Annotation of src/usr.bin/ssh/ssh-ecdsa.c, Revision 1.2
1.1 djm 1: /* $OpenBSD */
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:
36: #include "xmalloc.h"
37: #include "buffer.h"
38: #include "compat.h"
39: #include "log.h"
40: #include "key.h"
41:
42: int
43: ssh_ecdsa_sign(const Key *key, u_char **sigp, u_int *lenp,
44: const u_char *data, u_int datalen)
45: {
46: ECDSA_SIG *sig;
47: const EVP_MD *evp_md = EVP_sha256();
48: EVP_MD_CTX md;
49: u_char digest[EVP_MAX_MD_SIZE];
50: u_int len, dlen;
51: Buffer b, bb;
52:
53: if (key == NULL || key->ecdsa == NULL ||
54: (key->type != KEY_ECDSA && key->type != KEY_ECDSA_CERT)) {
55: error("%s: no ECDSA key", __func__);
56: return -1;
57: }
58: EVP_DigestInit(&md, evp_md);
59: EVP_DigestUpdate(&md, data, datalen);
60: EVP_DigestFinal(&md, digest, &dlen);
61:
62: sig = ECDSA_do_sign(digest, dlen, key->ecdsa);
63: memset(digest, 'd', sizeof(digest));
64:
65: if (sig == NULL) {
66: error("%s: sign failed", __func__);
67: return -1;
68: }
69:
70: buffer_init(&bb);
71: buffer_put_bignum2(&bb, sig->r);
72: buffer_put_bignum2(&bb, sig->s);
73: ECDSA_SIG_free(sig);
74:
75: buffer_init(&b);
76: buffer_put_cstring(&b, key_ssh_name_plain(key));
77: buffer_put_string(&b, buffer_ptr(&bb), buffer_len(&bb));
78: buffer_free(&bb);
79: len = buffer_len(&b);
80: if (lenp != NULL)
81: *lenp = len;
82: if (sigp != NULL) {
83: *sigp = xmalloc(len);
84: memcpy(*sigp, buffer_ptr(&b), len);
85: }
86: buffer_free(&b);
87:
88: return 0;
89: }
90: int
91: ssh_ecdsa_verify(const Key *key, const u_char *signature, u_int signaturelen,
92: const u_char *data, u_int datalen)
93: {
94: ECDSA_SIG *sig;
95: const EVP_MD *evp_md = EVP_sha256();
96: EVP_MD_CTX md;
97: u_char digest[EVP_MAX_MD_SIZE], *sigblob;
98: u_int len, dlen;
99: int rlen, ret;
100: Buffer b, bb;
1.2 ! deraadt 101: char *ktype;
1.1 djm 102:
103: if (key == NULL || key->ecdsa == NULL ||
104: (key->type != KEY_ECDSA && key->type != KEY_ECDSA_CERT)) {
105: error("%s: no ECDSA key", __func__);
106: return -1;
107: }
108:
109: /* fetch signature */
110: buffer_init(&b);
111: buffer_append(&b, signature, signaturelen);
112: ktype = buffer_get_string(&b, NULL);
113: if (strcmp(key_ssh_name_plain(key), ktype) != 0) {
114: error("%s: cannot handle type %s", __func__, ktype);
115: buffer_free(&b);
116: xfree(ktype);
117: return -1;
118: }
119: xfree(ktype);
120: sigblob = buffer_get_string(&b, &len);
121: rlen = buffer_len(&b);
122: buffer_free(&b);
123: if (rlen != 0) {
124: error("%s: remaining bytes in signature %d", __func__, rlen);
125: xfree(sigblob);
126: return -1;
127: }
128:
129: /* parse signature */
130: if ((sig = ECDSA_SIG_new()) == NULL)
131: fatal("%s: ECDSA_SIG_new failed", __func__);
132: if ((sig->r = BN_new()) == NULL ||
133: (sig->s = BN_new()) == NULL)
134: fatal("%s: BN_new failed", __func__);
135:
136: buffer_init(&bb);
137: buffer_append(&bb, sigblob, len);
138: buffer_get_bignum2(&bb, sig->r);
139: buffer_get_bignum2(&bb, sig->s);
140: if (buffer_len(&bb) != 0)
141: fatal("%s: remaining bytes in inner sigblob", __func__);
142:
143: /* clean up */
144: memset(sigblob, 0, len);
145: xfree(sigblob);
146:
147: /* hash the data */
148: EVP_DigestInit(&md, evp_md);
149: EVP_DigestUpdate(&md, data, datalen);
150: EVP_DigestFinal(&md, digest, &dlen);
151:
152: ret = ECDSA_do_verify(digest, dlen, sig, key->ecdsa);
153: memset(digest, 'd', sizeof(digest));
154:
155: ECDSA_SIG_free(sig);
156:
157: debug("%s: signature %s", __func__,
158: ret == 1 ? "correct" : ret == 0 ? "incorrect" : "error");
159: return ret;
160: }
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