gost94_keyx.c revision 306195 
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    int tmp_outlen;
108    EVP_PKEY *mykey = EVP_PKEY_CTX_get0_peerkey(ctx);
109
110    /* Do not use vizir cipher parameters with cryptopro */
111    if (!get_gost_engine_param(GOST_PARAM_CRYPT_PARAMS)
112        && param == gost_cipher_list) {
113        param = gost_cipher_list + 1;
114    }
115
116    if (mykey) {
117        /* If key already set, it is not ephemeral */
118        key_is_ephemeral = 0;
119        if (!gost_get0_priv_key(mykey)) {
120            GOSTerr(GOST_F_PKEY_GOST94CP_ENCRYPT,
121                    GOST_R_NO_PRIVATE_PART_OF_NON_EPHEMERAL_KEYPAIR);
122            goto err;
123        }
124    } else {
125        /* Otherwise generate ephemeral key */
126        key_is_ephemeral = 1;
127        if (out) {
128            mykey = EVP_PKEY_new();
129            if (!mykey)
130                goto memerr;
131            EVP_PKEY_assign(mykey, EVP_PKEY_base_id(pubk), DSA_new());
132            EVP_PKEY_copy_parameters(mykey, pubk);
133            if (!gost_sign_keygen(EVP_PKEY_get0(mykey))) {
134                goto err;
135            }
136        }
137    }
138    if (out)
139        make_cp_exchange_key(gost_get0_priv_key(mykey), pubk, shared_key);
140    if (data->shared_ukm) {
141        memcpy(ukm, data->shared_ukm, 8);
142    } else if (out) {
143        if (RAND_bytes(ukm, 8) <= 0) {
144            GOSTerr(GOST_F_PKEY_GOST94CP_ENCRYPT,
145                    GOST_R_RANDOM_GENERATOR_FAILURE);
146            goto err;
147        }
148    }
149
150    if (out) {
151        gost_init(&cctx, param->sblock);
152        keyWrapCryptoPro(&cctx, shared_key, ukm, key, crypted_key);
153    }
154    gkt = GOST_KEY_TRANSPORT_new();
155    if (!gkt) {
156        goto memerr;
157    }
158    if (!ASN1_OCTET_STRING_set(gkt->key_agreement_info->eph_iv, ukm, 8)) {
159        goto memerr;
160    }
161    if (!ASN1_OCTET_STRING_set(gkt->key_info->imit, crypted_key + 40, 4)) {
162        goto memerr;
163    }
164    if (!ASN1_OCTET_STRING_set
165        (gkt->key_info->encrypted_key, crypted_key + 8, 32)) {
166        goto memerr;
167    }
168    if (key_is_ephemeral) {
169        if (!X509_PUBKEY_set
170            (&gkt->key_agreement_info->ephem_key, out ? mykey : pubk)) {
171            GOSTerr(GOST_F_PKEY_GOST94CP_ENCRYPT,
172                    GOST_R_CANNOT_PACK_EPHEMERAL_KEY);
173            goto err;
174        }
175        if (out)
176            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    tmp_outlen = i2d_GOST_KEY_TRANSPORT(gkt, out ? &out : NULL);
181    if (tmp_outlen <= 0) {
182        GOSTerr(GOST_F_PKEY_GOST94CP_ENCRYPT,
183                GOST_R_ERROR_PACKING_KEY_TRANSPORT_INFO);
184        goto err;
185    }
186    *outlen = tmp_outlen;
187    if (!key_is_ephemeral) {
188        /* Set control "public key from client certificate used" */
189        if (EVP_PKEY_CTX_ctrl(ctx, -1, -1, EVP_PKEY_CTRL_PEER_KEY, 3, NULL) <=
190            0) {
191            GOSTerr(GOST_F_PKEY_GOST94CP_ENCRYPT, GOST_R_CTRL_CALL_FAILED);
192            goto err;
193        }
194    }
195    GOST_KEY_TRANSPORT_free(gkt);
196    return 1;
197 memerr:
198    if (key_is_ephemeral) {
199        EVP_PKEY_free(mykey);
200    }
201    GOSTerr(GOST_F_PKEY_GOST94CP_ENCRYPT, GOST_R_MALLOC_FAILURE);
202 err:
203    GOST_KEY_TRANSPORT_free(gkt);
204    return -1;
205}
206
207/*
208 * EVP_PLEY_METHOD callback decrypt for GOST R 34.10-94 cryptopro
209 * modification
210 */
211int pkey_GOST94cp_decrypt(EVP_PKEY_CTX *ctx, unsigned char *key,
212                          size_t *key_len, const unsigned char *in,
213                          size_t in_len)
214{
215    const unsigned char *p = in;
216    GOST_KEY_TRANSPORT *gkt = NULL;
217    unsigned char wrappedKey[44];
218    unsigned char sharedKey[32];
219    gost_ctx cctx;
220    const struct gost_cipher_info *param = NULL;
221    EVP_PKEY *eph_key = NULL, *peerkey = NULL;
222    EVP_PKEY *priv = EVP_PKEY_CTX_get0_pkey(ctx);
223
224    if (!key) {
225        *key_len = 32;
226        return 1;
227    }
228
229    gkt = d2i_GOST_KEY_TRANSPORT(NULL, (const unsigned char **)&p, in_len);
230    if (!gkt) {
231        GOSTerr(GOST_F_PKEY_GOST94CP_DECRYPT,
232                GOST_R_ERROR_PARSING_KEY_TRANSPORT_INFO);
233        return 0;
234    }
235    eph_key = X509_PUBKEY_get(gkt->key_agreement_info->ephem_key);
236    if (eph_key) {
237        if (EVP_PKEY_derive_set_peer(ctx, eph_key) <= 0) {
238            GOSTerr(GOST_F_PKEY_GOST94CP_DECRYPT,
239                    GOST_R_INCOMPATIBLE_PEER_KEY);
240            goto err;
241        }
242    } else {
243        /* Set control "public key from client certificate used" */
244        if (EVP_PKEY_CTX_ctrl(ctx, -1, -1, EVP_PKEY_CTRL_PEER_KEY, 3, NULL) <=
245            0) {
246            GOSTerr(GOST_F_PKEY_GOST94CP_DECRYPT, GOST_R_CTRL_CALL_FAILED);
247            goto err;
248        }
249    }
250    peerkey = EVP_PKEY_CTX_get0_peerkey(ctx);
251    if (!peerkey) {
252        GOSTerr(GOST_F_PKEY_GOST94CP_DECRYPT, GOST_R_NO_PEER_KEY);
253        goto err;
254    }
255
256    param = get_encryption_params(gkt->key_agreement_info->cipher);
257    if (!param) {
258        goto err;
259    }
260
261    gost_init(&cctx, param->sblock);
262    OPENSSL_assert(gkt->key_agreement_info->eph_iv->length == 8);
263    memcpy(wrappedKey, gkt->key_agreement_info->eph_iv->data, 8);
264    OPENSSL_assert(gkt->key_info->encrypted_key->length == 32);
265    memcpy(wrappedKey + 8, gkt->key_info->encrypted_key->data, 32);
266    OPENSSL_assert(gkt->key_info->imit->length == 4);
267    memcpy(wrappedKey + 40, gkt->key_info->imit->data, 4);
268    make_cp_exchange_key(gost_get0_priv_key(priv), peerkey, sharedKey);
269    if (!keyUnwrapCryptoPro(&cctx, sharedKey, wrappedKey, key)) {
270        GOSTerr(GOST_F_PKEY_GOST94CP_DECRYPT,
271                GOST_R_ERROR_COMPUTING_SHARED_KEY);
272        goto err;
273    }
274
275    EVP_PKEY_free(eph_key);
276    GOST_KEY_TRANSPORT_free(gkt);
277    return 1;
278 err:
279    EVP_PKEY_free(eph_key);
280    GOST_KEY_TRANSPORT_free(gkt);
281    return -1;
282}
283