+
+/*
+ * EVP_PKEY_METHOD callback decrypt
+ * Implementation of GOST2018 key transport
+ */
+static int pkey_gost2018_decrypt(EVP_PKEY_CTX *pctx, unsigned char *key,
+ size_t *key_len, const unsigned char *in,
+ size_t in_len)
+{
+ const unsigned char *p = in;
+ struct gost_pmeth_data *data;
+ EVP_PKEY *priv;
+ PSKeyTransport_gost *pst = NULL;
+ int ret = 0;
+ unsigned char expkeys[64];
+ EVP_PKEY *eph_key = NULL;
+ int pkey_nid;
+ int mac_nid = NID_undef;
+ int iv_len = 0;
+
+ if (!(data = EVP_PKEY_CTX_get_data(pctx)) ||
+ !(priv = EVP_PKEY_CTX_get0_pkey(pctx))) {
+ GOSTerr(GOST_F_PKEY_GOST2018_DECRYPT, GOST_R_ERROR_COMPUTING_EXPORT_KEYS);
+ ret = 0;
+ goto err;
+ }
+ pkey_nid = EVP_PKEY_base_id(priv);
+
+ switch (data->cipher_nid) {
+ case NID_magma_ctr:
+ mac_nid = NID_magma_mac;
+ iv_len = 4;
+ break;
+ case NID_grasshopper_ctr:
+ mac_nid = NID_grasshopper_mac;
+ iv_len = 8;
+ break;
+ default:
+ GOSTerr(GOST_F_PKEY_GOST2018_DECRYPT, GOST_R_INVALID_CIPHER);
+ return -1;
+ break;
+ }
+
+ pst = d2i_PSKeyTransport_gost(NULL, (const unsigned char **)&p, in_len);
+ if (!pst) {
+ GOSTerr(GOST_F_PKEY_GOST2018_DECRYPT,
+ GOST_R_ERROR_PARSING_KEY_TRANSPORT_INFO);
+ return -1;
+ }
+
+ eph_key = X509_PUBKEY_get(pst->ephem_key);
+/*
+ * TODO beldmit
+ 1. Checks the next three conditions fulfilling and terminates the
+ connection with fatal error if not.
+
+ o Q_eph is on the same curve as server public key;
+
+ o Q_eph is not equal to zero point;
+
+ o q * Q_eph is not equal to zero point.
+*/
+ if (eph_key == NULL) {
+ GOSTerr(GOST_F_PKEY_GOST2018_DECRYPT,
+ GOST_R_ERROR_COMPUTING_EXPORT_KEYS);
+ ret = 0;
+ goto err;
+ }
+
+ if (data->shared_ukm_size == 0 && pst->ukm != NULL) {
+ if (EVP_PKEY_CTX_ctrl(pctx, -1, -1, EVP_PKEY_CTRL_SET_IV,
+ ASN1_STRING_length(pst->ukm), (void *)ASN1_STRING_get0_data(pst->ukm)) < 0) {
+ GOSTerr(GOST_F_PKEY_GOST2018_DECRYPT, GOST_R_UKM_NOT_SET);
+ goto err;
+ }
+ }
+
+ if (gost_keg(data->shared_ukm, pkey_nid,
+ EC_KEY_get0_public_key(EVP_PKEY_get0(eph_key)),
+ EVP_PKEY_get0(priv), expkeys) <= 0) {
+ GOSTerr(GOST_F_PKEY_GOST2018_DECRYPT,
+ GOST_R_ERROR_COMPUTING_EXPORT_KEYS);
+ goto err;
+ }
+
+ if (gost_kimp15(ASN1_STRING_get0_data(pst->psexp),
+ ASN1_STRING_length(pst->psexp), data->cipher_nid,
+ expkeys + 32, mac_nid, expkeys + 0, data->shared_ukm + 24,
+ iv_len, key) <= 0) {
+ GOSTerr(GOST_F_PKEY_GOST2018_DECRYPT, GOST_R_CANNOT_UNPACK_EPHEMERAL_KEY);
+ goto err;
+ }
+
+ *key_len = 32;
+ ret = 1;
+ err:
+ OPENSSL_cleanse(expkeys, sizeof(expkeys));
+ EVP_PKEY_free(eph_key);
+ PSKeyTransport_gost_free(pst);
+ return ret;
+}
+
+int pkey_gost_decrypt(EVP_PKEY_CTX *pctx, unsigned char *key,
+ size_t *key_len, const unsigned char *in, size_t in_len)
+{
+ struct gost_pmeth_data *gctx = EVP_PKEY_CTX_get_data(pctx);
+
+ if (key == NULL) {
+ *key_len = 32;
+ return 1;
+ }
+
+ if (key != NULL && *key_len < 32) {
+ GOSTerr(GOST_F_PKEY_GOST_DECRYPT, GOST_R_INVALID_BUFFER_SIZE);
+ return 0;
+ }
+
+ switch (gctx->cipher_nid)
+ {
+ case NID_id_Gost28147_89:
+ case NID_undef: /* FIXME */
+ return pkey_GOST_ECcp_decrypt(pctx, key, key_len, in, in_len);
+ case NID_kuznyechik_ctr:
+ case NID_magma_ctr:
+ return pkey_gost2018_decrypt(pctx, key, key_len, in, in_len);
+ default:
+ GOSTerr(GOST_F_PKEY_GOST_DECRYPT, ERR_R_INTERNAL_ERROR);
+ return -1;
+ }
+}
+/* vim: set expandtab cinoptions=\:0,l1,t0,g0,(0 sw=4 : */