1 /* crypto/srp/srp_lib.c */ 2 /* 3 * Written by Christophe Renou (christophe.renou@edelweb.fr) with the 4 * precious help of Peter Sylvester (peter.sylvester@edelweb.fr) for the 5 * EdelKey project and contributed to the OpenSSL project 2004. 6 */ 7 /* ==================================================================== 8 * Copyright (c) 2004 The OpenSSL Project. All rights reserved. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 14 * 1. Redistributions of source code must retain the above copyright 15 * notice, this list of conditions and the following disclaimer. 16 * 17 * 2. Redistributions in binary form must reproduce the above copyright 18 * notice, this list of conditions and the following disclaimer in 19 * the documentation and/or other materials provided with the 20 * distribution. 21 * 22 * 3. All advertising materials mentioning features or use of this 23 * software must display the following acknowledgment: 24 * "This product includes software developed by the OpenSSL Project 25 * for use in the OpenSSL Toolkit. (http://www.OpenSSL.org/)" 26 * 27 * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to 28 * endorse or promote products derived from this software without 29 * prior written permission. For written permission, please contact 30 * licensing@OpenSSL.org. 31 * 32 * 5. Products derived from this software may not be called "OpenSSL" 33 * nor may "OpenSSL" appear in their names without prior written 34 * permission of the OpenSSL Project. 35 * 36 * 6. Redistributions of any form whatsoever must retain the following 37 * acknowledgment: 38 * "This product includes software developed by the OpenSSL Project 39 * for use in the OpenSSL Toolkit (http://www.OpenSSL.org/)" 40 * 41 * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY 42 * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 43 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 44 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR 45 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 46 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 47 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 48 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 49 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, 50 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 51 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED 52 * OF THE POSSIBILITY OF SUCH DAMAGE. 53 * ==================================================================== 54 * 55 * This product includes cryptographic software written by Eric Young 56 * (eay@cryptsoft.com). This product includes software written by Tim 57 * Hudson (tjh@cryptsoft.com). 58 * 59 */ 60 #ifndef OPENSSL_NO_SRP 61 # include "cryptlib.h" 62 # include "srp_lcl.h" 63 # include <openssl/srp.h> 64 # include <openssl/evp.h> 65 66 # if (BN_BYTES == 8) 67 # if (defined(_WIN32) || defined(_WIN64)) && !defined(__MINGW32__) 68 # define bn_pack4(a1,a2,a3,a4) ((a1##UI64<<48)|(a2##UI64<<32)|(a3##UI64<<16)|a4##UI64) 69 # elif defined(__arch64__) 70 # define bn_pack4(a1,a2,a3,a4) ((a1##UL<<48)|(a2##UL<<32)|(a3##UL<<16)|a4##UL) 71 # else 72 # define bn_pack4(a1,a2,a3,a4) ((a1##ULL<<48)|(a2##ULL<<32)|(a3##ULL<<16)|a4##ULL) 73 # endif 74 # elif (BN_BYTES == 4) 75 # define bn_pack4(a1,a2,a3,a4) ((a3##UL<<16)|a4##UL), ((a1##UL<<16)|a2##UL) 76 # else 77 # error "unsupported BN_BYTES" 78 # endif 79 80 # include "srp_grps.h" 81 82 static BIGNUM *srp_Calc_k(BIGNUM *N, BIGNUM *g) 83 { 84 /* k = SHA1(N | PAD(g)) -- tls-srp draft 8 */ 85 86 unsigned char digest[SHA_DIGEST_LENGTH]; 87 unsigned char *tmp; 88 EVP_MD_CTX ctxt; 89 int longg; 90 int longN = BN_num_bytes(N); 91 92 if (BN_ucmp(g, N) >= 0) 93 return NULL; 94 95 if ((tmp = OPENSSL_malloc(longN)) == NULL) 96 return NULL; 97 BN_bn2bin(N, tmp); 98 99 EVP_MD_CTX_init(&ctxt); 100 EVP_DigestInit_ex(&ctxt, EVP_sha1(), NULL); 101 EVP_DigestUpdate(&ctxt, tmp, longN); 102 103 memset(tmp, 0, longN); 104 longg = BN_bn2bin(g, tmp); 105 /* use the zeros behind to pad on left */ 106 EVP_DigestUpdate(&ctxt, tmp + longg, longN - longg); 107 EVP_DigestUpdate(&ctxt, tmp, longg); 108 OPENSSL_free(tmp); 109 110 EVP_DigestFinal_ex(&ctxt, digest, NULL); 111 EVP_MD_CTX_cleanup(&ctxt); 112 return BN_bin2bn(digest, sizeof(digest), NULL); 113 } 114 115 BIGNUM *SRP_Calc_u(BIGNUM *A, BIGNUM *B, BIGNUM *N) 116 { 117 /* k = SHA1(PAD(A) || PAD(B) ) -- tls-srp draft 8 */ 118 119 BIGNUM *u; 120 unsigned char cu[SHA_DIGEST_LENGTH]; 121 unsigned char *cAB; 122 EVP_MD_CTX ctxt; 123 int longN; 124 if ((A == NULL) || (B == NULL) || (N == NULL)) 125 return NULL; 126 127 if (BN_ucmp(A, N) >= 0 || BN_ucmp(B, N) >= 0) 128 return NULL; 129 130 longN = BN_num_bytes(N); 131 132 if ((cAB = OPENSSL_malloc(2 * longN)) == NULL) 133 return NULL; 134 135 memset(cAB, 0, longN); 136 137 EVP_MD_CTX_init(&ctxt); 138 EVP_DigestInit_ex(&ctxt, EVP_sha1(), NULL); 139 EVP_DigestUpdate(&ctxt, cAB + BN_bn2bin(A, cAB + longN), longN); 140 EVP_DigestUpdate(&ctxt, cAB + BN_bn2bin(B, cAB + longN), longN); 141 OPENSSL_free(cAB); 142 EVP_DigestFinal_ex(&ctxt, cu, NULL); 143 EVP_MD_CTX_cleanup(&ctxt); 144 145 if (!(u = BN_bin2bn(cu, sizeof(cu), NULL))) 146 return NULL; 147 if (!BN_is_zero(u)) 148 return u; 149 BN_free(u); 150 return NULL; 151 } 152 153 BIGNUM *SRP_Calc_server_key(BIGNUM *A, BIGNUM *v, BIGNUM *u, BIGNUM *b, 154 BIGNUM *N) 155 { 156 BIGNUM *tmp = NULL, *S = NULL; 157 BN_CTX *bn_ctx; 158 159 if (u == NULL || A == NULL || v == NULL || b == NULL || N == NULL) 160 return NULL; 161 162 if ((bn_ctx = BN_CTX_new()) == NULL || (tmp = BN_new()) == NULL) 163 goto err; 164 165 /* S = (A*v**u) ** b */ 166 167 if (!BN_mod_exp(tmp, v, u, N, bn_ctx)) 168 goto err; 169 if (!BN_mod_mul(tmp, A, tmp, N, bn_ctx)) 170 goto err; 171 172 S = BN_new(); 173 if (S != NULL && !BN_mod_exp(S, tmp, b, N, bn_ctx)) { 174 BN_free(S); 175 S = NULL; 176 } 177 err: 178 BN_CTX_free(bn_ctx); 179 BN_clear_free(tmp); 180 return S; 181 } 182 183 BIGNUM *SRP_Calc_B(BIGNUM *b, BIGNUM *N, BIGNUM *g, BIGNUM *v) 184 { 185 BIGNUM *kv = NULL, *gb = NULL; 186 BIGNUM *B = NULL, *k = NULL; 187 BN_CTX *bn_ctx; 188 189 if (b == NULL || N == NULL || g == NULL || v == NULL || 190 (bn_ctx = BN_CTX_new()) == NULL) 191 return NULL; 192 193 if ((kv = BN_new()) == NULL || 194 (gb = BN_new()) == NULL || (B = BN_new()) == NULL) 195 goto err; 196 197 /* B = g**b + k*v */ 198 199 if (!BN_mod_exp(gb, g, b, N, bn_ctx) || 200 !(k = srp_Calc_k(N, g)) || 201 !BN_mod_mul(kv, v, k, N, bn_ctx) || 202 !BN_mod_add(B, gb, kv, N, bn_ctx)) { 203 BN_free(B); 204 B = NULL; 205 } 206 err: 207 BN_CTX_free(bn_ctx); 208 BN_clear_free(kv); 209 BN_clear_free(gb); 210 BN_free(k); 211 return B; 212 } 213 214 BIGNUM *SRP_Calc_x(BIGNUM *s, const char *user, const char *pass) 215 { 216 unsigned char dig[SHA_DIGEST_LENGTH]; 217 EVP_MD_CTX ctxt; 218 unsigned char *cs; 219 220 if ((s == NULL) || (user == NULL) || (pass == NULL)) 221 return NULL; 222 223 if ((cs = OPENSSL_malloc(BN_num_bytes(s))) == NULL) 224 return NULL; 225 226 EVP_MD_CTX_init(&ctxt); 227 EVP_DigestInit_ex(&ctxt, EVP_sha1(), NULL); 228 EVP_DigestUpdate(&ctxt, user, strlen(user)); 229 EVP_DigestUpdate(&ctxt, ":", 1); 230 EVP_DigestUpdate(&ctxt, pass, strlen(pass)); 231 EVP_DigestFinal_ex(&ctxt, dig, NULL); 232 233 EVP_DigestInit_ex(&ctxt, EVP_sha1(), NULL); 234 BN_bn2bin(s, cs); 235 EVP_DigestUpdate(&ctxt, cs, BN_num_bytes(s)); 236 OPENSSL_free(cs); 237 EVP_DigestUpdate(&ctxt, dig, sizeof(dig)); 238 EVP_DigestFinal_ex(&ctxt, dig, NULL); 239 EVP_MD_CTX_cleanup(&ctxt); 240 241 return BN_bin2bn(dig, sizeof(dig), NULL); 242 } 243 244 BIGNUM *SRP_Calc_A(BIGNUM *a, BIGNUM *N, BIGNUM *g) 245 { 246 BN_CTX *bn_ctx; 247 BIGNUM *A = NULL; 248 249 if (a == NULL || N == NULL || g == NULL || 250 (bn_ctx = BN_CTX_new()) == NULL) 251 return NULL; 252 253 if ((A = BN_new()) != NULL && !BN_mod_exp(A, g, a, N, bn_ctx)) { 254 BN_free(A); 255 A = NULL; 256 } 257 BN_CTX_free(bn_ctx); 258 return A; 259 } 260 261 BIGNUM *SRP_Calc_client_key(BIGNUM *N, BIGNUM *B, BIGNUM *g, BIGNUM *x, 262 BIGNUM *a, BIGNUM *u) 263 { 264 BIGNUM *tmp = NULL, *tmp2 = NULL, *tmp3 = NULL, *k = NULL, *K = NULL; 265 BN_CTX *bn_ctx; 266 267 if (u == NULL || B == NULL || N == NULL || g == NULL || x == NULL 268 || a == NULL || (bn_ctx = BN_CTX_new()) == NULL) 269 return NULL; 270 271 if ((tmp = BN_new()) == NULL || 272 (tmp2 = BN_new()) == NULL || 273 (tmp3 = BN_new()) == NULL) 274 goto err; 275 276 if (!BN_mod_exp(tmp, g, x, N, bn_ctx)) 277 goto err; 278 if (!(k = srp_Calc_k(N, g))) 279 goto err; 280 if (!BN_mod_mul(tmp2, tmp, k, N, bn_ctx)) 281 goto err; 282 if (!BN_mod_sub(tmp, B, tmp2, N, bn_ctx)) 283 goto err; 284 285 if (!BN_mul(tmp3, u, x, bn_ctx)) 286 goto err; 287 if (!BN_add(tmp2, a, tmp3)) 288 goto err; 289 K = BN_new(); 290 if (K != NULL && !BN_mod_exp(K, tmp, tmp2, N, bn_ctx)) { 291 BN_free(K); 292 K = NULL; 293 } 294 295 err: 296 BN_CTX_free(bn_ctx); 297 BN_clear_free(tmp); 298 BN_clear_free(tmp2); 299 BN_clear_free(tmp3); 300 BN_free(k); 301 return K; 302 } 303 304 int SRP_Verify_B_mod_N(BIGNUM *B, BIGNUM *N) 305 { 306 BIGNUM *r; 307 BN_CTX *bn_ctx; 308 int ret = 0; 309 310 if (B == NULL || N == NULL || (bn_ctx = BN_CTX_new()) == NULL) 311 return 0; 312 313 if ((r = BN_new()) == NULL) 314 goto err; 315 /* Checks if B % N == 0 */ 316 if (!BN_nnmod(r, B, N, bn_ctx)) 317 goto err; 318 ret = !BN_is_zero(r); 319 err: 320 BN_CTX_free(bn_ctx); 321 BN_free(r); 322 return ret; 323 } 324 325 int SRP_Verify_A_mod_N(BIGNUM *A, BIGNUM *N) 326 { 327 /* Checks if A % N == 0 */ 328 return SRP_Verify_B_mod_N(A, N); 329 } 330 331 /* 332 * Check if G and N are kwown parameters. The values have been generated 333 * from the ietf-tls-srp draft version 8 334 */ 335 char *SRP_check_known_gN_param(BIGNUM *g, BIGNUM *N) 336 { 337 size_t i; 338 if ((g == NULL) || (N == NULL)) 339 return 0; 340 341 srp_bn_print(g); 342 srp_bn_print(N); 343 344 for (i = 0; i < KNOWN_GN_NUMBER; i++) { 345 if (BN_cmp(knowngN[i].g, g) == 0 && BN_cmp(knowngN[i].N, N) == 0) 346 return knowngN[i].id; 347 } 348 return NULL; 349 } 350 351 SRP_gN *SRP_get_default_gN(const char *id) 352 { 353 size_t i; 354 355 if (id == NULL) 356 return knowngN; 357 for (i = 0; i < KNOWN_GN_NUMBER; i++) { 358 if (strcmp(knowngN[i].id, id) == 0) 359 return knowngN + i; 360 } 361 return NULL; 362 } 363 #endif 364