Annotation of src/usr.bin/ssh/ssh-dss.c, Revision 1.19.8.2
1.19.8.2! brad 1: /* $OpenBSD: ssh-dss.c,v 1.24 2006/11/06 21:25:28 markus Exp $ */
1.1 markus 2: /*
3: * Copyright (c) 2000 Markus Friedl. All rights reserved.
4: *
5: * Redistribution and use in source and binary forms, with or without
6: * modification, are permitted provided that the following conditions
7: * are met:
8: * 1. Redistributions of source code must retain the above copyright
9: * notice, this list of conditions and the following disclaimer.
10: * 2. Redistributions in binary form must reproduce the above copyright
11: * notice, this list of conditions and the following disclaimer in the
12: * documentation and/or other materials provided with the distribution.
13: *
14: * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
15: * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
16: * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
17: * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
18: * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
19: * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
20: * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
21: * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
22: * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
23: * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
24: */
25:
1.19.8.1 brad 26: #include <sys/types.h>
1.4 markus 27:
28: #include <openssl/bn.h>
29: #include <openssl/evp.h>
1.1 markus 30:
1.19.8.1 brad 31: #include <string.h>
32:
1.1 markus 33: #include "xmalloc.h"
34: #include "buffer.h"
35: #include "compat.h"
1.4 markus 36: #include "log.h"
1.1 markus 37: #include "key.h"
38:
39: #define INTBLOB_LEN 20
40: #define SIGBLOB_LEN (2*INTBLOB_LEN)
41:
42: int
1.19 jakob 43: ssh_dss_sign(const Key *key, u_char **sigp, u_int *lenp,
44: const u_char *data, u_int datalen)
1.1 markus 45: {
46: DSA_SIG *sig;
1.14 markus 47: const EVP_MD *evp_md = EVP_sha1();
1.1 markus 48: EVP_MD_CTX md;
1.17 markus 49: u_char digest[EVP_MAX_MD_SIZE], sigblob[SIGBLOB_LEN];
1.7 markus 50: u_int rlen, slen, len, dlen;
1.1 markus 51: Buffer b;
52:
53: if (key == NULL || key->type != KEY_DSA || key->dsa == NULL) {
54: error("ssh_dss_sign: no DSA key");
55: return -1;
56: }
57: EVP_DigestInit(&md, evp_md);
58: EVP_DigestUpdate(&md, data, datalen);
1.12 markus 59: EVP_DigestFinal(&md, digest, &dlen);
1.1 markus 60:
1.3 markus 61: sig = DSA_do_sign(digest, dlen, key->dsa);
1.12 markus 62: memset(digest, 'd', sizeof(digest));
1.7 markus 63:
1.1 markus 64: if (sig == NULL) {
1.7 markus 65: error("ssh_dss_sign: sign failed");
66: return -1;
1.1 markus 67: }
68:
69: rlen = BN_num_bytes(sig->r);
70: slen = BN_num_bytes(sig->s);
71: if (rlen > INTBLOB_LEN || slen > INTBLOB_LEN) {
1.15 deraadt 72: error("bad sig size %u %u", rlen, slen);
1.1 markus 73: DSA_SIG_free(sig);
74: return -1;
75: }
76: memset(sigblob, 0, SIGBLOB_LEN);
77: BN_bn2bin(sig->r, sigblob+ SIGBLOB_LEN - INTBLOB_LEN - rlen);
78: BN_bn2bin(sig->s, sigblob+ SIGBLOB_LEN - slen);
79: DSA_SIG_free(sig);
80:
81: if (datafellows & SSH_BUG_SIGBLOB) {
82: if (lenp != NULL)
83: *lenp = SIGBLOB_LEN;
1.17 markus 84: if (sigp != NULL) {
85: *sigp = xmalloc(SIGBLOB_LEN);
86: memcpy(*sigp, sigblob, SIGBLOB_LEN);
87: }
1.1 markus 88: } else {
89: /* ietf-drafts */
90: buffer_init(&b);
91: buffer_put_cstring(&b, "ssh-dss");
92: buffer_put_string(&b, sigblob, SIGBLOB_LEN);
93: len = buffer_len(&b);
94: if (lenp != NULL)
95: *lenp = len;
1.17 markus 96: if (sigp != NULL) {
97: *sigp = xmalloc(len);
98: memcpy(*sigp, buffer_ptr(&b), len);
99: }
100: buffer_free(&b);
1.1 markus 101: }
102: return 0;
103: }
104: int
1.19 jakob 105: ssh_dss_verify(const Key *key, const u_char *signature, u_int signaturelen,
106: const u_char *data, u_int datalen)
1.1 markus 107: {
108: DSA_SIG *sig;
1.14 markus 109: const EVP_MD *evp_md = EVP_sha1();
1.1 markus 110: EVP_MD_CTX md;
1.12 markus 111: u_char digest[EVP_MAX_MD_SIZE], *sigblob;
1.2 markus 112: u_int len, dlen;
1.7 markus 113: int rlen, ret;
114: Buffer b;
1.1 markus 115:
116: if (key == NULL || key->type != KEY_DSA || key->dsa == NULL) {
117: error("ssh_dss_verify: no DSA key");
118: return -1;
119: }
120:
121: /* fetch signature */
122: if (datafellows & SSH_BUG_SIGBLOB) {
1.19 jakob 123: sigblob = xmalloc(signaturelen);
124: memcpy(sigblob, signature, signaturelen);
1.1 markus 125: len = signaturelen;
126: } else {
127: /* ietf-drafts */
128: char *ktype;
129: buffer_init(&b);
1.8 stevesk 130: buffer_append(&b, signature, signaturelen);
1.1 markus 131: ktype = buffer_get_string(&b, NULL);
132: if (strcmp("ssh-dss", ktype) != 0) {
133: error("ssh_dss_verify: cannot handle type %s", ktype);
134: buffer_free(&b);
1.9 markus 135: xfree(ktype);
1.1 markus 136: return -1;
137: }
1.9 markus 138: xfree(ktype);
1.8 stevesk 139: sigblob = buffer_get_string(&b, &len);
1.1 markus 140: rlen = buffer_len(&b);
1.9 markus 141: buffer_free(&b);
1.10 deraadt 142: if (rlen != 0) {
1.9 markus 143: error("ssh_dss_verify: "
144: "remaining bytes in signature %d", rlen);
145: xfree(sigblob);
1.1 markus 146: return -1;
147: }
148: }
149:
150: if (len != SIGBLOB_LEN) {
1.15 deraadt 151: fatal("bad sigbloblen %u != SIGBLOB_LEN", len);
1.1 markus 152: }
153:
154: /* parse signature */
1.11 markus 155: if ((sig = DSA_SIG_new()) == NULL)
156: fatal("ssh_dss_verify: DSA_SIG_new failed");
157: if ((sig->r = BN_new()) == NULL)
158: fatal("ssh_dss_verify: BN_new failed");
159: if ((sig->s = BN_new()) == NULL)
160: fatal("ssh_dss_verify: BN_new failed");
1.19.8.2! brad 161: if ((BN_bin2bn(sigblob, INTBLOB_LEN, sig->r) == NULL) ||
! 162: (BN_bin2bn(sigblob+ INTBLOB_LEN, INTBLOB_LEN, sig->s) == NULL))
! 163: fatal("ssh_dss_verify: BN_bin2bn failed");
1.1 markus 164:
1.19 jakob 165: /* clean up */
166: memset(sigblob, 0, len);
167: xfree(sigblob);
1.5 stevesk 168:
1.1 markus 169: /* sha1 the data */
170: EVP_DigestInit(&md, evp_md);
171: EVP_DigestUpdate(&md, data, datalen);
1.12 markus 172: EVP_DigestFinal(&md, digest, &dlen);
1.1 markus 173:
174: ret = DSA_do_verify(digest, dlen, sig, key->dsa);
1.12 markus 175: memset(digest, 'd', sizeof(digest));
1.1 markus 176:
177: DSA_SIG_free(sig);
178:
1.7 markus 179: debug("ssh_dss_verify: signature %s",
180: ret == 1 ? "correct" : ret == 0 ? "incorrect" : "error");
1.1 markus 181: return ret;
182: }
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