/* return A = g^a % N */
int
_gnutls_gen_srp_client_kx (gnutls_session_t session, opaque ** data)
{
size_t n_a;
int ret;
uint8_t *data_a;
char *username, *password;
char buf[64];
gnutls_srp_client_credentials_t cred;
cred = (gnutls_srp_client_credentials_t)
_gnutls_get_cred (session->key, GNUTLS_CRD_SRP, NULL);
if (cred == NULL)
{
gnutls_assert ();
return GNUTLS_E_INSUFFICIENT_CREDENTIALS;
}
if (session->internals.srp_username == NULL)
{
username = cred->username;
password = cred->password;
}
else
{
username = session->internals.srp_username;
password = session->internals.srp_password;
}
if (username == NULL || password == NULL)
{
gnutls_assert ();
return GNUTLS_E_INSUFFICIENT_CREDENTIALS;
}
/* calc A = g^a % N
*/
if (G == NULL || N == NULL)
{
gnutls_assert ();
return GNUTLS_E_INSUFFICIENT_CREDENTIALS;
}
A = _gnutls_calc_srp_A (&_a, G, N);
if (A == NULL)
{
gnutls_assert ();
return GNUTLS_E_MEMORY_ERROR;
}
/* Rest of SRP calculations
*/
/* calculate u */
session->key->u = _gnutls_calc_srp_u (A, B, N);
if (session->key->u == NULL)
{
gnutls_assert ();
return GNUTLS_E_MEMORY_ERROR;
}
_gnutls_dump_mpi ("SRP U: ", session->key->u);
/* S = (B - g^x) ^ (a + u * x) % N */
S = _gnutls_calc_srp_S2 (B, G, session->key->x, _a, session->key->u, N);
if (S == NULL)
{
gnutls_assert ();
return GNUTLS_E_MEMORY_ERROR;
}
_gnutls_dump_mpi ("SRP B: ", B);
_gnutls_mpi_release (&_b);
_gnutls_mpi_release (&V);
_gnutls_mpi_release (&session->key->u);
_gnutls_mpi_release (&B);
ret = _gnutls_mpi_dprint (&session->key->key, session->key->KEY);
_gnutls_mpi_release (&S);
if (ret < 0)
{
gnutls_assert();
return ret;
}
if (_gnutls_mpi_print (NULL, &n_a, A) != 0)
{
gnutls_assert ();
return GNUTLS_E_MPI_PRINT_FAILED;
}
(*data) = gnutls_malloc (n_a + 2);
if ((*data) == NULL)
{
gnutls_assert ();
return GNUTLS_E_MEMORY_ERROR;
}
/* copy A */
data_a = (*data);
if (_gnutls_mpi_print (&data_a[2], &n_a, A) != 0)
{
gnutls_free (*data);
return GNUTLS_E_MPI_PRINT_FAILED;
}
_gnutls_hard_log ("INT: SRP A[%d]: %s\n", n_a,
_gnutls_bin2hex (&data_a[2], n_a, buf, sizeof (buf)));
_gnutls_mpi_release (&A);
_gnutls_write_uint16 (n_a, data_a);
return n_a + 2;
}
/* return A = g^a % N */
int
_gnutls_gen_srp_client_kx(gnutls_session_t session,
gnutls_buffer_st * data)
{
int ret;
char *username, *password;
gnutls_srp_client_credentials_t cred;
extension_priv_data_t epriv;
srp_ext_st *priv;
ret =
_gnutls_ext_get_session_data(session, GNUTLS_EXTENSION_SRP,
&epriv);
if (ret < 0) { /* peer didn't send a username */
gnutls_assert();
return GNUTLS_E_UNKNOWN_SRP_USERNAME;
}
priv = epriv;
cred = (gnutls_srp_client_credentials_t)
_gnutls_get_cred(session, GNUTLS_CRD_SRP);
if (cred == NULL) {
gnutls_assert();
return GNUTLS_E_INSUFFICIENT_CREDENTIALS;
}
if (priv->username == NULL) {
username = cred->username;
password = cred->password;
} else {
username = priv->username;
password = priv->password;
}
if (username == NULL || password == NULL) {
gnutls_assert();
return GNUTLS_E_INSUFFICIENT_CREDENTIALS;
}
/* calc A = g^a % N
*/
if (G == NULL || N == NULL) {
gnutls_assert();
return GNUTLS_E_INSUFFICIENT_CREDENTIALS;
}
A = _gnutls_calc_srp_A(&_a, G, N);
if (A == NULL) {
gnutls_assert();
return GNUTLS_E_MEMORY_ERROR;
}
/* Rest of SRP calculations
*/
/* calculate u */
session->key.u = _gnutls_calc_srp_u(A, B, N);
if (session->key.u == NULL) {
gnutls_assert();
return GNUTLS_E_MEMORY_ERROR;
}
_gnutls_mpi_log("SRP U: ", session->key.u);
/* S = (B - g^x) ^ (a + u * x) % N */
S = _gnutls_calc_srp_S2(B, G, session->key.x, _a, session->key.u,
N);
if (S == NULL) {
gnutls_assert();
return GNUTLS_E_MEMORY_ERROR;
}
_gnutls_mpi_log("SRP B: ", B);
zrelease_temp_mpi_key(&_b);
zrelease_temp_mpi_key(&V);
zrelease_temp_mpi_key(&session->key.u);
zrelease_temp_mpi_key(&B);
ret = _gnutls_mpi_dprint(session->key.srp_key, &session->key.key);
zrelease_temp_mpi_key(&S);
if (ret < 0) {
gnutls_assert();
return ret;
}
ret = _gnutls_buffer_append_mpi(data, 16, A, 0);
if (ret < 0)
return gnutls_assert_val(ret);
_gnutls_mpi_log("SRP A: ", A);
_gnutls_mpi_release(&A);
return data->length;
}