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/*
* Copyright (c) 2017, [Ribose Inc](https://www.ribose.com).
* 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 <botan/ffi.h>
#include <string.h>
#include <cassert>
#include "ec.h"
#include "types.h"
#include "utils.h"
#include "mem.h"
#include "bn.h"
static id_str_pair ec_algo_to_botan[] = {
{PGP_PKA_ECDH, "ECDH"},
{PGP_PKA_ECDSA, "ECDSA"},
{PGP_PKA_SM2, "SM2_Sig"},
{0, NULL},
};
rnp_result_t
x25519_generate(rnp::RNG *rng, pgp_ec_key_t *key)
{
botan_privkey_t pr_key = NULL;
botan_pubkey_t pu_key = NULL;
rnp_result_t ret = RNP_ERROR_KEY_GENERATION;
rnp::secure_array<uint8_t, 32> keyle;
if (botan_privkey_create(&pr_key, "Curve25519", "", rng->handle())) {
goto end;
}
if (botan_privkey_export_pubkey(&pu_key, pr_key)) {
goto end;
}
/* botan returns key in little-endian, while mpi is big-endian */
if (botan_privkey_x25519_get_privkey(pr_key, keyle.data())) {
goto end;
}
for (int i = 0; i < 32; i++) {
key->x.mpi[31 - i] = keyle[i];
}
key->x.len = 32;
/* botan doesn't tweak secret key bits, so we should do that here */
if (!x25519_tweak_bits(*key)) {
goto end;
}
if (botan_pubkey_x25519_get_pubkey(pu_key, &key->p.mpi[1])) {
goto end;
}
key->p.len = 33;
key->p.mpi[0] = 0x40;
ret = RNP_SUCCESS;
end:
botan_privkey_destroy(pr_key);
botan_pubkey_destroy(pu_key);
return ret;
}
rnp_result_t
ec_generate(rnp::RNG * rng,
pgp_ec_key_t * key,
const pgp_pubkey_alg_t alg_id,
const pgp_curve_t curve)
{
/**
* Keeps "0x04 || x || y"
* \see 13.2. ECDSA, ECDH, SM2 Conversion Primitives
*
* P-521 is biggest supported curve
*/
botan_privkey_t pr_key = NULL;
botan_pubkey_t pu_key = NULL;
bignum_t * px = NULL;
bignum_t * py = NULL;
bignum_t * x = NULL;
rnp_result_t ret = RNP_ERROR_KEY_GENERATION;
size_t filed_byte_size = 0;
if (!alg_allows_curve(alg_id, curve)) {
return RNP_ERROR_BAD_PARAMETERS;
}
const char *ec_algo = id_str_pair::lookup(ec_algo_to_botan, alg_id, NULL);
assert(ec_algo);
const ec_curve_desc_t *ec_desc = get_curve_desc(curve);
if (!ec_desc) {
ret = RNP_ERROR_BAD_PARAMETERS;
goto end;
}
filed_byte_size = BITS_TO_BYTES(ec_desc->bitlen);
// at this point it must succeed
if (botan_privkey_create(&pr_key, ec_algo, ec_desc->botan_name, rng->handle())) {
goto end;
}
if (botan_privkey_export_pubkey(&pu_key, pr_key)) {
goto end;
}
// Crash if seckey is null. It's clean and easy to debug design
px = bn_new();
py = bn_new();
x = bn_new();
if (!px || !py || !x) {
RNP_LOG("Allocation failed");
ret = RNP_ERROR_OUT_OF_MEMORY;
goto end;
}
if (botan_pubkey_get_field(BN_HANDLE_PTR(px), pu_key, "public_x")) {
goto end;
}
if (botan_pubkey_get_field(BN_HANDLE_PTR(py), pu_key, "public_y")) {
goto end;
}
if (botan_privkey_get_field(BN_HANDLE_PTR(x), pr_key, "x")) {
goto end;
}
size_t x_bytes;
size_t y_bytes;
x_bytes = bn_num_bytes(*px);
y_bytes = bn_num_bytes(*py);
// Safety check
if ((x_bytes > filed_byte_size) || (y_bytes > filed_byte_size)) {
RNP_LOG("Key generation failed");
ret = RNP_ERROR_BAD_PARAMETERS;
goto end;
}
/*
* Convert coordinates to MPI stored as
* "0x04 || x || y"
*
* \see 13.2. ECDSA and ECDH Conversion Primitives
*
* Note: Generated pk/sk may not always have exact number of bytes
* which is important when converting to octet-string
*/
memset(key->p.mpi, 0, sizeof(key->p.mpi));
key->p.mpi[0] = 0x04;
bn_bn2bin(px, &key->p.mpi[1 + filed_byte_size - x_bytes]);
bn_bn2bin(py, &key->p.mpi[1 + filed_byte_size + (filed_byte_size - y_bytes)]);
key->p.len = 2 * filed_byte_size + 1;
/* secret key value */
bn2mpi(x, &key->x);
ret = RNP_SUCCESS;
end:
botan_privkey_destroy(pr_key);
botan_pubkey_destroy(pu_key);
bn_free(px);
bn_free(py);
bn_free(x);
return ret;
}
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