Annotation of src/usr.bin/ssh/ssh-dss.c, Revision 1.29
1.29 ! djm 1: /* $OpenBSD: ssh-dss.c,v 1.28 2013/05/17 00:13:14 djm 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:
1.23 deraadt 26: #include <sys/types.h>
1.4 markus 27:
28: #include <openssl/bn.h>
29: #include <openssl/evp.h>
1.22 stevesk 30:
31: #include <string.h>
1.1 markus 32:
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:
1.29 ! djm 53: if (key == NULL || key_type_plain(key->type) != KEY_DSA ||
! 54: key->dsa == NULL) {
! 55: error("%s: no DSA key", __func__);
1.1 markus 56: return -1;
57: }
1.29 ! djm 58:
1.1 markus 59: EVP_DigestInit(&md, evp_md);
60: EVP_DigestUpdate(&md, data, datalen);
1.12 markus 61: EVP_DigestFinal(&md, digest, &dlen);
1.1 markus 62:
1.3 markus 63: sig = DSA_do_sign(digest, dlen, key->dsa);
1.12 markus 64: memset(digest, 'd', sizeof(digest));
1.7 markus 65:
1.1 markus 66: if (sig == NULL) {
1.7 markus 67: error("ssh_dss_sign: sign failed");
68: return -1;
1.1 markus 69: }
70:
71: rlen = BN_num_bytes(sig->r);
72: slen = BN_num_bytes(sig->s);
73: if (rlen > INTBLOB_LEN || slen > INTBLOB_LEN) {
1.15 deraadt 74: error("bad sig size %u %u", rlen, slen);
1.1 markus 75: DSA_SIG_free(sig);
76: return -1;
77: }
78: memset(sigblob, 0, SIGBLOB_LEN);
79: BN_bn2bin(sig->r, sigblob+ SIGBLOB_LEN - INTBLOB_LEN - rlen);
80: BN_bn2bin(sig->s, sigblob+ SIGBLOB_LEN - slen);
81: DSA_SIG_free(sig);
82:
83: if (datafellows & SSH_BUG_SIGBLOB) {
84: if (lenp != NULL)
85: *lenp = SIGBLOB_LEN;
1.17 markus 86: if (sigp != NULL) {
87: *sigp = xmalloc(SIGBLOB_LEN);
88: memcpy(*sigp, sigblob, SIGBLOB_LEN);
89: }
1.1 markus 90: } else {
91: /* ietf-drafts */
92: buffer_init(&b);
93: buffer_put_cstring(&b, "ssh-dss");
94: buffer_put_string(&b, sigblob, SIGBLOB_LEN);
95: len = buffer_len(&b);
96: if (lenp != NULL)
97: *lenp = len;
1.17 markus 98: if (sigp != NULL) {
99: *sigp = xmalloc(len);
100: memcpy(*sigp, buffer_ptr(&b), len);
101: }
102: buffer_free(&b);
1.1 markus 103: }
104: return 0;
105: }
106: int
1.19 jakob 107: ssh_dss_verify(const Key *key, const u_char *signature, u_int signaturelen,
108: const u_char *data, u_int datalen)
1.1 markus 109: {
110: DSA_SIG *sig;
1.14 markus 111: const EVP_MD *evp_md = EVP_sha1();
1.1 markus 112: EVP_MD_CTX md;
1.12 markus 113: u_char digest[EVP_MAX_MD_SIZE], *sigblob;
1.2 markus 114: u_int len, dlen;
1.7 markus 115: int rlen, ret;
116: Buffer b;
1.1 markus 117:
1.29 ! djm 118: if (key == NULL || key_type_plain(key->type) != KEY_DSA ||
! 119: key->dsa == NULL) {
! 120: error("%s: no DSA key", __func__);
1.1 markus 121: return -1;
122: }
123:
124: /* fetch signature */
125: if (datafellows & SSH_BUG_SIGBLOB) {
1.19 jakob 126: sigblob = xmalloc(signaturelen);
127: memcpy(sigblob, signature, signaturelen);
1.1 markus 128: len = signaturelen;
129: } else {
130: /* ietf-drafts */
131: char *ktype;
132: buffer_init(&b);
1.8 stevesk 133: buffer_append(&b, signature, signaturelen);
1.27 djm 134: ktype = buffer_get_cstring(&b, NULL);
1.1 markus 135: if (strcmp("ssh-dss", ktype) != 0) {
1.29 ! djm 136: error("%s: cannot handle type %s", __func__, ktype);
1.1 markus 137: buffer_free(&b);
1.28 djm 138: free(ktype);
1.1 markus 139: return -1;
140: }
1.28 djm 141: free(ktype);
1.8 stevesk 142: sigblob = buffer_get_string(&b, &len);
1.1 markus 143: rlen = buffer_len(&b);
1.9 markus 144: buffer_free(&b);
1.10 deraadt 145: if (rlen != 0) {
1.29 ! djm 146: error("%s: remaining bytes in signature %d",
! 147: __func__, rlen);
1.28 djm 148: free(sigblob);
1.1 markus 149: return -1;
150: }
151: }
152:
153: if (len != SIGBLOB_LEN) {
1.15 deraadt 154: fatal("bad sigbloblen %u != SIGBLOB_LEN", len);
1.1 markus 155: }
156:
157: /* parse signature */
1.11 markus 158: if ((sig = DSA_SIG_new()) == NULL)
1.29 ! djm 159: fatal("%s: DSA_SIG_new failed", __func__);
1.11 markus 160: if ((sig->r = BN_new()) == NULL)
1.29 ! djm 161: fatal("%s: BN_new failed", __func__);
1.11 markus 162: if ((sig->s = BN_new()) == NULL)
163: fatal("ssh_dss_verify: BN_new failed");
1.24 markus 164: if ((BN_bin2bn(sigblob, INTBLOB_LEN, sig->r) == NULL) ||
165: (BN_bin2bn(sigblob+ INTBLOB_LEN, INTBLOB_LEN, sig->s) == NULL))
1.29 ! djm 166: fatal("%s: BN_bin2bn failed", __func__);
1.1 markus 167:
1.19 jakob 168: /* clean up */
169: memset(sigblob, 0, len);
1.28 djm 170: free(sigblob);
1.5 stevesk 171:
1.1 markus 172: /* sha1 the data */
173: EVP_DigestInit(&md, evp_md);
174: EVP_DigestUpdate(&md, data, datalen);
1.12 markus 175: EVP_DigestFinal(&md, digest, &dlen);
1.1 markus 176:
177: ret = DSA_do_verify(digest, dlen, sig, key->dsa);
1.12 markus 178: memset(digest, 'd', sizeof(digest));
1.1 markus 179:
180: DSA_SIG_free(sig);
181:
1.29 ! djm 182: debug("%s: signature %s", __func__,
1.7 markus 183: ret == 1 ? "correct" : ret == 0 ? "incorrect" : "error");
1.1 markus 184: return ret;
185: }
![[BACK]](/icons/back.gif){kind=icon}
Return to ssh-dss.c CVS log ![[TXT]](/icons/text.gif){kind=icon}
![[DIR]](/icons/dir.gif){kind=icon}
Up to [local] / src / usr.bin / ssh