Annotation of src/usr.bin/ssh/ssh-dss.c, Revision 1.6.2.5
1.1 markus 1: /*
2: * Copyright (c) 2000 Markus Friedl. All rights reserved.
3: *
4: * Redistribution and use in source and binary forms, with or without
5: * modification, are permitted provided that the following conditions
6: * are met:
7: * 1. Redistributions of source code must retain the above copyright
8: * notice, this list of conditions and the following disclaimer.
9: * 2. Redistributions in binary form must reproduce the above copyright
10: * notice, this list of conditions and the following disclaimer in the
11: * documentation and/or other materials provided with the distribution.
12: *
13: * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
14: * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
15: * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
16: * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
17: * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
18: * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
19: * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
20: * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
21: * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
22: * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
23: */
24:
25: #include "includes.h"
1.6.2.5 ! miod 26: RCSID("$OpenBSD: ssh-dss.c,v 1.8 2001/09/17 19:27:15 stevesk Exp $");
1.4 markus 27:
28: #include <openssl/bn.h>
29: #include <openssl/evp.h>
1.1 markus 30:
31: #include "xmalloc.h"
32: #include "buffer.h"
33: #include "bufaux.h"
34: #include "compat.h"
1.4 markus 35: #include "log.h"
1.1 markus 36: #include "key.h"
1.6 itojun 37: #include "ssh-dss.h"
1.1 markus 38:
39: #define INTBLOB_LEN 20
40: #define SIGBLOB_LEN (2*INTBLOB_LEN)
41:
42: int
43: ssh_dss_sign(
44: Key *key,
1.2 markus 45: u_char **sigp, int *lenp,
46: u_char *data, int datalen)
1.1 markus 47: {
48: DSA_SIG *sig;
49: EVP_MD *evp_md = EVP_sha1();
50: EVP_MD_CTX md;
1.6.2.5 ! miod 51: u_char *digest, *ret, sigblob[SIGBLOB_LEN];
! 52: u_int rlen, slen, len, dlen;
1.1 markus 53: Buffer b;
54:
55: if (key == NULL || key->type != KEY_DSA || key->dsa == NULL) {
56: error("ssh_dss_sign: no DSA key");
57: return -1;
58: }
1.3 markus 59: dlen = evp_md->md_size;
60: digest = xmalloc(dlen);
1.1 markus 61: EVP_DigestInit(&md, evp_md);
62: EVP_DigestUpdate(&md, data, datalen);
63: EVP_DigestFinal(&md, digest, NULL);
64:
1.3 markus 65: sig = DSA_do_sign(digest, dlen, key->dsa);
1.6.2.5 ! miod 66:
1.3 markus 67: memset(digest, 0, dlen);
68: xfree(digest);
1.6.2.5 ! miod 69: if (sig == NULL) {
! 70: error("ssh_dss_sign: sign failed");
! 71: return -1;
! 72: }
1.1 markus 73:
74: rlen = BN_num_bytes(sig->r);
75: slen = BN_num_bytes(sig->s);
76: if (rlen > INTBLOB_LEN || slen > INTBLOB_LEN) {
77: error("bad sig size %d %d", rlen, slen);
78: DSA_SIG_free(sig);
79: return -1;
80: }
81: memset(sigblob, 0, SIGBLOB_LEN);
82: BN_bn2bin(sig->r, sigblob+ SIGBLOB_LEN - INTBLOB_LEN - rlen);
83: BN_bn2bin(sig->s, sigblob+ SIGBLOB_LEN - slen);
84: DSA_SIG_free(sig);
85:
86: if (datafellows & SSH_BUG_SIGBLOB) {
87: ret = xmalloc(SIGBLOB_LEN);
88: memcpy(ret, sigblob, SIGBLOB_LEN);
89: if (lenp != NULL)
90: *lenp = SIGBLOB_LEN;
91: if (sigp != NULL)
92: *sigp = ret;
93: } else {
94: /* ietf-drafts */
95: buffer_init(&b);
96: buffer_put_cstring(&b, "ssh-dss");
97: buffer_put_string(&b, sigblob, SIGBLOB_LEN);
98: len = buffer_len(&b);
99: ret = xmalloc(len);
100: memcpy(ret, buffer_ptr(&b), len);
101: buffer_free(&b);
102: if (lenp != NULL)
103: *lenp = len;
104: if (sigp != NULL)
105: *sigp = ret;
106: }
107: return 0;
108: }
109: int
110: ssh_dss_verify(
111: Key *key,
1.2 markus 112: u_char *signature, int signaturelen,
113: u_char *data, int datalen)
1.1 markus 114: {
115: DSA_SIG *sig;
116: EVP_MD *evp_md = EVP_sha1();
117: EVP_MD_CTX md;
1.6.2.5 ! miod 118: u_char *digest, *sigblob;
1.2 markus 119: u_int len, dlen;
1.6.2.5 ! miod 120: int rlen, ret;
! 121: Buffer b;
1.1 markus 122:
123: if (key == NULL || key->type != KEY_DSA || key->dsa == NULL) {
124: error("ssh_dss_verify: no DSA key");
125: return -1;
126: }
127:
128: /* fetch signature */
129: if (datafellows & SSH_BUG_SIGBLOB) {
130: sigblob = signature;
131: len = signaturelen;
132: } else {
133: /* ietf-drafts */
134: char *ktype;
135: buffer_init(&b);
1.6.2.5 ! miod 136: buffer_append(&b, signature, signaturelen);
1.1 markus 137: ktype = buffer_get_string(&b, NULL);
138: if (strcmp("ssh-dss", ktype) != 0) {
139: error("ssh_dss_verify: cannot handle type %s", ktype);
140: buffer_free(&b);
141: return -1;
142: }
1.6.2.5 ! miod 143: sigblob = buffer_get_string(&b, &len);
1.1 markus 144: rlen = buffer_len(&b);
145: if(rlen != 0) {
146: error("remaining bytes in signature %d", rlen);
147: buffer_free(&b);
148: return -1;
149: }
150: buffer_free(&b);
151: xfree(ktype);
152: }
153:
154: if (len != SIGBLOB_LEN) {
155: fatal("bad sigbloblen %d != SIGBLOB_LEN", len);
156: }
157:
158: /* parse signature */
159: sig = DSA_SIG_new();
160: sig->r = BN_new();
161: sig->s = BN_new();
162: BN_bin2bn(sigblob, INTBLOB_LEN, sig->r);
163: BN_bin2bn(sigblob+ INTBLOB_LEN, INTBLOB_LEN, sig->s);
164:
165: if (!(datafellows & SSH_BUG_SIGBLOB)) {
166: memset(sigblob, 0, len);
167: xfree(sigblob);
168: }
1.5 stevesk 169:
1.1 markus 170: /* sha1 the data */
171: dlen = evp_md->md_size;
172: digest = xmalloc(dlen);
173: EVP_DigestInit(&md, evp_md);
174: EVP_DigestUpdate(&md, data, datalen);
175: EVP_DigestFinal(&md, digest, NULL);
176:
177: ret = DSA_do_verify(digest, dlen, sig, key->dsa);
178:
179: memset(digest, 0, dlen);
180: xfree(digest);
181: DSA_SIG_free(sig);
182:
1.6.2.5 ! miod 183: debug("ssh_dss_verify: signature %s",
! 184: ret == 1 ? "correct" : ret == 0 ? "incorrect" : "error");
1.1 markus 185: return ret;
186: }
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