[331] | 1 | /*
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| 2 | * Copyright 2011-2016 The OpenSSL Project Authors. All Rights Reserved.
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| 3 | *
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| 4 | * Licensed under the OpenSSL license (the "License"). You may not use
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| 5 | * this file except in compliance with the License. You can obtain a copy
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| 6 | * in the file LICENSE in the source distribution or at
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| 7 | * https://www.openssl.org/source/license.html
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| 8 | */
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| 9 |
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| 10 | #ifndef OPENSSL_NO_SRP
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| 11 | # include "internal/cryptlib.h"
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| 12 | # include <openssl/sha.h>
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| 13 | # include <openssl/srp.h>
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| 14 | # include <openssl/evp.h>
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| 15 | # include "internal/bn_srp.h"
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| 16 |
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| 17 | /* calculate = SHA1(PAD(x) || PAD(y)) */
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| 18 |
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| 19 | static BIGNUM *srp_Calc_xy(const BIGNUM *x, const BIGNUM *y, const BIGNUM *N)
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| 20 | {
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| 21 | unsigned char digest[SHA_DIGEST_LENGTH];
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| 22 | unsigned char *tmp = NULL;
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| 23 | int numN = BN_num_bytes(N);
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| 24 | BIGNUM *res = NULL;
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| 25 | if (x != N && BN_ucmp(x, N) >= 0)
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| 26 | return NULL;
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| 27 | if (y != N && BN_ucmp(y, N) >= 0)
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| 28 | return NULL;
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| 29 | if ((tmp = OPENSSL_malloc(numN * 2)) == NULL)
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| 30 | goto err;
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| 31 | if (BN_bn2binpad(x, tmp, numN) < 0
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| 32 | || BN_bn2binpad(y, tmp + numN, numN) < 0
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| 33 | || !EVP_Digest(tmp, numN * 2, digest, NULL, EVP_sha1(), NULL))
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| 34 | goto err;
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| 35 | res = BN_bin2bn(digest, sizeof(digest), NULL);
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| 36 | err:
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| 37 | OPENSSL_free(tmp);
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| 38 | return res;
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| 39 | }
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| 40 |
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| 41 | static BIGNUM *srp_Calc_k(const BIGNUM *N, const BIGNUM *g)
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| 42 | {
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| 43 | /* k = SHA1(N | PAD(g)) -- tls-srp draft 8 */
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| 44 | return srp_Calc_xy(N, g, N);
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| 45 | }
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| 46 |
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| 47 | BIGNUM *SRP_Calc_u(const BIGNUM *A, const BIGNUM *B, const BIGNUM *N)
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| 48 | {
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| 49 | /* k = SHA1(PAD(A) || PAD(B) ) -- tls-srp draft 8 */
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| 50 | return srp_Calc_xy(A, B, N);
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| 51 | }
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| 52 |
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| 53 | BIGNUM *SRP_Calc_server_key(const BIGNUM *A, const BIGNUM *v, const BIGNUM *u,
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| 54 | const BIGNUM *b, const BIGNUM *N)
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| 55 | {
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| 56 | BIGNUM *tmp = NULL, *S = NULL;
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| 57 | BN_CTX *bn_ctx;
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| 58 |
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| 59 | if (u == NULL || A == NULL || v == NULL || b == NULL || N == NULL)
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| 60 | return NULL;
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| 61 |
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| 62 | if ((bn_ctx = BN_CTX_new()) == NULL || (tmp = BN_new()) == NULL)
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| 63 | goto err;
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| 64 |
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| 65 | /* S = (A*v**u) ** b */
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| 66 |
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| 67 | if (!BN_mod_exp(tmp, v, u, N, bn_ctx))
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| 68 | goto err;
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| 69 | if (!BN_mod_mul(tmp, A, tmp, N, bn_ctx))
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| 70 | goto err;
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| 71 |
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| 72 | S = BN_new();
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| 73 | if (S != NULL && !BN_mod_exp(S, tmp, b, N, bn_ctx)) {
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| 74 | BN_free(S);
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| 75 | S = NULL;
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| 76 | }
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| 77 | err:
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| 78 | BN_CTX_free(bn_ctx);
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| 79 | BN_clear_free(tmp);
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| 80 | return S;
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| 81 | }
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| 82 |
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| 83 | BIGNUM *SRP_Calc_B(const BIGNUM *b, const BIGNUM *N, const BIGNUM *g,
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| 84 | const BIGNUM *v)
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| 85 | {
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| 86 | BIGNUM *kv = NULL, *gb = NULL;
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| 87 | BIGNUM *B = NULL, *k = NULL;
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| 88 | BN_CTX *bn_ctx;
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| 89 |
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| 90 | if (b == NULL || N == NULL || g == NULL || v == NULL ||
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| 91 | (bn_ctx = BN_CTX_new()) == NULL)
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| 92 | return NULL;
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| 93 |
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| 94 | if ((kv = BN_new()) == NULL ||
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| 95 | (gb = BN_new()) == NULL || (B = BN_new()) == NULL)
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| 96 | goto err;
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| 97 |
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| 98 | /* B = g**b + k*v */
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| 99 |
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| 100 | if (!BN_mod_exp(gb, g, b, N, bn_ctx)
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| 101 | || (k = srp_Calc_k(N, g)) == NULL
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| 102 | || !BN_mod_mul(kv, v, k, N, bn_ctx)
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| 103 | || !BN_mod_add(B, gb, kv, N, bn_ctx)) {
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| 104 | BN_free(B);
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| 105 | B = NULL;
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| 106 | }
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| 107 | err:
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| 108 | BN_CTX_free(bn_ctx);
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| 109 | BN_clear_free(kv);
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| 110 | BN_clear_free(gb);
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| 111 | BN_free(k);
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| 112 | return B;
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| 113 | }
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| 114 |
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| 115 | BIGNUM *SRP_Calc_x(const BIGNUM *s, const char *user, const char *pass)
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| 116 | {
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| 117 | unsigned char dig[SHA_DIGEST_LENGTH];
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| 118 | EVP_MD_CTX *ctxt;
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| 119 | unsigned char *cs = NULL;
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| 120 | BIGNUM *res = NULL;
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| 121 |
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| 122 | if ((s == NULL) || (user == NULL) || (pass == NULL))
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| 123 | return NULL;
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| 124 |
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| 125 | ctxt = EVP_MD_CTX_new();
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| 126 | if (ctxt == NULL)
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| 127 | return NULL;
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| 128 | if ((cs = OPENSSL_malloc(BN_num_bytes(s))) == NULL)
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| 129 | goto err;
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| 130 |
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| 131 | if (!EVP_DigestInit_ex(ctxt, EVP_sha1(), NULL)
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| 132 | || !EVP_DigestUpdate(ctxt, user, strlen(user))
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| 133 | || !EVP_DigestUpdate(ctxt, ":", 1)
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| 134 | || !EVP_DigestUpdate(ctxt, pass, strlen(pass))
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| 135 | || !EVP_DigestFinal_ex(ctxt, dig, NULL)
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| 136 | || !EVP_DigestInit_ex(ctxt, EVP_sha1(), NULL))
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| 137 | goto err;
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| 138 | BN_bn2bin(s, cs);
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| 139 | if (!EVP_DigestUpdate(ctxt, cs, BN_num_bytes(s)))
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| 140 | goto err;
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| 141 |
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| 142 | if (!EVP_DigestUpdate(ctxt, dig, sizeof(dig))
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| 143 | || !EVP_DigestFinal_ex(ctxt, dig, NULL))
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| 144 | goto err;
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| 145 |
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| 146 | res = BN_bin2bn(dig, sizeof(dig), NULL);
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| 147 |
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| 148 | err:
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| 149 | OPENSSL_free(cs);
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| 150 | EVP_MD_CTX_free(ctxt);
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| 151 | return res;
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| 152 | }
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| 153 |
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| 154 | BIGNUM *SRP_Calc_A(const BIGNUM *a, const BIGNUM *N, const BIGNUM *g)
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| 155 | {
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| 156 | BN_CTX *bn_ctx;
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| 157 | BIGNUM *A = NULL;
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| 158 |
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| 159 | if (a == NULL || N == NULL || g == NULL || (bn_ctx = BN_CTX_new()) == NULL)
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| 160 | return NULL;
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| 161 |
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| 162 | if ((A = BN_new()) != NULL && !BN_mod_exp(A, g, a, N, bn_ctx)) {
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| 163 | BN_free(A);
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| 164 | A = NULL;
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| 165 | }
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| 166 | BN_CTX_free(bn_ctx);
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| 167 | return A;
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| 168 | }
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| 169 |
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| 170 | BIGNUM *SRP_Calc_client_key(const BIGNUM *N, const BIGNUM *B, const BIGNUM *g,
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| 171 | const BIGNUM *x, const BIGNUM *a, const BIGNUM *u)
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| 172 | {
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| 173 | BIGNUM *tmp = NULL, *tmp2 = NULL, *tmp3 = NULL, *k = NULL, *K = NULL;
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| 174 | BN_CTX *bn_ctx;
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| 175 |
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| 176 | if (u == NULL || B == NULL || N == NULL || g == NULL || x == NULL
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| 177 | || a == NULL || (bn_ctx = BN_CTX_new()) == NULL)
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| 178 | return NULL;
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| 179 |
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| 180 | if ((tmp = BN_new()) == NULL ||
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| 181 | (tmp2 = BN_new()) == NULL ||
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| 182 | (tmp3 = BN_new()) == NULL)
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| 183 | goto err;
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| 184 |
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| 185 | if (!BN_mod_exp(tmp, g, x, N, bn_ctx))
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| 186 | goto err;
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| 187 | if ((k = srp_Calc_k(N, g)) == NULL)
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| 188 | goto err;
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| 189 | if (!BN_mod_mul(tmp2, tmp, k, N, bn_ctx))
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| 190 | goto err;
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| 191 | if (!BN_mod_sub(tmp, B, tmp2, N, bn_ctx))
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| 192 | goto err;
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| 193 | if (!BN_mul(tmp3, u, x, bn_ctx))
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| 194 | goto err;
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| 195 | if (!BN_add(tmp2, a, tmp3))
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| 196 | goto err;
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| 197 | K = BN_new();
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| 198 | if (K != NULL && !BN_mod_exp(K, tmp, tmp2, N, bn_ctx)) {
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| 199 | BN_free(K);
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| 200 | K = NULL;
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| 201 | }
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| 202 |
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| 203 | err:
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| 204 | BN_CTX_free(bn_ctx);
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| 205 | BN_clear_free(tmp);
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| 206 | BN_clear_free(tmp2);
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| 207 | BN_clear_free(tmp3);
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| 208 | BN_free(k);
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| 209 | return K;
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| 210 | }
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| 211 |
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| 212 | int SRP_Verify_B_mod_N(const BIGNUM *B, const BIGNUM *N)
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| 213 | {
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| 214 | BIGNUM *r;
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| 215 | BN_CTX *bn_ctx;
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| 216 | int ret = 0;
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| 217 |
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| 218 | if (B == NULL || N == NULL || (bn_ctx = BN_CTX_new()) == NULL)
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| 219 | return 0;
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| 220 |
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| 221 | if ((r = BN_new()) == NULL)
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| 222 | goto err;
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| 223 | /* Checks if B % N == 0 */
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| 224 | if (!BN_nnmod(r, B, N, bn_ctx))
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| 225 | goto err;
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| 226 | ret = !BN_is_zero(r);
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| 227 | err:
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| 228 | BN_CTX_free(bn_ctx);
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| 229 | BN_free(r);
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| 230 | return ret;
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| 231 | }
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| 232 |
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| 233 | int SRP_Verify_A_mod_N(const BIGNUM *A, const BIGNUM *N)
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| 234 | {
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| 235 | /* Checks if A % N == 0 */
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| 236 | return SRP_Verify_B_mod_N(A, N);
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| 237 | }
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| 238 |
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| 239 | static SRP_gN knowngN[] = {
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| 240 | {"8192", &bn_generator_19, &bn_group_8192},
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| 241 | {"6144", &bn_generator_5, &bn_group_6144},
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| 242 | {"4096", &bn_generator_5, &bn_group_4096},
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| 243 | {"3072", &bn_generator_5, &bn_group_3072},
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| 244 | {"2048", &bn_generator_2, &bn_group_2048},
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| 245 | {"1536", &bn_generator_2, &bn_group_1536},
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| 246 | {"1024", &bn_generator_2, &bn_group_1024},
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| 247 | };
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| 248 |
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| 249 | # define KNOWN_GN_NUMBER sizeof(knowngN) / sizeof(SRP_gN)
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| 250 |
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| 251 | /*
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| 252 | * Check if G and N are known parameters. The values have been generated
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| 253 | * from the ietf-tls-srp draft version 8
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| 254 | */
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| 255 | char *SRP_check_known_gN_param(const BIGNUM *g, const BIGNUM *N)
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| 256 | {
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| 257 | size_t i;
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| 258 | if ((g == NULL) || (N == NULL))
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| 259 | return 0;
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| 260 |
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| 261 | for (i = 0; i < KNOWN_GN_NUMBER; i++) {
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| 262 | if (BN_cmp(knowngN[i].g, g) == 0 && BN_cmp(knowngN[i].N, N) == 0)
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| 263 | return knowngN[i].id;
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| 264 | }
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| 265 | return NULL;
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| 266 | }
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| 267 |
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| 268 | SRP_gN *SRP_get_default_gN(const char *id)
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| 269 | {
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| 270 | size_t i;
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| 271 |
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| 272 | if (id == NULL)
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| 273 | return knowngN;
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| 274 | for (i = 0; i < KNOWN_GN_NUMBER; i++) {
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| 275 | if (strcmp(knowngN[i].id, id) == 0)
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| 276 | return knowngN + i;
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| 277 | }
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| 278 | return NULL;
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| 279 | }
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| 280 | #endif
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