440 lines
11 KiB
C
440 lines
11 KiB
C
/**
|
|
* Copyright (C) 2015-2016 Virgil Security Inc.
|
|
*
|
|
* Lead Maintainer: Virgil Security Inc. <support@virgilsecurity.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.
|
|
*
|
|
* (3) Neither the name of the copyright holder nor the names of its
|
|
* contributors may be used to endorse or promote products derived from
|
|
* this software without specific prior written permission.
|
|
*
|
|
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ''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 AUTHOR 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.
|
|
*
|
|
* This file is part of extension to mbed TLS (https://tls.mbed.org)
|
|
*
|
|
* Low level implementation was taken from Orson Peters library,
|
|
* see https://github.com/orlp/ed25519 and license.txt file
|
|
*/
|
|
|
|
#include <string.h>
|
|
|
|
#include "mbedtls/ed25519.h"
|
|
#include "mbedtls/sha512.h"
|
|
|
|
#include "fe.h"
|
|
#include "ge.h"
|
|
#include "sc.h"
|
|
|
|
/* Implementation that should never be optimized out by the compiler */
|
|
static void mbedtls_ed25519_zeroize( void *v, size_t n ) {
|
|
volatile unsigned char *p = v; while( n-- ) *p++ = 0;
|
|
}
|
|
|
|
int mbedtls_ed25519_get_pubkey(unsigned char public_key[32], const unsigned char secret_key[32]) {
|
|
unsigned char az[64];
|
|
ge_p3 A;
|
|
|
|
mbedtls_sha512(secret_key, 32, az, 0);
|
|
|
|
az[0] &= 248;
|
|
az[31] &= 63;
|
|
az[31] |= 64;
|
|
|
|
ge_scalarmult_base(&A, az);
|
|
ge_p3_tobytes(public_key, &A);
|
|
|
|
mbedtls_ed25519_zeroize(az, sizeof(az));
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* due to CodesInChaos: montgomeryX = (edwardsY + 1)*inverse(1 - edwardsY) mod p
|
|
*/
|
|
int mbedtls_ed25519_pubkey_to_curve25519(
|
|
unsigned char curve_public_key[32], const unsigned char ed_public_key[32]) {
|
|
|
|
fe x1, tmp0, tmp1;
|
|
|
|
fe_frombytes(x1, ed_public_key);
|
|
fe_1(tmp1);
|
|
fe_add(tmp0, x1, tmp1);
|
|
fe_sub(tmp1, tmp1, x1);
|
|
fe_invert(tmp1, tmp1);
|
|
fe_mul(x1, tmp0, tmp1);
|
|
|
|
fe_tobytes(curve_public_key, x1);
|
|
|
|
return 0;
|
|
}
|
|
|
|
int mbedtls_ed25519_key_to_curve25519(
|
|
unsigned char curve_secret_key[32], const unsigned char ed_secret_key[32]) {
|
|
|
|
unsigned char az[64];
|
|
|
|
mbedtls_sha512(ed_secret_key, 32, az, 0);
|
|
memcpy(curve_secret_key, az, 32);
|
|
mbedtls_ed25519_zeroize(az, sizeof(az));
|
|
|
|
return 0;
|
|
}
|
|
|
|
|
|
int mbedtls_ed25519_sign(
|
|
unsigned char signature[64],
|
|
const unsigned char secret_key[32],
|
|
const unsigned char* msg, size_t msg_len) {
|
|
|
|
mbedtls_sha512_context hash;
|
|
unsigned char hram[64];
|
|
unsigned char nonce[64];
|
|
unsigned char az[64];
|
|
unsigned char public_key[32];
|
|
ge_p3 A, R;
|
|
|
|
mbedtls_sha512_starts(&hash, 0);
|
|
mbedtls_sha512_update(&hash, secret_key, 32);
|
|
mbedtls_sha512_finish(&hash, az);
|
|
|
|
az[0] &= 248;
|
|
az[31] &= 63;
|
|
az[31] |= 64;
|
|
|
|
ge_scalarmult_base(&A, az);
|
|
ge_p3_tobytes(public_key, &A);
|
|
|
|
mbedtls_sha512_starts(&hash, 0);
|
|
mbedtls_sha512_update(&hash, az + 32, 32);
|
|
mbedtls_sha512_update(&hash, msg, msg_len);
|
|
mbedtls_sha512_finish(&hash, nonce);
|
|
|
|
sc_reduce(nonce);
|
|
ge_scalarmult_base(&R, nonce);
|
|
ge_p3_tobytes(signature, &R);
|
|
|
|
memmove(signature + 32, public_key, 32);
|
|
|
|
mbedtls_sha512_starts(&hash, 0);
|
|
mbedtls_sha512_update(&hash, signature, 64);
|
|
mbedtls_sha512_update(&hash, msg, msg_len);
|
|
mbedtls_sha512_finish(&hash, hram);
|
|
|
|
sc_reduce(hram);
|
|
sc_muladd(signature + 32, hram, az, nonce); // (R, S)
|
|
|
|
mbedtls_ed25519_zeroize(nonce, sizeof(nonce));
|
|
mbedtls_ed25519_zeroize(az, sizeof(az));
|
|
mbedtls_sha512_free(&hash);
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int consttime_equal(const unsigned char* x, const unsigned char* y) {
|
|
unsigned char r = 0;
|
|
|
|
r = x[0] ^ y[0];
|
|
#define F(i) r |= x[i] ^ y[i]
|
|
F(1);
|
|
F(2);
|
|
F(3);
|
|
F(4);
|
|
F(5);
|
|
F(6);
|
|
F(7);
|
|
F(8);
|
|
F(9);
|
|
F(10);
|
|
F(11);
|
|
F(12);
|
|
F(13);
|
|
F(14);
|
|
F(15);
|
|
F(16);
|
|
F(17);
|
|
F(18);
|
|
F(19);
|
|
F(20);
|
|
F(21);
|
|
F(22);
|
|
F(23);
|
|
F(24);
|
|
F(25);
|
|
F(26);
|
|
F(27);
|
|
F(28);
|
|
F(29);
|
|
F(30);
|
|
F(31);
|
|
#undef F
|
|
|
|
return !r;
|
|
}
|
|
|
|
int mbedtls_ed25519_verify(
|
|
const unsigned char signature[64],
|
|
const unsigned char public_key[32],
|
|
const unsigned char* msg, size_t msg_len) {
|
|
|
|
mbedtls_sha512_context hash;
|
|
unsigned char h[64];
|
|
unsigned char checker[32];
|
|
ge_p3 A;
|
|
ge_p2 R;
|
|
|
|
|
|
if (signature[63] & 224) {
|
|
return 1;
|
|
}
|
|
|
|
if (ge_frombytes_negate_vartime(&A, public_key) != 0) {
|
|
return 1;
|
|
}
|
|
|
|
mbedtls_sha512_starts(&hash, 0);
|
|
mbedtls_sha512_update(&hash, signature, 32);
|
|
mbedtls_sha512_update(&hash, public_key, 32);
|
|
mbedtls_sha512_update(&hash, msg, msg_len);
|
|
mbedtls_sha512_finish(&hash, h);
|
|
|
|
sc_reduce(h);
|
|
ge_double_scalarmult_vartime(&R, h, &A, signature + 32);
|
|
ge_tobytes(checker, &R);
|
|
|
|
if (!consttime_equal(checker, signature)) {
|
|
return 2;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
/**
|
|
* @brief Derive Curve25519 public key from the secret key.
|
|
* @param[out] public_key Curve25519 public key.
|
|
* @param[in] secret_key Curve25519 secret key.
|
|
* @return 0 if success, non zero - otherwise.
|
|
*/
|
|
int mbedtls_curve25519_get_pubkey(unsigned char public_key[32], const unsigned char secret_key[32]) {
|
|
|
|
unsigned char e[32];
|
|
ge_p3 A;
|
|
|
|
memcpy(e, secret_key, sizeof(e));
|
|
|
|
e[0] &= 248;
|
|
e[31] &= 63;
|
|
e[31] |= 64;
|
|
|
|
ge_scalarmult_base(&A, e);
|
|
ge_p3_tobytes(public_key, &A);
|
|
|
|
mbedtls_ed25519_pubkey_to_curve25519(public_key, public_key);
|
|
|
|
mbedtls_ed25519_zeroize(e, sizeof(e));
|
|
return 0;
|
|
}
|
|
|
|
int mbedtls_curve25519_key_exchange(
|
|
unsigned char shared_secret[32], const unsigned char public_key[32], const unsigned char secret_key[32]) {
|
|
|
|
fe x1;
|
|
fe x2;
|
|
fe z2;
|
|
fe x3;
|
|
fe z3;
|
|
fe tmp0;
|
|
fe tmp1;
|
|
|
|
int pos;
|
|
unsigned int swap;
|
|
unsigned int b;
|
|
unsigned char e[32];
|
|
|
|
fe_frombytes(x1, public_key);
|
|
|
|
fe_1(x2);
|
|
fe_0(z2);
|
|
fe_copy(x3, x1);
|
|
fe_1(z3);
|
|
|
|
|
|
memcpy(e, secret_key, sizeof(e));
|
|
|
|
e[0] &= 248;
|
|
e[31] &= 63;
|
|
e[31] |= 64;
|
|
|
|
swap = 0;
|
|
for (pos = 254; pos >= 0; --pos) {
|
|
b = e[pos / 8] >> (pos & 7);
|
|
b &= 1;
|
|
swap ^= b;
|
|
fe_cswap(x2, x3, swap);
|
|
fe_cswap(z2, z3, swap);
|
|
swap = b;
|
|
|
|
/* from montgomery.h */
|
|
fe_sub(tmp0, x3, z3);
|
|
fe_sub(tmp1, x2, z2);
|
|
fe_add(x2, x2, z2);
|
|
fe_add(z2, x3, z3);
|
|
fe_mul(z3, tmp0, x2);
|
|
fe_mul(z2, z2, tmp1);
|
|
fe_sq(tmp0, tmp1);
|
|
fe_sq(tmp1, x2);
|
|
fe_add(x3, z3, z2);
|
|
fe_sub(z2, z3, z2);
|
|
fe_mul(x2, tmp1, tmp0);
|
|
fe_sub(tmp1, tmp1, tmp0);
|
|
fe_sq(z2, z2);
|
|
fe_mul121666(z3, tmp1);
|
|
fe_sq(x3, x3);
|
|
fe_add(tmp0, tmp0, z3);
|
|
fe_mul(z3, x1, z2);
|
|
fe_mul(z2, tmp1, tmp0);
|
|
}
|
|
|
|
fe_cswap(x2, x3, swap);
|
|
fe_cswap(z2, z3, swap);
|
|
|
|
fe_invert(z2, z2);
|
|
fe_mul(x2, x2, z2);
|
|
fe_tobytes(shared_secret, x2);
|
|
|
|
mbedtls_ed25519_zeroize(e, sizeof(e));
|
|
|
|
/* The all-zero output results when the input is a point of small order. */
|
|
return fe_isnonzero(x2) ? (0) : (-1);
|
|
}
|
|
|
|
//////////////////////////////////////////////////////////////////
|
|
|
|
/*
|
|
* edwardsY = (montgomeryX - 1)*inverse(montgomeryX + 1) mod p
|
|
*/
|
|
static int mbedtls_x25519_ext_montgomery_to_edwards_pubkey(
|
|
unsigned char ed_public_key[32], const unsigned char curve_public_key[32]) {
|
|
|
|
fe mont_x, mont_x_minus_one, mont_x_plus_one, inv_mont_x_plus_one, one, ed_y;
|
|
|
|
fe_frombytes(mont_x, curve_public_key);
|
|
fe_1(one);
|
|
fe_sub(mont_x_minus_one, mont_x, one);
|
|
fe_add(mont_x_plus_one, mont_x, one);
|
|
fe_invert(inv_mont_x_plus_one, mont_x_plus_one);
|
|
fe_mul(ed_y, mont_x_minus_one, inv_mont_x_plus_one);
|
|
fe_tobytes(ed_public_key, ed_y);
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int mbedtls_ed25519_sign_az(
|
|
unsigned char signature[64],
|
|
const unsigned char az[64],
|
|
const unsigned char* msg, size_t msg_len) {
|
|
|
|
mbedtls_sha512_context hash;
|
|
unsigned char hram[64];
|
|
unsigned char nonce[64];
|
|
unsigned char public_key[32];
|
|
ge_p3 A, R;
|
|
|
|
ge_scalarmult_base(&A, az);
|
|
ge_p3_tobytes(public_key, &A);
|
|
|
|
mbedtls_sha512_starts(&hash, 0);
|
|
mbedtls_sha512_update(&hash, az + 32, 32);
|
|
mbedtls_sha512_update(&hash, msg, msg_len);
|
|
mbedtls_sha512_finish(&hash, nonce);
|
|
|
|
sc_reduce(nonce);
|
|
ge_scalarmult_base(&R, nonce);
|
|
ge_p3_tobytes(signature, &R);
|
|
|
|
memmove(signature + 32, public_key, 32);
|
|
|
|
mbedtls_sha512_starts(&hash, 0);
|
|
mbedtls_sha512_update(&hash, signature, 64);
|
|
mbedtls_sha512_update(&hash, msg, msg_len);
|
|
mbedtls_sha512_finish(&hash, hram);
|
|
|
|
sc_reduce(hram);
|
|
sc_muladd(signature + 32, hram, az, nonce); // (R, S)
|
|
|
|
mbedtls_ed25519_zeroize(nonce, sizeof(nonce));
|
|
mbedtls_sha512_free(&hash);
|
|
|
|
return 0;
|
|
}
|
|
|
|
int mbedtls_curve25519_sign(
|
|
unsigned char signature[64],
|
|
const unsigned char secret_key[32],
|
|
const unsigned char* msg, size_t msg_len)
|
|
{
|
|
|
|
unsigned char ed_public_key[32];
|
|
|
|
unsigned char az[64];
|
|
unsigned char sign_bit = 0;
|
|
ge_p3 A;
|
|
|
|
mbedtls_sha512(secret_key, 32, az, 0);
|
|
memcpy(az, secret_key, 32);
|
|
|
|
ge_scalarmult_base(&A, az);
|
|
ge_p3_tobytes(ed_public_key, &A);
|
|
|
|
sign_bit = ed_public_key[31] & (unsigned char) 0x80;
|
|
|
|
mbedtls_ed25519_sign_az(signature, az, msg, msg_len);
|
|
|
|
signature[63] &= 0x7F; // bit should be zero already, but just in case
|
|
signature[63] |= sign_bit;
|
|
|
|
mbedtls_ed25519_zeroize(az, sizeof(az));
|
|
return 0;
|
|
}
|
|
|
|
|
|
int mbedtls_curve25519_verify(
|
|
const unsigned char signature[64],
|
|
const unsigned char public_key[32],
|
|
const unsigned char* msg, size_t msg_len)
|
|
{
|
|
unsigned char ed_public_key[32];
|
|
|
|
unsigned char fixed_signature[64];
|
|
|
|
mbedtls_x25519_ext_montgomery_to_edwards_pubkey(ed_public_key, public_key);
|
|
ed_public_key[31] |= (signature[63] & 0x80);
|
|
|
|
memmove(fixed_signature, signature, 64);
|
|
|
|
fixed_signature[63] &= 0x7F;
|
|
|
|
return mbedtls_ed25519_verify(fixed_signature, ed_public_key, msg, msg_len);
|
|
}
|