diff options
Diffstat (limited to 'ssh-dss.c')
-rw-r--r-- | ssh-dss.c | 216 |
1 files changed, 216 insertions, 0 deletions
diff --git a/ssh-dss.c b/ssh-dss.c new file mode 100644 index 000000000..fea1fe2d5 --- /dev/null +++ b/ssh-dss.c | |||
@@ -0,0 +1,216 @@ | |||
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" | ||
26 | RCSID("$OpenBSD: ssh-dss.c,v 1.1 2000/11/12 19:50:38 markus Exp $"); | ||
27 | |||
28 | #include "ssh.h" | ||
29 | #include "xmalloc.h" | ||
30 | #include "buffer.h" | ||
31 | #include "bufaux.h" | ||
32 | #include "compat.h" | ||
33 | |||
34 | #include <openssl/bn.h> | ||
35 | #include <openssl/rsa.h> | ||
36 | #include <openssl/dsa.h> | ||
37 | #include <openssl/evp.h> | ||
38 | |||
39 | #include "key.h" | ||
40 | |||
41 | #define INTBLOB_LEN 20 | ||
42 | #define SIGBLOB_LEN (2*INTBLOB_LEN) | ||
43 | |||
44 | int | ||
45 | ssh_dss_sign( | ||
46 | Key *key, | ||
47 | unsigned char **sigp, int *lenp, | ||
48 | unsigned char *data, int datalen) | ||
49 | { | ||
50 | unsigned char *digest; | ||
51 | unsigned char *ret; | ||
52 | DSA_SIG *sig; | ||
53 | EVP_MD *evp_md = EVP_sha1(); | ||
54 | EVP_MD_CTX md; | ||
55 | unsigned int rlen; | ||
56 | unsigned int slen; | ||
57 | unsigned int len; | ||
58 | unsigned char sigblob[SIGBLOB_LEN]; | ||
59 | Buffer b; | ||
60 | |||
61 | if (key == NULL || key->type != KEY_DSA || key->dsa == NULL) { | ||
62 | error("ssh_dss_sign: no DSA key"); | ||
63 | return -1; | ||
64 | } | ||
65 | digest = xmalloc(evp_md->md_size); | ||
66 | EVP_DigestInit(&md, evp_md); | ||
67 | EVP_DigestUpdate(&md, data, datalen); | ||
68 | EVP_DigestFinal(&md, digest, NULL); | ||
69 | |||
70 | sig = DSA_do_sign(digest, evp_md->md_size, key->dsa); | ||
71 | if (sig == NULL) { | ||
72 | fatal("ssh_dss_sign: cannot sign"); | ||
73 | } | ||
74 | |||
75 | rlen = BN_num_bytes(sig->r); | ||
76 | slen = BN_num_bytes(sig->s); | ||
77 | if (rlen > INTBLOB_LEN || slen > INTBLOB_LEN) { | ||
78 | error("bad sig size %d %d", rlen, slen); | ||
79 | DSA_SIG_free(sig); | ||
80 | return -1; | ||
81 | } | ||
82 | debug("sig size %d %d", rlen, slen); | ||
83 | |||
84 | memset(sigblob, 0, SIGBLOB_LEN); | ||
85 | BN_bn2bin(sig->r, sigblob+ SIGBLOB_LEN - INTBLOB_LEN - rlen); | ||
86 | BN_bn2bin(sig->s, sigblob+ SIGBLOB_LEN - slen); | ||
87 | DSA_SIG_free(sig); | ||
88 | |||
89 | if (datafellows & SSH_BUG_SIGBLOB) { | ||
90 | debug("datafellows"); | ||
91 | ret = xmalloc(SIGBLOB_LEN); | ||
92 | memcpy(ret, sigblob, SIGBLOB_LEN); | ||
93 | if (lenp != NULL) | ||
94 | *lenp = SIGBLOB_LEN; | ||
95 | if (sigp != NULL) | ||
96 | *sigp = ret; | ||
97 | } else { | ||
98 | /* ietf-drafts */ | ||
99 | buffer_init(&b); | ||
100 | buffer_put_cstring(&b, "ssh-dss"); | ||
101 | buffer_put_string(&b, sigblob, SIGBLOB_LEN); | ||
102 | len = buffer_len(&b); | ||
103 | ret = xmalloc(len); | ||
104 | memcpy(ret, buffer_ptr(&b), len); | ||
105 | buffer_free(&b); | ||
106 | if (lenp != NULL) | ||
107 | *lenp = len; | ||
108 | if (sigp != NULL) | ||
109 | *sigp = ret; | ||
110 | } | ||
111 | return 0; | ||
112 | } | ||
113 | int | ||
114 | ssh_dss_verify( | ||
115 | Key *key, | ||
116 | unsigned char *signature, int signaturelen, | ||
117 | unsigned char *data, int datalen) | ||
118 | { | ||
119 | Buffer b; | ||
120 | unsigned char *digest; | ||
121 | DSA_SIG *sig; | ||
122 | EVP_MD *evp_md = EVP_sha1(); | ||
123 | EVP_MD_CTX md; | ||
124 | unsigned char *sigblob; | ||
125 | char *txt; | ||
126 | unsigned int len, dlen; | ||
127 | int rlen; | ||
128 | int ret; | ||
129 | |||
130 | if (key == NULL || key->type != KEY_DSA || key->dsa == NULL) { | ||
131 | error("ssh_dss_verify: no DSA key"); | ||
132 | return -1; | ||
133 | } | ||
134 | |||
135 | if (!(datafellows & SSH_BUG_SIGBLOB) && | ||
136 | signaturelen == SIGBLOB_LEN) { | ||
137 | datafellows |= ~SSH_BUG_SIGBLOB; | ||
138 | log("autodetect SSH_BUG_SIGBLOB"); | ||
139 | } else if ((datafellows & SSH_BUG_SIGBLOB) && | ||
140 | signaturelen != SIGBLOB_LEN) { | ||
141 | log("autoremove SSH_BUG_SIGBLOB"); | ||
142 | datafellows &= ~SSH_BUG_SIGBLOB; | ||
143 | } | ||
144 | |||
145 | debug("len %d datafellows %d", signaturelen, datafellows); | ||
146 | |||
147 | /* fetch signature */ | ||
148 | if (datafellows & SSH_BUG_SIGBLOB) { | ||
149 | sigblob = signature; | ||
150 | len = signaturelen; | ||
151 | } else { | ||
152 | /* ietf-drafts */ | ||
153 | char *ktype; | ||
154 | buffer_init(&b); | ||
155 | buffer_append(&b, (char *) signature, signaturelen); | ||
156 | ktype = buffer_get_string(&b, NULL); | ||
157 | if (strcmp("ssh-dss", ktype) != 0) { | ||
158 | error("ssh_dss_verify: cannot handle type %s", ktype); | ||
159 | buffer_free(&b); | ||
160 | return -1; | ||
161 | } | ||
162 | sigblob = (unsigned char *)buffer_get_string(&b, &len); | ||
163 | rlen = buffer_len(&b); | ||
164 | if(rlen != 0) { | ||
165 | error("remaining bytes in signature %d", rlen); | ||
166 | buffer_free(&b); | ||
167 | return -1; | ||
168 | } | ||
169 | buffer_free(&b); | ||
170 | xfree(ktype); | ||
171 | } | ||
172 | |||
173 | if (len != SIGBLOB_LEN) { | ||
174 | fatal("bad sigbloblen %d != SIGBLOB_LEN", len); | ||
175 | } | ||
176 | |||
177 | /* parse signature */ | ||
178 | sig = DSA_SIG_new(); | ||
179 | sig->r = BN_new(); | ||
180 | sig->s = BN_new(); | ||
181 | BN_bin2bn(sigblob, INTBLOB_LEN, sig->r); | ||
182 | BN_bin2bn(sigblob+ INTBLOB_LEN, INTBLOB_LEN, sig->s); | ||
183 | |||
184 | if (!(datafellows & SSH_BUG_SIGBLOB)) { | ||
185 | memset(sigblob, 0, len); | ||
186 | xfree(sigblob); | ||
187 | } | ||
188 | |||
189 | /* sha1 the data */ | ||
190 | dlen = evp_md->md_size; | ||
191 | digest = xmalloc(dlen); | ||
192 | EVP_DigestInit(&md, evp_md); | ||
193 | EVP_DigestUpdate(&md, data, datalen); | ||
194 | EVP_DigestFinal(&md, digest, NULL); | ||
195 | |||
196 | ret = DSA_do_verify(digest, dlen, sig, key->dsa); | ||
197 | |||
198 | memset(digest, 0, dlen); | ||
199 | xfree(digest); | ||
200 | DSA_SIG_free(sig); | ||
201 | |||
202 | switch (ret) { | ||
203 | case 1: | ||
204 | txt = "correct"; | ||
205 | break; | ||
206 | case 0: | ||
207 | txt = "incorrect"; | ||
208 | break; | ||
209 | case -1: | ||
210 | default: | ||
211 | txt = "error"; | ||
212 | break; | ||
213 | } | ||
214 | debug("ssh_dss_verify: signature %s", txt); | ||
215 | return ret; | ||
216 | } | ||