ppsspp/Common/Crypto/ec.cpp
2012-11-01 16:19:01 +01:00

401 lines
6.2 KiB
C++

// Copyright 2007,2008 Segher Boessenkool <segher@kernel.crashing.org>
// Licensed under the terms of the GNU GPL, version 2
// http://www.gnu.org/licenses/old-licenses/gpl-2.0.txt
#include <string.h>
#include <stdio.h>
#include <time.h>
#include <stdlib.h>
#include "../Common.h"
#include "tools.h"
// y**2 + x*y = x**3 + x + b
/*
static u8 ec_b[30] =
{0x00,0x66,0x64,0x7e,0xde,0x6c,0x33,0x2c,0x7f,0x8c,0x09,0x23,0xbb,0x58,0x21
,0x3b,0x33,0x3b,0x20,0xe9,0xce,0x42,0x81,0xfe,0x11,0x5f,0x7d,0x8f,0x90,0xad};
*/
// order of the addition group of points
static u8 ec_N[30] =
{0x01,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00
,0x13,0xe9,0x74,0xe7,0x2f,0x8a,0x69,0x22,0x03,0x1d,0x26,0x03,0xcf,0xe0,0xd7};
// base point
static u8 ec_G[60] =
{0x00,0xfa,0xc9,0xdf,0xcb,0xac,0x83,0x13,0xbb,0x21,0x39,0xf1,0xbb,0x75,0x5f
,0xef,0x65,0xbc,0x39,0x1f,0x8b,0x36,0xf8,0xf8,0xeb,0x73,0x71,0xfd,0x55,0x8b
,0x01,0x00,0x6a,0x08,0xa4,0x19,0x03,0x35,0x06,0x78,0xe5,0x85,0x28,0xbe,0xbf
,0x8a,0x0b,0xef,0xf8,0x67,0xa7,0xca,0x36,0x71,0x6f,0x7e,0x01,0xf8,0x10,0x52};
/*static void elt_print(char *name, u8 *a)
{
u32 i;
printf("%s = ", name);
for (i = 0; i < 30; i++)
printf("%02x", a[i]);
printf("\n");
}*/
static void elt_copy(u8 *d, u8 *a)
{
memcpy(d, a, 30);
}
static void elt_zero(u8 *d)
{
memset(d, 0, 30);
}
static int elt_is_zero(u8 *d)
{
u32 i;
for (i = 0; i < 30; i++)
if (d[i] != 0)
return 0;
return 1;
}
static void elt_add(u8 *d, u8 *a, u8 *b)
{
u32 i;
for (i = 0; i < 30; i++)
d[i] = a[i] ^ b[i];
}
static void elt_mul_x(u8 *d, u8 *a)
{
u8 carry, x, y;
u32 i;
carry = a[0] & 1;
x = 0;
for (i = 0; i < 29; i++) {
y = a[i + 1];
d[i] = x ^ (y >> 7);
x = y << 1;
}
d[29] = x ^ carry;
d[20] ^= carry << 2;
}
static void elt_mul(u8 *d, u8 *a, u8 *b)
{
u32 i, n;
u8 mask;
elt_zero(d);
i = 0;
mask = 1;
for (n = 0; n < 233; n++) {
elt_mul_x(d, d);
if ((a[i] & mask) != 0)
elt_add(d, d, b);
mask >>= 1;
if (mask == 0) {
mask = 0x80;
i++;
}
}
}
static const u8 square[16] =
{0x00,0x01,0x04,0x05,0x10,0x11,0x14,0x15,0x40,0x41,0x44,0x45,0x50,0x51,0x54,0x55};
static void elt_square_to_wide(u8 *d, u8 *a)
{
u32 i;
for (i = 0; i < 30; i++) {
d[2*i] = square[a[i] >> 4];
d[2*i + 1] = square[a[i] & 15];
}
}
static void wide_reduce(u8 *d)
{
u32 i;
u8 x;
for (i = 0; i < 30; i++) {
x = d[i];
d[i + 19] ^= x >> 7;
d[i + 20] ^= x << 1;
d[i + 29] ^= x >> 1;
d[i + 30] ^= x << 7;
}
x = d[30] & ~1;
d[49] ^= x >> 7;
d[50] ^= x << 1;
d[59] ^= x >> 1;
d[30] &= 1;
}
static void elt_square(u8 *d, u8 *a)
{
u8 wide[60];
elt_square_to_wide(wide, a);
wide_reduce(wide);
elt_copy(d, wide + 30);
}
static void itoh_tsujii(u8 *d, u8 *a, u8 *b, u32 j)
{
u8 t[30];
elt_copy(t, a);
while (j--) {
elt_square(d, t);
elt_copy(t, d);
}
elt_mul(d, t, b);
}
static void elt_inv(u8 *d, u8 *a)
{
u8 t[30];
u8 s[30];
itoh_tsujii(t, a, a, 1);
itoh_tsujii(s, t, a, 1);
itoh_tsujii(t, s, s, 3);
itoh_tsujii(s, t, a, 1);
itoh_tsujii(t, s, s, 7);
itoh_tsujii(s, t, t, 14);
itoh_tsujii(t, s, a, 1);
itoh_tsujii(s, t, t, 29);
itoh_tsujii(t, s, s, 58);
itoh_tsujii(s, t, t, 116);
elt_square(d, s);
}
/*static int point_is_on_curve(u8 *p)
{
u8 s[30], t[30];
u8 *x, *y;
x = p;
y = p + 30;
elt_square(t, x);
elt_mul(s, t, x);
elt_add(s, s, t);
elt_square(t, y);
elt_add(s, s, t);
elt_mul(t, x, y);
elt_add(s, s, t);
elt_add(s, s, ec_b);
return elt_is_zero(s);
}
*/
static int point_is_zero(u8 *p)
{
return elt_is_zero(p) && elt_is_zero(p + 30);
}
static void point_double(u8 *r, u8 *p)
{
u8 s[30], t[30];
u8 *px, *py, *rx, *ry;
px = p;
py = p + 30;
rx = r;
ry = r + 30;
if (elt_is_zero(px)) {
elt_zero(rx);
elt_zero(ry);
return;
}
elt_inv(t, px);
elt_mul(s, py, t);
elt_add(s, s, px);
elt_square(t, px);
elt_square(rx, s);
elt_add(rx, rx, s);
rx[29] ^= 1;
elt_mul(ry, s, rx);
elt_add(ry, ry, rx);
elt_add(ry, ry, t);
}
static void point_add(u8 *r, u8 *p, u8 *q)
{
u8 s[30], t[30], u[30];
u8 *px, *py, *qx, *qy, *rx, *ry;
px = p;
py = p + 30;
qx = q;
qy = q + 30;
rx = r;
ry = r + 30;
if (point_is_zero(p)) {
elt_copy(rx, qx);
elt_copy(ry, qy);
return;
}
if (point_is_zero(q)) {
elt_copy(rx, px);
elt_copy(ry, py);
return;
}
elt_add(u, px, qx);
if (elt_is_zero(u)) {
elt_add(u, py, qy);
if (elt_is_zero(u))
point_double(r, p);
else {
elt_zero(rx);
elt_zero(ry);
}
return;
}
elt_inv(t, u);
elt_add(u, py, qy);
elt_mul(s, t, u);
elt_square(t, s);
elt_add(t, t, s);
elt_add(t, t, qx);
t[29] ^= 1;
elt_mul(u, s, t);
elt_add(s, u, py);
elt_add(rx, t, px);
elt_add(ry, s, rx);
}
static void point_mul(u8 *d, u8 *a, u8 *b) // a is bignum
{
u32 i;
u8 mask;
elt_zero(d);
elt_zero(d + 30);
for (i = 0; i < 30; i++)
for (mask = 0x80; mask != 0; mask >>= 1) {
point_double(d, d);
if ((a[i] & mask) != 0)
point_add(d, d, b);
}
}
void silly_random(u8 * rndArea, u8 count)
{
u16 i;
srand((unsigned) (time(NULL)));
for(i=0;i<count;i++)
{
rndArea[i]=rand();
}
}
void generate_ecdsa(u8 *R, u8 *S, u8 *k, u8 *hash)
{
u8 e[30];
u8 kk[30];
u8 m[30];
u8 minv[30];
u8 mG[60];
//FILE *fp;
elt_zero(e);
memcpy(e + 10, hash, 20);
//Changing random number generator to a lame one...
silly_random(m, sizeof(m));
//fp = fopen("/dev/random", "rb");
//if (fread(m, sizeof m, 1, fp) != 1)
// fatal("reading random");
//fclose(fp);
m[0] = 0;
// R = (mG).x
point_mul(mG, m, ec_G);
elt_copy(R, mG);
if (bn_compare(R, ec_N, 30) >= 0)
bn_sub_modulus(R, ec_N, 30);
// S = m**-1*(e + Rk) (mod N)
elt_copy(kk, k);
if (bn_compare(kk, ec_N, 30) >= 0)
bn_sub_modulus(kk, ec_N, 30);
bn_mul(S, R, kk, ec_N, 30);
bn_add(kk, S, e, ec_N, 30);
bn_inv(minv, m, ec_N, 30);
bn_mul(S, minv, kk, ec_N, 30);
}
int check_ecdsa(u8 *Q, u8 *R, u8 *S, u8 *hash)
{
u8 Sinv[30];
u8 e[30];
u8 w1[30], w2[30];
u8 r1[60], r2[60];
bn_inv(Sinv, S, ec_N, 30);
elt_zero(e);
memcpy(e + 10, hash, 20);
bn_mul(w1, e, Sinv, ec_N, 30);
bn_mul(w2, R, Sinv, ec_N, 30);
point_mul(r1, w1, ec_G);
point_mul(r2, w2, Q);
point_add(r1, r1, r2);
if (bn_compare(r1, ec_N, 30) >= 0)
bn_sub_modulus(r1, ec_N, 30);
return (bn_compare(r1, R, 30) == 0);
}
void ec_priv_to_pub(u8 *k, u8 *Q)
{
point_mul(Q, k, ec_G);
}