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csrp-gmp
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Fix couple of issues 

Adds some changes of csrp forks:
* Pad in H_nn
* Try to become rfc 5054 compatible (still omitting 1536 bit)
* Make calculations of B and S based modulo N (this breaks compat, use with care)
* couple of other fixes (like freeing when aborting, or checking H_nn return value)
master
est31 2015-04-16 19:00:04 +02:00
parent 1d6e37db06
commit e91130a97e
1 changed files with 59 additions and 17 deletions
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76
srp.c
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@ -305,18 +305,45 @@ inline static void mpz_from_bin( const unsigned char * s, int len, mpz_t ret )
mpz_import(ret, len, 1, 1, 1, 0, s);
}
static int H_nn( mpz_t result, SRP_HashAlgorithm alg, const mpz_t n1, const mpz_t n2 )
// set op to (op1 * op2) mod d, using tmp for the calculation
inline static void mpz_mulm( mpz_t op, const mpz_t op1, const mpz_t op2, const mpz_t d, mpz_t tmp )
{
mpz_mul( tmp, op1, op2 );
mpz_mod( op, tmp, d );
}
// set op to (op1 + op2) mod d, using tmp for the calculation
inline static void mpz_addm( mpz_t op, const mpz_t op1, const mpz_t op2, const mpz_t d, mpz_t tmp )
{
mpz_add( tmp, op1, op2 );
mpz_mod( op, tmp, d );
}
// set op to (op1 - op2) mod d, using tmp for the calculation
inline static void mpz_subm( mpz_t op, const mpz_t op1, const mpz_t op2, const mpz_t d, mpz_t tmp )
{
mpz_sub( tmp, op1, op2 );
mpz_mod( op, tmp, d );
}
static int H_nn( mpz_t result, SRP_HashAlgorithm alg, const mpz_t N, const mpz_t n1, const mpz_t n2 )
{
unsigned char buff[ SHA512_DIGEST_LENGTH ];
int len_N = mpz_num_bytes(N);
int len_n1 = mpz_num_bytes(n1);
int len_n2 = mpz_num_bytes(n2);
int nbytes = len_n1 + len_n2;
unsigned char * bin = (unsigned char *) malloc( nbytes );
if (!bin) {
if (!bin)
return 0;
if (len_n1 > len_N || len_n2 > len_N)
{
free(bin);
return 0;
}
mpz_to_bin(n1, bin);
mpz_to_bin(n2, bin + len_n1);
memset(bin, 0, nbytes);
mpz_to_bin(n1, bin + (len_N - len_n1));
mpz_to_bin(n2, bin + (len_N + len_N - len_n2));
hash( alg, bin, nbytes, buff );
free(bin);
mpz_from_bin(buff, hash_length(alg), result);
@ -543,6 +570,7 @@ struct SRPVerifier * srp_verifier_new( SRP_HashAlgorithm alg, SRP_NGType ng_typ
mpz_t k; mpz_init(k);
mpz_t tmp1; mpz_init(tmp1);
mpz_t tmp2; mpz_init(tmp2);
mpz_t tmp3; mpz_init(tmp3);
int ulen = strlen(username) + 1;
NGConstant *ng = new_ng( ng_type, n_hex, g_hex );
struct SRPVerifier *ver = 0;
@ -581,18 +609,28 @@ struct SRPVerifier * srp_verifier_new( SRP_HashAlgorithm alg, SRP_NGType ng_typ
{
mpz_fill_random(b);
H_nn(k, alg, ng->N, ng->g);
if (!H_nn(k, alg, ng->N, ng->N, ng->g))
{
free(ver);
ver = 0;
goto cleanup_and_exit;
}
/* B = kv + g^b */
mpz_mul(tmp1, k, v);
mpz_mulm(tmp1, k, v, ng->N, tmp3);
mpz_powm(tmp2, ng->g, b, ng->N);
mpz_add(B, tmp1, tmp2);
mpz_addm(B, tmp1, tmp2, ng->N, tmp3);
H_nn(u, alg, A, B);
if (!H_nn(u, alg, ng->N, A, B))
{
free(ver);
ver = 0;
goto cleanup_and_exit;
}
/* S = (A *(v^u)) ^ b */
mpz_powm(tmp1, v, u, ng->N);
mpz_mul(tmp2, A, tmp1);
mpz_mulm(tmp2, A, tmp1, ng->N, tmp3);
mpz_powm(S, tmp2, b, ng->N);
hash_num(alg, S, ver->session_key);
@ -615,6 +653,9 @@ struct SRPVerifier * srp_verifier_new( SRP_HashAlgorithm alg, SRP_NGType ng_typ
mpz_to_bin( B, (unsigned char *) *bytes_B );
ver->bytes_B = *bytes_B;
} else {
free(ver);
ver = 0;
}
cleanup_and_exit:
@ -627,6 +668,7 @@ struct SRPVerifier * srp_verifier_new( SRP_HashAlgorithm alg, SRP_NGType ng_typ
mpz_clear(b);
mpz_clear(tmp1);
mpz_clear(tmp2);
mpz_clear(tmp3);
return ver;
}
@ -845,6 +887,7 @@ void srp_user_process_challenge( struct SRPUser * usr,
mpz_t tmp1; mpz_init(tmp1);
mpz_t tmp2; mpz_init(tmp2);
mpz_t tmp3; mpz_init(tmp3);
mpz_t tmp4; mpz_init(tmp4);
*len_M = 0;
*bytes_M = 0;
@ -852,7 +895,7 @@ void srp_user_process_challenge( struct SRPUser * usr,
if( !B || !u || !x || !k || !v || !tmp1 || !tmp2 || !tmp3 )
goto cleanup_and_exit;
if (!H_nn(u, usr->hash_alg, usr->A, B))
if (!H_nn(u, usr->hash_alg, usr->ng->N, usr->A, B))
goto cleanup_and_exit;
calculate_x( x, usr->hash_alg, bytes_s, len_s, usr->username_verifier, usr->password, usr->password_len );
@ -860,9 +903,7 @@ void srp_user_process_challenge( struct SRPUser * usr,
if (!x)
goto cleanup_and_exit;
H_nn(k, usr->hash_alg, usr->ng->N, usr->ng->g);
if (!k)
if (!H_nn(k, usr->hash_alg, usr->ng->N, usr->ng->N, usr->ng->g))
goto cleanup_and_exit;
/* SRP-6a safety check */
@ -872,10 +913,10 @@ void srp_user_process_challenge( struct SRPUser * usr,
/* S = (B - k*(g^x)) ^ (a + ux) */
mpz_mul(tmp1, u, x);
mpz_add(tmp2, usr->a, tmp1); /* tmp2 = (a + ux) */
mpz_powm(tmp1, usr->ng->g, x, usr->ng->N);
mpz_mul(tmp3, k, tmp1); /* tmp3 = k*(g^x) */
mpz_sub(tmp1, B, tmp3); /* tmp1 = (B - K*(g^x)) */
mpz_add(tmp2, usr->a, tmp1); /* tmp2 = (a + ux) */
mpz_powm(tmp1, usr->ng->g, x, usr->ng->N); /* tmp1 = g^x */
mpz_mulm(tmp3, k, tmp1, usr->ng->N, tmp4); /* tmp3 = k*(g^x) */
mpz_subm(tmp1, B, tmp3, usr->ng->N, tmp4); /* tmp1 = (B - K*(g^x)) */
mpz_powm(usr->S, tmp1, tmp2, usr->ng->N);
hash_num(usr->hash_alg, usr->S, usr->session_key);
@ -904,6 +945,7 @@ void srp_user_process_challenge( struct SRPUser * usr,
mpz_clear(tmp1);
mpz_clear(tmp2);
mpz_clear(tmp3);
mpz_clear(tmp4);
}