Electroneum
curve25519-donna-helpers.h
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1 /*
2  Public domain by Andrew M. <liquidsun@gmail.com>
3  See: https://github.com/floodyberry/curve25519-donna
4 
5  Curve25519 implementation agnostic helpers
6 */
7 
8 /*
9  * In: b = 2^5 - 2^0
10  * Out: b = 2^250 - 2^0
11  */
12 static void
13 curve25519_pow_two5mtwo0_two250mtwo0(bignum25519 b) {
14  bignum25519 ALIGN(16) t0,c;
15 
16  /* 2^5 - 2^0 */ /* b */
17  /* 2^10 - 2^5 */ curve25519_square_times(t0, b, 5);
18  /* 2^10 - 2^0 */ curve25519_mul_noinline(b, t0, b);
19  /* 2^20 - 2^10 */ curve25519_square_times(t0, b, 10);
20  /* 2^20 - 2^0 */ curve25519_mul_noinline(c, t0, b);
21  /* 2^40 - 2^20 */ curve25519_square_times(t0, c, 20);
22  /* 2^40 - 2^0 */ curve25519_mul_noinline(t0, t0, c);
23  /* 2^50 - 2^10 */ curve25519_square_times(t0, t0, 10);
24  /* 2^50 - 2^0 */ curve25519_mul_noinline(b, t0, b);
25  /* 2^100 - 2^50 */ curve25519_square_times(t0, b, 50);
26  /* 2^100 - 2^0 */ curve25519_mul_noinline(c, t0, b);
27  /* 2^200 - 2^100 */ curve25519_square_times(t0, c, 100);
28  /* 2^200 - 2^0 */ curve25519_mul_noinline(t0, t0, c);
29  /* 2^250 - 2^50 */ curve25519_square_times(t0, t0, 50);
30  /* 2^250 - 2^0 */ curve25519_mul_noinline(b, t0, b);
31 }
32 
33 /*
34  * z^(p - 2) = z(2^255 - 21)
35  */
36 static void
37 curve25519_recip(bignum25519 out, const bignum25519 z) {
38  bignum25519 ALIGN(16) a,t0,b;
39 
40  /* 2 */ curve25519_square_times(a, z, 1); /* a = 2 */
41  /* 8 */ curve25519_square_times(t0, a, 2);
42  /* 9 */ curve25519_mul_noinline(b, t0, z); /* b = 9 */
43  /* 11 */ curve25519_mul_noinline(a, b, a); /* a = 11 */
44  /* 22 */ curve25519_square_times(t0, a, 1);
45  /* 2^5 - 2^0 = 31 */ curve25519_mul_noinline(b, t0, b);
46  /* 2^250 - 2^0 */ curve25519_pow_two5mtwo0_two250mtwo0(b);
47  /* 2^255 - 2^5 */ curve25519_square_times(b, b, 5);
48  /* 2^255 - 21 */ curve25519_mul_noinline(out, b, a);
49 }
50 
51 /*
52  * z^((p-5)/8) = z^(2^252 - 3)
53  */
54 static void
55 curve25519_pow_two252m3(bignum25519 two252m3, const bignum25519 z) {
56  bignum25519 ALIGN(16) b,c,t0;
57 
58  /* 2 */ curve25519_square_times(c, z, 1); /* c = 2 */
59  /* 8 */ curve25519_square_times(t0, c, 2); /* t0 = 8 */
60  /* 9 */ curve25519_mul_noinline(b, t0, z); /* b = 9 */
61  /* 11 */ curve25519_mul_noinline(c, b, c); /* c = 11 */
62  /* 22 */ curve25519_square_times(t0, c, 1);
63  /* 2^5 - 2^0 = 31 */ curve25519_mul_noinline(b, t0, b);
64  /* 2^250 - 2^0 */ curve25519_pow_two5mtwo0_two250mtwo0(b);
65  /* 2^252 - 2^2 */ curve25519_square_times(b, b, 2);
66  /* 2^252 - 3 */ curve25519_mul_noinline(two252m3, b, z);
67 }
#define ALIGN(x)
uint32_t bignum25519[10]
t0
Definition: pow22523.h:53
#define curve25519_mul_noinline
const GenericPointer< typename T::ValueType > T2 T::AllocatorType & a
Definition: pointer.h:1124