yggm/libs/f25519.cuh
2025-03-13 04:09:27 +05:00

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#ifndef __F25519_CUH
#define __F25519_CUH
#include <stdint.h>
#define F25519_SIZE 32
__device__ __constant__ uint8_t f25519_zero[F25519_SIZE] = { 0 };
__device__ __constant__ uint8_t f25519_one[F25519_SIZE] = { 1 };
__device__ __forceinline__ void f25519_load(uint8_t* __restrict__ x, uint32_t c) {
#pragma unroll
for (unsigned int i = 0; i < sizeof(c); i++) {
x[i] = c & 0xFF;
c >>= 8;
}
#pragma unroll
for (unsigned int i = sizeof(c); i < F25519_SIZE; i++) {
x[i] = 0;
}
}
__device__ __forceinline__ void f25519_copy(uint8_t* __restrict__ x, const uint8_t* __restrict__ a) {
#pragma unroll
for (int i = 0; i < F25519_SIZE; i++) {
x[i] = a[i];
}
}
__device__ __forceinline__ void f25519_select(uint8_t* __restrict__ dst,
const uint8_t* __restrict__ zero,
const uint8_t* __restrict__ one, uint8_t cond) {
const uint8_t mask = 0 - cond;
#pragma unroll
for (int i = 0; i < F25519_SIZE; i++) {
dst[i] = zero[i] ^ (mask & (one[i] ^ zero[i]));
}
}
__device__ __forceinline__ void f25519_normalize(uint8_t* __restrict__ x) {
uint8_t minusp[F25519_SIZE];
uint16_t c = (x[31] >> 7) * 19;
x[31] &= 127;
#pragma unroll
for (int i = 0; i < F25519_SIZE; i++) {
c += x[i];
x[i] = (uint8_t)c;
c >>= 8;
}
c = 19;
#pragma unroll
for (int i = 0; i + 1 < F25519_SIZE; i++) {
c += x[i];
minusp[i] = (uint8_t)c;
c >>= 8;
}
c += x[F25519_SIZE - 1] - 128;
minusp[F25519_SIZE - 1] = (uint8_t)c;
f25519_select(x, minusp, x, (c >> 15) & 1);
}
__device__ __forceinline__ uint8_t f25519_eq(const uint8_t* __restrict__ x, const uint8_t* __restrict__ y) {
uint8_t s = 0;
#pragma unroll
for (int i = 0; i < F25519_SIZE; i++)
s |= x[i] ^ y[i];
s |= s >> 4;
s |= s >> 2;
s |= s >> 1;
return (s ^ 1) & 1;
}
__device__ __forceinline__ void f25519_add(uint8_t* __restrict__ r,
const uint8_t* __restrict__ a,
const uint8_t* __restrict__ b) {
uint16_t c = 0;
#pragma unroll
for (int i = 0; i < F25519_SIZE; i++) {
c = (c >> 8) + ((uint16_t)a[i]) + ((uint16_t)b[i]);
r[i] = (uint8_t)c;
}
r[F25519_SIZE - 1] &= 127;
c = (c >> 7) * 19;
#pragma unroll
for (int i = 0; i < F25519_SIZE; i++) {
c += r[i];
r[i] = (uint8_t)c;
c >>= 8;
}
}
__device__ __forceinline__ void f25519_sub(uint8_t* __restrict__ r,
const uint8_t* __restrict__ a,
const uint8_t* __restrict__ b) {
uint32_t c = 218;
int i = 0;
#pragma unroll
for (i = 0; i + 1 < F25519_SIZE; i++) {
c += 65280 + ((uint32_t)a[i]) - ((uint32_t)b[i]);
r[i] = (uint8_t)c;
c >>= 8;
}
c += ((uint32_t)a[i]) - ((uint32_t)b[i]);
r[i] = (uint8_t)(c & 127);
c = (c >> 7) * 19;
#pragma unroll
for (i = 0; i < F25519_SIZE; i++) {
c += r[i];
r[i] = (uint8_t)c;
c >>= 8;
}
}
__device__ __forceinline__ void f25519_neg(uint8_t* __restrict__ r,
const uint8_t* __restrict__ a) {
uint32_t c = 218;
int i = 0;
#pragma unroll
for (i = 0; i + 1 < F25519_SIZE; i++) {
c += 65280 - ((uint32_t)a[i]);
r[i] = (uint8_t)c;
c >>= 8;
}
c -= ((uint32_t)a[i]);
r[i] = (uint8_t)(c & 127);
c = (c >> 7) * 19;
#pragma unroll
for (i = 0; i < F25519_SIZE; i++) {
c += r[i];
r[i] = (uint8_t)c;
c >>= 8;
}
}
__device__ __forceinline__ void f25519_mul__distinct(uint8_t* __restrict__ r,
const uint8_t* __restrict__ a,
const uint8_t* __restrict__ b) {
uint32_t c = 0;
#pragma unroll
for (int i = 0; i < F25519_SIZE; i++) {
c >>= 8;
for (int j = 0; j <= i; j++) {
c += ((uint32_t)a[j]) * ((uint32_t)b[i - j]);
}
for (int j = i + 1; j < F25519_SIZE; j++) {
c += ((uint32_t)a[j]) * ((uint32_t)b[F25519_SIZE + i - j]) * 38;
}
r[i] = (uint8_t)c;
}
r[F25519_SIZE - 1] &= 127;
c = (c >> 7) * 19;
#pragma unroll
for (int i = 0; i < F25519_SIZE; i++) {
c += r[i];
r[i] = (uint8_t)c;
c >>= 8;
}
}
__device__ __forceinline__ void f25519_mul_c(uint8_t* __restrict__ r,
const uint8_t* __restrict__ a, uint32_t b) {
uint32_t c = 0;
#pragma unroll
for (int i = 0; i < F25519_SIZE; i++) {
c = (c >> 8) + b * ((uint32_t)a[i]);
r[i] = (uint8_t)c;
}
r[F25519_SIZE - 1] &= 127;
c = (c >> 7) * 19;
#pragma unroll
for (int i = 0; i < F25519_SIZE; i++) {
c += r[i];
r[i] = (uint8_t)c;
c >>= 8;
}
}
__device__ __forceinline__ void f25519_inv__distinct(uint8_t* __restrict__ r,
const uint8_t* __restrict__ x) {
uint8_t s[F25519_SIZE];
f25519_mul__distinct(s, x, x);
f25519_mul__distinct(r, s, x);
#pragma unroll
for (int i = 0; i < 248; i++) {
f25519_mul__distinct(s, r, r);
f25519_mul__distinct(r, s, x);
}
f25519_mul__distinct(s, r, r);
f25519_mul__distinct(r, s, s);
f25519_mul__distinct(s, r, x);
f25519_mul__distinct(r, s, s);
f25519_mul__distinct(s, r, r);
f25519_mul__distinct(r, s, x);
f25519_mul__distinct(s, r, r);
f25519_mul__distinct(r, s, x);
}
__device__ __forceinline__ void exp2523(uint8_t* __restrict__ r,
const uint8_t* __restrict__ x,
uint8_t* __restrict__ s) {
int i;
f25519_mul__distinct(r, x, x);
f25519_mul__distinct(s, r, x);
#pragma unroll
for (i = 0; i < 248; i++) {
f25519_mul__distinct(r, s, s);
f25519_mul__distinct(s, r, x);
}
f25519_mul__distinct(r, s, s);
f25519_mul__distinct(s, r, r);
f25519_mul__distinct(r, s, x);
}
__device__ __forceinline__ void f25519_sqrt(uint8_t* __restrict__ r,
const uint8_t* __restrict__ a) {
uint8_t v[F25519_SIZE], i_val[F25519_SIZE], x[F25519_SIZE], y[F25519_SIZE];
f25519_mul_c(x, a, 2);
exp2523(v, x, y);
f25519_mul__distinct(y, v, v);
f25519_mul__distinct(i_val, x, y);
uint8_t one[F25519_SIZE];
f25519_load(one, 1);
f25519_sub(i_val, i_val, one);
f25519_mul__distinct(x, v, a);
f25519_mul__distinct(r, x, i_val);
}
#endif