mirror of
https://github.com/trezor/trezor-firmware.git
synced 2024-12-19 04:48:12 +00:00
44 lines
1.4 KiB
C
44 lines
1.4 KiB
C
|
/*
|
||
|
|
* In: b = 2^5 - 2^0
|
||
|
|
* Out: b = 2^250 - 2^0
|
||
|
|
*/
|
||
|
|
static void
|
||
|
|
curve25519_pow_two5mtwo0_two250mtwo0(bignum25519 b) {
|
||
|
|
bignum25519 ALIGN(16) t0,c;
|
||
|
|
|
||
|
|
/* 2^5 - 2^0 */ /* b */
|
||
|
|
/* 2^10 - 2^5 */ curve25519_square_times(t0, b, 5);
|
||
|
|
/* 2^10 - 2^0 */ curve25519_mul(b, t0, b);
|
||
|
|
/* 2^20 - 2^10 */ curve25519_square_times(t0, b, 10);
|
||
|
|
/* 2^20 - 2^0 */ curve25519_mul(c, t0, b);
|
||
|
|
/* 2^40 - 2^20 */ curve25519_square_times(t0, c, 20);
|
||
|
|
/* 2^40 - 2^0 */ curve25519_mul(t0, t0, c);
|
||
|
|
/* 2^50 - 2^10 */ curve25519_square_times(t0, t0, 10);
|
||
|
|
/* 2^50 - 2^0 */ curve25519_mul(b, t0, b);
|
||
|
|
/* 2^100 - 2^50 */ curve25519_square_times(t0, b, 50);
|
||
|
|
/* 2^100 - 2^0 */ curve25519_mul(c, t0, b);
|
||
|
|
/* 2^200 - 2^100 */ curve25519_square_times(t0, c, 100);
|
||
|
|
/* 2^200 - 2^0 */ curve25519_mul(t0, t0, c);
|
||
|
|
/* 2^250 - 2^50 */ curve25519_square_times(t0, t0, 50);
|
||
|
|
/* 2^250 - 2^0 */ curve25519_mul(b, t0, b);
|
||
|
|
}
|
||
|
|
|
||
|
|
/*
|
||
|
|
* z^(p - 2) = z(2^255 - 21)
|
||
|
|
*/
|
||
|
|
static void
|
||
|
|
curve25519_recip(bignum25519 out, const bignum25519 z) {
|
||
|
|
bignum25519 ALIGN(16) a,t0,b;
|
||
|
|
|
||
|
|
/* 2 */ curve25519_square(a, z); /* a = 2 */
|
||
|
|
/* 8 */ curve25519_square_times(t0, a, 2);
|
||
|
|
/* 9 */ curve25519_mul(b, t0, z); /* b = 9 */
|
||
|
|
/* 11 */ curve25519_mul(a, b, a); /* a = 11 */
|
||
|
|
/* 22 */ curve25519_square(t0, a);
|
||
|
|
/* 2^5 - 2^0 = 31 */ curve25519_mul(b, t0, b);
|
||
|
|
/* 2^250 - 2^0 */ curve25519_pow_two5mtwo0_two250mtwo0(b);
|
||
|
|
/* 2^255 - 2^5 */ curve25519_square_times(b, b, 5);
|
||
|
|
/* 2^255 - 21 */ curve25519_mul(out, b, a);
|
||
|
|
}
|
||
|
|
|