/* crypto/srp/srp_lib.c */
/* Written by Christophe Renou (christophe.renou@edelweb.fr) with
* the precious help of Peter Sylvester (peter.sylvester@edelweb.fr)
* for the EdelKey project and contributed to the OpenSSL project 2004.
*/
/* ====================================================================
* Copyright (c) 2004 The OpenSSL Project. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* 3. All advertising materials mentioning features or use of this
* software must display the following acknowledgment:
* "This product includes software developed by the OpenSSL Project
* for use in the OpenSSL Toolkit. (http://www.OpenSSL.org/)"
*
* 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
* endorse or promote products derived from this software without
* prior written permission. For written permission, please contact
* licensing@OpenSSL.org.
*
* 5. Products derived from this software may not be called "OpenSSL"
* nor may "OpenSSL" appear in their names without prior written
* permission of the OpenSSL Project.
*
* 6. Redistributions of any form whatsoever must retain the following
* acknowledgment:
* "This product includes software developed by the OpenSSL Project
* for use in the OpenSSL Toolkit (http://www.OpenSSL.org/)"
*
* THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
* EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR
* ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
* OF THE POSSIBILITY OF SUCH DAMAGE.
* ====================================================================
*
* This product includes cryptographic software written by Eric Young
* (eay@cryptsoft.com). This product includes software written by Tim
* Hudson (tjh@cryptsoft.com).
*
*/
#ifndef OPENSSL_NO_SRP
#include "cryptlib.h"
#include "srp_lcl.h"
#include <openssl/srp.h>
#include <openssl/evp.h>
#if (BN_BYTES == 8)
#define bn_pack4(a1,a2,a3,a4) 0x##a1##a2##a3##a4##ul
#endif
#if (BN_BYTES == 4)
#define bn_pack4(a1,a2,a3,a4) 0x##a3##a4##ul, 0x##a1##a2##ul
#endif
#if (BN_BYTES == 2)
#define bn_pack4(a1,a2,a3,a4) 0x##a4##u,0x##a3##u,0x##a2##u,0x##a1##u
#endif
#include "srp_grps.h"
static BIGNUM *srp_Calc_k(BIGNUM *N, BIGNUM *g)
{
/* k = SHA1(N | PAD(g)) -- tls-srp draft 8 */
unsigned char digest[SHA_DIGEST_LENGTH];
unsigned char *tmp;
EVP_MD_CTX ctxt;
int longg ;
int longN = BN_num_bytes(N);
if ((tmp = OPENSSL_malloc(longN)) == NULL)
return NULL;
BN_bn2bin(N,tmp) ;
EVP_MD_CTX_init(&ctxt);
EVP_DigestInit_ex(&ctxt, EVP_sha1(), NULL);
EVP_DigestUpdate(&ctxt, tmp, longN);
memset(tmp, 0, longN);
longg = BN_bn2bin(g,tmp) ;
/* use the zeros behind to pad on left */
EVP_DigestUpdate(&ctxt, tmp + longg, longN-longg);
EVP_DigestUpdate(&ctxt, tmp, longg);
OPENSSL_free(tmp);
EVP_DigestFinal_ex(&ctxt, digest, NULL);
EVP_MD_CTX_cleanup(&ctxt);
return BN_bin2bn(digest, sizeof(digest), NULL);
}
BIGNUM *SRP_Calc_u(BIGNUM *A, BIGNUM *B, BIGNUM *N)
{
/* k = SHA1(PAD(A) || PAD(B) ) -- tls-srp draft 8 */
BIGNUM *u;
unsigned char cu[SHA_DIGEST_LENGTH];
unsigned char *cAB;
EVP_MD_CTX ctxt;
int longN;
if ((A == NULL) ||(B == NULL) || (N == NULL))
return NULL;
longN= BN_num_bytes(N);
if ((cAB = OPENSSL_malloc(2*longN)) == NULL)
return NULL;
memset(cAB, 0, longN);
EVP_MD_CTX_init(&ctxt);
EVP_DigestInit_ex(&ctxt, EVP_sha1(), NULL);
EVP_DigestUpdate(&ctxt, cAB + BN_bn2bin(A,cAB+longN), longN);
EVP_DigestUpdate(&ctxt, cAB + BN_bn2bin(B,cAB+longN), longN);
OPENSSL_free(cAB);
EVP_DigestFinal_ex(&ctxt, cu, NULL);
EVP_MD_CTX_cleanup(&ctxt);
if (!(u = BN_bin2bn(cu, sizeof(cu), NULL)))
return NULL;
if (!BN_is_zero(u))
return u;
BN_free(u);
return NULL;
}
BIGNUM *SRP_Calc_server_key(BIGNUM *A, BIGNUM *v, BIGNUM *u, BIGNUM *b, 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 ||
(S = 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;
if (!BN_mod_exp(S,tmp,b,N,bn_ctx))
goto err;
err:
BN_CTX_free(bn_ctx);
BN_clear_free(tmp);
return S;
}
BIGNUM *SRP_Calc_B(BIGNUM *b, BIGNUM *N, BIGNUM *g, 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)) ||
!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(BIGNUM *s, const char *user, const char *pass)
{
unsigned char dig[SHA_DIGEST_LENGTH];
EVP_MD_CTX ctxt;
unsigned char *cs;
if ((s == NULL) ||
(user == NULL) ||
(pass == NULL))
return NULL;
if ((cs = OPENSSL_malloc(BN_num_bytes(s))) == NULL)
return NULL;
EVP_MD_CTX_init(&ctxt);
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);
BN_bn2bin(s,cs);
EVP_DigestUpdate(&ctxt, cs, BN_num_bytes(s));
OPENSSL_free(cs);
EVP_DigestUpdate(&ctxt, dig, sizeof(dig));
EVP_DigestFinal_ex(&ctxt, dig, NULL);
EVP_MD_CTX_cleanup(&ctxt);
return BN_bin2bn(dig, sizeof(dig), NULL);
}
BIGNUM *SRP_Calc_A(BIGNUM *a, BIGNUM *N, 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(BIGNUM *N, BIGNUM *B, BIGNUM *g, BIGNUM *x, BIGNUM *a, 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 ||
(K = BN_new()) == NULL)
goto err;
if (!BN_mod_exp(tmp,g,x,N,bn_ctx))
goto err;
if (!(k = srp_Calc_k(N,g)))
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_mod_mul(tmp3,u,x,N,bn_ctx))
goto err;
if (!BN_mod_add(tmp2,a,tmp3,N,bn_ctx))
goto err;
if (!BN_mod_exp(K,tmp,tmp2,N,bn_ctx))
goto err;
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(BIGNUM *B, 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(BIGNUM *A, BIGNUM *N)
{
/* Checks if A % N == 0 */
return SRP_Verify_B_mod_N(A,N) ;
}
/* Check if G and N are kwown parameters.
The values have been generated from the ietf-tls-srp draft version 8
*/
char *SRP_check_known_gN_param(BIGNUM *g, BIGNUM *N)
{
size_t i;
if ((g == NULL) || (N == NULL))
return 0;
srp_bn_print(g);
srp_bn_print(N);
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