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/*-
* Copyright (c) 2017-2022 Ribose Inc.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDERS OR CONTRIBUTORS
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
#include <string.h>
#include <botan/ffi.h>
#include "hash_botan.hpp"
#include "sm2.h"
#include "utils.h"
#include "bn.h"
static bool
sm2_load_public_key(botan_pubkey_t *pubkey, const pgp_ec_key_t *keydata)
{
const ec_curve_desc_t *curve = NULL;
botan_mp_t px = NULL;
botan_mp_t py = NULL;
size_t sz;
bool res = false;
if (!(curve = get_curve_desc(keydata->curve))) {
return false;
}
const size_t sign_half_len = BITS_TO_BYTES(curve->bitlen);
sz = mpi_bytes(&keydata->p);
if (!sz || (sz != (2 * sign_half_len + 1)) || (keydata->p.mpi[0] != 0x04)) {
goto end;
}
if (botan_mp_init(&px) || botan_mp_init(&py) ||
botan_mp_from_bin(px, &keydata->p.mpi[1], sign_half_len) ||
botan_mp_from_bin(py, &keydata->p.mpi[1 + sign_half_len], sign_half_len)) {
goto end;
}
res = !botan_pubkey_load_sm2(pubkey, px, py, curve->botan_name);
end:
botan_mp_destroy(px);
botan_mp_destroy(py);
return res;
}
static bool
sm2_load_secret_key(botan_privkey_t *seckey, const pgp_ec_key_t *keydata)
{
const ec_curve_desc_t *curve = NULL;
bignum_t * x = NULL;
bool res = false;
if (!(curve = get_curve_desc(keydata->curve))) {
return false;
}
if (!(x = mpi2bn(&keydata->x))) {
return false;
}
res = !botan_privkey_load_sm2(seckey, BN_HANDLE_PTR(x), curve->botan_name);
bn_free(x);
return res;
}
rnp_result_t
sm2_compute_za(const pgp_ec_key_t &key, rnp::Hash &hash, const char *ident_field)
{
rnp_result_t result = RNP_ERROR_GENERIC;
botan_pubkey_t sm2_key = NULL;
int rc;
const char *hash_algo = rnp::Hash_Botan::name_backend(hash.alg());
size_t digest_len = hash.size();
uint8_t *digest_buf = (uint8_t *) malloc(digest_len);
if (!digest_buf) {
return RNP_ERROR_OUT_OF_MEMORY;
}
if (!sm2_load_public_key(&sm2_key, &key)) {
RNP_LOG("Failed to load SM2 key");
goto done;
}
if (ident_field == NULL)
ident_field = "1234567812345678";
rc = botan_pubkey_sm2_compute_za(digest_buf, &digest_len, ident_field, hash_algo, sm2_key);
if (rc != 0) {
RNP_LOG("compute_za failed %d", rc);
goto done;
}
try {
hash.add(digest_buf, digest_len);
} catch (const std::exception &e) {
RNP_LOG("Failed to update hash: %s", e.what());
goto done;
}
result = RNP_SUCCESS;
done:
free(digest_buf);
botan_pubkey_destroy(sm2_key);
return result;
}
rnp_result_t
sm2_validate_key(rnp::RNG *rng, const pgp_ec_key_t *key, bool secret)
{
botan_pubkey_t bpkey = NULL;
botan_privkey_t bskey = NULL;
rnp_result_t ret = RNP_ERROR_BAD_PARAMETERS;
if (!sm2_load_public_key(&bpkey, key) || botan_pubkey_check_key(bpkey, rng->handle(), 0)) {
goto done;
}
if (!secret) {
ret = RNP_SUCCESS;
goto done;
}
if (!sm2_load_secret_key(&bskey, key) ||
botan_privkey_check_key(bskey, rng->handle(), 0)) {
goto done;
}
ret = RNP_SUCCESS;
done:
botan_privkey_destroy(bskey);
botan_pubkey_destroy(bpkey);
return ret;
}
rnp_result_t
sm2_sign(rnp::RNG * rng,
pgp_ec_signature_t *sig,
pgp_hash_alg_t hash_alg,
const uint8_t * hash,
size_t hash_len,
const pgp_ec_key_t *key)
{
const ec_curve_desc_t *curve = NULL;
botan_pk_op_sign_t signer = NULL;
botan_privkey_t b_key = NULL;
uint8_t out_buf[2 * MAX_CURVE_BYTELEN] = {0};
size_t sign_half_len = 0;
size_t sig_len = 0;
rnp_result_t ret = RNP_ERROR_SIGNING_FAILED;
if (botan_ffi_supports_api(20180713) != 0) {
RNP_LOG("SM2 signatures requires Botan 2.8 or higher");
return RNP_ERROR_NOT_SUPPORTED;
}
if (hash_len != rnp::Hash::size(hash_alg)) {
return RNP_ERROR_BAD_PARAMETERS;
}
if (!(curve = get_curve_desc(key->curve))) {
return RNP_ERROR_BAD_PARAMETERS;
}
sign_half_len = BITS_TO_BYTES(curve->bitlen);
sig_len = 2 * sign_half_len;
if (!sm2_load_secret_key(&b_key, key)) {
RNP_LOG("Can't load private key");
ret = RNP_ERROR_BAD_PARAMETERS;
goto end;
}
if (botan_pk_op_sign_create(&signer, b_key, ",Raw", 0)) {
goto end;
}
if (botan_pk_op_sign_update(signer, hash, hash_len)) {
goto end;
}
if (botan_pk_op_sign_finish(signer, rng->handle(), out_buf, &sig_len)) {
RNP_LOG("Signing failed");
goto end;
}
// Allocate memory and copy results
if (mem2mpi(&sig->r, out_buf, sign_half_len) &&
mem2mpi(&sig->s, out_buf + sign_half_len, sign_half_len)) {
// All good now
ret = RNP_SUCCESS;
}
end:
botan_privkey_destroy(b_key);
botan_pk_op_sign_destroy(signer);
return ret;
}
rnp_result_t
sm2_verify(const pgp_ec_signature_t *sig,
pgp_hash_alg_t hash_alg,
const uint8_t * hash,
size_t hash_len,
const pgp_ec_key_t * key)
{
const ec_curve_desc_t *curve = NULL;
botan_pubkey_t pub = NULL;
botan_pk_op_verify_t verifier = NULL;
rnp_result_t ret = RNP_ERROR_SIGNATURE_INVALID;
uint8_t sign_buf[2 * MAX_CURVE_BYTELEN] = {0};
size_t r_blen, s_blen, sign_half_len;
if (botan_ffi_supports_api(20180713) != 0) {
RNP_LOG("SM2 signatures requires Botan 2.8 or higher");
return RNP_ERROR_NOT_SUPPORTED;
}
if (hash_len != rnp::Hash::size(hash_alg)) {
return RNP_ERROR_BAD_PARAMETERS;
}
curve = get_curve_desc(key->curve);
if (curve == NULL) {
return RNP_ERROR_BAD_PARAMETERS;
}
sign_half_len = BITS_TO_BYTES(curve->bitlen);
if (!sm2_load_public_key(&pub, key)) {
RNP_LOG("Failed to load public key");
goto end;
}
if (botan_pk_op_verify_create(&verifier, pub, ",Raw", 0)) {
goto end;
}
if (botan_pk_op_verify_update(verifier, hash, hash_len)) {
goto end;
}
r_blen = sig->r.len;
s_blen = sig->s.len;
if (!r_blen || (r_blen > sign_half_len) || !s_blen || (s_blen > sign_half_len) ||
(sign_half_len > MAX_CURVE_BYTELEN)) {
goto end;
}
mpi2mem(&sig->r, sign_buf + sign_half_len - r_blen);
mpi2mem(&sig->s, sign_buf + 2 * sign_half_len - s_blen);
if (!botan_pk_op_verify_finish(verifier, sign_buf, sign_half_len * 2)) {
ret = RNP_SUCCESS;
}
end:
botan_pubkey_destroy(pub);
botan_pk_op_verify_destroy(verifier);
return ret;
}
rnp_result_t
sm2_encrypt(rnp::RNG * rng,
pgp_sm2_encrypted_t *out,
const uint8_t * in,
size_t in_len,
pgp_hash_alg_t hash_algo,
const pgp_ec_key_t * key)
{
rnp_result_t ret = RNP_ERROR_GENERIC;
const ec_curve_desc_t *curve = NULL;
botan_pubkey_t sm2_key = NULL;
botan_pk_op_encrypt_t enc_op = NULL;
size_t point_len;
size_t hash_alg_len;
size_t ctext_len;
curve = get_curve_desc(key->curve);
if (curve == NULL) {
return RNP_ERROR_GENERIC;
}
point_len = BITS_TO_BYTES(curve->bitlen);
hash_alg_len = rnp::Hash::size(hash_algo);
if (!hash_alg_len) {
RNP_LOG("Unknown hash algorithm for SM2 encryption");
goto done;
}
/*
* Format of SM2 ciphertext is a point (2*point_len+1) plus
* the masked ciphertext (out_len) plus a hash.
*/
ctext_len = (2 * point_len + 1) + in_len + hash_alg_len;
if (ctext_len > PGP_MPINT_SIZE) {
RNP_LOG("too large output for SM2 encryption");
goto done;
}
if (!sm2_load_public_key(&sm2_key, key)) {
RNP_LOG("Failed to load public key");
goto done;
}
/*
SM2 encryption doesn't have any kind of format specifier because
it's an all in one scheme, only the hash (used for the integrity
check) is specified.
*/
if (botan_pk_op_encrypt_create(
&enc_op, sm2_key, rnp::Hash_Botan::name_backend(hash_algo), 0)) {
goto done;
}
out->m.len = sizeof(out->m.mpi);
if (botan_pk_op_encrypt(enc_op, rng->handle(), out->m.mpi, &out->m.len, in, in_len) == 0) {
out->m.mpi[out->m.len++] = hash_algo;
ret = RNP_SUCCESS;
}
done:
botan_pk_op_encrypt_destroy(enc_op);
botan_pubkey_destroy(sm2_key);
return ret;
}
rnp_result_t
sm2_decrypt(uint8_t * out,
size_t * out_len,
const pgp_sm2_encrypted_t *in,
const pgp_ec_key_t * key)
{
const ec_curve_desc_t *curve;
botan_pk_op_decrypt_t decrypt_op = NULL;
botan_privkey_t b_key = NULL;
size_t in_len;
rnp_result_t ret = RNP_ERROR_GENERIC;
uint8_t hash_id;
const char * hash_name = NULL;
curve = get_curve_desc(key->curve);
in_len = mpi_bytes(&in->m);
if (curve == NULL || in_len < 64) {
goto done;
}
if (!sm2_load_secret_key(&b_key, key)) {
RNP_LOG("Can't load private key");
goto done;
}
hash_id = in->m.mpi[in_len - 1];
hash_name = rnp::Hash_Botan::name_backend((pgp_hash_alg_t) hash_id);
if (!hash_name) {
RNP_LOG("Unknown hash used in SM2 ciphertext");
goto done;
}
if (botan_pk_op_decrypt_create(&decrypt_op, b_key, hash_name, 0) != 0) {
goto done;
}
if (botan_pk_op_decrypt(decrypt_op, out, out_len, in->m.mpi, in_len - 1) == 0) {
ret = RNP_SUCCESS;
}
done:
botan_privkey_destroy(b_key);
botan_pk_op_decrypt_destroy(decrypt_op);
return ret;
}