are met:
9: * 1. Redistributions of source code must retain the above copyright
10: * notice, this list of conditions and the following disclaimer.
11: * 2. Redistributions in binary form must reproduce the above copyright
12: * notice, this list of conditions and the following disclaimer in the
13: * documentation and/or other materials provided with the distribution.
14: *
15: * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
16: * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
17: * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
18: * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
19: * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
20: * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
21: * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
22: * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
23: * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
24: * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
25: */
26:
27: #include <sys/types.h>
28:
29: #include <openssl/bn.h>
30: #include <openssl/ec.h>
31: #include <openssl/ecdsa.h>
32: #include <openssl/evp.h>
33:
34: #include <string.h>
35:
1.11 djm 36: #include "sshbuf.h"
37: #include "ssherr.h"
1.8 djm 38: #include "digest.h"
1.11 djm 39: #define SSHKEY_INTERNAL
40: #include "sshkey.h"
1.1 djm 41:
1.11 djm 42: /* ARGSUSED */
1.1 djm 43: int
1.11 djm 44: ssh_ecdsa_sign(const struct sshkey *key, u_char **sigp, size_t *lenp,
45: const u_char *data, size_t datalen, u_int compat)
1.1 djm 46: {
1.11 djm 47: ECDSA_SIG *sig = NULL;
1.8 djm 48: int hash_alg;
49: u_char digest[SSH_DIGEST_MAX_LENGTH];
1.11 djm 50: size_t len, dlen;
51: struct sshbuf *b = NULL, *bb = NULL;
52: int ret = SSH_ERR_INTERNAL_ERROR;
1.1 djm 53:
1.11 djm 54: if (lenp != NULL)
55: *lenp = 0;
56: if (sigp != NULL)
57: *sigp = NULL;
58:
59: if (key == NULL || key->ecdsa == NULL ||
60: sshkey_type_plain(key->type) != KEY_ECDSA)
61: return SSH_ERR_INVALID_ARGUMENT;
62:
63: if ((hash_alg = sshkey_ec_nid_to_hash_alg(key->ecdsa_nid)) == -1 ||
64: (dlen = ssh_digest_bytes(hash_alg)) == 0)
65: return SSH_ERR_INTERNAL_ERROR;
66: if ((ret = ssh_digest_memory(hash_alg, data, datalen,
67: digest, sizeof(digest))) != 0)
68: goto out;
69:
70: if ((sig = ECDSA_do_sign(digest, dlen, key->ecdsa)) == NULL) {
71: ret = SSH_ERR_LIBCRYPTO_ERROR;
72: goto out;
73: }
74:
75: if ((bb = sshbuf_new()) == NULL || (b = sshbuf_new()) == NULL) {
76: ret = SSH_ERR_ALLOC_FAIL;
77: goto out;
78: }
79: if ((ret = sshbuf_put_bignum2(bb, sig->r)) != 0 ||
80: (ret = sshbuf_put_bignum2(bb, sig->s)) != 0)
81: goto out;
82: if ((ret = sshbuf_put_cstring(b, sshkey_ssh_name_plain(key))) != 0 ||
83: (ret = sshbuf_put_stringb(b, bb)) != 0)
84: goto out;
85: len = sshbuf_len(b);
86: if (sigp != NULL) {
87: if ((*sigp = malloc(len)) == NULL) {
88: ret = SSH_ERR_ALLOC_FAIL;
89: goto out;
90: }
91: memcpy(*sigp, sshbuf_ptr(b), len);
1.1 djm 92: }
93: if (lenp != NULL)
94: *lenp = len;
1.11 djm 95: ret = 0;
96: out:
97: explicit_bzero(digest, sizeof(digest));
1.12 mmcc 98: sshbuf_free(b);
99: sshbuf_free(bb);
1.11 djm 100: if (sig != NULL)
101: ECDSA_SIG_free(sig);
102: return ret;
103: }
1.1 djm 104:
1.11 djm 105: /* ARGSUSED */
1.1 djm 106: int
1.11 djm 107: ssh_ecdsa_verify(const struct sshkey *key,
108: const u_char *signature, size_t signaturelen,
109: const u_char *data, size_t datalen, u_int compat)
1.1 djm 110: {
1.11 djm 111: ECDSA_SIG *sig = NULL;
1.8 djm 112: int hash_alg;
1.11 djm 113: u_char digest[SSH_DIGEST_MAX_LENGTH];
114: size_t dlen;
115: int ret = SSH_ERR_INTERNAL_ERROR;
116: struct sshbuf *b = NULL, *sigbuf = NULL;
117: char *ktype = NULL;
118:
119: if (key == NULL || key->ecdsa == NULL ||
1.13 ! djm 120: sshkey_type_plain(key->type) != KEY_ECDSA ||
! 121: signature == NULL || signaturelen == 0)
1.11 djm 122: return SSH_ERR_INVALID_ARGUMENT;
123:
124: if ((hash_alg = sshkey_ec_nid_to_hash_alg(key->ecdsa_nid)) == -1 ||
125: (dlen = ssh_digest_bytes(hash_alg)) == 0)
126: return SSH_ERR_INTERNAL_ERROR;
1.7 djm 127:
1.1 djm 128: /* fetch signature */
1.11 djm 129: if ((b = sshbuf_from(signature, signaturelen)) == NULL)
130: return SSH_ERR_ALLOC_FAIL;
131: if (sshbuf_get_cstring(b, &ktype, NULL) != 0 ||
132: sshbuf_froms(b, &sigbuf) != 0) {
133: ret = SSH_ERR_INVALID_FORMAT;
134: goto out;
135: }
136: if (strcmp(sshkey_ssh_name_plain(key), ktype) != 0) {
137: ret = SSH_ERR_KEY_TYPE_MISMATCH;
138: goto out;
139: }
140: if (sshbuf_len(b) != 0) {
141: ret = SSH_ERR_UNEXPECTED_TRAILING_DATA;
142: goto out;
1.1 djm 143: }
144:
145: /* parse signature */
1.11 djm 146: if ((sig = ECDSA_SIG_new()) == NULL) {
147: ret = SSH_ERR_ALLOC_FAIL;
148: goto out;
149: }
150: if (sshbuf_get_bignum2(sigbuf, sig->r) != 0 ||
151: sshbuf_get_bignum2(sigbuf, sig->s) != 0) {
152: ret = SSH_ERR_INVALID_FORMAT;
153: goto out;
154: }
155: if (sshbuf_len(sigbuf) != 0) {
156: ret = SSH_ERR_UNEXPECTED_TRAILING_DATA;
157: goto out;
158: }
159: if ((ret = ssh_digest_memory(hash_alg, data, datalen,
160: digest, sizeof(digest))) != 0)
161: goto out;
162:
163: switch (ECDSA_do_verify(digest, dlen, sig, key->ecdsa)) {
164: case 1:
165: ret = 0;
166: break;
167: case 0:
168: ret = SSH_ERR_SIGNATURE_INVALID;
169: goto out;
170: default:
171: ret = SSH_ERR_LIBCRYPTO_ERROR;
172: goto out;
1.8 djm 173: }
1.1 djm 174:
1.11 djm 175: out:
1.9 djm 176: explicit_bzero(digest, sizeof(digest));
1.12 mmcc 177: sshbuf_free(sigbuf);
178: sshbuf_free(b);
1.11 djm 179: if (sig != NULL)
180: ECDSA_SIG_free(sig);
181: free(ktype);
1.1 djm 182: return ret;
183: }
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