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 int decrypt_cryptocom_key(unsigned char *sess_key,int max_key_len,
  24         const unsigned char *crypted_key,int crypted_key_len, gost_ctx *ctx)
  25         {
  26         int i;
  27         int j;
  28         int blocks = crypted_key_len >>3;
  29         unsigned char gamma[8];
  30         if (max_key_len <crypted_key_len)
  31                 {
  32                 GOSTerr(GOST_F_DECRYPT_CRYPTOCOM_KEY,GOST_R_NOT_ENOUGH_SPACE_FOR_KEY);
  33                 return 0;
  34                 }
  35         if ((crypted_key_len & 7) !=0)
  36                 {
  37                 GOSTerr(GOST_F_DECRYPT_CRYPTOCOM_KEY,GOST_R_INVALID_ENCRYPTED_KEY_SIZE);
  38                 return 0;
  39                 }
  40         for (i=blocks-1;i>0;i--)
  41                 {
  42                 gostcrypt(ctx,crypted_key+(i-1)*8,gamma);
  43                 for(j=0;j<8;j++)
  44                         {
  45                         sess_key[i*8+j]=gamma[j]^crypted_key[i*8+j];
  46                         }
  47                 }
  48         gostcrypt(ctx,sess_key+crypted_key_len-8,gamma);
  49         for(j=0;j<8;j++)
  50                 {
  51                 sess_key[j]=gamma[j]^crypted_key[j];
  52                 }
  53         return 1;
  54         }
  55 int encrypt_cryptocom_key(const unsigned char *sess_key,int key_len,
  56         unsigned char *crypted_key, gost_ctx *ctx)
  57         {
  58         int i;
  59         int j;
  60         unsigned char gamma[8];
  61         memcpy(gamma,sess_key+key_len-8,8);
  62         for (i=0;i<key_len;i+=8)
  63                 {
  64                 gostcrypt(ctx,gamma,gamma);
  65                 for (j=0;j<8;j++)
  66                         gamma[j]=crypted_key[i+j]=sess_key[i+j]^gamma[j];
  67                 }
  68         return 1;
  69         }
  70 /* Implementation of the Diffi-Hellman key agreement scheme based on
  71  * GOST-94 keys */
  72
  73 /* Computes Diffie-Hellman key and stores it into buffer in
  74  * little-endian byte order as expected by both versions of GOST 94
  75  * algorigthm
  76  */
  77 static int compute_pair_key_le(unsigned char *pair_key,BIGNUM *pub_key,DH *dh)
  78         {
  79         unsigned char be_key[128];
  80         int i,key_size;
  81         key_size=DH_compute_key(be_key,pub_key,dh);
  82         if (!key_size) return 0;
  83         memset(pair_key,0,128);
  84         for (i=0;i<key_size;i++)
  85                 {
  86                 pair_key[i]=be_key[key_size-1-i];
  87                 }
  88         return key_size;
  89         }
  90 /*
  91  * Computes 256 bit key exchange key for CryptoCom variation of GOST 94
  92  * algorithm
  93  */
  94 static int make_gost_shared_key(DH *dh,EVP_PKEY *pubk,unsigned char *shared_key)
  95         {
  96         unsigned char dh_key [128];
  97         int i;
  98         /* Compute key */
  99         memset(dh_key,0,128);
 100         if (!compute_pair_key_le(dh_key,((DSA *)EVP_PKEY_get0(pubk))->pub_key,dh)) return 0;
 101         /* Fold it down to 256 bit */
 102         /* According to GOST  either 2^1020<p<2^1024 or
 103          * 2^509<p<2^512, so DH_size can be exactly 128 or exactly 64 only
 104          */
 105
 106         if (DH_size(dh)==128)
 107                 {
 108                 for (i=0;i<64;i++)
 109                         {
 110                         dh_key[i]^=dh_key[64+i];
 111                         }
 112                 }
 113         for (i=0;i<32;i++)
 114                 {
 115                 shared_key[i]=dh_key[i]^dh_key[32+i];
 116                 }
 117         return 1;
 118         }
 119
 120 static DH *make_ephemeral_key(EVP_PKEY *pubk,BIGNUM *ephemeral_key)
 121         {
 122         DH *dh = DH_new();
 123         dh->g = BN_dup(pubk->pkey.dsa->g);
 124         dh->p = BN_dup(pubk->pkey.dsa->p);
 125         dh->priv_key = BN_dup(ephemeral_key);
 126         /* Generate ephemeral key pair */
 127         if (!DH_generate_key(dh))
 128                 {
 129                 DH_free(dh);
 130                 return NULL;
 131                 }
 132         return dh;
 133         }
 134 /*
 135  * Computes 256 bit Key exchange key as specified in RFC 4357
 136  */
 137 static int make_cp_exchange_key(DH *dh,EVP_PKEY *pubk, unsigned char *shared_key)
 138         {
 139         unsigned char dh_key [128];
 140         gost_hash_ctx hash_ctx;
 141         memset(dh_key,0,128);
 142         if (!compute_pair_key_le(dh_key,((DSA *)(EVP_PKEY_get0(pubk)))->pub_key,dh)) return 0;
 143         init_gost_hash_ctx(&hash_ctx,&GostR3411_94_CryptoProParamSet);
 144         start_hash(&hash_ctx);
 145         hash_block(&hash_ctx,dh_key,128);
 146         finish_hash(&hash_ctx,shared_key);
 147         done_gost_hash_ctx(&hash_ctx);
 148         return 1;
 149         }
 150
 151 /* EVP_PKEY_METHOD callback encrypt for
 152  * GOST R 34.10-94 cryptopro modification
 153  */
 154
 155 int pkey_GOST94cp_encrypt(EVP_PKEY_CTX *ctx, unsigned char *out, size_t *outlen, const unsigned char* key, size_t key_len )
 156         {
 157         GOST_KEY_TRANSPORT *gkt=NULL;
 158         DH *dh = NULL;
 159         unsigned char shared_key[32], ukm[8],crypted_key[44];
 160         const struct gost_cipher_info *param=get_encryption_params(NULL);
 161         EVP_PKEY *pubk = EVP_PKEY_CTX_get0_pkey(ctx);
 162         struct gost_pmeth_data *data = EVP_PKEY_CTX_get_data(ctx);
 163         int size=-1;
 164         gost_ctx cctx;
 165
 166         if (!(data->eph_seckey))
 167                 {
 168                 GOSTerr(GOST_F_PKEY_GOST94CP_ENCRYPT,
 169                         GOST_R_CTX_NOT_INITIALIZED_FOR_ENCRYPT);
 170                 return -1;
 171                 }
 172
 173         dh = make_ephemeral_key(pubk,gost_get_priv_key(data->eph_seckey));
 174         gost_init(&cctx,param->sblock);
 175         make_cp_exchange_key(dh,pubk,shared_key);
 176         if (RAND_bytes(ukm,8)<=0)
 177                 {
 178                 GOSTerr(GOST_F_PKEY_GOST94CP_ENCRYPT,
 179                         GOST_R_RANDOM_GENERATOR_FAILURE);
 180                 return -1;
 181                 }
 182         keyWrapCryptoPro(&cctx,shared_key,ukm,key,crypted_key);
 183         gkt = GOST_KEY_TRANSPORT_new();
 184         if (!gkt)
 185                 {
 186                 goto memerr;
 187                 }
 188         if(!ASN1_OCTET_STRING_set(gkt->key_agreement_info->eph_iv,
 189                         ukm,8))
 190                 {
 191                 goto memerr;
 192                 }
 193         if (!ASN1_OCTET_STRING_set(gkt->key_info->imit,crypted_key+40,4))
 194                 {
 195                 goto memerr;
 196                 }
 197         if (!ASN1_OCTET_STRING_set(gkt->key_info->encrypted_key,crypted_key+8,32))
 198                 {
 199                 goto memerr;
 200                 }
 201         if (!X509_PUBKEY_set(&gkt->key_agreement_info->ephem_key,data->eph_seckey))
 202                 {
 203                 GOSTerr(GOST_F_PKEY_GOST94CP_ENCRYPT,GOST_R_CANNOT_PACK_EPHEMERAL_KEY);
 204                 goto err;
 205                 }
 206         ASN1_OBJECT_free(gkt->key_agreement_info->cipher);
 207         gkt->key_agreement_info->cipher = OBJ_nid2obj(param->nid);
 208         *outlen = i2d_GOST_KEY_TRANSPORT(gkt,&out);
 209         if (!size)
 210                 {
 211                 GOSTerr(GOST_F_PKEY_GOST94CP_ENCRYPT,GOST_R_ERROR_PACKING_KEY_TRANSPORT_INFO);
 212                 size=-1;
 213                 }
 214         GOST_KEY_TRANSPORT_free(gkt);
 215         DH_free(dh);
 216         return 1;
 217         memerr:
 218         GOSTerr(GOST_F_PKEY_GOST94CP_ENCRYPT,
 219                 GOST_R_MALLOC_FAILURE);
 220         err:
 221         GOST_KEY_TRANSPORT_free(gkt);
 222         DH_free(dh);
 223         return -1;
 224         }
 225
 226 /* EVP_PKEY_METHOD callback encrypt for
 227  * GOST R 34.10-94 cryptocom modification
 228  */
 229
 230 int pkey_GOST94cc_encrypt (EVP_PKEY_CTX *ctx, unsigned char *out, size_t *outlen,  const unsigned char *   key,size_t key_len)
 231         {
 232         EVP_PKEY *pubk = EVP_PKEY_CTX_get0_pkey(ctx);
 233         struct gost_pmeth_data *data = EVP_PKEY_CTX_get_data(ctx);
 234         /* create DH structure filling parameters from passed pub_key */
 235         DH *dh = NULL;
 236         GOST_KEY_TRANSPORT *gkt = NULL;
 237         const struct gost_cipher_info *cipher_info;
 238         gost_ctx cctx;
 239         EVP_PKEY *newkey=NULL;
 240         unsigned char shared_key[32],encrypted_key[32],hmac[4],
 241                 iv[8]={0,0,0,0,0,0,0,0};
 242
 243         if (! data->eph_seckey)
 244                 {
 245                 GOSTerr(GOST_F_PKEY_GOST94CP_ENCRYPT,
 246                         GOST_R_CTX_NOT_INITIALIZED_FOR_ENCRYPT);
 247                 return -1;
 248                 }
 249         dh = make_ephemeral_key(pubk,gost_get_priv_key(data->eph_seckey));
 250         if (!dh) goto err;
 251         /* compute shared key */
 252         if (!make_gost_shared_key(dh,pubk,shared_key))
 253                 {
 254                 GOSTerr(GOST_F_PKEY_GOST94CC_ENCRYPT,GOST_R_ERROR_COMPUTING_SHARED_KEY);
 255                 goto err;
 256                 }
 257         /* encrypt session key */
 258         cipher_info = get_encryption_params(NULL);
 259         gost_init(&cctx, cipher_info->sblock);
 260         gost_key(&cctx,shared_key);
 261         encrypt_cryptocom_key(key,key_len,encrypted_key,&cctx);
 262         /* compute hmac of session key */
 263         if (!gost_mac(&cctx,32,key,32,hmac))
 264                 {
 265                 DH_free(dh);
 266                 GOSTerr(GOST_F_PKEY_GOST94CC_ENCRYPT,GOST_R_ERROR_COMPUTING_MAC);
 267                 return -1;
 268                 }
 269         gkt = GOST_KEY_TRANSPORT_new();
 270         if (!gkt)
 271                 {
 272                 DH_free(dh);
 273                 GOSTerr(GOST_F_PKEY_GOST94CC_ENCRYPT,GOST_R_NO_MEMORY);
 274                 return -1;
 275                 }
 276         /* Store IV which is always zero in our case */
 277         if (!ASN1_OCTET_STRING_set(gkt->key_agreement_info->eph_iv,iv,8))
 278                 {
 279                 GOSTerr(GOST_F_PKEY_GOST94CC_ENCRYPT,GOST_R_ERROR_STORING_IV);
 280                 goto err;
 281                 }
 282         if (!ASN1_OCTET_STRING_set(gkt->key_info->imit,hmac,4))
 283                 {
 284                 GOSTerr(GOST_F_PKEY_GOST94CC_ENCRYPT,GOST_R_ERROR_STORING_MAC);
 285                 goto err;
 286                 }
 287         if (!ASN1_OCTET_STRING_set(gkt->key_info->encrypted_key,encrypted_key,32))
 288                 {
 289                 GOSTerr(GOST_F_PKEY_GOST94CC_ENCRYPT,GOST_R_ERROR_STORING_ENCRYPTED_KEY);
 290                 goto err;
 291                 }
 292         if (!X509_PUBKEY_set(&gkt->key_agreement_info->ephem_key,data->eph_seckey))
 293                 {
 294                 GOSTerr(GOST_F_PKEY_GOST94CC_ENCRYPT,GOST_R_CANNOT_PACK_EPHEMERAL_KEY);
 295                 goto err;
 296                 }
 297         ASN1_OBJECT_free(gkt->key_agreement_info->cipher);
 298         gkt->key_agreement_info->cipher = OBJ_nid2obj(cipher_info->nid);
 299         *outlen = i2d_GOST_KEY_TRANSPORT(gkt,&out);
 300         err:
 301         if (gkt) GOST_KEY_TRANSPORT_free(gkt);
 302         if (dh) DH_free(dh);
 303         if (newkey) EVP_PKEY_free(newkey);
 304         return 1;
 305         }
 306
 307 /* EVP_PLEY_METHOD callback decrypt for
 308  * GOST R 34.10-94 cryptopro modification
 309  */
 310 int pkey_GOST94cp_decrypt (EVP_PKEY_CTX *ctx, unsigned char *key, size_t *key_len,const unsigned char *in, size_t in_len) {
 311         DH *dh = DH_new();
 312         const unsigned char *p = in;
 313         GOST_KEY_TRANSPORT *gkt = NULL;
 314         unsigned char wrappedKey[44];
 315         unsigned char sharedKey[32];
 316         gost_ctx cctx;
 317         const struct gost_cipher_info *param=NULL;
 318         EVP_PKEY *eph_key=NULL;
 319         EVP_PKEY *priv= EVP_PKEY_CTX_get0_pkey(ctx);
 320
 321         if (!key)
 322                 {
 323                 *key_len = 32;
 324                 return 1;
 325                 }
 326
 327         dh->g = BN_dup(priv->pkey.dsa->g);
 328         dh->p = BN_dup(priv->pkey.dsa->p);
 329         dh->priv_key = BN_dup(priv->pkey.dsa->priv_key);
 330         gkt = d2i_GOST_KEY_TRANSPORT(NULL,(const unsigned char **)&p,
 331                 in_len);
 332         if (!gkt)
 333                 {
 334                 GOSTerr(GOST_F_PKEY_GOST94CP_DECRYPT,GOST_R_ERROR_PARSING_KEY_TRANSPORT_INFO);
 335                 DH_free(dh);
 336                 return 0;
 337                 }
 338         eph_key = X509_PUBKEY_get(gkt->key_agreement_info->ephem_key);
 339         param = get_encryption_params(gkt->key_agreement_info->cipher);
 340         gost_init(&cctx,param->sblock);
 341         OPENSSL_assert(gkt->key_agreement_info->eph_iv->length==8);
 342         memcpy(wrappedKey,gkt->key_agreement_info->eph_iv->data,8);
 343         OPENSSL_assert(gkt->key_info->encrypted_key->length==32);
 344         memcpy(wrappedKey+8,gkt->key_info->encrypted_key->data,32);
 345         OPENSSL_assert(gkt->key_info->imit->length==4);
 346         memcpy(wrappedKey+40,gkt->key_info->imit->data,4);
 347         make_cp_exchange_key(dh,eph_key,sharedKey);
 348         if (!keyUnwrapCryptoPro(&cctx,sharedKey,wrappedKey,key))
 349                 {
 350                 GOSTerr(GOST_F_PKEY_GOST94CP_DECRYPT,
 351                         GOST_R_ERROR_COMPUTING_SHARED_KEY);
 352                 goto err;
 353                 }
 354
 355         EVP_PKEY_free(eph_key);
 356         GOST_KEY_TRANSPORT_free(gkt);
 357         DH_free(dh);
 358         return 1;
 359 err:
 360         EVP_PKEY_free(eph_key);
 361         GOST_KEY_TRANSPORT_free(gkt);
 362         DH_free(dh);
 363         return -1;
 364         }
 365
 366 /* EVP_PKEY_METHOD callback decrypt for
 367  * GOST R 34.10-94 cryptocom modification
 368  */
 369
 370 int pkey_GOST94cc_decrypt (EVP_PKEY_CTX *pctx, unsigned char *key, size_t *key_len, const unsigned char *in, size_t in_len)
 371         {
 372         /* Form DH params from compute shared key */
 373         GOST_KEY_TRANSPORT *gkt = NULL;
 374         const unsigned char *p=in;
 375         unsigned char shared_key[32];
 376         unsigned char hmac[4],hmac_comp[4];
 377         unsigned char iv[8];
 378         int i;
 379         const struct gost_cipher_info *cipher_info;
 380         gost_ctx ctx;
 381         DH *dh = DH_new();
 382         EVP_PKEY *eph_key;
 383         EVP_PKEY *priv = EVP_PKEY_CTX_get0_pkey(pctx);
 384
 385         if (!key)
 386                 {
 387                 *key_len = 32;
 388                 return 1;
 389                 }
 390         /* Construct DH structure from the our GOST private key */
 391         dh->g = BN_dup(priv->pkey.dsa->g);
 392         dh->p = BN_dup(priv->pkey.dsa->p);
 393         dh->priv_key = BN_dup(priv->pkey.dsa->priv_key);
 394         /* Parse passed octet string and find out public key, iv and HMAC*/
 395         gkt = d2i_GOST_KEY_TRANSPORT(NULL,(const unsigned char **)&p,
 396                 in_len);
 397         if (!gkt)
 398                 {
 399                 GOSTerr(GOST_F_PKEY_GOST94CC_DECRYPT,GOST_R_ERROR_PARSING_KEY_TRANSPORT_INFO);
 400                 DH_free(dh);
 401                 return 0;
 402                 }
 403         eph_key = X509_PUBKEY_get(gkt->key_agreement_info->ephem_key);
 404         /* Initialization vector is really ignored here */
 405         OPENSSL_assert(gkt->key_agreement_info->eph_iv->length==8);
 406         memcpy(iv,gkt->key_agreement_info->eph_iv->data,8);
 407         /* HMAC should be computed and checked */
 408         OPENSSL_assert(gkt->key_info->imit->length==4);
 409         memcpy(hmac,gkt->key_info->imit->data,4);
 410         /* Compute shared key */
 411         i=make_gost_shared_key(dh,eph_key,shared_key);
 412         EVP_PKEY_free(eph_key);
 413         DH_free(dh);
 414         if (!i)
 415                 {
 416                 GOSTerr(GOST_F_PKEY_GOST94CC_DECRYPT,GOST_R_ERROR_COMPUTING_SHARED_KEY);
 417                 GOST_KEY_TRANSPORT_free(gkt);
 418                 return 0;
 419                 }
 420         /* Decrypt session key */
 421         cipher_info = get_encryption_params(gkt->key_agreement_info->cipher);
 422         gost_init(&ctx, cipher_info->sblock);
 423         gost_key(&ctx,shared_key);
 424
 425         if (!decrypt_cryptocom_key(key,*key_len,gkt->key_info->encrypted_key->data,
 426                         gkt->key_info->encrypted_key->length, &ctx))
 427                 {
 428                 GOST_KEY_TRANSPORT_free(gkt);
 429                 return 0;
 430                 }
 431         GOST_KEY_TRANSPORT_free(gkt);
 432         /* check HMAC of session key*/
 433         if (!gost_mac(&ctx,32,key,32,hmac_comp))
 434                 {
 435                 GOSTerr(GOST_F_PKEY_GOST94CC_DECRYPT,GOST_R_ERROR_COMPUTING_MAC);
 436                 return 0;
 437                 }
 438         /* HMAC of session key is not correct */
 439     if (memcmp(hmac,hmac_comp,4)!=0)
 440                 {
 441                 GOSTerr(GOST_F_PKEY_GOST94CC_DECRYPT,GOST_R_SESSION_KEY_MAC_DOES_NOT_MATCH);
 442                 return 0;
 443                 }
 444         return 1;
 445         }