mkp224o/ed25519/amd64-51-30k/fe25519_batchinvert.c

27 lines
462 B
C

#include "fe25519.h"
// tmp MUST != out
// in MAY == out
void fe25519_batchinvert(fe25519 *out[],fe25519 tmp[],fe25519 * const in[], size_t num)
{
fe25519 acc;
fe25519 tmpacc;
size_t i;
fe25519_setint(&acc,1);
for (i = 0;i < num;++i) {
tmp[i] = acc;
fe25519_mul(&acc,&acc,in[i]);
}
fe25519_invert(&acc,&acc);
i = num;
while (i--) {
fe25519_mul(&tmpacc,&acc,in[i]);
fe25519_mul(out[i],&acc,&tmp[i]);
acc = tmpacc;
}
}