| Index: crypto/curve25519-donna.c
|
| diff --git a/crypto/curve25519-donna.c b/crypto/curve25519-donna.c
|
| deleted file mode 100644
|
| index f141ac028b0f7bba419c218aad66275b507eb8c3..0000000000000000000000000000000000000000
|
| --- a/crypto/curve25519-donna.c
|
| +++ /dev/null
|
| @@ -1,592 +0,0 @@
|
| -// Copyright (c) 2013 The Chromium Authors. All rights reserved.
|
| -// Use of this source code is governed by a BSD-style license that can be
|
| -// found in the LICENSE file.
|
| -
|
| -/*
|
| - * curve25519-donna: Curve25519 elliptic curve, public key function
|
| - *
|
| - * http://code.google.com/p/curve25519-donna/
|
| - *
|
| - * Adam Langley <agl@imperialviolet.org>
|
| - *
|
| - * Derived from public domain C code by Daniel J. Bernstein <djb@cr.yp.to>
|
| - *
|
| - * More information about curve25519 can be found here
|
| - * http://cr.yp.to/ecdh.html
|
| - *
|
| - * djb's sample implementation of curve25519 is written in a special assembly
|
| - * language called qhasm and uses the floating point registers.
|
| - *
|
| - * This is, almost, a clean room reimplementation from the curve25519 paper. It
|
| - * uses many of the tricks described therein. Only the crecip function is taken
|
| - * from the sample implementation.
|
| - */
|
| -
|
| -#include <string.h>
|
| -#include <stdint.h>
|
| -
|
| -typedef uint8_t u8;
|
| -typedef int32_t s32;
|
| -typedef int64_t limb;
|
| -
|
| -/* Field element representation:
|
| - *
|
| - * Field elements are written as an array of signed, 64-bit limbs, least
|
| - * significant first. The value of the field element is:
|
| - * x[0] + 2^26·x[1] + x^51·x[2] + 2^102·x[3] + ...
|
| - *
|
| - * i.e. the limbs are 26, 25, 26, 25, ... bits wide.
|
| - */
|
| -
|
| -/* Sum two numbers: output += in */
|
| -static void fsum(limb *output, const limb *in) {
|
| - unsigned i;
|
| - for (i = 0; i < 10; i += 2) {
|
| - output[0+i] = (output[0+i] + in[0+i]);
|
| - output[1+i] = (output[1+i] + in[1+i]);
|
| - }
|
| -}
|
| -
|
| -/* Find the difference of two numbers: output = in - output
|
| - * (note the order of the arguments!)
|
| - */
|
| -static void fdifference(limb *output, const limb *in) {
|
| - unsigned i;
|
| - for (i = 0; i < 10; ++i) {
|
| - output[i] = (in[i] - output[i]);
|
| - }
|
| -}
|
| -
|
| -/* Multiply a number my a scalar: output = in * scalar */
|
| -static void fscalar_product(limb *output, const limb *in, const limb scalar) {
|
| - unsigned i;
|
| - for (i = 0; i < 10; ++i) {
|
| - output[i] = in[i] * scalar;
|
| - }
|
| -}
|
| -
|
| -/* Multiply two numbers: output = in2 * in
|
| - *
|
| - * output must be distinct to both inputs. The inputs are reduced coefficient
|
| - * form, the output is not.
|
| - */
|
| -static void fproduct(limb *output, const limb *in2, const limb *in) {
|
| - output[0] = ((limb) ((s32) in2[0])) * ((s32) in[0]);
|
| - output[1] = ((limb) ((s32) in2[0])) * ((s32) in[1]) +
|
| - ((limb) ((s32) in2[1])) * ((s32) in[0]);
|
| - output[2] = 2 * ((limb) ((s32) in2[1])) * ((s32) in[1]) +
|
| - ((limb) ((s32) in2[0])) * ((s32) in[2]) +
|
| - ((limb) ((s32) in2[2])) * ((s32) in[0]);
|
| - output[3] = ((limb) ((s32) in2[1])) * ((s32) in[2]) +
|
| - ((limb) ((s32) in2[2])) * ((s32) in[1]) +
|
| - ((limb) ((s32) in2[0])) * ((s32) in[3]) +
|
| - ((limb) ((s32) in2[3])) * ((s32) in[0]);
|
| - output[4] = ((limb) ((s32) in2[2])) * ((s32) in[2]) +
|
| - 2 * (((limb) ((s32) in2[1])) * ((s32) in[3]) +
|
| - ((limb) ((s32) in2[3])) * ((s32) in[1])) +
|
| - ((limb) ((s32) in2[0])) * ((s32) in[4]) +
|
| - ((limb) ((s32) in2[4])) * ((s32) in[0]);
|
| - output[5] = ((limb) ((s32) in2[2])) * ((s32) in[3]) +
|
| - ((limb) ((s32) in2[3])) * ((s32) in[2]) +
|
| - ((limb) ((s32) in2[1])) * ((s32) in[4]) +
|
| - ((limb) ((s32) in2[4])) * ((s32) in[1]) +
|
| - ((limb) ((s32) in2[0])) * ((s32) in[5]) +
|
| - ((limb) ((s32) in2[5])) * ((s32) in[0]);
|
| - output[6] = 2 * (((limb) ((s32) in2[3])) * ((s32) in[3]) +
|
| - ((limb) ((s32) in2[1])) * ((s32) in[5]) +
|
| - ((limb) ((s32) in2[5])) * ((s32) in[1])) +
|
| - ((limb) ((s32) in2[2])) * ((s32) in[4]) +
|
| - ((limb) ((s32) in2[4])) * ((s32) in[2]) +
|
| - ((limb) ((s32) in2[0])) * ((s32) in[6]) +
|
| - ((limb) ((s32) in2[6])) * ((s32) in[0]);
|
| - output[7] = ((limb) ((s32) in2[3])) * ((s32) in[4]) +
|
| - ((limb) ((s32) in2[4])) * ((s32) in[3]) +
|
| - ((limb) ((s32) in2[2])) * ((s32) in[5]) +
|
| - ((limb) ((s32) in2[5])) * ((s32) in[2]) +
|
| - ((limb) ((s32) in2[1])) * ((s32) in[6]) +
|
| - ((limb) ((s32) in2[6])) * ((s32) in[1]) +
|
| - ((limb) ((s32) in2[0])) * ((s32) in[7]) +
|
| - ((limb) ((s32) in2[7])) * ((s32) in[0]);
|
| - output[8] = ((limb) ((s32) in2[4])) * ((s32) in[4]) +
|
| - 2 * (((limb) ((s32) in2[3])) * ((s32) in[5]) +
|
| - ((limb) ((s32) in2[5])) * ((s32) in[3]) +
|
| - ((limb) ((s32) in2[1])) * ((s32) in[7]) +
|
| - ((limb) ((s32) in2[7])) * ((s32) in[1])) +
|
| - ((limb) ((s32) in2[2])) * ((s32) in[6]) +
|
| - ((limb) ((s32) in2[6])) * ((s32) in[2]) +
|
| - ((limb) ((s32) in2[0])) * ((s32) in[8]) +
|
| - ((limb) ((s32) in2[8])) * ((s32) in[0]);
|
| - output[9] = ((limb) ((s32) in2[4])) * ((s32) in[5]) +
|
| - ((limb) ((s32) in2[5])) * ((s32) in[4]) +
|
| - ((limb) ((s32) in2[3])) * ((s32) in[6]) +
|
| - ((limb) ((s32) in2[6])) * ((s32) in[3]) +
|
| - ((limb) ((s32) in2[2])) * ((s32) in[7]) +
|
| - ((limb) ((s32) in2[7])) * ((s32) in[2]) +
|
| - ((limb) ((s32) in2[1])) * ((s32) in[8]) +
|
| - ((limb) ((s32) in2[8])) * ((s32) in[1]) +
|
| - ((limb) ((s32) in2[0])) * ((s32) in[9]) +
|
| - ((limb) ((s32) in2[9])) * ((s32) in[0]);
|
| - output[10] = 2 * (((limb) ((s32) in2[5])) * ((s32) in[5]) +
|
| - ((limb) ((s32) in2[3])) * ((s32) in[7]) +
|
| - ((limb) ((s32) in2[7])) * ((s32) in[3]) +
|
| - ((limb) ((s32) in2[1])) * ((s32) in[9]) +
|
| - ((limb) ((s32) in2[9])) * ((s32) in[1])) +
|
| - ((limb) ((s32) in2[4])) * ((s32) in[6]) +
|
| - ((limb) ((s32) in2[6])) * ((s32) in[4]) +
|
| - ((limb) ((s32) in2[2])) * ((s32) in[8]) +
|
| - ((limb) ((s32) in2[8])) * ((s32) in[2]);
|
| - output[11] = ((limb) ((s32) in2[5])) * ((s32) in[6]) +
|
| - ((limb) ((s32) in2[6])) * ((s32) in[5]) +
|
| - ((limb) ((s32) in2[4])) * ((s32) in[7]) +
|
| - ((limb) ((s32) in2[7])) * ((s32) in[4]) +
|
| - ((limb) ((s32) in2[3])) * ((s32) in[8]) +
|
| - ((limb) ((s32) in2[8])) * ((s32) in[3]) +
|
| - ((limb) ((s32) in2[2])) * ((s32) in[9]) +
|
| - ((limb) ((s32) in2[9])) * ((s32) in[2]);
|
| - output[12] = ((limb) ((s32) in2[6])) * ((s32) in[6]) +
|
| - 2 * (((limb) ((s32) in2[5])) * ((s32) in[7]) +
|
| - ((limb) ((s32) in2[7])) * ((s32) in[5]) +
|
| - ((limb) ((s32) in2[3])) * ((s32) in[9]) +
|
| - ((limb) ((s32) in2[9])) * ((s32) in[3])) +
|
| - ((limb) ((s32) in2[4])) * ((s32) in[8]) +
|
| - ((limb) ((s32) in2[8])) * ((s32) in[4]);
|
| - output[13] = ((limb) ((s32) in2[6])) * ((s32) in[7]) +
|
| - ((limb) ((s32) in2[7])) * ((s32) in[6]) +
|
| - ((limb) ((s32) in2[5])) * ((s32) in[8]) +
|
| - ((limb) ((s32) in2[8])) * ((s32) in[5]) +
|
| - ((limb) ((s32) in2[4])) * ((s32) in[9]) +
|
| - ((limb) ((s32) in2[9])) * ((s32) in[4]);
|
| - output[14] = 2 * (((limb) ((s32) in2[7])) * ((s32) in[7]) +
|
| - ((limb) ((s32) in2[5])) * ((s32) in[9]) +
|
| - ((limb) ((s32) in2[9])) * ((s32) in[5])) +
|
| - ((limb) ((s32) in2[6])) * ((s32) in[8]) +
|
| - ((limb) ((s32) in2[8])) * ((s32) in[6]);
|
| - output[15] = ((limb) ((s32) in2[7])) * ((s32) in[8]) +
|
| - ((limb) ((s32) in2[8])) * ((s32) in[7]) +
|
| - ((limb) ((s32) in2[6])) * ((s32) in[9]) +
|
| - ((limb) ((s32) in2[9])) * ((s32) in[6]);
|
| - output[16] = ((limb) ((s32) in2[8])) * ((s32) in[8]) +
|
| - 2 * (((limb) ((s32) in2[7])) * ((s32) in[9]) +
|
| - ((limb) ((s32) in2[9])) * ((s32) in[7]));
|
| - output[17] = ((limb) ((s32) in2[8])) * ((s32) in[9]) +
|
| - ((limb) ((s32) in2[9])) * ((s32) in[8]);
|
| - output[18] = 2 * ((limb) ((s32) in2[9])) * ((s32) in[9]);
|
| -}
|
| -
|
| -/* Reduce a long form to a short form by taking the input mod 2^255 - 19. */
|
| -static void freduce_degree(limb *output) {
|
| - /* Each of these shifts and adds ends up multiplying the value by 19. */
|
| - output[8] += output[18] << 4;
|
| - output[8] += output[18] << 1;
|
| - output[8] += output[18];
|
| - output[7] += output[17] << 4;
|
| - output[7] += output[17] << 1;
|
| - output[7] += output[17];
|
| - output[6] += output[16] << 4;
|
| - output[6] += output[16] << 1;
|
| - output[6] += output[16];
|
| - output[5] += output[15] << 4;
|
| - output[5] += output[15] << 1;
|
| - output[5] += output[15];
|
| - output[4] += output[14] << 4;
|
| - output[4] += output[14] << 1;
|
| - output[4] += output[14];
|
| - output[3] += output[13] << 4;
|
| - output[3] += output[13] << 1;
|
| - output[3] += output[13];
|
| - output[2] += output[12] << 4;
|
| - output[2] += output[12] << 1;
|
| - output[2] += output[12];
|
| - output[1] += output[11] << 4;
|
| - output[1] += output[11] << 1;
|
| - output[1] += output[11];
|
| - output[0] += output[10] << 4;
|
| - output[0] += output[10] << 1;
|
| - output[0] += output[10];
|
| -}
|
| -
|
| -/* Reduce all coefficients of the short form input so that |x| < 2^26.
|
| - *
|
| - * On entry: |output[i]| < 2^62
|
| - */
|
| -static void freduce_coefficients(limb *output) {
|
| - unsigned i;
|
| - do {
|
| - output[10] = 0;
|
| -
|
| - for (i = 0; i < 10; i += 2) {
|
| - limb over = output[i] / 0x4000000l;
|
| - output[i+1] += over;
|
| - output[i] -= over * 0x4000000l;
|
| -
|
| - over = output[i+1] / 0x2000000;
|
| - output[i+2] += over;
|
| - output[i+1] -= over * 0x2000000;
|
| - }
|
| - output[0] += 19 * output[10];
|
| - } while (output[10]);
|
| -}
|
| -
|
| -/* A helpful wrapper around fproduct: output = in * in2.
|
| - *
|
| - * output must be distinct to both inputs. The output is reduced degree and
|
| - * reduced coefficient.
|
| - */
|
| -static void
|
| -fmul(limb *output, const limb *in, const limb *in2) {
|
| - limb t[19];
|
| - fproduct(t, in, in2);
|
| - freduce_degree(t);
|
| - freduce_coefficients(t);
|
| - memcpy(output, t, sizeof(limb) * 10);
|
| -}
|
| -
|
| -static void fsquare_inner(limb *output, const limb *in) {
|
| - output[0] = ((limb) ((s32) in[0])) * ((s32) in[0]);
|
| - output[1] = 2 * ((limb) ((s32) in[0])) * ((s32) in[1]);
|
| - output[2] = 2 * (((limb) ((s32) in[1])) * ((s32) in[1]) +
|
| - ((limb) ((s32) in[0])) * ((s32) in[2]));
|
| - output[3] = 2 * (((limb) ((s32) in[1])) * ((s32) in[2]) +
|
| - ((limb) ((s32) in[0])) * ((s32) in[3]));
|
| - output[4] = ((limb) ((s32) in[2])) * ((s32) in[2]) +
|
| - 4 * ((limb) ((s32) in[1])) * ((s32) in[3]) +
|
| - 2 * ((limb) ((s32) in[0])) * ((s32) in[4]);
|
| - output[5] = 2 * (((limb) ((s32) in[2])) * ((s32) in[3]) +
|
| - ((limb) ((s32) in[1])) * ((s32) in[4]) +
|
| - ((limb) ((s32) in[0])) * ((s32) in[5]));
|
| - output[6] = 2 * (((limb) ((s32) in[3])) * ((s32) in[3]) +
|
| - ((limb) ((s32) in[2])) * ((s32) in[4]) +
|
| - ((limb) ((s32) in[0])) * ((s32) in[6]) +
|
| - 2 * ((limb) ((s32) in[1])) * ((s32) in[5]));
|
| - output[7] = 2 * (((limb) ((s32) in[3])) * ((s32) in[4]) +
|
| - ((limb) ((s32) in[2])) * ((s32) in[5]) +
|
| - ((limb) ((s32) in[1])) * ((s32) in[6]) +
|
| - ((limb) ((s32) in[0])) * ((s32) in[7]));
|
| - output[8] = ((limb) ((s32) in[4])) * ((s32) in[4]) +
|
| - 2 * (((limb) ((s32) in[2])) * ((s32) in[6]) +
|
| - ((limb) ((s32) in[0])) * ((s32) in[8]) +
|
| - 2 * (((limb) ((s32) in[1])) * ((s32) in[7]) +
|
| - ((limb) ((s32) in[3])) * ((s32) in[5])));
|
| - output[9] = 2 * (((limb) ((s32) in[4])) * ((s32) in[5]) +
|
| - ((limb) ((s32) in[3])) * ((s32) in[6]) +
|
| - ((limb) ((s32) in[2])) * ((s32) in[7]) +
|
| - ((limb) ((s32) in[1])) * ((s32) in[8]) +
|
| - ((limb) ((s32) in[0])) * ((s32) in[9]));
|
| - output[10] = 2 * (((limb) ((s32) in[5])) * ((s32) in[5]) +
|
| - ((limb) ((s32) in[4])) * ((s32) in[6]) +
|
| - ((limb) ((s32) in[2])) * ((s32) in[8]) +
|
| - 2 * (((limb) ((s32) in[3])) * ((s32) in[7]) +
|
| - ((limb) ((s32) in[1])) * ((s32) in[9])));
|
| - output[11] = 2 * (((limb) ((s32) in[5])) * ((s32) in[6]) +
|
| - ((limb) ((s32) in[4])) * ((s32) in[7]) +
|
| - ((limb) ((s32) in[3])) * ((s32) in[8]) +
|
| - ((limb) ((s32) in[2])) * ((s32) in[9]));
|
| - output[12] = ((limb) ((s32) in[6])) * ((s32) in[6]) +
|
| - 2 * (((limb) ((s32) in[4])) * ((s32) in[8]) +
|
| - 2 * (((limb) ((s32) in[5])) * ((s32) in[7]) +
|
| - ((limb) ((s32) in[3])) * ((s32) in[9])));
|
| - output[13] = 2 * (((limb) ((s32) in[6])) * ((s32) in[7]) +
|
| - ((limb) ((s32) in[5])) * ((s32) in[8]) +
|
| - ((limb) ((s32) in[4])) * ((s32) in[9]));
|
| - output[14] = 2 * (((limb) ((s32) in[7])) * ((s32) in[7]) +
|
| - ((limb) ((s32) in[6])) * ((s32) in[8]) +
|
| - 2 * ((limb) ((s32) in[5])) * ((s32) in[9]));
|
| - output[15] = 2 * (((limb) ((s32) in[7])) * ((s32) in[8]) +
|
| - ((limb) ((s32) in[6])) * ((s32) in[9]));
|
| - output[16] = ((limb) ((s32) in[8])) * ((s32) in[8]) +
|
| - 4 * ((limb) ((s32) in[7])) * ((s32) in[9]);
|
| - output[17] = 2 * ((limb) ((s32) in[8])) * ((s32) in[9]);
|
| - output[18] = 2 * ((limb) ((s32) in[9])) * ((s32) in[9]);
|
| -}
|
| -
|
| -static void
|
| -fsquare(limb *output, const limb *in) {
|
| - limb t[19];
|
| - fsquare_inner(t, in);
|
| - freduce_degree(t);
|
| - freduce_coefficients(t);
|
| - memcpy(output, t, sizeof(limb) * 10);
|
| -}
|
| -
|
| -/* Take a little-endian, 32-byte number and expand it into polynomial form */
|
| -static void
|
| -fexpand(limb *output, const u8 *input) {
|
| -#define F(n,start,shift,mask) \
|
| - output[n] = ((((limb) input[start + 0]) | \
|
| - ((limb) input[start + 1]) << 8 | \
|
| - ((limb) input[start + 2]) << 16 | \
|
| - ((limb) input[start + 3]) << 24) >> shift) & mask;
|
| - F(0, 0, 0, 0x3ffffff);
|
| - F(1, 3, 2, 0x1ffffff);
|
| - F(2, 6, 3, 0x3ffffff);
|
| - F(3, 9, 5, 0x1ffffff);
|
| - F(4, 12, 6, 0x3ffffff);
|
| - F(5, 16, 0, 0x1ffffff);
|
| - F(6, 19, 1, 0x3ffffff);
|
| - F(7, 22, 3, 0x1ffffff);
|
| - F(8, 25, 4, 0x3ffffff);
|
| - F(9, 28, 6, 0x1ffffff);
|
| -#undef F
|
| -}
|
| -
|
| -/* Take a fully reduced polynomial form number and contract it into a
|
| - * little-endian, 32-byte array
|
| - */
|
| -static void
|
| -fcontract(u8 *output, limb *input) {
|
| - int i;
|
| -
|
| - do {
|
| - for (i = 0; i < 9; ++i) {
|
| - if ((i & 1) == 1) {
|
| - while (input[i] < 0) {
|
| - input[i] += 0x2000000;
|
| - input[i + 1]--;
|
| - }
|
| - } else {
|
| - while (input[i] < 0) {
|
| - input[i] += 0x4000000;
|
| - input[i + 1]--;
|
| - }
|
| - }
|
| - }
|
| - while (input[9] < 0) {
|
| - input[9] += 0x2000000;
|
| - input[0] -= 19;
|
| - }
|
| - } while (input[0] < 0);
|
| -
|
| - input[1] <<= 2;
|
| - input[2] <<= 3;
|
| - input[3] <<= 5;
|
| - input[4] <<= 6;
|
| - input[6] <<= 1;
|
| - input[7] <<= 3;
|
| - input[8] <<= 4;
|
| - input[9] <<= 6;
|
| -#define F(i, s) \
|
| - output[s+0] |= input[i] & 0xff; \
|
| - output[s+1] = (input[i] >> 8) & 0xff; \
|
| - output[s+2] = (input[i] >> 16) & 0xff; \
|
| - output[s+3] = (input[i] >> 24) & 0xff;
|
| - output[0] = 0;
|
| - output[16] = 0;
|
| - F(0,0);
|
| - F(1,3);
|
| - F(2,6);
|
| - F(3,9);
|
| - F(4,12);
|
| - F(5,16);
|
| - F(6,19);
|
| - F(7,22);
|
| - F(8,25);
|
| - F(9,28);
|
| -#undef F
|
| -}
|
| -
|
| -/* Input: Q, Q', Q-Q'
|
| - * Output: 2Q, Q+Q'
|
| - *
|
| - * x2 z3: long form
|
| - * x3 z3: long form
|
| - * x z: short form, destroyed
|
| - * xprime zprime: short form, destroyed
|
| - * qmqp: short form, preserved
|
| - */
|
| -static void fmonty(limb *x2, limb *z2, /* output 2Q */
|
| - limb *x3, limb *z3, /* output Q + Q' */
|
| - limb *x, limb *z, /* input Q */
|
| - limb *xprime, limb *zprime, /* input Q' */
|
| - const limb *qmqp /* input Q - Q' */) {
|
| - limb origx[10], origxprime[10], zzz[19], xx[19], zz[19], xxprime[19],
|
| - zzprime[19], zzzprime[19], xxxprime[19];
|
| -
|
| - memcpy(origx, x, 10 * sizeof(limb));
|
| - fsum(x, z);
|
| - fdifference(z, origx); // does x - z
|
| -
|
| - memcpy(origxprime, xprime, sizeof(limb) * 10);
|
| - fsum(xprime, zprime);
|
| - fdifference(zprime, origxprime);
|
| - fproduct(xxprime, xprime, z);
|
| - fproduct(zzprime, x, zprime);
|
| - freduce_degree(xxprime);
|
| - freduce_coefficients(xxprime);
|
| - freduce_degree(zzprime);
|
| - freduce_coefficients(zzprime);
|
| - memcpy(origxprime, xxprime, sizeof(limb) * 10);
|
| - fsum(xxprime, zzprime);
|
| - fdifference(zzprime, origxprime);
|
| - fsquare(xxxprime, xxprime);
|
| - fsquare(zzzprime, zzprime);
|
| - fproduct(zzprime, zzzprime, qmqp);
|
| - freduce_degree(zzprime);
|
| - freduce_coefficients(zzprime);
|
| - memcpy(x3, xxxprime, sizeof(limb) * 10);
|
| - memcpy(z3, zzprime, sizeof(limb) * 10);
|
| -
|
| - fsquare(xx, x);
|
| - fsquare(zz, z);
|
| - fproduct(x2, xx, zz);
|
| - freduce_degree(x2);
|
| - freduce_coefficients(x2);
|
| - fdifference(zz, xx); // does zz = xx - zz
|
| - memset(zzz + 10, 0, sizeof(limb) * 9);
|
| - fscalar_product(zzz, zz, 121665);
|
| - freduce_degree(zzz);
|
| - freduce_coefficients(zzz);
|
| - fsum(zzz, xx);
|
| - fproduct(z2, zz, zzz);
|
| - freduce_degree(z2);
|
| - freduce_coefficients(z2);
|
| -}
|
| -
|
| -/* Calculates nQ where Q is the x-coordinate of a point on the curve
|
| - *
|
| - * resultx/resultz: the x coordinate of the resulting curve point (short form)
|
| - * n: a little endian, 32-byte number
|
| - * q: a point of the curve (short form)
|
| - */
|
| -static void
|
| -cmult(limb *resultx, limb *resultz, const u8 *n, const limb *q) {
|
| - limb a[19] = {0}, b[19] = {1}, c[19] = {1}, d[19] = {0};
|
| - limb *nqpqx = a, *nqpqz = b, *nqx = c, *nqz = d, *t;
|
| - limb e[19] = {0}, f[19] = {1}, g[19] = {0}, h[19] = {1};
|
| - limb *nqpqx2 = e, *nqpqz2 = f, *nqx2 = g, *nqz2 = h;
|
| -
|
| - unsigned i, j;
|
| -
|
| - memcpy(nqpqx, q, sizeof(limb) * 10);
|
| -
|
| - for (i = 0; i < 32; ++i) {
|
| - u8 byte = n[31 - i];
|
| - for (j = 0; j < 8; ++j) {
|
| - if (byte & 0x80) {
|
| - fmonty(nqpqx2, nqpqz2,
|
| - nqx2, nqz2,
|
| - nqpqx, nqpqz,
|
| - nqx, nqz,
|
| - q);
|
| - } else {
|
| - fmonty(nqx2, nqz2,
|
| - nqpqx2, nqpqz2,
|
| - nqx, nqz,
|
| - nqpqx, nqpqz,
|
| - q);
|
| - }
|
| -
|
| - t = nqx;
|
| - nqx = nqx2;
|
| - nqx2 = t;
|
| - t = nqz;
|
| - nqz = nqz2;
|
| - nqz2 = t;
|
| - t = nqpqx;
|
| - nqpqx = nqpqx2;
|
| - nqpqx2 = t;
|
| - t = nqpqz;
|
| - nqpqz = nqpqz2;
|
| - nqpqz2 = t;
|
| -
|
| - byte <<= 1;
|
| - }
|
| - }
|
| -
|
| - memcpy(resultx, nqx, sizeof(limb) * 10);
|
| - memcpy(resultz, nqz, sizeof(limb) * 10);
|
| -}
|
| -
|
| -// -----------------------------------------------------------------------------
|
| -// Shamelessly copied from djb's code
|
| -// -----------------------------------------------------------------------------
|
| -static void
|
| -crecip(limb *out, const limb *z) {
|
| - limb z2[10];
|
| - limb z9[10];
|
| - limb z11[10];
|
| - limb z2_5_0[10];
|
| - limb z2_10_0[10];
|
| - limb z2_20_0[10];
|
| - limb z2_50_0[10];
|
| - limb z2_100_0[10];
|
| - limb t0[10];
|
| - limb t1[10];
|
| - int i;
|
| -
|
| - /* 2 */ fsquare(z2,z);
|
| - /* 4 */ fsquare(t1,z2);
|
| - /* 8 */ fsquare(t0,t1);
|
| - /* 9 */ fmul(z9,t0,z);
|
| - /* 11 */ fmul(z11,z9,z2);
|
| - /* 22 */ fsquare(t0,z11);
|
| - /* 2^5 - 2^0 = 31 */ fmul(z2_5_0,t0,z9);
|
| -
|
| - /* 2^6 - 2^1 */ fsquare(t0,z2_5_0);
|
| - /* 2^7 - 2^2 */ fsquare(t1,t0);
|
| - /* 2^8 - 2^3 */ fsquare(t0,t1);
|
| - /* 2^9 - 2^4 */ fsquare(t1,t0);
|
| - /* 2^10 - 2^5 */ fsquare(t0,t1);
|
| - /* 2^10 - 2^0 */ fmul(z2_10_0,t0,z2_5_0);
|
| -
|
| - /* 2^11 - 2^1 */ fsquare(t0,z2_10_0);
|
| - /* 2^12 - 2^2 */ fsquare(t1,t0);
|
| - /* 2^20 - 2^10 */
|
| - for (i = 2;i < 10;i += 2) { fsquare(t0,t1); fsquare(t1,t0); }
|
| - /* 2^20 - 2^0 */ fmul(z2_20_0,t1,z2_10_0);
|
| -
|
| - /* 2^21 - 2^1 */ fsquare(t0,z2_20_0);
|
| - /* 2^22 - 2^2 */ fsquare(t1,t0);
|
| - /* 2^40 - 2^20 */
|
| - for (i = 2;i < 20;i += 2) { fsquare(t0,t1); fsquare(t1,t0); }
|
| - /* 2^40 - 2^0 */ fmul(t0,t1,z2_20_0);
|
| -
|
| - /* 2^41 - 2^1 */ fsquare(t1,t0);
|
| - /* 2^42 - 2^2 */ fsquare(t0,t1);
|
| - /* 2^50 - 2^10 */
|
| - for (i = 2;i < 10;i += 2) { fsquare(t1,t0); fsquare(t0,t1); }
|
| - /* 2^50 - 2^0 */ fmul(z2_50_0,t0,z2_10_0);
|
| -
|
| - /* 2^51 - 2^1 */ fsquare(t0,z2_50_0);
|
| - /* 2^52 - 2^2 */ fsquare(t1,t0);
|
| - /* 2^100 - 2^50 */
|
| - for (i = 2;i < 50;i += 2) { fsquare(t0,t1); fsquare(t1,t0); }
|
| - /* 2^100 - 2^0 */ fmul(z2_100_0,t1,z2_50_0);
|
| -
|
| - /* 2^101 - 2^1 */ fsquare(t1,z2_100_0);
|
| - /* 2^102 - 2^2 */ fsquare(t0,t1);
|
| - /* 2^200 - 2^100 */
|
| - for (i = 2;i < 100;i += 2) { fsquare(t1,t0); fsquare(t0,t1); }
|
| - /* 2^200 - 2^0 */ fmul(t1,t0,z2_100_0);
|
| -
|
| - /* 2^201 - 2^1 */ fsquare(t0,t1);
|
| - /* 2^202 - 2^2 */ fsquare(t1,t0);
|
| - /* 2^250 - 2^50 */
|
| - for (i = 2;i < 50;i += 2) { fsquare(t0,t1); fsquare(t1,t0); }
|
| - /* 2^250 - 2^0 */ fmul(t0,t1,z2_50_0);
|
| -
|
| - /* 2^251 - 2^1 */ fsquare(t1,t0);
|
| - /* 2^252 - 2^2 */ fsquare(t0,t1);
|
| - /* 2^253 - 2^3 */ fsquare(t1,t0);
|
| - /* 2^254 - 2^4 */ fsquare(t0,t1);
|
| - /* 2^255 - 2^5 */ fsquare(t1,t0);
|
| - /* 2^255 - 21 */ fmul(out,t1,z11);
|
| -}
|
| -
|
| -int
|
| -curve25519_donna(u8 *mypublic, const u8 *secret, const u8 *basepoint) {
|
| - limb bp[10], x[10], z[10], zmone[10];
|
| - uint8_t e[32];
|
| - int i;
|
| -
|
| - for (i = 0; i < 32; ++i) e[i] = secret[i];
|
| - e[0] &= 248;
|
| - e[31] &= 127;
|
| - e[31] |= 64;
|
| -
|
| - fexpand(bp, basepoint);
|
| - cmult(x, z, e, bp);
|
| - crecip(zmone, z);
|
| - fmul(z, x, zmone);
|
| - fcontract(mypublic, z);
|
| - return 0;
|
| -}
|
|
|