engines/ccgost/gost2001_keyx.c

   1 /**********************************************************************
   2  *                          gost_keyx.c                               *
   3  *             Copyright (c) 2005-2006 Cryptocom LTD                  *
   4  *         This file is distributed under the same license as OpenSSL *
   5  *                                                                    *
   6  *   VK0 34.10-2001 key exchange and GOST R 34.10-2001                *
   7  *   based PKCS7/SMIME support                                        *
   8  *          Requires OpenSSL 0.9.9 for compilation                    *
   9  **********************************************************************/
  10 #include <openssl/evp.h>
  11 #include <openssl/rand.h>
  12 #include <string.h>
  13 #include <openssl/objects.h>
  14 #include "gost89.h"
  15 #include "gosthash.h"
  16 #include "e_gost_err.h"
  17 #include "gost_keywrap.h"
  18 #include "gost_lcl.h"
  19 #include "gost2001_keyx.h"
  20
  21 /* Transform ECDH shared key into little endian as required by Cryptocom
  22  * key exchange */
  23 static void *make_key_le(const void *in, size_t inlen, void *out, size_t *outlen)
  24         {
  25         const char* inbuf= in;
  26         char* outbuf= out;
  27         int i;
  28         if (*outlen < inlen)
  29                 {
  30                 return NULL;
  31                 }
  32         for (i=0;i<inlen;i++)
  33                 {
  34                 outbuf[inlen-1-i]=inbuf[i];
  35                 }
  36         *outlen = inlen;
  37         return out;
  38         }
  39
  40 /* Create gost 2001 ephemeral key with same parameters as peer key */
  41 static EC_KEY *make_ec_ephemeral_key(EC_KEY *peer_key,BIGNUM *seckey)
  42         {
  43         EC_KEY *out = EC_KEY_new();
  44         EC_KEY_copy(out,peer_key);
  45         EC_KEY_set_private_key(out,seckey);
  46         gost2001_compute_public(out);
  47         return out;
  48         }
  49 /* Packs GOST elliptic curve key into EVP_PKEY setting same parameters
  50  * as in passed pubkey
  51  */
  52 static EVP_PKEY *ec_ephemeral_key_to_EVP(EVP_PKEY *pubk,int type,EC_KEY *ephemeral)
  53         {
  54         EVP_PKEY *newkey;
  55         newkey = EVP_PKEY_new();
  56         EVP_PKEY_assign(newkey,type,ephemeral);
  57         return newkey;
  58         }
  59
  60 /*
  61  * EVP_PKEY_METHOD callback encrypt
  62  * Implementation of GOST2001 key transport, cryptocom variation
  63  */
  64
  65 int pkey_GOST01cc_encrypt (EVP_PKEY_CTX *pctx,unsigned char *out,
  66         size_t *out_len, const unsigned char *key,size_t key_len)
  67         {
  68         EVP_PKEY *pubk = EVP_PKEY_CTX_get0_pkey(pctx);
  69         struct gost_pmeth_data *data = EVP_PKEY_CTX_get_data(pctx);
  70         GOST_KEY_TRANSPORT *gkt = NULL;
  71         int ret=0;
  72         gost_ctx ctx;
  73         EC_KEY *ephemeral=NULL;
  74         const EC_POINT *pub_key_point=NULL;
  75         unsigned char shared_key[32],encrypted_key[32],hmac[4],
  76                 iv[8]={0,0,0,0,0,0,0,0};
  77         ephemeral = make_ec_ephemeral_key(EVP_PKEY_get0(pubk), gost_get_priv_key(data->eph_seckey));
  78         if (!ephemeral) goto err;
  79         /* compute shared key */
  80         pub_key_point=EC_KEY_get0_public_key(EVP_PKEY_get0(pubk));
  81         if (!ECDH_compute_key(shared_key,32,pub_key_point,ephemeral,make_key_le))
  82                 {
  83                 GOSTerr(GOST_F_PKEY_GOST01CC_ENCRYPT,GOST_R_ERROR_COMPUTING_SHARED_KEY);
  84                 goto err;
  85                 }
  86         /* encrypt session key */
  87         gost_init(&ctx, &GostR3411_94_CryptoProParamSet);
  88         gost_key(&ctx,shared_key);
  89         encrypt_cryptocom_key(key,key_len,encrypted_key,&ctx);
  90         /* compute hmac of session key */
  91         if (!gost_mac(&ctx,32,key,32,hmac))
  92                 {
  93                 GOSTerr(GOST_F_PKEY_GOST01CC_ENCRYPT,GOST_R_ERROR_COMPUTING_MAC);
  94                 return -1;
  95                 }
  96         gkt = GOST_KEY_TRANSPORT_new();
  97         if (!gkt)
  98                 {
  99                 GOSTerr(GOST_F_PKEY_GOST01CC_ENCRYPT,GOST_R_NO_MEMORY);
 100                 return -1;
 101                 }
 102         /* Store IV which is always zero in our case */
 103         if (!ASN1_OCTET_STRING_set(gkt->key_agreement_info->eph_iv,iv,8))
 104                 {
 105                 GOSTerr(GOST_F_PKEY_GOST01CC_ENCRYPT,GOST_R_ERROR_STORING_IV);
 106                 goto err;
 107                 }
 108         if (!ASN1_OCTET_STRING_set(gkt->key_info->imit,hmac,4))
 109                 {
 110                 GOSTerr(GOST_F_PKEY_GOST01CC_ENCRYPT,GOST_R_ERROR_STORING_MAC);
 111                 goto err;
 112                 }
 113         if (!ASN1_OCTET_STRING_set(gkt->key_info->encrypted_key,encrypted_key,32))
 114                 {
 115                 GOSTerr(GOST_F_PKEY_GOST01CC_ENCRYPT,GOST_R_ERROR_STORING_ENCRYPTED_KEY);
 116                 goto err;
 117                 }
 118
 119         if (!X509_PUBKEY_set(&gkt->key_agreement_info->ephem_key,data->eph_seckey))
 120                 {
 121                 GOSTerr(GOST_F_PKEY_GOST01CC_ENCRYPT,GOST_R_CANNOT_PACK_EPHEMERAL_KEY);
 122                 goto err;
 123                 }
 124         ASN1_OBJECT_free(gkt->key_agreement_info->cipher);
 125         gkt->key_agreement_info->cipher = OBJ_nid2obj(NID_id_Gost28147_89_cc);
 126         if ((*out_len = i2d_GOST_KEY_TRANSPORT(gkt,&out))>0) ret = 1;
 127         ;
 128         err:
 129         if (gkt) GOST_KEY_TRANSPORT_free(gkt);
 130         return ret;
 131         }
 132 /*
 133  * EVP_PKEY_METHOD callback decrypt
 134  * Implementation of GOST2001 key transport, cryptocom variation
 135  */
 136 int pkey_GOST01cc_decrypt (EVP_PKEY_CTX *pctx, unsigned char *key, size_t *key_len, const unsigned char *in, size_t in_len)
 137         {
 138         /* Form DH params from compute shared key */
 139         EVP_PKEY *priv=EVP_PKEY_CTX_get0_pkey(pctx);
 140         GOST_KEY_TRANSPORT *gkt = NULL;
 141         const unsigned char *p=in;
 142         unsigned char shared_key[32];
 143         unsigned char hmac[4],hmac_comp[4];
 144         unsigned char iv[8];
 145         int i;
 146         gost_ctx ctx;
 147         const EC_POINT *pub_key_point;
 148         EVP_PKEY *eph_key;
 149
 150         if (!key)
 151                 {
 152                 *key_len = 32;
 153                 return 1;
 154                 }
 155         /* Parse passed octet string and find out public key, iv and HMAC*/
 156         gkt = d2i_GOST_KEY_TRANSPORT(NULL,(const unsigned char **)&p,
 157                 in_len);
 158         if (!gkt)
 159                 {
 160                 GOSTerr(GOST_F_PKEY_GOST01CC_DECRYPT,GOST_R_ERROR_PARSING_KEY_TRANSPORT_INFO);
 161                 return 0;
 162                 }
 163         eph_key = X509_PUBKEY_get(gkt->key_agreement_info->ephem_key);
 164         /* Initialization vector is really ignored here */
 165         OPENSSL_assert(gkt->key_agreement_info->eph_iv->length==8);
 166         memcpy(iv,gkt->key_agreement_info->eph_iv->data,8);
 167         /* HMAC should be computed and checked */
 168         OPENSSL_assert(gkt->key_info->imit->length==4);
 169         memcpy(hmac,gkt->key_info->imit->data,4);
 170         /* Compute shared key */
 171         pub_key_point=EC_KEY_get0_public_key(EVP_PKEY_get0(eph_key));
 172         i=ECDH_compute_key(shared_key,32,pub_key_point,EVP_PKEY_get0(priv),make_key_le);
 173         EVP_PKEY_free(eph_key);
 174         if (!i)
 175                 {
 176                 GOSTerr(GOST_F_PKEY_GOST01CC_DECRYPT,GOST_R_ERROR_COMPUTING_SHARED_KEY);
 177                 GOST_KEY_TRANSPORT_free(gkt);
 178                 return 0;
 179                 }
 180         /* Decrypt session key */
 181         gost_init(&ctx, &GostR3411_94_CryptoProParamSet);
 182         gost_key(&ctx,shared_key);
 183
 184         if (!decrypt_cryptocom_key(key,*key_len,gkt->key_info->encrypted_key->data,
 185                         gkt->key_info->encrypted_key->length, &ctx))
 186                 {
 187                 GOST_KEY_TRANSPORT_free(gkt);
 188                 return 0;
 189                 }
 190         GOST_KEY_TRANSPORT_free(gkt);
 191         /* check HMAC of session key*/
 192         if (!gost_mac(&ctx,32,key,32,hmac_comp))
 193                 {
 194                 GOSTerr(GOST_F_PKEY_GOST01CC_DECRYPT,GOST_R_ERROR_COMPUTING_MAC);
 195                 return 0;
 196                 }
 197         /* HMAC of session key is not correct */
 198     if (memcmp(hmac,hmac_comp,4)!=0)
 199                 {
 200                 GOSTerr(GOST_F_PKEY_GOST01CC_DECRYPT,GOST_R_SESSION_KEY_MAC_DOES_NOT_MATCH);
 201                 return 0;
 202                 }
 203         return 1;
 204         }
 205
 206 /* Implementation of CryptoPro VKO 34.10-2001 algorithm */
 207 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)
 208         {
 209         unsigned char ukm_be[8],databuf[64],hashbuf[64];
 210         BIGNUM *UKM=NULL,*p=NULL,*order=NULL,*X=NULL,*Y=NULL;
 211         const BIGNUM* key=EC_KEY_get0_private_key(priv_key);
 212         EC_POINT *pnt=EC_POINT_new(EC_KEY_get0_group(priv_key));
 213         int i;
 214         gost_hash_ctx hash_ctx;
 215         BN_CTX *ctx = BN_CTX_new();
 216
 217         for (i=0;i<8;i++)
 218                 {
 219                 ukm_be[7-i]=ukm[i];
 220                 }
 221         BN_CTX_start(ctx);
 222         UKM=getbnfrombuf(ukm_be,8);
 223         p=BN_CTX_get(ctx);
 224         order = BN_CTX_get(ctx);
 225         X=BN_CTX_get(ctx);
 226         Y=BN_CTX_get(ctx);
 227         EC_GROUP_get_order(EC_KEY_get0_group(priv_key),order,ctx);
 228         BN_mod_mul(p,key,UKM,order,ctx);
 229         EC_POINT_mul(EC_KEY_get0_group(priv_key),pnt,NULL,pub_key,p,ctx);
 230         EC_POINT_get_affine_coordinates_GFp(EC_KEY_get0_group(priv_key),
 231                 pnt,X,Y,ctx);
 232         /*Serialize elliptic curve point same way as we do it when saving
 233          * key */
 234         store_bignum(Y,databuf,32);
 235         store_bignum(X,databuf+32,32);
 236         /* And reverse byte order of whole buffer */
 237         for (i=0;i<64;i++)
 238                 {
 239                 hashbuf[63-i]=databuf[i];
 240                 }
 241         init_gost_hash_ctx(&hash_ctx,&GostR3411_94_CryptoProParamSet);
 242         start_hash(&hash_ctx);
 243         hash_block(&hash_ctx,hashbuf,64);
 244         finish_hash(&hash_ctx,shared_key);
 245         done_gost_hash_ctx(&hash_ctx);
 246         BN_free(UKM);
 247         BN_CTX_end(ctx);
 248         BN_CTX_free(ctx);
 249         EC_POINT_free(pnt);
 250         return 32;
 251         }
 252
 253 /* Generates ephemeral key based on pubk algorithm
 254  * computes shared key using VKO and returns filled up
 255  * GOST_KEY_TRANSPORT structure
 256  */
 257 /* Public, because it would be needed in SSL implementation */
 258 GOST_KEY_TRANSPORT *make_rfc4490_keytransport_2001(EVP_PKEY *pubk,BIGNUM *eph_key,
 259         const unsigned char *key,size_t keylen, unsigned char *ukm,
 260         size_t ukm_len)
 261         {
 262
 263         const struct gost_cipher_info *param=get_encryption_params(NULL);
 264         EC_KEY *ephemeral = NULL;
 265         GOST_KEY_TRANSPORT *gkt=NULL;
 266         const EC_POINT *pub_key_point = EC_KEY_get0_public_key(EVP_PKEY_get0(pubk));
 267         unsigned char shared_key[32],crypted_key[44];
 268         gost_ctx ctx;
 269         EVP_PKEY *newkey=NULL;
 270
 271         /* Do not use vizir cipher parameters with cryptopro */
 272         if (!get_gost_engine_param(GOST_PARAM_CRYPT_PARAMS) && param ==  gost_cipher_list)
 273                 {
 274                 param= gost_cipher_list+1;
 275                 }
 276         ephemeral = make_ec_ephemeral_key(EVP_PKEY_get0(pubk),eph_key);
 277     VKO_compute_key(shared_key,32,pub_key_point,ephemeral,ukm);
 278         gost_init(&ctx,param->sblock);
 279         keyWrapCryptoPro(&ctx,shared_key,ukm,key,crypted_key);
 280         gkt = GOST_KEY_TRANSPORT_new();
 281         if (!gkt)
 282                 {
 283                 goto memerr;
 284                 }
 285         if(!ASN1_OCTET_STRING_set(gkt->key_agreement_info->eph_iv,
 286                         ukm,8))
 287                 {
 288                 goto memerr;
 289                 }
 290         if (!ASN1_OCTET_STRING_set(gkt->key_info->imit,crypted_key+40,4))
 291                 {
 292                 goto memerr;
 293                 }
 294         if (!ASN1_OCTET_STRING_set(gkt->key_info->encrypted_key,crypted_key+8,32))
 295                 {
 296                 goto memerr;
 297                 }
 298         newkey = ec_ephemeral_key_to_EVP(pubk,NID_id_GostR3410_2001,ephemeral);
 299         if (!X509_PUBKEY_set(&gkt->key_agreement_info->ephem_key,newkey))
 300                 {
 301                 GOSTerr(GOST_F_MAKE_RFC4490_KEYTRANSPORT_2001,GOST_R_CANNOT_PACK_EPHEMERAL_KEY);
 302                 goto err;
 303                 }
 304         ASN1_OBJECT_free(gkt->key_agreement_info->cipher);
 305         gkt->key_agreement_info->cipher = OBJ_nid2obj(param->nid);
 306         EVP_PKEY_free(newkey);
 307         return gkt;
 308         memerr:
 309         GOSTerr(GOST_F_MAKE_RFC4490_KEYTRANSPORT_2001,
 310                 GOST_R_MALLOC_FAILURE);
 311         err:
 312         GOST_KEY_TRANSPORT_free(gkt);
 313         return NULL;
 314         }
 315
 316 /*
 317  * EVP_PKEY_METHOD callback encrypt
 318  * Implementation of GOST2001 key transport, cryptopo variation
 319  */
 320
 321 int pkey_GOST01cp_encrypt (EVP_PKEY_CTX *pctx, unsigned char *out, size_t *out_len, const unsigned char *key,size_t key_len)
 322         {
 323         GOST_KEY_TRANSPORT *gkt=NULL;
 324         EVP_PKEY *pubk = EVP_PKEY_CTX_get0_pkey(pctx);
 325         struct gost_pmeth_data *data = EVP_PKEY_CTX_get_data(pctx);
 326         unsigned char ukm[8];
 327         int ret=0;
 328         if (RAND_bytes(ukm,8)<=0)
 329                 {
 330                 GOSTerr(GOST_F_PKEY_GOST01CP_ENCRYPT,
 331                         GOST_R_RANDOM_GENERATOR_FAILURE);
 332                 return 0;
 333                 }
 334
 335         if (!(gkt=make_rfc4490_keytransport_2001(pubk,gost_get_priv_key(data->eph_seckey),key, key_len,ukm,8)))
 336                 {
 337                 goto err;
 338                 }
 339         if ((*out_len = i2d_GOST_KEY_TRANSPORT(gkt,&out))>0) ret =1;
 340         GOST_KEY_TRANSPORT_free(gkt);
 341         return ret;
 342         err:
 343         GOST_KEY_TRANSPORT_free(gkt);
 344         return -1;
 345         }
 346 /* Public, because it would be needed in SSL implementation */
 347 int decrypt_rfc4490_shared_key_2001(EVP_PKEY *priv,GOST_KEY_TRANSPORT *gkt,
 348         unsigned char *key_buf,int key_buf_len)
 349         {
 350         unsigned char wrappedKey[44];
 351         unsigned char sharedKey[32];
 352         gost_ctx ctx;
 353         const struct gost_cipher_info *param=NULL;
 354         EVP_PKEY *eph_key=NULL;
 355
 356         eph_key = X509_PUBKEY_get(gkt->key_agreement_info->ephem_key);
 357         param = get_encryption_params(gkt->key_agreement_info->cipher);
 358         gost_init(&ctx,param->sblock);
 359         OPENSSL_assert(gkt->key_agreement_info->eph_iv->length==8);
 360         memcpy(wrappedKey,gkt->key_agreement_info->eph_iv->data,8);
 361         OPENSSL_assert(gkt->key_info->encrypted_key->length==32);
 362         memcpy(wrappedKey+8,gkt->key_info->encrypted_key->data,32);
 363         OPENSSL_assert(gkt->key_info->imit->length==4);
 364         memcpy(wrappedKey+40,gkt->key_info->imit->data,4);
 365         VKO_compute_key(sharedKey,32,EC_KEY_get0_public_key(EVP_PKEY_get0(eph_key)),
 366                 EVP_PKEY_get0(priv),wrappedKey);
 367         if (!keyUnwrapCryptoPro(&ctx,sharedKey,wrappedKey,key_buf))
 368                 {
 369                 GOSTerr(GOST_F_PKCS7_GOST94CP_KEY_TRANSPORT_DECRYPT,
 370                         GOST_R_ERROR_COMPUTING_SHARED_KEY);
 371                 goto err;
 372                 }
 373
 374         EVP_PKEY_free(eph_key);
 375         return 32;
 376         err:
 377         EVP_PKEY_free(eph_key);
 378         return -1;
 379         }
 380 /*
 381  * EVP_PKEY_METHOD callback decrypt
 382  * Implementation of GOST2001 key transport, cryptopo variation
 383  */
 384 int pkey_GOST01cp_decrypt (EVP_PKEY_CTX *pctx, unsigned char *key, size_t * key_len, const unsigned char *in, size_t in_len)
 385         {
 386         const unsigned char *p = in;
 387         EVP_PKEY *priv = EVP_PKEY_CTX_get0_pkey(pctx);
 388         GOST_KEY_TRANSPORT *gkt = NULL;
 389         int ret=0;
 390
 391         if (!key)
 392                 {
 393                 *key_len = 32;
 394                 return 1;
 395                 }
 396         gkt = d2i_GOST_KEY_TRANSPORT(NULL,(const unsigned char **)&p,
 397                 in_len);
 398         if (!gkt)
 399                 {
 400                 GOSTerr(GOST_F_PKCS7_GOST94CP_KEY_TRANSPORT_DECRYPT,GOST_R_ERROR_PARSING_KEY_TRANSPORT_INFO);
 401                 return -1;
 402                 }
 403         ret =   decrypt_rfc4490_shared_key_2001(priv,gkt,key,*key_len);
 404         GOST_KEY_TRANSPORT_free(gkt);
 405         return ret;
 406         }