410 lines
12 KiB
C
410 lines
12 KiB
C
/**********************************************************************
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* gost_keyx.c *
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* Copyright (c) 2005-2006 Cryptocom LTD *
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* This file is distributed under the same license as OpenSSL *
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* *
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* VK0 34.10-2001 key exchange and GOST R 34.10-2001 *
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* based PKCS7/SMIME support *
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* Requires OpenSSL 0.9.9 for compilation *
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**********************************************************************/
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#include <openssl/evp.h>
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#include <openssl/rand.h>
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#include <string.h>
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#include <openssl/objects.h>
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#include "gost89.h"
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#include "gosthash.h"
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#include "e_gost_err.h"
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#include "gost_keywrap.h"
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#include "gost_lcl.h"
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#include "gost2001_keyx.h"
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/* Transform ECDH shared key into little endian as required by Cryptocom
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* key exchange */
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static void *make_key_le(const void *in, size_t inlen, void *out, size_t *outlen)
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{
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const char* inbuf= in;
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char* outbuf= out;
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int i;
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if (*outlen < inlen)
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{
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return NULL;
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}
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for (i=0;i<inlen;i++)
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{
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outbuf[inlen-1-i]=inbuf[i];
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}
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*outlen = inlen;
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return out;
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}
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/* Create gost 2001 ephemeral key with same parameters as peer key */
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static EC_KEY *make_ec_ephemeral_key(EC_KEY *peer_key,BIGNUM *seckey)
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{
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EC_KEY *out = EC_KEY_new();
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EC_KEY_copy(out,peer_key);
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EC_KEY_set_private_key(out,seckey);
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gost2001_compute_public(out);
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return out;
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}
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/* Packs GOST elliptic curve key into EVP_PKEY setting same parameters
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* as in passed pubkey
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*/
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static EVP_PKEY *ec_ephemeral_key_to_EVP(EVP_PKEY *pubk,int type,EC_KEY *ephemeral)
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{
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EVP_PKEY *newkey;
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newkey = EVP_PKEY_new();
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EVP_PKEY_assign(newkey,type,ephemeral);
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return newkey;
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}
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/*
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* EVP_PKEY_METHOD callback encrypt
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* Implementation of GOST2001 key transport, cryptocom variation
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*/
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int pkey_GOST01cc_encrypt (EVP_PKEY_CTX *pctx,unsigned char *out,
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size_t *out_len, const unsigned char *key,size_t key_len)
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{
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EVP_PKEY *pubk = EVP_PKEY_CTX_get0_pkey(pctx);
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struct gost_pmeth_data *data = EVP_PKEY_CTX_get_data(pctx);
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GOST_KEY_TRANSPORT *gkt = NULL;
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int ret=0;
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const struct gost_cipher_info *cipher_info;
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gost_ctx ctx;
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EC_KEY *ephemeral=NULL;
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const EC_POINT *pub_key_point=NULL;
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unsigned char shared_key[32],encrypted_key[32],hmac[4],
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iv[8]={0,0,0,0,0,0,0,0};
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ephemeral = make_ec_ephemeral_key(EVP_PKEY_get0(pubk), gost_get_priv_key(data->eph_seckey));
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if (!ephemeral) goto err;
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/* compute shared key */
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pub_key_point=EC_KEY_get0_public_key(EVP_PKEY_get0(pubk));
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if (!ECDH_compute_key(shared_key,32,pub_key_point,ephemeral,make_key_le))
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{
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GOSTerr(GOST_F_PKEY_GOST01CC_ENCRYPT,GOST_R_ERROR_COMPUTING_SHARED_KEY);
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goto err;
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}
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/* encrypt session key */
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cipher_info = get_encryption_params(NULL);
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gost_init(&ctx, cipher_info->sblock);
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gost_key(&ctx,shared_key);
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encrypt_cryptocom_key(key,key_len,encrypted_key,&ctx);
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/* compute hmac of session key */
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if (!gost_mac(&ctx,32,key,32,hmac))
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{
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GOSTerr(GOST_F_PKEY_GOST01CC_ENCRYPT,GOST_R_ERROR_COMPUTING_MAC);
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return -1;
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}
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gkt = GOST_KEY_TRANSPORT_new();
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if (!gkt)
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{
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GOSTerr(GOST_F_PKEY_GOST01CC_ENCRYPT,GOST_R_NO_MEMORY);
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return -1;
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}
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/* Store IV which is always zero in our case */
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if (!ASN1_OCTET_STRING_set(gkt->key_agreement_info->eph_iv,iv,8))
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{
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GOSTerr(GOST_F_PKEY_GOST01CC_ENCRYPT,GOST_R_ERROR_STORING_IV);
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goto err;
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}
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if (!ASN1_OCTET_STRING_set(gkt->key_info->imit,hmac,4))
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{
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GOSTerr(GOST_F_PKEY_GOST01CC_ENCRYPT,GOST_R_ERROR_STORING_MAC);
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goto err;
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}
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if (!ASN1_OCTET_STRING_set(gkt->key_info->encrypted_key,encrypted_key,32))
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{
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GOSTerr(GOST_F_PKEY_GOST01CC_ENCRYPT,GOST_R_ERROR_STORING_ENCRYPTED_KEY);
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goto err;
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}
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if (!X509_PUBKEY_set(&gkt->key_agreement_info->ephem_key,data->eph_seckey))
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{
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GOSTerr(GOST_F_PKEY_GOST01CC_ENCRYPT,GOST_R_CANNOT_PACK_EPHEMERAL_KEY);
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goto err;
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}
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ASN1_OBJECT_free(gkt->key_agreement_info->cipher);
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gkt->key_agreement_info->cipher = OBJ_nid2obj(cipher_info->nid);
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if ((*out_len = i2d_GOST_KEY_TRANSPORT(gkt,&out))>0) ret = 1;
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;
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err:
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if (gkt) GOST_KEY_TRANSPORT_free(gkt);
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return ret;
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}
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/*
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* EVP_PKEY_METHOD callback decrypt
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* Implementation of GOST2001 key transport, cryptocom variation
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*/
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int pkey_GOST01cc_decrypt (EVP_PKEY_CTX *pctx, unsigned char *key, size_t *key_len, const unsigned char *in, size_t in_len)
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{
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/* Form DH params from compute shared key */
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EVP_PKEY *priv=EVP_PKEY_CTX_get0_pkey(pctx);
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GOST_KEY_TRANSPORT *gkt = NULL;
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const unsigned char *p=in;
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unsigned char shared_key[32];
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unsigned char hmac[4],hmac_comp[4];
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unsigned char iv[8];
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int i;
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const struct gost_cipher_info *cipher_info;
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gost_ctx ctx;
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const EC_POINT *pub_key_point;
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EVP_PKEY *eph_key;
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if (!key)
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{
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*key_len = 32;
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return 1;
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}
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/* Parse passed octet string and find out public key, iv and HMAC*/
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gkt = d2i_GOST_KEY_TRANSPORT(NULL,(const unsigned char **)&p,
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in_len);
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if (!gkt)
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{
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GOSTerr(GOST_F_PKEY_GOST01CC_DECRYPT,GOST_R_ERROR_PARSING_KEY_TRANSPORT_INFO);
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return 0;
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}
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eph_key = X509_PUBKEY_get(gkt->key_agreement_info->ephem_key);
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/* Initialization vector is really ignored here */
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OPENSSL_assert(gkt->key_agreement_info->eph_iv->length==8);
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memcpy(iv,gkt->key_agreement_info->eph_iv->data,8);
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/* HMAC should be computed and checked */
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OPENSSL_assert(gkt->key_info->imit->length==4);
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memcpy(hmac,gkt->key_info->imit->data,4);
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/* Compute shared key */
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pub_key_point=EC_KEY_get0_public_key(EVP_PKEY_get0(eph_key));
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i=ECDH_compute_key(shared_key,32,pub_key_point,EVP_PKEY_get0(priv),make_key_le);
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EVP_PKEY_free(eph_key);
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if (!i)
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{
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GOSTerr(GOST_F_PKEY_GOST01CC_DECRYPT,GOST_R_ERROR_COMPUTING_SHARED_KEY);
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GOST_KEY_TRANSPORT_free(gkt);
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return 0;
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}
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/* Decrypt session key */
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cipher_info = get_encryption_params(gkt->key_agreement_info->cipher);
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gost_init(&ctx, cipher_info->sblock);
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gost_key(&ctx,shared_key);
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if (!decrypt_cryptocom_key(key,*key_len,gkt->key_info->encrypted_key->data,
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gkt->key_info->encrypted_key->length, &ctx))
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{
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GOST_KEY_TRANSPORT_free(gkt);
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return 0;
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}
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GOST_KEY_TRANSPORT_free(gkt);
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/* check HMAC of session key*/
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if (!gost_mac(&ctx,32,key,32,hmac_comp))
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{
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GOSTerr(GOST_F_PKEY_GOST01CC_DECRYPT,GOST_R_ERROR_COMPUTING_MAC);
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return 0;
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}
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/* HMAC of session key is not correct */
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if (memcmp(hmac,hmac_comp,4)!=0)
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{
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GOSTerr(GOST_F_PKEY_GOST01CC_DECRYPT,GOST_R_SESSION_KEY_MAC_DOES_NOT_MATCH);
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return 0;
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}
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return 1;
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}
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/* Implementation of CryptoPro VKO 34.10-2001 algorithm */
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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)
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{
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unsigned char ukm_be[8],databuf[64],hashbuf[64];
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BIGNUM *UKM=NULL,*p=NULL,*order=NULL,*X=NULL,*Y=NULL;
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const BIGNUM* key=EC_KEY_get0_private_key(priv_key);
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EC_POINT *pnt=EC_POINT_new(EC_KEY_get0_group(priv_key));
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int i;
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gost_hash_ctx hash_ctx;
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BN_CTX *ctx = BN_CTX_new();
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for (i=0;i<8;i++)
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{
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ukm_be[7-i]=ukm[i];
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}
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BN_CTX_start(ctx);
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UKM=getbnfrombuf(ukm_be,8);
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p=BN_CTX_get(ctx);
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order = BN_CTX_get(ctx);
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X=BN_CTX_get(ctx);
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Y=BN_CTX_get(ctx);
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EC_GROUP_get_order(EC_KEY_get0_group(priv_key),order,ctx);
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BN_mod_mul(p,key,UKM,order,ctx);
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EC_POINT_mul(EC_KEY_get0_group(priv_key),pnt,NULL,pub_key,p,ctx);
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EC_POINT_get_affine_coordinates_GFp(EC_KEY_get0_group(priv_key),
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pnt,X,Y,ctx);
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/*Serialize elliptic curve point same way as we do it when saving
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* key */
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store_bignum(Y,databuf,32);
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store_bignum(X,databuf+32,32);
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/* And reverse byte order of whole buffer */
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for (i=0;i<64;i++)
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{
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hashbuf[63-i]=databuf[i];
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}
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init_gost_hash_ctx(&hash_ctx,&GostR3411_94_CryptoProParamSet);
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start_hash(&hash_ctx);
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hash_block(&hash_ctx,hashbuf,64);
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finish_hash(&hash_ctx,shared_key);
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done_gost_hash_ctx(&hash_ctx);
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BN_free(UKM);
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BN_CTX_end(ctx);
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BN_CTX_free(ctx);
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EC_POINT_free(pnt);
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return 32;
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}
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/* Generates ephemeral key based on pubk algorithm
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* computes shared key using VKO and returns filled up
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* GOST_KEY_TRANSPORT structure
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*/
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/* Public, because it would be needed in SSL implementation */
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GOST_KEY_TRANSPORT *make_rfc4490_keytransport_2001(EVP_PKEY *pubk,BIGNUM *eph_key,
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const unsigned char *key,size_t keylen, unsigned char *ukm,
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size_t ukm_len)
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{
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const struct gost_cipher_info *param=get_encryption_params(NULL);
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EC_KEY *ephemeral = NULL;
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GOST_KEY_TRANSPORT *gkt=NULL;
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const EC_POINT *pub_key_point = EC_KEY_get0_public_key(EVP_PKEY_get0(pubk));
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unsigned char shared_key[32],crypted_key[44];
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gost_ctx ctx;
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EVP_PKEY *newkey=NULL;
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/* Do not use vizir cipher parameters with cryptopro */
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if (!get_gost_engine_param(GOST_PARAM_CRYPT_PARAMS) && param == gost_cipher_list)
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{
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param= gost_cipher_list+1;
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}
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ephemeral = make_ec_ephemeral_key(EVP_PKEY_get0(pubk),eph_key);
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VKO_compute_key(shared_key,32,pub_key_point,ephemeral,ukm);
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gost_init(&ctx,param->sblock);
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keyWrapCryptoPro(&ctx,shared_key,ukm,key,crypted_key);
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gkt = GOST_KEY_TRANSPORT_new();
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if (!gkt)
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{
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goto memerr;
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}
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if(!ASN1_OCTET_STRING_set(gkt->key_agreement_info->eph_iv,
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ukm,8))
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{
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goto memerr;
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}
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if (!ASN1_OCTET_STRING_set(gkt->key_info->imit,crypted_key+40,4))
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{
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goto memerr;
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}
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if (!ASN1_OCTET_STRING_set(gkt->key_info->encrypted_key,crypted_key+8,32))
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{
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goto memerr;
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}
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newkey = ec_ephemeral_key_to_EVP(pubk,NID_id_GostR3410_2001,ephemeral);
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if (!X509_PUBKEY_set(&gkt->key_agreement_info->ephem_key,newkey))
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{
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GOSTerr(GOST_F_MAKE_RFC4490_KEYTRANSPORT_2001,GOST_R_CANNOT_PACK_EPHEMERAL_KEY);
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goto err;
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}
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ASN1_OBJECT_free(gkt->key_agreement_info->cipher);
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gkt->key_agreement_info->cipher = OBJ_nid2obj(param->nid);
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EVP_PKEY_free(newkey);
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return gkt;
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memerr:
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GOSTerr(GOST_F_MAKE_RFC4490_KEYTRANSPORT_2001,
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GOST_R_MALLOC_FAILURE);
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err:
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GOST_KEY_TRANSPORT_free(gkt);
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return NULL;
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}
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/*
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* EVP_PKEY_METHOD callback encrypt
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* Implementation of GOST2001 key transport, cryptopo variation
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*/
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int pkey_GOST01cp_encrypt (EVP_PKEY_CTX *pctx, unsigned char *out, size_t *out_len, const unsigned char *key,size_t key_len)
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{
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GOST_KEY_TRANSPORT *gkt=NULL;
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EVP_PKEY *pubk = EVP_PKEY_CTX_get0_pkey(pctx);
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struct gost_pmeth_data *data = EVP_PKEY_CTX_get_data(pctx);
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unsigned char ukm[8];
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int ret=0;
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if (RAND_bytes(ukm,8)<=0)
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{
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GOSTerr(GOST_F_PKEY_GOST01CP_ENCRYPT,
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GOST_R_RANDOM_GENERATOR_FAILURE);
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return 0;
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}
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if (!(gkt=make_rfc4490_keytransport_2001(pubk,gost_get_priv_key(data->eph_seckey),key, key_len,ukm,8)))
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{
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goto err;
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}
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if ((*out_len = i2d_GOST_KEY_TRANSPORT(gkt,&out))>0) ret =1;
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GOST_KEY_TRANSPORT_free(gkt);
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return ret;
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err:
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GOST_KEY_TRANSPORT_free(gkt);
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return -1;
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}
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/* Public, because it would be needed in SSL implementation */
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int decrypt_rfc4490_shared_key_2001(EVP_PKEY *priv,GOST_KEY_TRANSPORT *gkt,
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unsigned char *key_buf,int key_buf_len)
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{
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unsigned char wrappedKey[44];
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unsigned char sharedKey[32];
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gost_ctx ctx;
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const struct gost_cipher_info *param=NULL;
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EVP_PKEY *eph_key=NULL;
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eph_key = X509_PUBKEY_get(gkt->key_agreement_info->ephem_key);
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param = get_encryption_params(gkt->key_agreement_info->cipher);
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gost_init(&ctx,param->sblock);
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OPENSSL_assert(gkt->key_agreement_info->eph_iv->length==8);
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memcpy(wrappedKey,gkt->key_agreement_info->eph_iv->data,8);
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OPENSSL_assert(gkt->key_info->encrypted_key->length==32);
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memcpy(wrappedKey+8,gkt->key_info->encrypted_key->data,32);
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OPENSSL_assert(gkt->key_info->imit->length==4);
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memcpy(wrappedKey+40,gkt->key_info->imit->data,4);
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VKO_compute_key(sharedKey,32,EC_KEY_get0_public_key(EVP_PKEY_get0(eph_key)),
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EVP_PKEY_get0(priv),wrappedKey);
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if (!keyUnwrapCryptoPro(&ctx,sharedKey,wrappedKey,key_buf))
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{
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GOSTerr(GOST_F_PKCS7_GOST94CP_KEY_TRANSPORT_DECRYPT,
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GOST_R_ERROR_COMPUTING_SHARED_KEY);
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goto err;
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}
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EVP_PKEY_free(eph_key);
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return 32;
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err:
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EVP_PKEY_free(eph_key);
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return -1;
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}
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/*
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* EVP_PKEY_METHOD callback decrypt
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* Implementation of GOST2001 key transport, cryptopo variation
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*/
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int pkey_GOST01cp_decrypt (EVP_PKEY_CTX *pctx, unsigned char *key, size_t * key_len, const unsigned char *in, size_t in_len)
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{
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const unsigned char *p = in;
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EVP_PKEY *priv = EVP_PKEY_CTX_get0_pkey(pctx);
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GOST_KEY_TRANSPORT *gkt = NULL;
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int ret=0;
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if (!key)
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{
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*key_len = 32;
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return 1;
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}
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gkt = d2i_GOST_KEY_TRANSPORT(NULL,(const unsigned char **)&p,
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in_len);
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if (!gkt)
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{
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GOSTerr(GOST_F_PKCS7_GOST94CP_KEY_TRANSPORT_DECRYPT,GOST_R_ERROR_PARSING_KEY_TRANSPORT_INFO);
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return -1;
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}
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ret = decrypt_rfc4490_shared_key_2001(priv,gkt,key,*key_len);
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GOST_KEY_TRANSPORT_free(gkt);
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return ret;
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}
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