engines/ccgost/gost94_keyx.c

   1 /**********************************************************************
   2  *                             gost94_keyx.c                          *
   3  *             Copyright (c) 2005-2006 Cryptocom LTD                  *
   4  *         This file is distributed under the same license as OpenSSL *
   5  *                                                                    *
   6  *     Implements generation and parsing of GOST_KEY_TRANSPORT for    *
   7  *                      GOST R 34.10-94 algorithms                            *
   8  *                                                                                                                                        *
   9  *          Requires OpenSSL 0.9.9 for compilation                    *
  10  **********************************************************************/
  11 #include <string.h>
  12 #include <openssl/dh.h>
  13 #include <openssl/rand.h>
  14 #include <openssl/evp.h>
  15 #include <openssl/objects.h>
  16
  17 #include "gost89.h"
  18 #include "gosthash.h"
  19 #include "e_gost_err.h"
  20 #include "gost_keywrap.h"
  21 #include "gost_lcl.h"
  22 /* Common functions for both 94 and 2001 key exchange schemes */
  23 /* Implementation of the Diffi-Hellman key agreement scheme based on
  24  * GOST-94 keys */
  25
  26 /* Computes Diffie-Hellman key and stores it into buffer in
  27  * little-endian byte order as expected by both versions of GOST 94
  28  * algorigthm
  29  */
  30 static int compute_pair_key_le(unsigned char *pair_key,BIGNUM *pub_key,DH *dh)
  31         {
  32         unsigned char be_key[128];
  33         int i,key_size;
  34         key_size=DH_compute_key(be_key,pub_key,dh);
  35         if (!key_size) return 0;
  36         memset(pair_key,0,128);
  37         for (i=0;i<key_size;i++)
  38                 {
  39                 pair_key[i]=be_key[key_size-1-i];
  40                 }
  41         return key_size;
  42         }
  43
  44 /*
  45  * Computes 256 bit Key exchange key as specified in RFC 4357
  46  */
  47 static int make_cp_exchange_key(BIGNUM *priv_key,EVP_PKEY *pubk, unsigned char *shared_key)
  48         {
  49         unsigned char dh_key [128];
  50         int ret;
  51         gost_hash_ctx hash_ctx;
  52         DH *dh = DH_new();
  53
  54         if (!dh)
  55                 return 0;
  56         memset(dh_key,0,128);
  57         dh->g = BN_dup(pubk->pkey.dsa->g);
  58         dh->p = BN_dup(pubk->pkey.dsa->p);
  59         dh->priv_key = BN_dup(priv_key);
  60         ret=compute_pair_key_le(dh_key,((DSA *)(EVP_PKEY_get0(pubk)))->pub_key,dh) ;
  61         DH_free(dh);
  62         if (!ret)       return 0;
  63         init_gost_hash_ctx(&hash_ctx,&GostR3411_94_CryptoProParamSet);
  64         start_hash(&hash_ctx);
  65         hash_block(&hash_ctx,dh_key,128);
  66         finish_hash(&hash_ctx,shared_key);
  67         done_gost_hash_ctx(&hash_ctx);
  68         return 1;
  69         }
  70
  71 /* EVP_PKEY_METHOD callback derive. Implements VKO R 34.10-94 */
  72
  73 int pkey_gost94_derive(EVP_PKEY_CTX *ctx,unsigned char *key,size_t *keylen)
  74         {
  75                 EVP_PKEY *pubk = EVP_PKEY_CTX_get0_peerkey(ctx);
  76                 EVP_PKEY *mykey = EVP_PKEY_CTX_get0_pkey(ctx);
  77                 *keylen = 32;
  78                 if (key == NULL) return 1;
  79
  80                 return make_cp_exchange_key(gost_get0_priv_key(mykey), pubk, key);
  81         }
  82
  83 /* EVP_PKEY_METHOD callback encrypt for
  84  * GOST R 34.10-94 cryptopro modification
  85  */
  86
  87
  88 int pkey_GOST94cp_encrypt(EVP_PKEY_CTX *ctx, unsigned char *out, size_t *outlen, const unsigned char* key, size_t key_len )
  89         {
  90         GOST_KEY_TRANSPORT *gkt=NULL;
  91         unsigned char shared_key[32], ukm[8],crypted_key[44];
  92         const struct gost_cipher_info *param=get_encryption_params(NULL);
  93         EVP_PKEY *pubk = EVP_PKEY_CTX_get0_pkey(ctx);
  94         struct gost_pmeth_data *data = EVP_PKEY_CTX_get_data(ctx);
  95         int size=-1;
  96         gost_ctx cctx;
  97         int key_is_ephemeral=1;
  98         EVP_PKEY *mykey = EVP_PKEY_CTX_get0_peerkey(ctx);
  99
 100         /* Do not use vizir cipher parameters with cryptopro */
 101         if (!get_gost_engine_param(GOST_PARAM_CRYPT_PARAMS) && param ==  gost_cipher_list)
 102                 {
 103                 param= gost_cipher_list+1;
 104                 }
 105
 106         if (mykey)
 107                 {
 108                 /* If key already set, it is not ephemeral */
 109                 key_is_ephemeral=0;
 110                 if (!gost_get0_priv_key(mykey))
 111                         {
 112                         GOSTerr(GOST_F_PKEY_GOST94CP_ENCRYPT,
 113                         GOST_R_NO_PRIVATE_PART_OF_NON_EPHEMERAL_KEYPAIR);
 114                         goto err;
 115                         }
 116                 }
 117         else
 118                 {
 119                 /* Otherwise generate ephemeral key */
 120                 key_is_ephemeral = 1;
 121                 if (out)
 122                         {
 123                         mykey = EVP_PKEY_new();
 124                         EVP_PKEY_assign(mykey, EVP_PKEY_base_id(pubk),DSA_new());
 125                         EVP_PKEY_copy_parameters(mykey,pubk);
 126                         if (!gost_sign_keygen(EVP_PKEY_get0(mykey)))
 127                                 {
 128                                 goto err;
 129                                 }
 130                         }
 131                 }
 132         if (out)
 133                 make_cp_exchange_key(gost_get0_priv_key(mykey),pubk,shared_key);
 134         if (data->shared_ukm)
 135                 {
 136                 memcpy(ukm,data->shared_ukm,8);
 137                 }
 138         else if (out)
 139                 {
 140                 if (RAND_bytes(ukm,8)<=0)
 141                         {
 142                         GOSTerr(GOST_F_PKEY_GOST94CP_ENCRYPT,
 143                                         GOST_R_RANDOM_GENERATOR_FAILURE);
 144                         goto err;
 145                         }
 146                 }
 147
 148         if (out) {
 149                 gost_init(&cctx,param->sblock);
 150                 keyWrapCryptoPro(&cctx,shared_key,ukm,key,crypted_key);
 151         }
 152         gkt = GOST_KEY_TRANSPORT_new();
 153         if (!gkt)
 154                 {
 155                 goto memerr;
 156                 }
 157         if(!ASN1_OCTET_STRING_set(gkt->key_agreement_info->eph_iv,
 158                         ukm,8))
 159                 {
 160                 goto memerr;
 161                 }
 162         if (!ASN1_OCTET_STRING_set(gkt->key_info->imit,crypted_key+40,4))
 163                 {
 164                 goto memerr;
 165                 }
 166         if (!ASN1_OCTET_STRING_set(gkt->key_info->encrypted_key,crypted_key+8,32))
 167                 {
 168                 goto memerr;
 169                 }
 170         if (key_is_ephemeral) {
 171         if (!X509_PUBKEY_set(&gkt->key_agreement_info->ephem_key,out?mykey:pubk))
 172                 {
 173                 GOSTerr(GOST_F_PKEY_GOST94CP_ENCRYPT,GOST_R_CANNOT_PACK_EPHEMERAL_KEY);
 174                 goto err;
 175                 }
 176                 if (out) EVP_PKEY_free(mykey);
 177         }
 178         ASN1_OBJECT_free(gkt->key_agreement_info->cipher);
 179         gkt->key_agreement_info->cipher = OBJ_nid2obj(param->nid);
 180         *outlen = i2d_GOST_KEY_TRANSPORT(gkt,out?&out:NULL);
 181         if (!size)
 182                 {
 183                 GOSTerr(GOST_F_PKEY_GOST94CP_ENCRYPT,GOST_R_ERROR_PACKING_KEY_TRANSPORT_INFO);
 184                 size=-1;
 185                 }
 186         GOST_KEY_TRANSPORT_free(gkt);
 187         return 1;
 188         memerr:
 189                 if (key_is_ephemeral) {
 190                         EVP_PKEY_free(mykey);
 191                 }
 192         GOSTerr(GOST_F_PKEY_GOST94CP_ENCRYPT,
 193                 GOST_R_MALLOC_FAILURE);
 194         err:
 195         GOST_KEY_TRANSPORT_free(gkt);
 196         return -1;
 197         }
 198
 199
 200 /* EVP_PLEY_METHOD callback decrypt for
 201  * GOST R 34.10-94 cryptopro modification
 202  */
 203 int pkey_GOST94cp_decrypt(EVP_PKEY_CTX *ctx, unsigned char *key, size_t *key_len,const unsigned char *in, size_t in_len) {
 204         const unsigned char *p = in;
 205         GOST_KEY_TRANSPORT *gkt = NULL;
 206         unsigned char wrappedKey[44];
 207         unsigned char sharedKey[32];
 208         gost_ctx cctx;
 209         const struct gost_cipher_info *param=NULL;
 210         EVP_PKEY *eph_key=NULL;
 211         EVP_PKEY *priv= EVP_PKEY_CTX_get0_pkey(ctx);
 212
 213         if (!key)
 214                 {
 215                 *key_len = 32;
 216                 return 1;
 217                 }
 218
 219         gkt = d2i_GOST_KEY_TRANSPORT(NULL,(const unsigned char **)&p,
 220                 in_len);
 221         if (!gkt)
 222                 {
 223                 GOSTerr(GOST_F_PKEY_GOST94CP_DECRYPT,GOST_R_ERROR_PARSING_KEY_TRANSPORT_INFO);
 224                 return 0;
 225                 }
 226         eph_key = X509_PUBKEY_get(gkt->key_agreement_info->ephem_key);
 227         /* No ephemeral key in the structure. Check peer key in the context
 228          */
 229         if (!eph_key) {
 230                 eph_key = EVP_PKEY_CTX_get0_peerkey(ctx);
 231                 if (! eph_key) {
 232                         GOSTerr(GOST_F_PKEY_GOST94CP_DECRYPT,
 233                                 GOST_R_NO_PEER_KEY);
 234                         goto err;
 235                 }
 236                 /* Increment reference count of peer key */
 237                 CRYPTO_add(&(eph_key->references),1 ,CRYPTO_LOCK_EVP_PKEY);
 238         }
 239
 240
 241         param = get_encryption_params(gkt->key_agreement_info->cipher);
 242         gost_init(&cctx,param->sblock);
 243         OPENSSL_assert(gkt->key_agreement_info->eph_iv->length==8);
 244         memcpy(wrappedKey,gkt->key_agreement_info->eph_iv->data,8);
 245         OPENSSL_assert(gkt->key_info->encrypted_key->length==32);
 246         memcpy(wrappedKey+8,gkt->key_info->encrypted_key->data,32);
 247         OPENSSL_assert(gkt->key_info->imit->length==4);
 248         memcpy(wrappedKey+40,gkt->key_info->imit->data,4);
 249         make_cp_exchange_key(gost_get0_priv_key(priv),eph_key,sharedKey);
 250         if (!keyUnwrapCryptoPro(&cctx,sharedKey,wrappedKey,key))
 251                 {
 252                 GOSTerr(GOST_F_PKEY_GOST94CP_DECRYPT,
 253                         GOST_R_ERROR_COMPUTING_SHARED_KEY);
 254                 goto err;
 255                 }
 256
 257         EVP_PKEY_free(eph_key);
 258         GOST_KEY_TRANSPORT_free(gkt);
 259         return 1;
 260 err:
 261         EVP_PKEY_free(eph_key);
 262         GOST_KEY_TRANSPORT_free(gkt);
 263         return -1;
 264         }
 265