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c-kzg-4844
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Fix implementation of compute_powers

This commit is contained in:
Ramana Kumar 2022-09-29 22:23:14 +01:00
parent 90eadda3cb
commit cfa9675512
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1 changed files with 3 additions and 21 deletions
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min-src/c_kzg_4844.c
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@ -814,28 +814,10 @@ void free_trusted_setup(KZGSettings *s) {
free_kzg_settings(s); free_kzg_settings(s);
} }
/**
* Exponentiation of a field element.
*
* Uses square and multiply for log(@p n) performance.
*
* @remark A 64-bit exponent is sufficient for our needs here.
*
* @param[out] out @p a raised to the power of @p n
* @param[in] x The field element to be exponentiated
* @param[in] n The exponent
*/
void compute_powers(fr_t out[], const fr_t *x, uint64_t n) { void compute_powers(fr_t out[], const fr_t *x, uint64_t n) {
fr_t tmp = *x; uint64_t i = 0;
*out = fr_one; out[i] = fr_one;
while (++i < n) fr_mul(&out[i], &out[i-1], x);
while (true) {
if (n & 1) {
fr_mul(out, out, &tmp);
}
if ((n >>= 1) == 0) break;
fr_sqr(&tmp, &tmp);
}
} }
void bytes_to_bls_field(BLSFieldElement *out, const scalar_t *bytes) { void bytes_to_bls_field(BLSFieldElement *out, const scalar_t *bytes) {