gost94_keyx.c revision 280304 
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/*
24 * Implementation of the Diffi-Hellman key agreement scheme based on GOST-94
25 * keys
26 */
27
28/*
29 * Computes Diffie-Hellman key and stores it into buffer in little-endian
30 * byte order as expected by both versions of GOST 94 algorithm
31 */
32static int compute_pair_key_le(unsigned char *pair_key, BIGNUM *pub_key,
33                               DH *dh)
34{
35    unsigned char be_key[128];
36    int i, key_size;
37    key_size = DH_compute_key(be_key, pub_key, dh);
38    if (!key_size)
39        return 0;
40    memset(pair_key, 0, 128);
41    for (i = 0; i < key_size; i++) {
42        pair_key[i] = be_key[key_size - 1 - i];
43    }
44    return key_size;
45}
46
47/*
48 * Computes 256 bit Key exchange key as specified in RFC 4357
49 */
50static int make_cp_exchange_key(BIGNUM *priv_key, EVP_PKEY *pubk,
51                                unsigned char *shared_key)
52{
53    unsigned char dh_key[128];
54    int ret;
55    gost_hash_ctx hash_ctx;
56    DH *dh = DH_new();
57
58    if (!dh)
59        return 0;
60    memset(dh_key, 0, 128);
61    dh->g = BN_dup(pubk->pkey.dsa->g);
62    dh->p = BN_dup(pubk->pkey.dsa->p);
63    dh->priv_key = BN_dup(priv_key);
64    ret =
65        compute_pair_key_le(dh_key, ((DSA *)(EVP_PKEY_get0(pubk)))->pub_key,
66                            dh);
67    DH_free(dh);
68    if (!ret)
69        return 0;
70    init_gost_hash_ctx(&hash_ctx, &GostR3411_94_CryptoProParamSet);
71    start_hash(&hash_ctx);
72    hash_block(&hash_ctx, dh_key, 128);
73    finish_hash(&hash_ctx, shared_key);
74    done_gost_hash_ctx(&hash_ctx);
75    return 1;
76}
77
78/* EVP_PKEY_METHOD callback derive. Implements VKO R 34.10-94 */
79
80int pkey_gost94_derive(EVP_PKEY_CTX *ctx, unsigned char *key, size_t *keylen)
81{
82    EVP_PKEY *pubk = EVP_PKEY_CTX_get0_peerkey(ctx);
83    EVP_PKEY *mykey = EVP_PKEY_CTX_get0_pkey(ctx);
84    *keylen = 32;
85    if (key == NULL)
86        return 1;
87
88    return make_cp_exchange_key(gost_get0_priv_key(mykey), pubk, key);
89}
90
91/*
92 * EVP_PKEY_METHOD callback encrypt for GOST R 34.10-94 cryptopro
93 * modification
94 */
95
96int pkey_GOST94cp_encrypt(EVP_PKEY_CTX *ctx, unsigned char *out,
97                          size_t *outlen, const unsigned char *key,
98                          size_t key_len)
99{
100    GOST_KEY_TRANSPORT *gkt = NULL;
101    unsigned char shared_key[32], ukm[8], crypted_key[44];
102    const struct gost_cipher_info *param = get_encryption_params(NULL);
103    EVP_PKEY *pubk = EVP_PKEY_CTX_get0_pkey(ctx);
104    struct gost_pmeth_data *data = EVP_PKEY_CTX_get_data(ctx);
105    gost_ctx cctx;
106    int key_is_ephemeral = 1;
107    EVP_PKEY *mykey = EVP_PKEY_CTX_get0_peerkey(ctx);
108
109    /* Do not use vizir cipher parameters with cryptopro */
110    if (!get_gost_engine_param(GOST_PARAM_CRYPT_PARAMS)
111        && param == gost_cipher_list) {
112        param = gost_cipher_list + 1;
113    }
114
115    if (mykey) {
116        /* If key already set, it is not ephemeral */
117        key_is_ephemeral = 0;
118        if (!gost_get0_priv_key(mykey)) {
119            GOSTerr(GOST_F_PKEY_GOST94CP_ENCRYPT,
120                    GOST_R_NO_PRIVATE_PART_OF_NON_EPHEMERAL_KEYPAIR);
121            goto err;
122        }
123    } else {
124        /* Otherwise generate ephemeral key */
125        key_is_ephemeral = 1;
126        if (out) {
127            mykey = EVP_PKEY_new();
128            EVP_PKEY_assign(mykey, EVP_PKEY_base_id(pubk), DSA_new());
129            EVP_PKEY_copy_parameters(mykey, pubk);
130            if (!gost_sign_keygen(EVP_PKEY_get0(mykey))) {
131                goto err;
132            }
133        }
134    }
135    if (out)
136        make_cp_exchange_key(gost_get0_priv_key(mykey), pubk, shared_key);
137    if (data->shared_ukm) {
138        memcpy(ukm, data->shared_ukm, 8);
139    } else if (out) {
140        if (RAND_bytes(ukm, 8) <= 0) {
141            GOSTerr(GOST_F_PKEY_GOST94CP_ENCRYPT,
142                    GOST_R_RANDOM_GENERATOR_FAILURE);
143            goto err;
144        }
145    }
146
147    if (out) {
148        gost_init(&cctx, param->sblock);
149        keyWrapCryptoPro(&cctx, shared_key, ukm, key, crypted_key);
150    }
151    gkt = GOST_KEY_TRANSPORT_new();
152    if (!gkt) {
153        goto memerr;
154    }
155    if (!ASN1_OCTET_STRING_set(gkt->key_agreement_info->eph_iv, ukm, 8)) {
156        goto memerr;
157    }
158    if (!ASN1_OCTET_STRING_set(gkt->key_info->imit, crypted_key + 40, 4)) {
159        goto memerr;
160    }
161    if (!ASN1_OCTET_STRING_set
162        (gkt->key_info->encrypted_key, crypted_key + 8, 32)) {
163        goto memerr;
164    }
165    if (key_is_ephemeral) {
166        if (!X509_PUBKEY_set
167            (&gkt->key_agreement_info->ephem_key, out ? mykey : pubk)) {
168            GOSTerr(GOST_F_PKEY_GOST94CP_ENCRYPT,
169                    GOST_R_CANNOT_PACK_EPHEMERAL_KEY);
170            goto err;
171        }
172        if (out)
173            EVP_PKEY_free(mykey);
174    }
175    ASN1_OBJECT_free(gkt->key_agreement_info->cipher);
176    gkt->key_agreement_info->cipher = OBJ_nid2obj(param->nid);
177    *outlen = i2d_GOST_KEY_TRANSPORT(gkt, out ? &out : NULL);
178    if (*outlen <= 0) {
179        GOSTerr(GOST_F_PKEY_GOST94CP_ENCRYPT,
180                GOST_R_ERROR_PACKING_KEY_TRANSPORT_INFO);
181        goto err;
182    }
183    if (!key_is_ephemeral) {
184        /* Set control "public key from client certificate used" */
185        if (EVP_PKEY_CTX_ctrl(ctx, -1, -1, EVP_PKEY_CTRL_PEER_KEY, 3, NULL) <=
186            0) {
187            GOSTerr(GOST_F_PKEY_GOST94CP_ENCRYPT, GOST_R_CTRL_CALL_FAILED);
188            goto err;
189        }
190    }
191    GOST_KEY_TRANSPORT_free(gkt);
192    return 1;
193 memerr:
194    if (key_is_ephemeral) {
195        EVP_PKEY_free(mykey);
196    }
197    GOSTerr(GOST_F_PKEY_GOST94CP_ENCRYPT, GOST_R_MALLOC_FAILURE);
198 err:
199    GOST_KEY_TRANSPORT_free(gkt);
200    return -1;
201}
202
203/*
204 * EVP_PLEY_METHOD callback decrypt for GOST R 34.10-94 cryptopro
205 * modification
206 */
207int pkey_GOST94cp_decrypt(EVP_PKEY_CTX *ctx, unsigned char *key,
208                          size_t *key_len, const unsigned char *in,
209                          size_t in_len)
210{
211    const unsigned char *p = in;
212    GOST_KEY_TRANSPORT *gkt = NULL;
213    unsigned char wrappedKey[44];
214    unsigned char sharedKey[32];
215    gost_ctx cctx;
216    const struct gost_cipher_info *param = NULL;
217    EVP_PKEY *eph_key = NULL, *peerkey = NULL;
218    EVP_PKEY *priv = EVP_PKEY_CTX_get0_pkey(ctx);
219
220    if (!key) {
221        *key_len = 32;
222        return 1;
223    }
224
225    gkt = d2i_GOST_KEY_TRANSPORT(NULL, (const unsigned char **)&p, in_len);
226    if (!gkt) {
227        GOSTerr(GOST_F_PKEY_GOST94CP_DECRYPT,
228                GOST_R_ERROR_PARSING_KEY_TRANSPORT_INFO);
229        return 0;
230    }
231    eph_key = X509_PUBKEY_get(gkt->key_agreement_info->ephem_key);
232    if (eph_key) {
233        if (EVP_PKEY_derive_set_peer(ctx, eph_key) <= 0) {
234            GOSTerr(GOST_F_PKEY_GOST94CP_DECRYPT,
235                    GOST_R_INCOMPATIBLE_PEER_KEY);
236            goto err;
237        }
238    } else {
239        /* Set control "public key from client certificate used" */
240        if (EVP_PKEY_CTX_ctrl(ctx, -1, -1, EVP_PKEY_CTRL_PEER_KEY, 3, NULL) <=
241            0) {
242            GOSTerr(GOST_F_PKEY_GOST94CP_DECRYPT, GOST_R_CTRL_CALL_FAILED);
243            goto err;
244        }
245    }
246    peerkey = EVP_PKEY_CTX_get0_peerkey(ctx);
247    if (!peerkey) {
248        GOSTerr(GOST_F_PKEY_GOST94CP_DECRYPT, GOST_R_NO_PEER_KEY);
249        goto err;
250    }
251
252    param = get_encryption_params(gkt->key_agreement_info->cipher);
253    if (!param) {
254        goto err;
255    }
256
257    gost_init(&cctx, param->sblock);
258    OPENSSL_assert(gkt->key_agreement_info->eph_iv->length == 8);
259    memcpy(wrappedKey, gkt->key_agreement_info->eph_iv->data, 8);
260    OPENSSL_assert(gkt->key_info->encrypted_key->length == 32);
261    memcpy(wrappedKey + 8, gkt->key_info->encrypted_key->data, 32);
262    OPENSSL_assert(gkt->key_info->imit->length == 4);
263    memcpy(wrappedKey + 40, gkt->key_info->imit->data, 4);
264    make_cp_exchange_key(gost_get0_priv_key(priv), peerkey, sharedKey);
265    if (!keyUnwrapCryptoPro(&cctx, sharedKey, wrappedKey, key)) {
266        GOSTerr(GOST_F_PKEY_GOST94CP_DECRYPT,
267                GOST_R_ERROR_COMPUTING_SHARED_KEY);
268        goto err;
269    }
270
271    EVP_PKEY_free(eph_key);
272    GOST_KEY_TRANSPORT_free(gkt);
273    return 1;
274 err:
275    EVP_PKEY_free(eph_key);
276    GOST_KEY_TRANSPORT_free(gkt);
277    return -1;
278}
279