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trezor-firmware/embed/extmod/modtrezorcrypto/modtrezorcrypto-curve25519.h
2017-07-28 16:23:45 +02:00

81 lines
3.0 KiB
C

/*
* Copyright (c) Pavol Rusnak, SatoshiLabs
*
* Licensed under TREZOR License
* see LICENSE file for details
*/
#include "py/objstr.h"
#include "trezor-crypto/ed25519-donna/ed25519.h"
#include "rand.h"
/// def generate_secret() -> bytes:
/// '''
/// Generate secret key.
/// '''
STATIC mp_obj_t mod_trezorcrypto_curve25519_generate_secret() {
vstr_t vstr;
vstr_init_len(&vstr, 32);
random_buffer((uint8_t *)vstr.buf, 32);
// taken from https://cr.yp.to/ecdh.html
vstr.buf[0] &= 248;
vstr.buf[31] &= 127;
vstr.buf[31] |= 64;
return mp_obj_new_str_from_vstr(&mp_type_bytes, &vstr);
}
STATIC MP_DEFINE_CONST_FUN_OBJ_0(mod_trezorcrypto_curve25519_generate_secret_obj, mod_trezorcrypto_curve25519_generate_secret);
/// def publickey(secret_key: bytes) -> bytes:
/// '''
/// Computes public key from secret key.
/// '''
STATIC mp_obj_t mod_trezorcrypto_curve25519_publickey(mp_obj_t secret_key) {
mp_buffer_info_t sk;
mp_get_buffer_raise(secret_key, &sk, MP_BUFFER_READ);
if (sk.len != 32) {
mp_raise_ValueError("Invalid length of secret key");
}
vstr_t vstr;
vstr_init_len(&vstr, 32);
curve25519_scalarmult_basepoint((uint8_t *)vstr.buf, (const uint8_t *)sk.buf);
return mp_obj_new_str_from_vstr(&mp_type_bytes, &vstr);
}
STATIC MP_DEFINE_CONST_FUN_OBJ_1(mod_trezorcrypto_curve25519_publickey_obj, mod_trezorcrypto_curve25519_publickey);
/// def multiply(secret_key: bytes, public_key: bytes) -> bytes:
/// '''
/// Multiplies point defined by public_key with scalar defined by secret_key.
/// Useful for ECDH.
/// '''
STATIC mp_obj_t mod_trezorcrypto_curve25519_multiply(mp_obj_t secret_key, mp_obj_t public_key) {
mp_buffer_info_t sk, pk;
mp_get_buffer_raise(secret_key, &sk, MP_BUFFER_READ);
mp_get_buffer_raise(public_key, &pk, MP_BUFFER_READ);
if (sk.len != 32) {
mp_raise_ValueError("Invalid length of secret key");
}
if (pk.len != 32) {
mp_raise_ValueError("Invalid length of public key");
}
vstr_t vstr;
vstr_init_len(&vstr, 32);
curve25519_scalarmult((uint8_t *)vstr.buf, (const uint8_t *)sk.buf, (const uint8_t *)pk.buf);
return mp_obj_new_str_from_vstr(&mp_type_bytes, &vstr);
}
STATIC MP_DEFINE_CONST_FUN_OBJ_2(mod_trezorcrypto_curve25519_multiply_obj, mod_trezorcrypto_curve25519_multiply);
STATIC const mp_rom_map_elem_t mod_trezorcrypto_curve25519_globals_table[] = {
{ MP_ROM_QSTR(MP_QSTR___name__), MP_ROM_QSTR(MP_QSTR_curve25519) },
{ MP_ROM_QSTR(MP_QSTR_generate_secret), MP_ROM_PTR(&mod_trezorcrypto_curve25519_generate_secret_obj) },
{ MP_ROM_QSTR(MP_QSTR_publickey), MP_ROM_PTR(&mod_trezorcrypto_curve25519_publickey_obj) },
{ MP_ROM_QSTR(MP_QSTR_multiply), MP_ROM_PTR(&mod_trezorcrypto_curve25519_multiply_obj) },
};
STATIC MP_DEFINE_CONST_DICT(mod_trezorcrypto_curve25519_globals, mod_trezorcrypto_curve25519_globals_table);
STATIC const mp_obj_module_t mod_trezorcrypto_curve25519_module = {
.base = { &mp_type_module },
.globals = (mp_obj_dict_t*)&mod_trezorcrypto_curve25519_globals,
};