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/*
* Copyright 2011-2016 The OpenSSL Project Authors. All Rights Reserved.
*
* Licensed under the OpenSSL license (the "License"). You may not use
* this file except in compliance with the License. You can obtain a copy
* in the file LICENSE in the source distribution or at
* https://www.openssl.org/source/license.html
*/
#ifndef OPENSSL_NO_SRP
# include "internal/cryptlib.h"
# include <openssl/sha.h>
# include <openssl/srp.h>
# include <openssl/evp.h>
# include "internal/bn_srp.h"
/* calculate = SHA1(PAD(x) || PAD(y)) */
static BIGNUM *srp_Calc_xy(const BIGNUM *x, const BIGNUM *y, const BIGNUM *N)
{
unsigned char digest[SHA_DIGEST_LENGTH];
unsigned char *tmp = NULL;
int numN = BN_num_bytes(N);
BIGNUM *res = NULL;
if (x != N && BN_ucmp(x, N) >= 0)
return NULL;
if (y != N && BN_ucmp(y, N) >= 0)
return NULL;
if ((tmp = OPENSSL_malloc(numN * 2)) == NULL)
goto err;
if (BN_bn2binpad(x, tmp, numN) < 0
|| BN_bn2binpad(y, tmp + numN, numN) < 0
|| !EVP_Digest(tmp, numN * 2, digest, NULL, EVP_sha1(), NULL))
goto err;
res = BN_bin2bn(digest, sizeof(digest), NULL);
err:
OPENSSL_free(tmp);
return res;
}
static BIGNUM *srp_Calc_k(const BIGNUM *N, const BIGNUM *g)
{
/* k = SHA1(N | PAD(g)) -- tls-srp draft 8 */
return srp_Calc_xy(N, g, N);
}
BIGNUM *SRP_Calc_u(const BIGNUM *A, const BIGNUM *B, const BIGNUM *N)
{
/* k = SHA1(PAD(A) || PAD(B) ) -- tls-srp draft 8 */
return srp_Calc_xy(A, B, N);
}
BIGNUM *SRP_Calc_server_key(const BIGNUM *A, const BIGNUM *v, const BIGNUM *u,
const BIGNUM *b, const BIGNUM *N)
{
BIGNUM *tmp = NULL, *S = NULL;
BN_CTX *bn_ctx;
if (u == NULL || A == NULL || v == NULL || b == NULL || N == NULL)
return NULL;
if ((bn_ctx = BN_CTX_new()) == NULL || (tmp = BN_new()) == NULL)
goto err;
/* S = (A*v**u) ** b */
if (!BN_mod_exp(tmp, v, u, N, bn_ctx))
goto err;
if (!BN_mod_mul(tmp, A, tmp, N, bn_ctx))
goto err;
S = BN_new();
if (S != NULL && !BN_mod_exp(S, tmp, b, N, bn_ctx)) {
BN_free(S);
S = NULL;
}
err:
BN_CTX_free(bn_ctx);
BN_clear_free(tmp);
return S;
}
BIGNUM *SRP_Calc_B(const BIGNUM *b, const BIGNUM *N, const BIGNUM *g,
const BIGNUM *v)
{
BIGNUM *kv = NULL, *gb = NULL;
BIGNUM *B = NULL, *k = NULL;
BN_CTX *bn_ctx;
if (b == NULL || N == NULL || g == NULL || v == NULL ||
(bn_ctx = BN_CTX_new()) == NULL)
return NULL;
if ((kv = BN_new()) == NULL ||
(gb = BN_new()) == NULL || (B = BN_new()) == NULL)
goto err;
/* B = g**b + k*v */
if (!BN_mod_exp(gb, g, b, N, bn_ctx)
|| (k = srp_Calc_k(N, g)) == NULL
|| !BN_mod_mul(kv, v, k, N, bn_ctx)
|| !BN_mod_add(B, gb, kv, N, bn_ctx)) {
BN_free(B);
B = NULL;
}
err:
BN_CTX_free(bn_ctx);
BN_clear_free(kv);
BN_clear_free(gb);
BN_free(k);
return B;
}
BIGNUM *SRP_Calc_x(const BIGNUM *s, const char *user, const char *pass)
{
unsigned char dig[SHA_DIGEST_LENGTH];
EVP_MD_CTX *ctxt;
unsigned char *cs = NULL;
BIGNUM *res = NULL;
if ((s == NULL) || (user == NULL) || (pass == NULL))
return NULL;
ctxt = EVP_MD_CTX_new();
if (ctxt == NULL)
return NULL;
if ((cs = OPENSSL_malloc(BN_num_bytes(s))) == NULL)
goto err;
if (!EVP_DigestInit_ex(ctxt, EVP_sha1(), NULL)
|| !EVP_DigestUpdate(ctxt, user, strlen(user))
|| !EVP_DigestUpdate(ctxt, ":", 1)
|| !EVP_DigestUpdate(ctxt, pass, strlen(pass))
|| !EVP_DigestFinal_ex(ctxt, dig, NULL)
|| !EVP_DigestInit_ex(ctxt, EVP_sha1(), NULL))
goto err;
BN_bn2bin(s, cs);
if (!EVP_DigestUpdate(ctxt, cs, BN_num_bytes(s)))
goto err;
if (!EVP_DigestUpdate(ctxt, dig, sizeof(dig))
|| !EVP_DigestFinal_ex(ctxt, dig, NULL))
goto err;
res = BN_bin2bn(dig, sizeof(dig), NULL);
err:
OPENSSL_free(cs);
EVP_MD_CTX_free(ctxt);
return res;
}
BIGNUM *SRP_Calc_A(const BIGNUM *a, const BIGNUM *N, const BIGNUM *g)
{
BN_CTX *bn_ctx;
BIGNUM *A = NULL;
if (a == NULL || N == NULL || g == NULL || (bn_ctx = BN_CTX_new()) == NULL)
return NULL;
if ((A = BN_new()) != NULL && !BN_mod_exp(A, g, a, N, bn_ctx)) {
BN_free(A);
A = NULL;
}
BN_CTX_free(bn_ctx);
return A;
}
BIGNUM *SRP_Calc_client_key(const BIGNUM *N, const BIGNUM *B, const BIGNUM *g,
const BIGNUM *x, const BIGNUM *a, const BIGNUM *u)
{
BIGNUM *tmp = NULL, *tmp2 = NULL, *tmp3 = NULL, *k = NULL, *K = NULL;
BN_CTX *bn_ctx;
if (u == NULL || B == NULL || N == NULL || g == NULL || x == NULL
|| a == NULL || (bn_ctx = BN_CTX_new()) == NULL)
return NULL;
if ((tmp = BN_new()) == NULL ||
(tmp2 = BN_new()) == NULL ||
(tmp3 = BN_new()) == NULL)
goto err;
if (!BN_mod_exp(tmp, g, x, N, bn_ctx))
goto err;
if ((k = srp_Calc_k(N, g)) == NULL)
goto err;
if (!BN_mod_mul(tmp2, tmp, k, N, bn_ctx))
goto err;
if (!BN_mod_sub(tmp, B, tmp2, N, bn_ctx))
goto err;
if (!BN_mul(tmp3, u, x, bn_ctx))
goto err;
if (!BN_add(tmp2, a, tmp3))
goto err;
K = BN_new();
if (K != NULL && !BN_mod_exp(K, tmp, tmp2, N, bn_ctx)) {
BN_free(K);
K = NULL;
}
err:
BN_CTX_free(bn_ctx);
BN_clear_free(tmp);
BN_clear_free(tmp2);
BN_clear_free(tmp3);
BN_free(k);
return K;
}
int SRP_Verify_B_mod_N(const BIGNUM *B, const BIGNUM *N)
{
BIGNUM *r;
BN_CTX *bn_ctx;
int ret = 0;
if (B == NULL || N == NULL || (bn_ctx = BN_CTX_new()) == NULL)
return 0;
if ((r = BN_new()) == NULL)
goto err;
/* Checks if B % N == 0 */
if (!BN_nnmod(r, B, N, bn_ctx))
goto err;
ret = !BN_is_zero(r);
err:
BN_CTX_free(bn_ctx);
BN_free(r);
return ret;
}
int SRP_Verify_A_mod_N(const BIGNUM *A, const BIGNUM *N)
{
/* Checks if A % N == 0 */
return SRP_Verify_B_mod_N(A, N);
}
static SRP_gN knowngN[] = {
{"8192", &bn_generator_19, &bn_group_8192},
{"6144", &bn_generator_5, &bn_group_6144},
{"4096", &bn_generator_5, &bn_group_4096},
{"3072", &bn_generator_5, &bn_group_3072},
{"2048", &bn_generator_2, &bn_group_2048},
{"1536", &bn_generator_2, &bn_group_1536},
{"1024", &bn_generator_2, &bn_group_1024},
};
# define KNOWN_GN_NUMBER sizeof(knowngN) / sizeof(SRP_gN)
/*
* Check if G and N are known parameters. The values have been generated
* from the ietf-tls-srp draft version 8
*/
char *SRP_check_known_gN_param(const BIGNUM *g, const BIGNUM *N)
{
size_t i;
if ((g == NULL) || (N == NULL))
return 0;
for (i = 0; i < KNOWN_GN_NUMBER; i++) {
if (BN_cmp(knowngN[i].g, g) == 0 && BN_cmp(knowngN[i].N, N) == 0)
return knowngN[i].id;
}
return NULL;
}
SRP_gN *SRP_get_default_gN(const char *id)
{
size_t i;
if (id == NULL)
return knowngN;
for (i = 0; i < KNOWN_GN_NUMBER; i++) {
if (strcmp(knowngN[i].id, id) == 0)
return knowngN + i;
}
return NULL;
}
#endif
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