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/**********************************************************************
* gost_keyx.c *
* Copyright (c) 2005-2006 Cryptocom LTD *
* This file is distributed under the same license as OpenSSL *
* *
* VK0 34.10-2001 key exchange and GOST R 34.10-2001 *
* based PKCS7/SMIME support *
* Requires OpenSSL 0.9.9 for compilation *
**********************************************************************/
#include <openssl/evp.h>
#include <openssl/rand.h>
#include <string.h>
#include <openssl/objects.h>
#include "gost89.h"
#include "gosthash.h"
#include "e_gost_err.h"
#include "gost_keywrap.h"
#include "gost_lcl.h"
#include "gost2001_keyx.h"
/* Implementation of CryptoPro VKO 34.10-2001 algorithm */
static int VKO_compute_key(unsigned char *shared_key, size_t shared_key_size,
const EC_POINT *pub_key, EC_KEY *priv_key,
const unsigned char *ukm)
{
unsigned char ukm_be[8], databuf[64], hashbuf[64];
BIGNUM *UKM = NULL, *p = NULL, *order = NULL, *X = NULL, *Y = NULL;
const BIGNUM *key = EC_KEY_get0_private_key(priv_key);
EC_POINT *pnt = EC_POINT_new(EC_KEY_get0_group(priv_key));
int i;
gost_hash_ctx hash_ctx;
BN_CTX *ctx = BN_CTX_new();
for (i = 0; i < 8; i++) {
ukm_be[7 - i] = ukm[i];
}
BN_CTX_start(ctx);
UKM = getbnfrombuf(ukm_be, 8);
p = BN_CTX_get(ctx);
order = BN_CTX_get(ctx);
X = BN_CTX_get(ctx);
Y = BN_CTX_get(ctx);
EC_GROUP_get_order(EC_KEY_get0_group(priv_key), order, ctx);
BN_mod_mul(p, key, UKM, order, ctx);
EC_POINT_mul(EC_KEY_get0_group(priv_key), pnt, NULL, pub_key, p, ctx);
EC_POINT_get_affine_coordinates_GFp(EC_KEY_get0_group(priv_key),
pnt, X, Y, ctx);
/*
* Serialize elliptic curve point same way as we do it when saving key
*/
store_bignum(Y, databuf, 32);
store_bignum(X, databuf + 32, 32);
/* And reverse byte order of whole buffer */
for (i = 0; i < 64; i++) {
hashbuf[63 - i] = databuf[i];
}
init_gost_hash_ctx(&hash_ctx, &GostR3411_94_CryptoProParamSet);
start_hash(&hash_ctx);
hash_block(&hash_ctx, hashbuf, 64);
finish_hash(&hash_ctx, shared_key);
done_gost_hash_ctx(&hash_ctx);
BN_free(UKM);
BN_CTX_end(ctx);
BN_CTX_free(ctx);
EC_POINT_free(pnt);
return 32;
}
/*
* EVP_PKEY_METHOD callback derive. Implements VKO R 34.10-2001
* algorithm
*/
int pkey_gost2001_derive(EVP_PKEY_CTX *ctx, unsigned char *key,
size_t *keylen)
{
/*
* Public key of peer in the ctx field peerkey Our private key in the ctx
* pkey ukm is in the algorithm specific context data
*/
EVP_PKEY *my_key = EVP_PKEY_CTX_get0_pkey(ctx);
EVP_PKEY *peer_key = EVP_PKEY_CTX_get0_peerkey(ctx);
struct gost_pmeth_data *data = EVP_PKEY_CTX_get_data(ctx);
if (!data->shared_ukm) {
GOSTerr(GOST_F_PKEY_GOST2001_DERIVE, GOST_R_UKM_NOT_SET);
return 0;
}
if (key == NULL) {
*keylen = 32;
return 32;
}
*keylen =
VKO_compute_key(key, 32,
EC_KEY_get0_public_key(EVP_PKEY_get0(peer_key)),
(EC_KEY *)EVP_PKEY_get0(my_key), data->shared_ukm);
return 1;
}
/*
* EVP_PKEY_METHOD callback encrypt
* Implementation of GOST2001 key transport, cryptocom variation
*/
/*
* Generates ephemeral key based on pubk algorithm computes shared key using
* VKO and returns filled up GOST_KEY_TRANSPORT structure
*/
/*
* EVP_PKEY_METHOD callback encrypt
* Implementation of GOST2001 key transport, cryptopo variation
*/
int pkey_GOST01cp_encrypt(EVP_PKEY_CTX *pctx, unsigned char *out,
size_t *out_len, const unsigned char *key,
size_t key_len)
{
GOST_KEY_TRANSPORT *gkt = NULL;
EVP_PKEY *pubk = EVP_PKEY_CTX_get0_pkey(pctx);
struct gost_pmeth_data *data = EVP_PKEY_CTX_get_data(pctx);
const struct gost_cipher_info *param = get_encryption_params(NULL);
unsigned char ukm[8], shared_key[32], crypted_key[44];
int ret = 0;
int key_is_ephemeral = 1;
gost_ctx cctx;
EVP_PKEY *sec_key = EVP_PKEY_CTX_get0_peerkey(pctx);
if (data->shared_ukm) {
memcpy(ukm, data->shared_ukm, 8);
} else if (out) {
if (RAND_bytes(ukm, 8) <= 0) {
GOSTerr(GOST_F_PKEY_GOST01CP_ENCRYPT,
GOST_R_RANDOM_GENERATOR_FAILURE);
return 0;
}
}
/* Check for private key in the peer_key of context */
if (sec_key) {
key_is_ephemeral = 0;
if (!gost_get0_priv_key(sec_key)) {
GOSTerr(GOST_F_PKEY_GOST01CP_ENCRYPT,
GOST_R_NO_PRIVATE_PART_OF_NON_EPHEMERAL_KEYPAIR);
goto err;
}
} else {
key_is_ephemeral = 1;
if (out) {
sec_key = EVP_PKEY_new();
EVP_PKEY_assign(sec_key, EVP_PKEY_base_id(pubk), EC_KEY_new());
EVP_PKEY_copy_parameters(sec_key, pubk);
if (!gost2001_keygen(EVP_PKEY_get0(sec_key))) {
goto err;
}
}
}
if (!get_gost_engine_param(GOST_PARAM_CRYPT_PARAMS)
&& param == gost_cipher_list) {
param = gost_cipher_list + 1;
}
if (out) {
VKO_compute_key(shared_key, 32,
EC_KEY_get0_public_key(EVP_PKEY_get0(pubk)),
EVP_PKEY_get0(sec_key), ukm);
gost_init(&cctx, param->sblock);
keyWrapCryptoPro(&cctx, shared_key, ukm, key, crypted_key);
}
gkt = GOST_KEY_TRANSPORT_new();
if (!gkt) {
goto err;
}
if (!ASN1_OCTET_STRING_set(gkt->key_agreement_info->eph_iv, ukm, 8)) {
goto err;
}
if (!ASN1_OCTET_STRING_set(gkt->key_info->imit, crypted_key + 40, 4)) {
goto err;
}
if (!ASN1_OCTET_STRING_set
(gkt->key_info->encrypted_key, crypted_key + 8, 32)) {
goto err;
}
if (key_is_ephemeral) {
if (!X509_PUBKEY_set
(&gkt->key_agreement_info->ephem_key, out ? sec_key : pubk)) {
GOSTerr(GOST_F_PKEY_GOST01CP_ENCRYPT,
GOST_R_CANNOT_PACK_EPHEMERAL_KEY);
goto err;
}
}
ASN1_OBJECT_free(gkt->key_agreement_info->cipher);
gkt->key_agreement_info->cipher = OBJ_nid2obj(param->nid);
if (key_is_ephemeral && sec_key)
EVP_PKEY_free(sec_key);
if (!key_is_ephemeral) {
/* Set control "public key from client certificate used" */
if (EVP_PKEY_CTX_ctrl(pctx, -1, -1, EVP_PKEY_CTRL_PEER_KEY, 3, NULL)
<= 0) {
GOSTerr(GOST_F_PKEY_GOST01CP_ENCRYPT, GOST_R_CTRL_CALL_FAILED);
goto err;
}
}
if ((*out_len = i2d_GOST_KEY_TRANSPORT(gkt, out ? &out : NULL)) > 0)
ret = 1;
GOST_KEY_TRANSPORT_free(gkt);
return ret;
err:
if (key_is_ephemeral && sec_key)
EVP_PKEY_free(sec_key);
GOST_KEY_TRANSPORT_free(gkt);
return -1;
}
/*
* EVP_PKEY_METHOD callback decrypt
* Implementation of GOST2001 key transport, cryptopo variation
*/
int pkey_GOST01cp_decrypt(EVP_PKEY_CTX *pctx, unsigned char *key,
size_t *key_len, const unsigned char *in,
size_t in_len)
{
const unsigned char *p = in;
EVP_PKEY *priv = EVP_PKEY_CTX_get0_pkey(pctx);
GOST_KEY_TRANSPORT *gkt = NULL;
int ret = 0;
unsigned char wrappedKey[44];
unsigned char sharedKey[32];
gost_ctx ctx;
const struct gost_cipher_info *param = NULL;
EVP_PKEY *eph_key = NULL, *peerkey = NULL;
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_GOST01CP_DECRYPT,
GOST_R_ERROR_PARSING_KEY_TRANSPORT_INFO);
return -1;
}
/* If key transport structure contains public key, use it */
eph_key = X509_PUBKEY_get(gkt->key_agreement_info->ephem_key);
if (eph_key) {
if (EVP_PKEY_derive_set_peer(pctx, eph_key) <= 0) {
GOSTerr(GOST_F_PKEY_GOST01CP_DECRYPT,
GOST_R_INCOMPATIBLE_PEER_KEY);
goto err;
}
} else {
/* Set control "public key from client certificate used" */
if (EVP_PKEY_CTX_ctrl(pctx, -1, -1, EVP_PKEY_CTRL_PEER_KEY, 3, NULL)
<= 0) {
GOSTerr(GOST_F_PKEY_GOST01CP_DECRYPT, GOST_R_CTRL_CALL_FAILED);
goto err;
}
}
peerkey = EVP_PKEY_CTX_get0_peerkey(pctx);
if (!peerkey) {
GOSTerr(GOST_F_PKEY_GOST01CP_DECRYPT, GOST_R_NO_PEER_KEY);
goto err;
}
param = get_encryption_params(gkt->key_agreement_info->cipher);
if (!param) {
goto err;
}
gost_init(&ctx, 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);
VKO_compute_key(sharedKey, 32,
EC_KEY_get0_public_key(EVP_PKEY_get0(peerkey)),
EVP_PKEY_get0(priv), wrappedKey);
if (!keyUnwrapCryptoPro(&ctx, sharedKey, wrappedKey, key)) {
GOSTerr(GOST_F_PKEY_GOST01CP_DECRYPT,
GOST_R_ERROR_COMPUTING_SHARED_KEY);
goto err;
}
ret = 1;
err:
if (eph_key)
EVP_PKEY_free(eph_key);
if (gkt)
GOST_KEY_TRANSPORT_free(gkt);
return ret;
}
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