crypto/srp/srp_lib.c

   1 /*
   2  * Copyright 2004-2020 The OpenSSL Project Authors. All Rights Reserved.
   3  * Copyright (c) 2004, EdelKey Project. All Rights Reserved.
   4  *
   5  * Licensed under the Apache License 2.0 (the "License").  You may not use
   6  * this file except in compliance with the License.  You can obtain a copy
   7  * in the file LICENSE in the source distribution or at
   8  * https://www.openssl.org/source/license.html
   9  *
  10  * Originally written by Christophe Renou and Peter Sylvester,
  11  * for the EdelKey project.
  12  */
  13
  14 #ifndef OPENSSL_NO_SRP
  15 # include "internal/cryptlib.h"
  16 # include <openssl/sha.h>
  17 # include <openssl/srp.h>
  18 # include <openssl/evp.h>
  19 # include "crypto/bn_srp.h"
  20
  21 /* calculate = SHA1(PAD(x) || PAD(y)) */
  22
  23 static BIGNUM *srp_Calc_xy(const BIGNUM *x, const BIGNUM *y, const BIGNUM *N,
  24                            OPENSSL_CTX *libctx, const char *propq)
  25 {
  26     unsigned char digest[SHA_DIGEST_LENGTH];
  27     unsigned char *tmp = NULL;
  28     int numN = BN_num_bytes(N);
  29     BIGNUM *res = NULL;
  30     EVP_MD *sha1 = EVP_MD_fetch(libctx, "SHA1", propq);
  31
  32     if (sha1 == NULL)
  33         return NULL;
  34
  35     if (x != N && BN_ucmp(x, N) >= 0)
  36         goto err;
  37     if (y != N && BN_ucmp(y, N) >= 0)
  38         goto err;
  39     if ((tmp = OPENSSL_malloc(numN * 2)) == NULL)
  40         goto err;
  41     if (BN_bn2binpad(x, tmp, numN) < 0
  42         || BN_bn2binpad(y, tmp + numN, numN) < 0
  43         || !EVP_Digest(tmp, numN * 2, digest, NULL, sha1, NULL))
  44         goto err;
  45     res = BN_bin2bn(digest, sizeof(digest), NULL);
  46  err:
  47     EVP_MD_free(sha1);
  48     OPENSSL_free(tmp);
  49     return res;
  50 }
  51
  52 static BIGNUM *srp_Calc_k(const BIGNUM *N, const BIGNUM *g, OPENSSL_CTX *libctx,
  53                           const char *propq)
  54 {
  55     /* k = SHA1(N | PAD(g)) -- tls-srp RFC 5054 */
  56     return srp_Calc_xy(N, g, N, libctx, propq);
  57 }
  58
  59 BIGNUM *SRP_Calc_u_ex(const BIGNUM *A, const BIGNUM *B, const BIGNUM *N,
  60                       OPENSSL_CTX *libctx, const char *propq)
  61 {
  62     /* u = SHA1(PAD(A) || PAD(B) ) -- tls-srp RFC 5054 */
  63     return srp_Calc_xy(A, B, N, libctx, propq);
  64 }
  65
  66 BIGNUM *SRP_Calc_u(const BIGNUM *A, const BIGNUM *B, const BIGNUM *N)
  67 {
  68     /* u = SHA1(PAD(A) || PAD(B) ) -- tls-srp RFC 5054 */
  69     return srp_Calc_xy(A, B, N, NULL, NULL);
  70 }
  71
  72 BIGNUM *SRP_Calc_server_key(const BIGNUM *A, const BIGNUM *v, const BIGNUM *u,
  73                             const BIGNUM *b, const BIGNUM *N)
  74 {
  75     BIGNUM *tmp = NULL, *S = NULL;
  76     BN_CTX *bn_ctx;
  77
  78     if (u == NULL || A == NULL || v == NULL || b == NULL || N == NULL)
  79         return NULL;
  80
  81     if ((bn_ctx = BN_CTX_new()) == NULL || (tmp = BN_new()) == NULL)
  82         goto err;
  83
  84     /* S = (A*v**u) ** b */
  85
  86     if (!BN_mod_exp(tmp, v, u, N, bn_ctx))
  87         goto err;
  88     if (!BN_mod_mul(tmp, A, tmp, N, bn_ctx))
  89         goto err;
  90
  91     S = BN_new();
  92     if (S != NULL && !BN_mod_exp(S, tmp, b, N, bn_ctx)) {
  93         BN_free(S);
  94         S = NULL;
  95     }
  96  err:
  97     BN_CTX_free(bn_ctx);
  98     BN_clear_free(tmp);
  99     return S;
 100 }
 101
 102 BIGNUM *SRP_Calc_B_ex(const BIGNUM *b, const BIGNUM *N, const BIGNUM *g,
 103                       const BIGNUM *v, OPENSSL_CTX *libctx, const char *propq)
 104 {
 105     BIGNUM *kv = NULL, *gb = NULL;
 106     BIGNUM *B = NULL, *k = NULL;
 107     BN_CTX *bn_ctx;
 108
 109     if (b == NULL || N == NULL || g == NULL || v == NULL ||
 110         (bn_ctx = BN_CTX_new_ex(libctx)) == NULL)
 111         return NULL;
 112
 113     if ((kv = BN_new()) == NULL ||
 114         (gb = BN_new()) == NULL || (B = BN_new()) == NULL)
 115         goto err;
 116
 117     /* B = g**b + k*v */
 118
 119     if (!BN_mod_exp(gb, g, b, N, bn_ctx)
 120         || (k = srp_Calc_k(N, g, libctx, propq)) == NULL
 121         || !BN_mod_mul(kv, v, k, N, bn_ctx)
 122         || !BN_mod_add(B, gb, kv, N, bn_ctx)) {
 123         BN_free(B);
 124         B = NULL;
 125     }
 126  err:
 127     BN_CTX_free(bn_ctx);
 128     BN_clear_free(kv);
 129     BN_clear_free(gb);
 130     BN_free(k);
 131     return B;
 132 }
 133
 134 BIGNUM *SRP_Calc_B(const BIGNUM *b, const BIGNUM *N, const BIGNUM *g,
 135                    const BIGNUM *v)
 136 {
 137     return SRP_Calc_B_ex(b, N, g, v, NULL, NULL);
 138 }
 139
 140 BIGNUM *SRP_Calc_x_ex(const BIGNUM *s, const char *user, const char *pass,
 141                       OPENSSL_CTX *libctx, const char *propq)
 142 {
 143     unsigned char dig[SHA_DIGEST_LENGTH];
 144     EVP_MD_CTX *ctxt;
 145     unsigned char *cs = NULL;
 146     BIGNUM *res = NULL;
 147     EVP_MD *sha1 = NULL;
 148
 149     if ((s == NULL) || (user == NULL) || (pass == NULL))
 150         return NULL;
 151
 152     ctxt = EVP_MD_CTX_new();
 153     if (ctxt == NULL)
 154         return NULL;
 155     if ((cs = OPENSSL_malloc(BN_num_bytes(s))) == NULL)
 156         goto err;
 157
 158     sha1 = EVP_MD_fetch(libctx, "SHA1", propq);
 159     if (sha1 == NULL)
 160         goto err;
 161
 162     if (!EVP_DigestInit_ex(ctxt, sha1, NULL)
 163         || !EVP_DigestUpdate(ctxt, user, strlen(user))
 164         || !EVP_DigestUpdate(ctxt, ":", 1)
 165         || !EVP_DigestUpdate(ctxt, pass, strlen(pass))
 166         || !EVP_DigestFinal_ex(ctxt, dig, NULL)
 167         || !EVP_DigestInit_ex(ctxt, sha1, NULL))
 168         goto err;
 169     if (BN_bn2bin(s, cs) < 0)
 170         goto err;
 171     if (!EVP_DigestUpdate(ctxt, cs, BN_num_bytes(s)))
 172         goto err;
 173
 174     if (!EVP_DigestUpdate(ctxt, dig, sizeof(dig))
 175         || !EVP_DigestFinal_ex(ctxt, dig, NULL))
 176         goto err;
 177
 178     res = BN_bin2bn(dig, sizeof(dig), NULL);
 179
 180  err:
 181     EVP_MD_free(sha1);
 182     OPENSSL_free(cs);
 183     EVP_MD_CTX_free(ctxt);
 184     return res;
 185 }
 186
 187 BIGNUM *SRP_Calc_x(const BIGNUM *s, const char *user, const char *pass)
 188 {
 189     return SRP_Calc_x_ex(s, user, pass, NULL, NULL);
 190 }
 191
 192 BIGNUM *SRP_Calc_A(const BIGNUM *a, const BIGNUM *N, const BIGNUM *g)
 193 {
 194     BN_CTX *bn_ctx;
 195     BIGNUM *A = NULL;
 196
 197     if (a == NULL || N == NULL || g == NULL || (bn_ctx = BN_CTX_new()) == NULL)
 198         return NULL;
 199
 200     if ((A = BN_new()) != NULL && !BN_mod_exp(A, g, a, N, bn_ctx)) {
 201         BN_free(A);
 202         A = NULL;
 203     }
 204     BN_CTX_free(bn_ctx);
 205     return A;
 206 }
 207
 208 BIGNUM *SRP_Calc_client_key_ex(const BIGNUM *N, const BIGNUM *B, const BIGNUM *g,
 209                             const BIGNUM *x, const BIGNUM *a, const BIGNUM *u,
 210                             OPENSSL_CTX *libctx, const char *propq)
 211 {
 212     BIGNUM *tmp = NULL, *tmp2 = NULL, *tmp3 = NULL, *k = NULL, *K = NULL;
 213     BN_CTX *bn_ctx;
 214
 215     if (u == NULL || B == NULL || N == NULL || g == NULL || x == NULL
 216         || a == NULL || (bn_ctx = BN_CTX_new_ex(libctx)) == NULL)
 217         return NULL;
 218
 219     if ((tmp = BN_new()) == NULL ||
 220         (tmp2 = BN_new()) == NULL ||
 221         (tmp3 = BN_new()) == NULL)
 222         goto err;
 223
 224     if (!BN_mod_exp(tmp, g, x, N, bn_ctx))
 225         goto err;
 226     if ((k = srp_Calc_k(N, g, libctx, propq)) == NULL)
 227         goto err;
 228     if (!BN_mod_mul(tmp2, tmp, k, N, bn_ctx))
 229         goto err;
 230     if (!BN_mod_sub(tmp, B, tmp2, N, bn_ctx))
 231         goto err;
 232     if (!BN_mul(tmp3, u, x, bn_ctx))
 233         goto err;
 234     if (!BN_add(tmp2, a, tmp3))
 235         goto err;
 236     K = BN_new();
 237     if (K != NULL && !BN_mod_exp(K, tmp, tmp2, N, bn_ctx)) {
 238         BN_free(K);
 239         K = NULL;
 240     }
 241
 242  err:
 243     BN_CTX_free(bn_ctx);
 244     BN_clear_free(tmp);
 245     BN_clear_free(tmp2);
 246     BN_clear_free(tmp3);
 247     BN_free(k);
 248     return K;
 249 }
 250
 251 BIGNUM *SRP_Calc_client_key(const BIGNUM *N, const BIGNUM *B, const BIGNUM *g,
 252                             const BIGNUM *x, const BIGNUM *a, const BIGNUM *u)
 253 {
 254     return SRP_Calc_client_key_ex(N, B, g, x, a, u, NULL, NULL);
 255 }
 256
 257 int SRP_Verify_B_mod_N(const BIGNUM *B, const BIGNUM *N)
 258 {
 259     BIGNUM *r;
 260     BN_CTX *bn_ctx;
 261     int ret = 0;
 262
 263     if (B == NULL || N == NULL || (bn_ctx = BN_CTX_new()) == NULL)
 264         return 0;
 265
 266     if ((r = BN_new()) == NULL)
 267         goto err;
 268     /* Checks if B % N == 0 */
 269     if (!BN_nnmod(r, B, N, bn_ctx))
 270         goto err;
 271     ret = !BN_is_zero(r);
 272  err:
 273     BN_CTX_free(bn_ctx);
 274     BN_free(r);
 275     return ret;
 276 }
 277
 278 int SRP_Verify_A_mod_N(const BIGNUM *A, const BIGNUM *N)
 279 {
 280     /* Checks if A % N == 0 */
 281     return SRP_Verify_B_mod_N(A, N);
 282 }
 283
 284 static SRP_gN knowngN[] = {
 285     {"8192", &bn_generator_19, &bn_group_8192},
 286     {"6144", &bn_generator_5, &bn_group_6144},
 287     {"4096", &bn_generator_5, &bn_group_4096},
 288     {"3072", &bn_generator_5, &bn_group_3072},
 289     {"2048", &bn_generator_2, &bn_group_2048},
 290     {"1536", &bn_generator_2, &bn_group_1536},
 291     {"1024", &bn_generator_2, &bn_group_1024},
 292 };
 293
 294 # define KNOWN_GN_NUMBER sizeof(knowngN) / sizeof(SRP_gN)
 295
 296 /*
 297  * Check if G and N are known parameters. The values have been generated
 298  * from the IETF RFC 5054
 299  */
 300 char *SRP_check_known_gN_param(const BIGNUM *g, const BIGNUM *N)
 301 {
 302     size_t i;
 303     if ((g == NULL) || (N == NULL))
 304         return NULL;
 305
 306     for (i = 0; i < KNOWN_GN_NUMBER; i++) {
 307         if (BN_cmp(knowngN[i].g, g) == 0 && BN_cmp(knowngN[i].N, N) == 0)
 308             return knowngN[i].id;
 309     }
 310     return NULL;
 311 }
 312
 313 SRP_gN *SRP_get_default_gN(const char *id)
 314 {
 315     size_t i;
 316
 317     if (id == NULL)
 318         return knowngN;
 319     for (i = 0; i < KNOWN_GN_NUMBER; i++) {
 320         if (strcmp(knowngN[i].id, id) == 0)
 321             return knowngN + i;
 322     }
 323     return NULL;
 324 }
 325 #endif