/* * Copyright (C) 2001,2002,2003 Nikos Mavroyanopoulos * Copyright (C) 2004 Free Software Foundation * * This file is part of GNUTLS. * * GNUTLS-EXTRA is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 2 of the License, or * (at your option) any later version. * * GNUTLS-EXTRA is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA */ #include "gnutls_int.h" #ifdef ENABLE_SRP #include "gnutls_errors.h" #include "auth_srp_passwd.h" #include "gnutls_auth.h" #include "gnutls_auth_int.h" #include "gnutls_srp.h" #include "debug.h" #include "gnutls_num.h" #include "auth_srp.h" #include #include #include int _gnutls_gen_srp_server_kx(gnutls_session, opaque **); int _gnutls_gen_srp_client_kx(gnutls_session, opaque **); int _gnutls_proc_srp_server_kx(gnutls_session, opaque *, size_t); int _gnutls_proc_srp_client_kx(gnutls_session, opaque *, size_t); const MOD_AUTH_STRUCT srp_auth_struct = { "SRP", NULL, NULL, _gnutls_gen_srp_server_kx, _gnutls_gen_srp_client_kx, NULL, NULL, NULL, NULL, /* certificate */ _gnutls_proc_srp_server_kx, _gnutls_proc_srp_client_kx, NULL, NULL }; #define _b session->key->b #define B session->key->B #define _a session->key->a #define A session->key->A #define N session->key->client_p #define G session->key->client_g #define V session->key->x #define S session->key->KEY /* Checks if b%n==0 which is a fatal srp error. * Returns a proper error code in that case, and 0 when * all are ok. */ inline static int check_b_mod_n( GNUTLS_MPI b, GNUTLS_MPI n) { int ret; GNUTLS_MPI r = _gnutls_mpi_alloc_like(b); if (r == NULL) { gnutls_assert(); return GNUTLS_E_MEMORY_ERROR; } _gnutls_mpi_mod( r, b, n); ret = _gnutls_mpi_cmp_ui(r, 0); _gnutls_mpi_release( &r); if (ret == 0) { gnutls_assert(); return GNUTLS_E_RECEIVED_ILLEGAL_PARAMETER; } return 0; } /* Checks if a%n==0,+1,-1%n which is a fatal srp error. * Returns a proper error code in that case, and 0 when * all are ok. */ inline static int check_a_mod_n( GNUTLS_MPI a, GNUTLS_MPI n) { int ret; GNUTLS_MPI r = _gnutls_mpi_alloc_like(a); if (r == NULL) { gnutls_assert(); return GNUTLS_E_MEMORY_ERROR; } _gnutls_mpi_mod( r, a, n); ret = _gnutls_mpi_cmp_ui(r, 0); if (ret != 0) ret = _gnutls_mpi_cmp_ui(r, 1); if (ret != 0) { _gnutls_mpi_sub_ui( r, n, 1); ret = _gnutls_mpi_cmp(a, r); } _gnutls_mpi_release( &r); if (ret == 0) { gnutls_assert(); return GNUTLS_E_RECEIVED_ILLEGAL_PARAMETER; } return 0; } /* Send the first key exchange message ( g, n, s) and append the verifier algorithm number * Data is allocated by the caller, and should have data_size size. */ int _gnutls_gen_srp_server_kx(gnutls_session session, opaque ** data) { int ret; uint8 *data_n, *data_s; uint8 *data_g; char *username; SRP_PWD_ENTRY *pwd_entry; SRP_SERVER_AUTH_INFO info; ssize_t data_size; size_t n_b, tmp_size; char buf[64]; uint8 *data_b; if ( (ret=_gnutls_auth_info_set( session, GNUTLS_CRD_SRP, sizeof( SRP_SERVER_AUTH_INFO_INT), 1)) < 0) { gnutls_assert(); return ret; } info = _gnutls_get_auth_info( session); username = info->username; _gnutls_str_cpy( username, MAX_SRP_USERNAME, session->security_parameters.extensions.srp_username); ret = _gnutls_srp_pwd_read_entry( session, username, &pwd_entry); if (ret < 0) { gnutls_assert(); return ret; } /* copy from pwd_entry to local variables (actually in session) */ if (_gnutls_mpi_scan( &G, pwd_entry->g.data, &pwd_entry->g.size) < 0) { gnutls_assert(); return GNUTLS_E_MPI_SCAN_FAILED; } tmp_size = pwd_entry->n.size; if (_gnutls_mpi_scan( &N, pwd_entry->n.data, &tmp_size) < 0) { gnutls_assert(); return GNUTLS_E_MPI_SCAN_FAILED; } tmp_size = pwd_entry->v.size; if (_gnutls_mpi_scan( &V, pwd_entry->v.data, &tmp_size) < 0) { gnutls_assert(); return GNUTLS_E_MPI_SCAN_FAILED; } /* Calculate: B = (3v + g^b) % N */ B = _gnutls_calc_srp_B( &_b, G, N, V); if (B==NULL) { gnutls_assert(); return GNUTLS_E_MEMORY_ERROR; } if (_gnutls_mpi_print( NULL, &n_b, B)!=0) { gnutls_assert(); return GNUTLS_E_MPI_PRINT_FAILED; } /* Allocate size to hold the N, g, s, B */ data_size = (pwd_entry->n.size + 2 + pwd_entry->g.size + 2 + pwd_entry->salt.size + 1) + (n_b + 2); (*data) = gnutls_malloc( data_size); if ( (*data) == NULL) { gnutls_assert(); return GNUTLS_E_MEMORY_ERROR; } /* copy N (mod n) */ data_n = *data; _gnutls_write_datum16( data_n, pwd_entry->n); /* copy G (generator) to data */ data_g = &data_n[2 + pwd_entry->n.size]; _gnutls_write_datum16( data_g, pwd_entry->g); /* copy the salt */ data_s = &data_g[2 + pwd_entry->g.size]; _gnutls_write_datum8( data_s, pwd_entry->salt); /* Copy the B value */ data_b = &data_s[1+pwd_entry->salt.size]; if (_gnutls_mpi_print( &data_b[2], &n_b, B)!=0) return GNUTLS_E_MPI_PRINT_FAILED; _gnutls_write_uint16( n_b, data_b); _gnutls_hard_log( "INT: SRP B[%d]: %s\n", n_b, _gnutls_bin2hex(&data_b[2], n_b, buf, sizeof(buf))); _gnutls_srp_entry_free( pwd_entry); return data_size; } /* return A = g^a % N */ int _gnutls_gen_srp_client_kx(gnutls_session session, opaque ** data) { size_t n_a; int ret; uint8 *data_a; char *username; char buf[64]; char *password; const gnutls_srp_client_credentials cred = _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); 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_generate_session_key( session->key); _gnutls_mpi_release(&S); if (ret < 0) 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; } /* just read A and put it to session */ int _gnutls_proc_srp_client_kx(gnutls_session session, opaque * data, size_t _data_size) { size_t _n_A; ssize_t data_size = _data_size; int ret; DECR_LEN( data_size, 2); _n_A = _gnutls_read_uint16( &data[0]); DECR_LEN( data_size, _n_A); if (_gnutls_mpi_scan(&A, &data[2], &_n_A) || A == NULL) { gnutls_assert(); return GNUTLS_E_MPI_SCAN_FAILED; } _gnutls_dump_mpi( "SRP A: ", A); _gnutls_dump_mpi( "SRP B: ", B); /* Checks if A % n == 0 or * A % n == +-1. */ if ( (ret = check_a_mod_n( A, N)) < 0) { gnutls_assert(); return ret; } /* Start the SRP calculations. * - Calculate u */ session->key->u = _gnutls_calc_srp_u(A, B); if (session->key->u==NULL) { gnutls_assert(); return GNUTLS_E_MEMORY_ERROR; } _gnutls_dump_mpi( "SRP U: ", session->key->u); /* S = (A * v^u) ^ b % N */ S = _gnutls_calc_srp_S1( A, _b, session->key->u, V, N); if ( S==NULL) { gnutls_assert(); return GNUTLS_E_MEMORY_ERROR; } _gnutls_dump_mpi( "SRP S: ", S); _gnutls_mpi_release(&A); _gnutls_mpi_release(&_b); _gnutls_mpi_release(&V); _gnutls_mpi_release(&session->key->u); _gnutls_mpi_release(&B); ret = _gnutls_generate_session_key( session->key); _gnutls_mpi_release( &S); if (ret < 0) { gnutls_assert(); return ret; } return 0; } /* Static parameters according to draft-ietf-tls-srp-05 */ static const unsigned char srp_params_1024[] = { 0xEE, 0xAF, 0x0A, 0xB9, 0xAD, 0xB3, 0x8D, 0xD6, 0x9C, 0x33, 0xF8, 0x0A, 0xFA, 0x8F, 0xC5, 0xE8, 0x60, 0x72, 0x61, 0x87, 0x75, 0xFF, 0x3C, 0x0B, 0x9E, 0xA2, 0x31, 0x4C, 0x9C, 0x25, 0x65, 0x76, 0xD6, 0x74, 0xDF, 0x74, 0x96, 0xEA, 0x81, 0xD3, 0x38, 0x3B, 0x48, 0x13, 0xD6, 0x92, 0xC6, 0xE0, 0xE0, 0xD5, 0xD8, 0xE2, 0x50, 0xB9, 0x8B, 0xE4, 0x8E, 0x49, 0x5C, 0x1D, 0x60, 0x89, 0xDA, 0xD1, 0x5D, 0xC7, 0xD7, 0xB4, 0x61, 0x54, 0xD6, 0xB6, 0xCE, 0x8E, 0xF4, 0xAD, 0x69, 0xB1, 0x5D, 0x49, 0x82, 0x55, 0x9B, 0x29, 0x7B, 0xCF, 0x18, 0x85, 0xC5, 0x29, 0xF5, 0x66, 0x66, 0x0E, 0x57, 0xEC, 0x68, 0xED, 0xBC, 0x3C, 0x05, 0x72, 0x6C, 0xC0, 0x2F, 0xD4, 0xCB, 0xF4, 0x97, 0x6E, 0xAA, 0x9A, 0xFD, 0x51, 0x38, 0xFE, 0x83, 0x76, 0x43, 0x5B, 0x9F, 0xC6, 0x1D, 0x2F, 0xC0, 0xEB, 0x06, 0xE3 }; static const unsigned char srp_generator = 0x02; const gnutls_datum gnutls_srp_1024_group_prime = { (void*)srp_params_1024, sizeof(srp_params_1024) }; const gnutls_datum gnutls_srp_1024_group_generator = { (void*)&srp_generator, sizeof(srp_generator) }; static const unsigned char srp_params_1536[] = { 0x9D, 0xEF, 0x3C, 0xAF, 0xB9, 0x39, 0x27, 0x7A, 0xB1, 0xF1, 0x2A, 0x86, 0x17, 0xA4, 0x7B, 0xBB, 0xDB, 0xA5, 0x1D, 0xF4, 0x99, 0xAC, 0x4C, 0x80, 0xBE, 0xEE, 0xA9, 0x61, 0x4B, 0x19, 0xCC, 0x4D, 0x5F, 0x4F, 0x5F, 0x55, 0x6E, 0x27, 0xCB, 0xDE, 0x51, 0xC6, 0xA9, 0x4B, 0xE4, 0x60, 0x7A, 0x29, 0x15, 0x58, 0x90, 0x3B, 0xA0, 0xD0, 0xF8, 0x43, 0x80, 0xB6, 0x55, 0xBB, 0x9A, 0x22, 0xE8, 0xDC, 0xDF, 0x02, 0x8A, 0x7C, 0xEC, 0x67, 0xF0, 0xD0, 0x81, 0x34, 0xB1, 0xC8, 0xB9, 0x79, 0x89, 0x14, 0x9B, 0x60, 0x9E, 0x0B, 0xE3, 0xBA, 0xB6, 0x3D, 0x47, 0x54, 0x83, 0x81, 0xDB, 0xC5, 0xB1, 0xFC, 0x76, 0x4E, 0x3F, 0x4B, 0x53, 0xDD, 0x9D, 0xA1, 0x15, 0x8B, 0xFD, 0x3E, 0x2B, 0x9C, 0x8C, 0xF5, 0x6E, 0xDF, 0x01, 0x95, 0x39, 0x34, 0x96, 0x27, 0xDB, 0x2F, 0xD5, 0x3D, 0x24, 0xB7, 0xC4, 0x86, 0x65, 0x77, 0x2E, 0x43, 0x7D, 0x6C, 0x7F, 0x8C, 0xE4, 0x42, 0x73, 0x4A, 0xF7, 0xCC, 0xB7, 0xAE, 0x83, 0x7C, 0x26, 0x4A, 0xE3, 0xA9, 0xBE, 0xB8, 0x7F, 0x8A, 0x2F, 0xE9, 0xB8, 0xB5, 0x29, 0x2E, 0x5A, 0x02, 0x1F, 0xFF, 0x5E, 0x91, 0x47, 0x9E, 0x8C, 0xE7, 0xA2, 0x8C, 0x24, 0x42, 0xC6, 0xF3, 0x15, 0x18, 0x0F, 0x93, 0x49, 0x9A, 0x23, 0x4D, 0xCF, 0x76, 0xE3, 0xFE, 0xD1, 0x35, 0xF9, 0xBB }; const gnutls_datum gnutls_srp_1536_group_prime = { (void*)srp_params_1536, sizeof(srp_params_1536) }; const gnutls_datum gnutls_srp_1536_group_generator = { (void*)&srp_generator, sizeof(srp_generator) }; static const unsigned char srp_params_2048[] = { 0xAC, 0x6B, 0xDB, 0x41, 0x32, 0x4A, 0x9A, 0x9B, 0xF1, 0x66, 0xDE, 0x5E, 0x13, 0x89, 0x58, 0x2F, 0xAF, 0x72, 0xB6, 0x65, 0x19, 0x87, 0xEE, 0x07, 0xFC, 0x31, 0x92, 0x94, 0x3D, 0xB5, 0x60, 0x50, 0xA3, 0x73, 0x29, 0xCB, 0xB4, 0xA0, 0x99, 0xED, 0x81, 0x93, 0xE0, 0x75, 0x77, 0x67, 0xA1, 0x3D, 0xD5, 0x23, 0x12, 0xAB, 0x4B, 0x03, 0x31, 0x0D, 0xCD, 0x7F, 0x48, 0xA9, 0xDA, 0x04, 0xFD, 0x50, 0xE8, 0x08, 0x39, 0x69, 0xED, 0xB7, 0x67, 0xB0, 0xCF, 0x60, 0x95, 0x17, 0x9A, 0x16, 0x3A, 0xB3, 0x66, 0x1A, 0x05, 0xFB, 0xD5, 0xFA, 0xAA, 0xE8, 0x29, 0x18, 0xA9, 0x96, 0x2F, 0x0B, 0x93, 0xB8, 0x55, 0xF9, 0x79, 0x93, 0xEC, 0x97, 0x5E, 0xEA, 0xA8, 0x0D, 0x74, 0x0A, 0xDB, 0xF4, 0xFF, 0x74, 0x73, 0x59, 0xD0, 0x41, 0xD5, 0xC3, 0x3E, 0xA7, 0x1D, 0x28, 0x1E, 0x44, 0x6B, 0x14, 0x77, 0x3B, 0xCA, 0x97, 0xB4, 0x3A, 0x23, 0xFB, 0x80, 0x16, 0x76, 0xBD, 0x20, 0x7A, 0x43, 0x6C, 0x64, 0x81, 0xF1, 0xD2, 0xB9, 0x07, 0x87, 0x17, 0x46, 0x1A, 0x5B, 0x9D, 0x32, 0xE6, 0x88, 0xF8, 0x77, 0x48, 0x54, 0x45, 0x23, 0xB5, 0x24, 0xB0, 0xD5, 0x7D, 0x5E, 0xA7, 0x7A, 0x27, 0x75, 0xD2, 0xEC, 0xFA, 0x03, 0x2C, 0xFB, 0xDB, 0xF5, 0x2F, 0xB3, 0x78, 0x61, 0x60, 0x27, 0x90, 0x04, 0xE5, 0x7A, 0xE6, 0xAF, 0x87, 0x4E, 0x73, 0x03, 0xCE, 0x53, 0x29, 0x9C, 0xCC, 0x04, 0x1C, 0x7B, 0xC3, 0x08, 0xD8, 0x2A, 0x56, 0x98, 0xF3, 0xA8, 0xD0, 0xC3, 0x82, 0x71, 0xAE, 0x35, 0xF8, 0xE9, 0xDB, 0xFB, 0xB6, 0x94, 0xB5, 0xC8, 0x03, 0xD8, 0x9F, 0x7A, 0xE4, 0x35, 0xDE, 0x23, 0x6D, 0x52, 0x5F, 0x54, 0x75, 0x9B, 0x65, 0xE3, 0x72, 0xFC, 0xD6, 0x8E, 0xF2, 0x0F, 0xA7, 0x11, 0x1F, 0x9E, 0x4A, 0xFF, 0x73 }; const gnutls_datum gnutls_srp_2048_group_prime = { (void*)srp_params_2048, sizeof(srp_params_2048) }; const gnutls_datum gnutls_srp_2048_group_generator = { (void*)&srp_generator, sizeof(srp_generator) }; /* Check if G and N are parameters from the SRP draft. */ static int check_g_n( const opaque* g, size_t n_g, const opaque* n, size_t n_n) { if (n_g != 1 || g[0] != srp_generator) return GNUTLS_E_RECEIVED_ILLEGAL_PARAMETER; if (n_n == sizeof(srp_params_1024) && memcmp( srp_params_1024, n, n_n)==0) { return 0; } if (n_n == sizeof(srp_params_1536) && memcmp( srp_params_1536, n, n_n)==0) { return 0; } if (n_n == sizeof(srp_params_2048) && memcmp( srp_params_2048, n, n_n)==0) { return 0; } return GNUTLS_E_RECEIVED_ILLEGAL_PARAMETER; } /* Check if N is a prime and G a generator of the * group. */ static int group_check_g_n( GNUTLS_MPI g, GNUTLS_MPI n) { if (gcry_prime_check( n, 0) != 0) { _gnutls_dump_mpi( "no prime N: ", n); gnutls_assert(); return GNUTLS_E_RECEIVED_ILLEGAL_PARAMETER; } /* We should also check whether g is a generator, * but this is not possible. We now only check if * the generator is not too large. */ if (_gnutls_mpi_get_nbits(g) > 7) { gnutls_assert(); return GNUTLS_E_RECEIVED_ILLEGAL_PARAMETER; } return 0; } /* receive the key exchange message ( n, g, s, B) */ int _gnutls_proc_srp_server_kx(gnutls_session session, opaque * data, size_t _data_size) { uint8 n_s; uint16 n_g, n_n, n_b; size_t _n_s, _n_g, _n_n, _n_b; const uint8 *data_n; const uint8 *data_g; const uint8 *data_s; const uint8 *data_b; int i, ret; opaque hd[SRP_MAX_HASH_SIZE]; char *username, *password; ssize_t data_size = _data_size; const gnutls_srp_client_credentials cred = _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; } i = 0; /* Read N */ DECR_LEN( data_size, 2); n_n = _gnutls_read_uint16( &data[i]); i += 2; DECR_LEN( data_size, n_n); data_n = &data[i]; i += n_n; /* Read G */ DECR_LEN( data_size, 2); n_g = _gnutls_read_uint16( &data[i]); i += 2; DECR_LEN( data_size, n_g); data_g = &data[i]; i += n_g; /* Read salt */ DECR_LEN( data_size, 1); n_s = data[i]; i += 1; DECR_LEN( data_size, n_s); data_s = &data[i]; i += n_s; /* Read B */ DECR_LEN( data_size, 2); n_b = _gnutls_read_uint16( &data[i]); i += 2; DECR_LEN( data_size, n_b); data_b = &data[i]; i += n_b; _n_s = n_s; _n_g = n_g; _n_n = n_n; _n_b = n_b; if (_gnutls_mpi_scan(&N, data_n, &_n_n) != 0) { gnutls_assert(); return GNUTLS_E_MPI_SCAN_FAILED; } if (_gnutls_mpi_scan(&G, data_g, &_n_g) != 0) { gnutls_assert(); return GNUTLS_E_MPI_SCAN_FAILED; } if (_gnutls_mpi_scan(&B, data_b, &_n_b) != 0) { gnutls_assert(); return GNUTLS_E_MPI_SCAN_FAILED; } /* Check if the g and n are from the SRP * draft. Otherwise check if N is a prime and G * a generator. */ if ( (ret = check_g_n( data_g, _n_g, data_n, _n_n)) < 0) { _gnutls_x509_log("Checking the SRP group parameters.\n"); if ( (ret = group_check_g_n( G, N)) < 0) { gnutls_assert(); return ret; } } /* Checks if b % n == 0 */ if ( (ret = check_b_mod_n( B, N)) < 0) { gnutls_assert(); return ret; } /* generate x = SHA(s | SHA(U | ":" | p)) * (or the equivalent using bcrypt) */ if ( ( ret =_gnutls_calc_srp_x( username, password, (opaque*)data_s, n_s, &_n_g, hd)) < 0) { gnutls_assert(); return ret; } if (_gnutls_mpi_scan(&session->key->x, hd, &_n_g) != 0) { gnutls_assert(); return GNUTLS_E_MPI_SCAN_FAILED; } return i; /* return the processed data * needed in auth_srp_rsa. */ } #endif /* ENABLE_SRP */