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/**********************************************************************
* gost94_keyx.c *
* Copyright (c) 2005-2006 Cryptocom LTD *
* This file is distributed under the same license as OpenSSL *
* *
* Implements generation and parsing of GOST_KEY_TRANSPORT for *
* GOST R 34.10-94 algorithms *
* *
* Requires OpenSSL 0.9.9 for compilation *
**********************************************************************/
#include <string.h>
#include <openssl/dh.h>
#include <openssl/rand.h>
#include <openssl/evp.h>
#include <openssl/objects.h>
#include "gost89.h"
#include "gosthash.h"
#include "e_gost_err.h"
#include "gost_keywrap.h"
#include "gost_lcl.h"
/* Common functions for both 94 and 2001 key exchange schemes */
/*
* Implementation of the Diffi-Hellman key agreement scheme based on GOST-94
* keys
*/
/*
* Computes Diffie-Hellman key and stores it into buffer in little-endian
* byte order as expected by both versions of GOST 94 algorithm
*/
static int compute_pair_key_le(unsigned char *pair_key, BIGNUM *pub_key,
DH *dh)
{
unsigned char be_key[128];
int i, key_size;
key_size = DH_compute_key(be_key, pub_key, dh);
if (!key_size)
return 0;
memset(pair_key, 0, 128);
for (i = 0; i < key_size; i++) {
pair_key[i] = be_key[key_size - 1 - i];
}
return key_size;
}
/*
* Computes 256 bit Key exchange key as specified in RFC 4357
*/
static int make_cp_exchange_key(BIGNUM *priv_key, EVP_PKEY *pubk,
unsigned char *shared_key)
{
unsigned char dh_key[128];
int ret;
gost_hash_ctx hash_ctx;
DH *dh = DH_new();
if (!dh)
return 0;
memset(dh_key, 0, 128);
dh->g = BN_dup(pubk->pkey.dsa->g);
dh->p = BN_dup(pubk->pkey.dsa->p);
dh->priv_key = BN_dup(priv_key);
ret =
compute_pair_key_le(dh_key, ((DSA *)(EVP_PKEY_get0(pubk)))->pub_key,
dh);
DH_free(dh);
if (!ret)
return 0;
init_gost_hash_ctx(&hash_ctx, &GostR3411_94_CryptoProParamSet);
start_hash(&hash_ctx);
hash_block(&hash_ctx, dh_key, 128);
finish_hash(&hash_ctx, shared_key);
done_gost_hash_ctx(&hash_ctx);
return 1;
}
/* EVP_PKEY_METHOD callback derive. Implements VKO R 34.10-94 */
int pkey_gost94_derive(EVP_PKEY_CTX *ctx, unsigned char *key, size_t *keylen)
{
EVP_PKEY *pubk = EVP_PKEY_CTX_get0_peerkey(ctx);
EVP_PKEY *mykey = EVP_PKEY_CTX_get0_pkey(ctx);
*keylen = 32;
if (key == NULL)
return 1;
return make_cp_exchange_key(gost_get0_priv_key(mykey), pubk, key);
}
/*
* EVP_PKEY_METHOD callback encrypt for GOST R 34.10-94 cryptopro
* modification
*/
int pkey_GOST94cp_encrypt(EVP_PKEY_CTX *ctx, unsigned char *out,
size_t *outlen, const unsigned char *key,
size_t key_len)
{
GOST_KEY_TRANSPORT *gkt = NULL;
unsigned char shared_key[32], ukm[8], crypted_key[44];
const struct gost_cipher_info *param = get_encryption_params(NULL);
EVP_PKEY *pubk = EVP_PKEY_CTX_get0_pkey(ctx);
struct gost_pmeth_data *data = EVP_PKEY_CTX_get_data(ctx);
gost_ctx cctx;
int key_is_ephemeral = 1;
int tmp_outlen;
EVP_PKEY *mykey = EVP_PKEY_CTX_get0_peerkey(ctx);
/* Do not use vizir cipher parameters with cryptopro */
if (!get_gost_engine_param(GOST_PARAM_CRYPT_PARAMS)
&& param == gost_cipher_list) {
param = gost_cipher_list + 1;
}
if (mykey) {
/* If key already set, it is not ephemeral */
key_is_ephemeral = 0;
if (!gost_get0_priv_key(mykey)) {
GOSTerr(GOST_F_PKEY_GOST94CP_ENCRYPT,
GOST_R_NO_PRIVATE_PART_OF_NON_EPHEMERAL_KEYPAIR);
goto err;
}
} else {
/* Otherwise generate ephemeral key */
key_is_ephemeral = 1;
if (out) {
mykey = EVP_PKEY_new();
EVP_PKEY_assign(mykey, EVP_PKEY_base_id(pubk), DSA_new());
EVP_PKEY_copy_parameters(mykey, pubk);
if (!gost_sign_keygen(EVP_PKEY_get0(mykey))) {
goto err;
}
}
}
if (out)
make_cp_exchange_key(gost_get0_priv_key(mykey), pubk, shared_key);
if (data->shared_ukm) {
memcpy(ukm, data->shared_ukm, 8);
} else if (out) {
if (RAND_bytes(ukm, 8) <= 0) {
GOSTerr(GOST_F_PKEY_GOST94CP_ENCRYPT,
GOST_R_RANDOM_GENERATOR_FAILURE);
goto err;
}
}
if (out) {
gost_init(&cctx, param->sblock);
keyWrapCryptoPro(&cctx, shared_key, ukm, key, crypted_key);
}
gkt = GOST_KEY_TRANSPORT_new();
if (!gkt) {
goto memerr;
}
if (!ASN1_OCTET_STRING_set(gkt->key_agreement_info->eph_iv, ukm, 8)) {
goto memerr;
}
if (!ASN1_OCTET_STRING_set(gkt->key_info->imit, crypted_key + 40, 4)) {
goto memerr;
}
if (!ASN1_OCTET_STRING_set
(gkt->key_info->encrypted_key, crypted_key + 8, 32)) {
goto memerr;
}
if (key_is_ephemeral) {
if (!X509_PUBKEY_set
(&gkt->key_agreement_info->ephem_key, out ? mykey : pubk)) {
GOSTerr(GOST_F_PKEY_GOST94CP_ENCRYPT,
GOST_R_CANNOT_PACK_EPHEMERAL_KEY);
goto err;
}
if (out)
EVP_PKEY_free(mykey);
}
ASN1_OBJECT_free(gkt->key_agreement_info->cipher);
gkt->key_agreement_info->cipher = OBJ_nid2obj(param->nid);
tmp_outlen = i2d_GOST_KEY_TRANSPORT(gkt, out ? &out : NULL);
if (tmp_outlen <= 0) {
GOSTerr(GOST_F_PKEY_GOST94CP_ENCRYPT,
GOST_R_ERROR_PACKING_KEY_TRANSPORT_INFO);
goto err;
}
*outlen = tmp_outlen;
if (!key_is_ephemeral) {
/* Set control "public key from client certificate used" */
if (EVP_PKEY_CTX_ctrl(ctx, -1, -1, EVP_PKEY_CTRL_PEER_KEY, 3, NULL) <=
0) {
GOSTerr(GOST_F_PKEY_GOST94CP_ENCRYPT, GOST_R_CTRL_CALL_FAILED);
goto err;
}
}
GOST_KEY_TRANSPORT_free(gkt);
return 1;
memerr:
if (key_is_ephemeral) {
EVP_PKEY_free(mykey);
}
GOSTerr(GOST_F_PKEY_GOST94CP_ENCRYPT, GOST_R_MALLOC_FAILURE);
err:
GOST_KEY_TRANSPORT_free(gkt);
return -1;
}
/*
* EVP_PLEY_METHOD callback decrypt for GOST R 34.10-94 cryptopro
* modification
*/
int pkey_GOST94cp_decrypt(EVP_PKEY_CTX *ctx, unsigned char *key,
size_t *key_len, const unsigned char *in,
size_t in_len)
{
const unsigned char *p = in;
GOST_KEY_TRANSPORT *gkt = NULL;
unsigned char wrappedKey[44];
unsigned char sharedKey[32];
gost_ctx cctx;
const struct gost_cipher_info *param = NULL;
EVP_PKEY *eph_key = NULL, *peerkey = NULL;
EVP_PKEY *priv = EVP_PKEY_CTX_get0_pkey(ctx);
if (!key) {
*key_len = 32;
return 1;
}
gkt = d2i_GOST_KEY_TRANSPORT(NULL, (const unsigned char **)&p, in_len);
if (!gkt) {
GOSTerr(GOST_F_PKEY_GOST94CP_DECRYPT,
GOST_R_ERROR_PARSING_KEY_TRANSPORT_INFO);
return 0;
}
eph_key = X509_PUBKEY_get(gkt->key_agreement_info->ephem_key);
if (eph_key) {
if (EVP_PKEY_derive_set_peer(ctx, eph_key) <= 0) {
GOSTerr(GOST_F_PKEY_GOST94CP_DECRYPT,
GOST_R_INCOMPATIBLE_PEER_KEY);
goto err;
}
} else {
/* Set control "public key from client certificate used" */
if (EVP_PKEY_CTX_ctrl(ctx, -1, -1, EVP_PKEY_CTRL_PEER_KEY, 3, NULL) <=
0) {
GOSTerr(GOST_F_PKEY_GOST94CP_DECRYPT, GOST_R_CTRL_CALL_FAILED);
goto err;
}
}
peerkey = EVP_PKEY_CTX_get0_peerkey(ctx);
if (!peerkey) {
GOSTerr(GOST_F_PKEY_GOST94CP_DECRYPT, GOST_R_NO_PEER_KEY);
goto err;
}
param = get_encryption_params(gkt->key_agreement_info->cipher);
if (!param) {
goto err;
}
gost_init(&cctx, param->sblock);
OPENSSL_assert(gkt->key_agreement_info->eph_iv->length == 8);
memcpy(wrappedKey, gkt->key_agreement_info->eph_iv->data, 8);
OPENSSL_assert(gkt->key_info->encrypted_key->length == 32);
memcpy(wrappedKey + 8, gkt->key_info->encrypted_key->data, 32);
OPENSSL_assert(gkt->key_info->imit->length == 4);
memcpy(wrappedKey + 40, gkt->key_info->imit->data, 4);
make_cp_exchange_key(gost_get0_priv_key(priv), peerkey, sharedKey);
if (!keyUnwrapCryptoPro(&cctx, sharedKey, wrappedKey, key)) {
GOSTerr(GOST_F_PKEY_GOST94CP_DECRYPT,
GOST_R_ERROR_COMPUTING_SHARED_KEY);
goto err;
}
EVP_PKEY_free(eph_key);
GOST_KEY_TRANSPORT_free(gkt);
return 1;
err:
EVP_PKEY_free(eph_key);
GOST_KEY_TRANSPORT_free(gkt);
return -1;
}
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