60 lines
1.7 KiB
C
60 lines
1.7 KiB
C
|
#include "fe25519.h"
|
||
|
|
|
||
|
|
void fe25519_invert(fe25519 *r, const fe25519 *x)
|
||
|
|
{
|
||
|
|
fe25519 z2;
|
||
|
|
fe25519 z9;
|
||
|
|
fe25519 z11;
|
||
|
|
fe25519 z2_5_0;
|
||
|
|
fe25519 z2_10_0;
|
||
|
|
fe25519 z2_20_0;
|
||
|
|
fe25519 z2_50_0;
|
||
|
|
fe25519 z2_100_0;
|
||
|
|
fe25519 t;
|
||
|
|
|
||
|
|
/* 2 */ fe25519_square(&z2,x);
|
||
|
|
/* 4 */ fe25519_square(&t,&z2);
|
||
|
|
/* 8 */ fe25519_square(&t,&t);
|
||
|
|
/* 9 */ fe25519_mul(&z9,&t,x);
|
||
|
|
/* 11 */ fe25519_mul(&z11,&z9,&z2);
|
||
|
|
/* 22 */ fe25519_square(&t,&z11);
|
||
|
|
/* 2^5 - 2^0 = 31 */ fe25519_mul(&z2_5_0,&t,&z9);
|
||
|
|
|
||
|
|
/* 2^6 - 2^1 */ fe25519_square(&t,&z2_5_0);
|
||
|
|
/* 2^10 - 2^5 */ fe25519_nsquare(&t,4);
|
||
|
|
/* 2^10 - 2^0 */ fe25519_mul(&z2_10_0,&t,&z2_5_0);
|
||
|
|
|
||
|
|
/* 2^11 - 2^1 */ fe25519_square(&t,&z2_10_0);
|
||
|
|
/* 2^20 - 2^10 */ fe25519_nsquare(&t,9);
|
||
|
|
/* 2^20 - 2^0 */ fe25519_mul(&z2_20_0,&t,&z2_10_0);
|
||
|
|
|
||
|
|
/* 2^21 - 2^1 */ fe25519_square(&t,&z2_20_0);
|
||
|
|
/* 2^40 - 2^20 */ fe25519_nsquare(&t,19);
|
||
|
|
/* 2^40 - 2^0 */ fe25519_mul(&t,&t,&z2_20_0);
|
||
|
|
|
||
|
|
/* 2^41 - 2^1 */ fe25519_square(&t,&t);
|
||
|
|
/* 2^50 - 2^10 */ fe25519_nsquare(&t,9);
|
||
|
|
/* 2^50 - 2^0 */ fe25519_mul(&z2_50_0,&t,&z2_10_0);
|
||
|
|
|
||
|
|
/* 2^51 - 2^1 */ fe25519_square(&t,&z2_50_0);
|
||
|
|
/* 2^100 - 2^50 */ fe25519_nsquare(&t,49);
|
||
|
|
/* 2^100 - 2^0 */ fe25519_mul(&z2_100_0,&t,&z2_50_0);
|
||
|
|
|
||
|
|
/* 2^101 - 2^1 */ fe25519_square(&t,&z2_100_0);
|
||
|
|
/* 2^200 - 2^100 */ fe25519_nsquare(&t,99);
|
||
|
|
/* 2^200 - 2^0 */ fe25519_mul(&t,&t,&z2_100_0);
|
||
|
|
|
||
|
|
/* 2^201 - 2^1 */ fe25519_square(&t,&t);
|
||
|
|
/* 2^250 - 2^50 */ fe25519_nsquare(&t,49);
|
||
|
|
/* 2^250 - 2^0 */ fe25519_mul(&t,&t,&z2_50_0);
|
||
|
|
|
||
|
|
/* 2^251 - 2^1 */ fe25519_square(&t,&t);
|
||
|
|
/* 2^252 - 2^2 */ fe25519_square(&t,&t);
|
||
|
|
/* 2^253 - 2^3 */ fe25519_square(&t,&t);
|
||
|
|
|
||
|
|
/* 2^254 - 2^4 */ fe25519_square(&t,&t);
|
||
|
|
|
||
|
|
/* 2^255 - 2^5 */ fe25519_square(&t,&t);
|
||
|
|
/* 2^255 - 21 */ fe25519_mul(r,&t,&z11);
|
||
|
|
}
|