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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 <string.h>
#include <botan/ffi.h>
#include "eddsa.h"
#include "utils.h"
static bool
eddsa_load_public_key(botan_pubkey_t *pubkey, const pgp_ec_key_t *keydata)
{
if (keydata->curve != PGP_CURVE_ED25519) {
return false;
}
/*
* See draft-ietf-openpgp-rfc4880bis-01 section 13.3
*/
if ((mpi_bytes(&keydata->p) != 33) || (keydata->p.mpi[0] != 0x40)) {
return false;
}
if (botan_pubkey_load_ed25519(pubkey, keydata->p.mpi + 1)) {
return false;
}
return true;
}
static bool
eddsa_load_secret_key(botan_privkey_t *seckey, const pgp_ec_key_t *keydata)
{
uint8_t keybuf[32] = {0};
size_t sz;
if (keydata->curve != PGP_CURVE_ED25519) {
return false;
}
sz = mpi_bytes(&keydata->x);
if (!sz || (sz > 32)) {
return false;
}
mpi2mem(&keydata->x, keybuf + 32 - sz);
if (botan_privkey_load_ed25519(seckey, keybuf)) {
return false;
}
return true;
}
rnp_result_t
eddsa_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 (!eddsa_load_public_key(&bpkey, key) ||
botan_pubkey_check_key(bpkey, rng->handle(), 0)) {
goto done;
}
if (!secret) {
ret = RNP_SUCCESS;
goto done;
}
if (!eddsa_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
eddsa_generate(rnp::RNG *rng, pgp_ec_key_t *key)
{
botan_privkey_t eddsa = NULL;
rnp_result_t ret = RNP_ERROR_GENERIC;
uint8_t key_bits[64];
if (botan_privkey_create(&eddsa, "Ed25519", NULL, rng->handle()) != 0) {
goto end;
}
if (botan_privkey_ed25519_get_privkey(eddsa, key_bits)) {
goto end;
}
// First 32 bytes of key_bits are the EdDSA seed (private key)
// Second 32 bytes are the EdDSA public key
mem2mpi(&key->x, key_bits, 32);
// insert the required 0x40 prefix on the public key
key_bits[31] = 0x40;
mem2mpi(&key->p, key_bits + 31, 33);
key->curve = PGP_CURVE_ED25519;
ret = RNP_SUCCESS;
end:
botan_privkey_destroy(eddsa);
return ret;
}
rnp_result_t
eddsa_verify(const pgp_ec_signature_t *sig,
const uint8_t * hash,
size_t hash_len,
const pgp_ec_key_t * key)
{
botan_pubkey_t eddsa = NULL;
botan_pk_op_verify_t verify_op = NULL;
rnp_result_t ret = RNP_ERROR_SIGNATURE_INVALID;
uint8_t bn_buf[64] = {0};
if (!eddsa_load_public_key(&eddsa, key)) {
ret = RNP_ERROR_BAD_PARAMETERS;
goto done;
}
if (botan_pk_op_verify_create(&verify_op, eddsa, "Pure", 0) != 0) {
goto done;
}
if (botan_pk_op_verify_update(verify_op, hash, hash_len) != 0) {
goto done;
}
// Unexpected size for Ed25519 signature
if ((mpi_bytes(&sig->r) > 32) || (mpi_bytes(&sig->s) > 32)) {
goto done;
}
mpi2mem(&sig->r, &bn_buf[32 - mpi_bytes(&sig->r)]);
mpi2mem(&sig->s, &bn_buf[64 - mpi_bytes(&sig->s)]);
if (botan_pk_op_verify_finish(verify_op, bn_buf, 64) == 0) {
ret = RNP_SUCCESS;
}
done:
botan_pk_op_verify_destroy(verify_op);
botan_pubkey_destroy(eddsa);
return ret;
}
rnp_result_t
eddsa_sign(rnp::RNG * rng,
pgp_ec_signature_t *sig,
const uint8_t * hash,
size_t hash_len,
const pgp_ec_key_t *key)
{
botan_privkey_t eddsa = NULL;
botan_pk_op_sign_t sign_op = NULL;
rnp_result_t ret = RNP_ERROR_SIGNING_FAILED;
uint8_t bn_buf[64] = {0};
size_t sig_size = sizeof(bn_buf);
if (!eddsa_load_secret_key(&eddsa, key)) {
ret = RNP_ERROR_BAD_PARAMETERS;
goto done;
}
if (botan_pk_op_sign_create(&sign_op, eddsa, "Pure", 0) != 0) {
goto done;
}
if (botan_pk_op_sign_update(sign_op, hash, hash_len) != 0) {
goto done;
}
if (botan_pk_op_sign_finish(sign_op, rng->handle(), bn_buf, &sig_size) != 0) {
goto done;
}
// Unexpected size...
if (sig_size != 64) {
goto done;
}
mem2mpi(&sig->r, bn_buf, 32);
mem2mpi(&sig->s, bn_buf + 32, 32);
ret = RNP_SUCCESS;
done:
botan_pk_op_sign_destroy(sign_op);
botan_privkey_destroy(eddsa);
return ret;
}
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