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/err.h>
  15 #include <openssl/evp.h>
  16 #include <openssl/objects.h>
  17
  18 #include "gost89.h"
  19 #include "gosthash.h"
  20 #include "e_gost_err.h"
  21 #include "gost_keywrap.h"
  22 #include "gost_lcl.h"
  23 /* Common functions for both 94 and 2001 key exchange schemes */
  24 /*
  25  * Implementation of the Diffi-Hellman key agreement scheme based on GOST-94
  26  * keys
  27  */
  28
  29 /*
  30  * Computes Diffie-Hellman key and stores it into buffer in little-endian
  31  * byte order as expected by both versions of GOST 94 algorithm
  32  */
  33 static int compute_pair_key_le(unsigned char *pair_key, BIGNUM *pub_key,
  34                                DH *dh)
  35 {
  36     unsigned char be_key[128];
  37     int i, key_size;
  38     key_size = DH_compute_key(be_key, pub_key, dh);
  39     if (!key_size)
  40         return 0;
  41     memset(pair_key, 0, 128);
  42     for (i = 0; i < key_size; i++) {
  43         pair_key[i] = be_key[key_size - 1 - i];
  44     }
  45     return key_size;
  46 }
  47
  48 /*
  49  * Computes 256 bit Key exchange key as specified in RFC 4357
  50  */
  51 static int make_cp_exchange_key(BIGNUM *priv_key, EVP_PKEY *pubk,
  52                                 unsigned char *shared_key)
  53 {
  54     unsigned char dh_key[128];
  55     int ret;
  56     gost_hash_ctx hash_ctx;
  57     DH *dh = DH_new();
  58
  59     if (!dh)
  60         return 0;
  61     memset(dh_key, 0, 128);
  62     dh->g = BN_dup(pubk->pkey.dsa->g);
  63     dh->p = BN_dup(pubk->pkey.dsa->p);
  64     dh->priv_key = BN_dup(priv_key);
  65     ret =
  66         compute_pair_key_le(dh_key, ((DSA *)(EVP_PKEY_get0(pubk)))->pub_key,
  67                             dh);
  68     DH_free(dh);
  69     if (!ret)
  70         return 0;
  71     init_gost_hash_ctx(&hash_ctx, &GostR3411_94_CryptoProParamSet);
  72     start_hash(&hash_ctx);
  73     hash_block(&hash_ctx, dh_key, 128);
  74     finish_hash(&hash_ctx, shared_key);
  75     done_gost_hash_ctx(&hash_ctx);
  76     return 1;
  77 }
  78
  79 /* EVP_PKEY_METHOD callback derive. Implements VKO R 34.10-94 */
  80
  81 int pkey_gost94_derive(EVP_PKEY_CTX *ctx, unsigned char *key, size_t *keylen)
  82 {
  83     EVP_PKEY *pubk = EVP_PKEY_CTX_get0_peerkey(ctx);
  84     EVP_PKEY *mykey = EVP_PKEY_CTX_get0_pkey(ctx);
  85     *keylen = 32;
  86     if (key == NULL)
  87         return 1;
  88
  89     return make_cp_exchange_key(gost_get0_priv_key(mykey), pubk, key);
  90 }
  91
  92 /*
  93  * EVP_PKEY_METHOD callback encrypt for GOST R 34.10-94 cryptopro
  94  * modification
  95  */
  96
  97 int pkey_GOST94cp_encrypt(EVP_PKEY_CTX *ctx, unsigned char *out,
  98                           size_t *outlen, const unsigned char *key,
  99                           size_t key_len)
 100 {
 101     GOST_KEY_TRANSPORT *gkt = NULL;
 102     unsigned char shared_key[32], ukm[8], crypted_key[44];
 103     const struct gost_cipher_info *param = get_encryption_params(NULL);
 104     EVP_PKEY *pubk = EVP_PKEY_CTX_get0_pkey(ctx);
 105     struct gost_pmeth_data *data = EVP_PKEY_CTX_get_data(ctx);
 106     gost_ctx cctx;
 107     int key_is_ephemeral = 1;
 108     int tmp_outlen;
 109     EVP_PKEY *mykey = EVP_PKEY_CTX_get0_peerkey(ctx);
 110
 111     /* Do not use vizir cipher parameters with cryptopro */
 112     if (!get_gost_engine_param(GOST_PARAM_CRYPT_PARAMS)
 113         && param == gost_cipher_list) {
 114         param = gost_cipher_list + 1;
 115     }
 116
 117     if (mykey) {
 118         /* If key already set, it is not ephemeral */
 119         key_is_ephemeral = 0;
 120         if (!gost_get0_priv_key(mykey)) {
 121             GOSTerr(GOST_F_PKEY_GOST94CP_ENCRYPT,
 122                     GOST_R_NO_PRIVATE_PART_OF_NON_EPHEMERAL_KEYPAIR);
 123             goto err;
 124         }
 125     } else {
 126         /* Otherwise generate ephemeral key */
 127         key_is_ephemeral = 1;
 128         if (out) {
 129             mykey = EVP_PKEY_new();
 130             EVP_PKEY_assign(mykey, EVP_PKEY_base_id(pubk), DSA_new());
 131             EVP_PKEY_copy_parameters(mykey, pubk);
 132             if (!gost_sign_keygen(EVP_PKEY_get0(mykey))) {
 133                 goto err;
 134             }
 135         }
 136     }
 137     if (out)
 138         make_cp_exchange_key(gost_get0_priv_key(mykey), pubk, shared_key);
 139     if (data->shared_ukm) {
 140         memcpy(ukm, data->shared_ukm, 8);
 141     } else if (out) {
 142         if (RAND_bytes(ukm, 8) <= 0) {
 143             GOSTerr(GOST_F_PKEY_GOST94CP_ENCRYPT,
 144                     GOST_R_RANDOM_GENERATOR_FAILURE);
 145             goto err;
 146         }
 147     }
 148
 149     if (out) {
 150         gost_init(&cctx, param->sblock);
 151         keyWrapCryptoPro(&cctx, shared_key, ukm, key, crypted_key);
 152     }
 153     gkt = GOST_KEY_TRANSPORT_new();
 154     if (!gkt) {
 155         goto memerr;
 156     }
 157     if (!ASN1_OCTET_STRING_set(gkt->key_agreement_info->eph_iv, ukm, 8)) {
 158         goto memerr;
 159     }
 160     if (!ASN1_OCTET_STRING_set(gkt->key_info->imit, crypted_key + 40, 4)) {
 161         goto memerr;
 162     }
 163     if (!ASN1_OCTET_STRING_set
 164         (gkt->key_info->encrypted_key, crypted_key + 8, 32)) {
 165         goto memerr;
 166     }
 167     if (key_is_ephemeral) {
 168         if (!X509_PUBKEY_set
 169             (&gkt->key_agreement_info->ephem_key, out ? mykey : pubk)) {
 170             GOSTerr(GOST_F_PKEY_GOST94CP_ENCRYPT,
 171                     GOST_R_CANNOT_PACK_EPHEMERAL_KEY);
 172             goto err;
 173         }
 174         if (out)
 175             EVP_PKEY_free(mykey);
 176     }
 177     ASN1_OBJECT_free(gkt->key_agreement_info->cipher);
 178     gkt->key_agreement_info->cipher = OBJ_nid2obj(param->nid);
 179     tmp_outlen = i2d_GOST_KEY_TRANSPORT(gkt, out ? &out : NULL);
 180     if (tmp_outlen <= 0) {
 181         GOSTerr(GOST_F_PKEY_GOST94CP_ENCRYPT,
 182                 GOST_R_ERROR_PACKING_KEY_TRANSPORT_INFO);
 183         goto err;
 184     }
 185     *outlen = tmp_outlen;
 186     if (!key_is_ephemeral) {
 187         /* Set control "public key from client certificate used" */
 188         if (EVP_PKEY_CTX_ctrl(ctx, -1, -1, EVP_PKEY_CTRL_PEER_KEY, 3, NULL) <=
 189             0) {
 190             GOSTerr(GOST_F_PKEY_GOST94CP_ENCRYPT, GOST_R_CTRL_CALL_FAILED);
 191             goto err;
 192         }
 193     }
 194     GOST_KEY_TRANSPORT_free(gkt);
 195     return 1;
 196  memerr:
 197     if (key_is_ephemeral) {
 198         EVP_PKEY_free(mykey);
 199     }
 200     GOSTerr(GOST_F_PKEY_GOST94CP_ENCRYPT, ERR_R_MALLOC_FAILURE);
 201  err:
 202     GOST_KEY_TRANSPORT_free(gkt);
 203     return -1;
 204 }
 205
 206 /*
 207  * EVP_PLEY_METHOD callback decrypt for GOST R 34.10-94 cryptopro
 208  * modification
 209  */
 210 int pkey_GOST94cp_decrypt(EVP_PKEY_CTX *ctx, unsigned char *key,
 211                           size_t *key_len, const unsigned char *in,
 212                           size_t in_len)
 213 {
 214     const unsigned char *p = in;
 215     GOST_KEY_TRANSPORT *gkt = NULL;
 216     unsigned char wrappedKey[44];
 217     unsigned char sharedKey[32];
 218     gost_ctx cctx;
 219     const struct gost_cipher_info *param = NULL;
 220     EVP_PKEY *eph_key = NULL, *peerkey = NULL;
 221     EVP_PKEY *priv = EVP_PKEY_CTX_get0_pkey(ctx);
 222
 223     if (!key) {
 224         *key_len = 32;
 225         return 1;
 226     }
 227
 228     gkt = d2i_GOST_KEY_TRANSPORT(NULL, (const unsigned char **)&p, in_len);
 229     if (!gkt) {
 230         GOSTerr(GOST_F_PKEY_GOST94CP_DECRYPT,
 231                 GOST_R_ERROR_PARSING_KEY_TRANSPORT_INFO);
 232         return 0;
 233     }
 234     eph_key = X509_PUBKEY_get(gkt->key_agreement_info->ephem_key);
 235     if (eph_key) {
 236         if (EVP_PKEY_derive_set_peer(ctx, eph_key) <= 0) {
 237             GOSTerr(GOST_F_PKEY_GOST94CP_DECRYPT,
 238                     GOST_R_INCOMPATIBLE_PEER_KEY);
 239             goto err;
 240         }
 241     } else {
 242         /* Set control "public key from client certificate used" */
 243         if (EVP_PKEY_CTX_ctrl(ctx, -1, -1, EVP_PKEY_CTRL_PEER_KEY, 3, NULL) <=
 244             0) {
 245             GOSTerr(GOST_F_PKEY_GOST94CP_DECRYPT, GOST_R_CTRL_CALL_FAILED);
 246             goto err;
 247         }
 248     }
 249     peerkey = EVP_PKEY_CTX_get0_peerkey(ctx);
 250     if (!peerkey) {
 251         GOSTerr(GOST_F_PKEY_GOST94CP_DECRYPT, GOST_R_NO_PEER_KEY);
 252         goto err;
 253     }
 254
 255     param = get_encryption_params(gkt->key_agreement_info->cipher);
 256     if (!param) {
 257         goto err;
 258     }
 259
 260     gost_init(&cctx, param->sblock);
 261     OPENSSL_assert(gkt->key_agreement_info->eph_iv->length == 8);
 262     memcpy(wrappedKey, gkt->key_agreement_info->eph_iv->data, 8);
 263     OPENSSL_assert(gkt->key_info->encrypted_key->length == 32);
 264     memcpy(wrappedKey + 8, gkt->key_info->encrypted_key->data, 32);
 265     OPENSSL_assert(gkt->key_info->imit->length == 4);
 266     memcpy(wrappedKey + 40, gkt->key_info->imit->data, 4);
 267     make_cp_exchange_key(gost_get0_priv_key(priv), peerkey, sharedKey);
 268     if (!keyUnwrapCryptoPro(&cctx, sharedKey, wrappedKey, key)) {
 269         GOSTerr(GOST_F_PKEY_GOST94CP_DECRYPT,
 270                 GOST_R_ERROR_COMPUTING_SHARED_KEY);
 271         goto err;
 272     }
 273
 274     EVP_PKEY_free(eph_key);
 275     GOST_KEY_TRANSPORT_free(gkt);
 276     return 1;
 277  err:
 278     EVP_PKEY_free(eph_key);
 279     GOST_KEY_TRANSPORT_free(gkt);
 280     return -1;
 281 }