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/* Copyright (c) 2001, Matej Pfajfar.
* Copyright (c) 2001-2004, Roger Dingledine.
* Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
* Copyright (c) 2007-2019, The Tor Project, Inc. */
/* See LICENSE for licensing information */
/**
* \file crypto_dh.c
* \brief Block of functions related with DH utilities and operations.
* over Z_p. We aren't using this for any new crypto -- EC is more
* efficient.
**/
#include "lib/crypt_ops/compat_openssl.h"
#include "lib/crypt_ops/crypto_dh.h"
#include "lib/crypt_ops/crypto_digest.h"
#include "lib/crypt_ops/crypto_hkdf.h"
#include "lib/crypt_ops/crypto_util.h"
#include "lib/log/log.h"
#include "lib/log/util_bug.h"
/** Our DH 'g' parameter */
const unsigned DH_GENERATOR = 2;
/** This is the 1024-bit safe prime that Apache uses for its DH stuff; see
* modules/ssl/ssl_engine_dh.c; Apache also uses a generator of 2 with this
* prime.
*/
const char TLS_DH_PRIME[] =
"D67DE440CBBBDC1936D693D34AFD0AD50C84D239A45F520BB88174CB98"
"BCE951849F912E639C72FB13B4B4D7177E16D55AC179BA420B2A29FE324A"
"467A635E81FF5901377BEDDCFD33168A461AAD3B72DAE8860078045B07A7"
"DBCA7874087D1510EA9FCC9DDD330507DD62DB88AEAA747DE0F4D6E2BD68"
"B0E7393E0F24218EB3";
/**
* This is from rfc2409, section 6.2. It's a safe prime, and
* supposedly it equals:
* 2^1024 - 2^960 - 1 + 2^64 * { [2^894 pi] + 129093 }.
*/
const char OAKLEY_PRIME_2[] =
"FFFFFFFFFFFFFFFFC90FDAA22168C234C4C6628B80DC1CD129024E08"
"8A67CC74020BBEA63B139B22514A08798E3404DDEF9519B3CD3A431B"
"302B0A6DF25F14374FE1356D6D51C245E485B576625E7EC6F44C42E9"
"A637ED6B0BFF5CB6F406B7EDEE386BFB5A899FA5AE9F24117C4B1FE6"
"49286651ECE65381FFFFFFFFFFFFFFFF";
void
crypto_dh_init(void)
{
#ifdef ENABLE_OPENSSL
crypto_dh_init_openssl();
#endif
#ifdef ENABLE_NSS
crypto_dh_init_nss();
#endif
}
void
crypto_dh_free_all(void)
{
#ifdef ENABLE_OPENSSL
crypto_dh_free_all_openssl();
#endif
#ifdef ENABLE_NSS
crypto_dh_free_all_nss();
#endif
}
/** Given a DH key exchange object, and our peer's value of g^y (as a
* <b>pubkey_len</b>-byte value in <b>pubkey</b>) generate
* <b>secret_bytes_out</b> bytes of shared key material and write them
* to <b>secret_out</b>. Return the number of bytes generated on success,
* or -1 on failure.
*
* (We generate key material by computing
* SHA1( g^xy || "\x00" ) || SHA1( g^xy || "\x01" ) || ...
* where || is concatenation.)
*/
ssize_t
crypto_dh_compute_secret(int severity, crypto_dh_t *dh,
const char *pubkey, size_t pubkey_len,
char *secret_out, size_t secret_bytes_out)
{
tor_assert(secret_bytes_out/DIGEST_LEN <= 255);
unsigned char *secret_tmp = NULL;
size_t secret_len=0, secret_tmp_len=0;
secret_tmp_len = crypto_dh_get_bytes(dh);
secret_tmp = tor_malloc(secret_tmp_len);
ssize_t result = crypto_dh_handshake(severity, dh, pubkey, pubkey_len,
secret_tmp, secret_tmp_len);
if (result < 0)
goto error;
secret_len = result;
if (crypto_expand_key_material_TAP(secret_tmp, secret_len,
(uint8_t*)secret_out, secret_bytes_out)<0)
goto error;
secret_len = secret_bytes_out;
goto done;
error:
result = -1;
done:
if (secret_tmp) {
memwipe(secret_tmp, 0, secret_tmp_len);
tor_free(secret_tmp);
}
if (result < 0)
return result;
else
return secret_len;
}
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