Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 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 | * 3. All advertising materials mentioning features or use of this software |
| 13 | * must display the following acknowledgement: |
| 14 | * This product includes software developed by Markus Friedl. |
| 15 | * 4. The name of the author may not be used to endorse or promote products |
| 16 | * derived from this software without specific prior written permission. |
| 17 | * |
| 18 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR |
| 19 | * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
| 20 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. |
| 21 | * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, |
| 22 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT |
| 23 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
| 24 | * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
| 25 | * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| 26 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF |
| 27 | * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| 28 | */ |
| 29 | |
| 30 | #include "includes.h" |
| 31 | RCSID("$Id: dsa.c,v 1.4 2000/04/14 10:30:31 markus Exp $"); |
| 32 | |
| 33 | #include "ssh.h" |
| 34 | #include "xmalloc.h" |
| 35 | #include "buffer.h" |
| 36 | #include "bufaux.h" |
| 37 | #include "compat.h" |
| 38 | |
| 39 | #include <openssl/bn.h> |
| 40 | #include <openssl/dh.h> |
| 41 | #include <openssl/rsa.h> |
| 42 | #include <openssl/dsa.h> |
| 43 | #include <openssl/evp.h> |
| 44 | #include <openssl/bio.h> |
| 45 | #include <openssl/pem.h> |
| 46 | |
| 47 | #include <openssl/hmac.h> |
| 48 | #include "kex.h" |
| 49 | #include "key.h" |
| 50 | |
| 51 | #define INTBLOB_LEN 20 |
| 52 | #define SIGBLOB_LEN (2*INTBLOB_LEN) |
| 53 | |
| 54 | Key * |
| 55 | dsa_serverkey_from_blob( |
| 56 | char *serverhostkey, int serverhostkeylen) |
| 57 | { |
| 58 | Buffer b; |
| 59 | char *ktype; |
| 60 | int rlen; |
| 61 | DSA *dsa; |
| 62 | Key *key; |
| 63 | |
| 64 | /* fetch & parse DSA/DSS pubkey */ |
| 65 | key = key_new(KEY_DSA); |
| 66 | dsa = key->dsa; |
| 67 | buffer_init(&b); |
| 68 | buffer_append(&b, serverhostkey, serverhostkeylen); |
| 69 | ktype = buffer_get_string(&b, NULL); |
| 70 | if (strcmp(KEX_DSS, ktype) != 0) { |
| 71 | error("dsa_serverkey_from_blob: cannot handle type %s", ktype); |
| 72 | key_free(key); |
| 73 | return NULL; |
| 74 | } |
| 75 | buffer_get_bignum2(&b, dsa->p); |
| 76 | buffer_get_bignum2(&b, dsa->q); |
| 77 | buffer_get_bignum2(&b, dsa->g); |
| 78 | buffer_get_bignum2(&b, dsa->pub_key); |
| 79 | rlen = buffer_len(&b); |
| 80 | if(rlen != 0) |
| 81 | error("dsa_serverkey_from_blob: remaining bytes in serverhostkey %d", rlen); |
| 82 | buffer_free(&b); |
| 83 | |
| 84 | debug("keytype %s", ktype); |
| 85 | #ifdef DEBUG_DSS |
| 86 | DSA_print_fp(stderr, dsa, 8); |
| 87 | #endif |
| 88 | return key; |
| 89 | } |
| 90 | DSA * |
| 91 | dsa_load_private(char *filename) |
| 92 | { |
| 93 | DSA *dsa; |
| 94 | BIO *in; |
| 95 | |
| 96 | in = BIO_new(BIO_s_file()); |
| 97 | if (in == NULL) |
| 98 | fatal("BIO_new failed"); |
| 99 | if (BIO_read_filename(in, filename) <= 0) |
| 100 | fatal("BIO_read failed %s: %s", filename, strerror(errno)); |
| 101 | fprintf(stderr, "read DSA private key\n"); |
| 102 | dsa = PEM_read_bio_DSAPrivateKey(in,NULL,NULL,NULL); |
| 103 | if (dsa == NULL) |
| 104 | fatal("PEM_read_bio_DSAPrivateKey failed %s", filename); |
| 105 | BIO_free(in); |
| 106 | return dsa; |
| 107 | } |
| 108 | Key * |
| 109 | dsa_get_serverkey(char *filename) |
| 110 | { |
| 111 | Key *k = key_new(KEY_EMPTY); |
| 112 | k->type = KEY_DSA; |
| 113 | k->dsa = dsa_load_private(filename); |
| 114 | #ifdef DEBUG_DSS |
| 115 | DSA_print_fp(stderr, dsa, 8); |
| 116 | #endif |
| 117 | return k; |
| 118 | } |
| 119 | int |
| 120 | dsa_make_serverkey_blob(Key *key, unsigned char **blobp, unsigned int *lenp) |
| 121 | { |
| 122 | Buffer b; |
| 123 | int len; |
| 124 | unsigned char *buf; |
| 125 | |
| 126 | if (key == NULL || key->type != KEY_DSA) |
| 127 | return 0; |
| 128 | buffer_init(&b); |
| 129 | buffer_put_cstring(&b, KEX_DSS); |
| 130 | buffer_put_bignum2(&b, key->dsa->p); |
| 131 | buffer_put_bignum2(&b, key->dsa->q); |
| 132 | buffer_put_bignum2(&b, key->dsa->g); |
| 133 | buffer_put_bignum2(&b, key->dsa->pub_key); |
| 134 | len = buffer_len(&b); |
| 135 | buf = xmalloc(len); |
| 136 | memcpy(buf, buffer_ptr(&b), len); |
| 137 | memset(buffer_ptr(&b), 0, len); |
| 138 | buffer_free(&b); |
| 139 | if (lenp != NULL) |
| 140 | *lenp = len; |
| 141 | if (blobp != NULL) |
| 142 | *blobp = buf; |
| 143 | return len; |
| 144 | } |
| 145 | int |
| 146 | dsa_sign( |
| 147 | Key *key, |
| 148 | unsigned char **sigp, int *lenp, |
| 149 | unsigned char *hash, int hlen) |
| 150 | { |
| 151 | unsigned char *digest; |
| 152 | unsigned char *ret; |
| 153 | DSA_SIG *sig; |
| 154 | EVP_MD *evp_md = EVP_sha1(); |
| 155 | EVP_MD_CTX md; |
| 156 | unsigned int rlen; |
| 157 | unsigned int slen; |
| 158 | unsigned int len; |
| 159 | unsigned char sigblob[SIGBLOB_LEN]; |
| 160 | Buffer b; |
| 161 | |
| 162 | if (key == NULL || key->type != KEY_DSA || key->dsa == NULL) { |
| 163 | error("dsa_sign: no DSA key"); |
| 164 | return -1; |
| 165 | } |
| 166 | digest = xmalloc(evp_md->md_size); |
| 167 | EVP_DigestInit(&md, evp_md); |
| 168 | EVP_DigestUpdate(&md, hash, hlen); |
| 169 | EVP_DigestFinal(&md, digest, NULL); |
| 170 | |
| 171 | sig = DSA_do_sign(digest, evp_md->md_size, key->dsa); |
| 172 | |
| 173 | rlen = BN_num_bytes(sig->r); |
| 174 | slen = BN_num_bytes(sig->s); |
| 175 | if (rlen > INTBLOB_LEN || slen > INTBLOB_LEN) { |
| 176 | error("bad sig size %d %d", rlen, slen); |
| 177 | DSA_SIG_free(sig); |
| 178 | return -1; |
| 179 | } |
| 180 | debug("sig size %d %d", rlen, slen); |
| 181 | |
| 182 | memset(sigblob, 0, SIGBLOB_LEN); |
| 183 | BN_bn2bin(sig->r, sigblob+ SIGBLOB_LEN - INTBLOB_LEN - rlen); |
| 184 | BN_bn2bin(sig->s, sigblob+ SIGBLOB_LEN - slen); |
| 185 | DSA_SIG_free(sig); |
| 186 | |
| 187 | if (datafellows) { |
| 188 | debug("datafellows"); |
| 189 | ret = xmalloc(SIGBLOB_LEN); |
| 190 | memcpy(ret, sigblob, SIGBLOB_LEN); |
| 191 | if (lenp != NULL) |
| 192 | *lenp = SIGBLOB_LEN; |
| 193 | if (sigp != NULL) |
| 194 | *sigp = ret; |
| 195 | } else { |
| 196 | /* ietf-drafts */ |
| 197 | buffer_init(&b); |
| 198 | buffer_put_cstring(&b, KEX_DSS); |
| 199 | buffer_put_string(&b, sigblob, SIGBLOB_LEN); |
| 200 | len = buffer_len(&b); |
| 201 | ret = xmalloc(len); |
| 202 | memcpy(ret, buffer_ptr(&b), len); |
| 203 | buffer_free(&b); |
| 204 | if (lenp != NULL) |
| 205 | *lenp = len; |
| 206 | if (sigp != NULL) |
| 207 | *sigp = ret; |
| 208 | } |
| 209 | return 0; |
| 210 | } |
| 211 | int |
| 212 | dsa_verify( |
| 213 | Key *key, |
| 214 | unsigned char *signature, int signaturelen, |
| 215 | unsigned char *hash, int hlen) |
| 216 | { |
| 217 | Buffer b; |
| 218 | unsigned char *digest; |
| 219 | DSA_SIG *sig; |
| 220 | EVP_MD *evp_md = EVP_sha1(); |
| 221 | EVP_MD_CTX md; |
| 222 | char *ktype; |
| 223 | unsigned char *sigblob; |
| 224 | char *txt; |
| 225 | unsigned int len; |
| 226 | int rlen; |
| 227 | int ret; |
| 228 | |
| 229 | if (key == NULL || key->type != KEY_DSA || key->dsa == NULL) { |
| 230 | error("dsa_verify: no DSA key"); |
| 231 | return -1; |
| 232 | } |
| 233 | |
| 234 | if (datafellows && signaturelen != SIGBLOB_LEN) { |
| 235 | log("heh? datafellows ssh2 complies with ietf-drafts????"); |
| 236 | datafellows = 0; |
| 237 | } |
| 238 | |
| 239 | debug("len %d datafellows %d", signaturelen, datafellows); |
| 240 | |
| 241 | /* fetch signature */ |
| 242 | if (datafellows) { |
| 243 | sigblob = signature; |
| 244 | len = signaturelen; |
| 245 | } else { |
| 246 | /* ietf-drafts */ |
| 247 | buffer_init(&b); |
| 248 | buffer_append(&b, (char *) signature, signaturelen); |
| 249 | ktype = buffer_get_string(&b, NULL); |
| 250 | sigblob = (unsigned char *)buffer_get_string(&b, &len); |
| 251 | rlen = buffer_len(&b); |
| 252 | if(rlen != 0) |
| 253 | error("remaining bytes in signature %d", rlen); |
| 254 | buffer_free(&b); |
| 255 | } |
| 256 | |
| 257 | if (len != SIGBLOB_LEN) { |
| 258 | fatal("bad sigbloblen %d != SIGBLOB_LEN", len); |
| 259 | } |
| 260 | |
| 261 | /* parse signature */ |
| 262 | sig = DSA_SIG_new(); |
| 263 | sig->r = BN_new(); |
| 264 | sig->s = BN_new(); |
| 265 | BN_bin2bn(sigblob, INTBLOB_LEN, sig->r); |
| 266 | BN_bin2bn(sigblob+ INTBLOB_LEN, INTBLOB_LEN, sig->s); |
| 267 | if (!datafellows) { |
| 268 | memset(sigblob, 0, len); |
| 269 | xfree(sigblob); |
| 270 | } |
| 271 | |
| 272 | /* sha1 the signed data (== session_id == hash) */ |
| 273 | digest = xmalloc(evp_md->md_size); |
| 274 | EVP_DigestInit(&md, evp_md); |
| 275 | EVP_DigestUpdate(&md, hash, hlen); |
| 276 | EVP_DigestFinal(&md, digest, NULL); |
| 277 | |
| 278 | ret = DSA_do_verify(digest, evp_md->md_size, sig, key->dsa); |
| 279 | |
| 280 | memset(digest, 0, evp_md->md_size); |
| 281 | xfree(digest); |
| 282 | DSA_SIG_free(sig); |
| 283 | |
| 284 | switch (ret) { |
| 285 | case 1: |
| 286 | txt = "correct"; |
| 287 | break; |
| 288 | case 0: |
| 289 | txt = "incorrect"; |
| 290 | break; |
| 291 | case -1: |
| 292 | default: |
| 293 | txt = "error"; |
| 294 | break; |
| 295 | } |
| 296 | debug("dsa_verify: signature %s", txt); |
| 297 | return ret; |
| 298 | } |