status-im/c-kzg-4844
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Simplify by removing the unnecessary extended polynomial

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This commit is contained in:
Ben Edgington 2021-02-11 07:43:49 +00:00
parent 5dc78d40f2
commit 1a196dd748
2 changed files with 21 additions and 36 deletions
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55
src/fk20_proofs.c
View File

@ -107,9 +107,18 @@ C_KZG_RET toeplitz_part_2(blst_p1 *out, const poly *toeplitz_coeffs, const FK20S
return C_KZG_OK; return C_KZG_OK;
} }
// Transform back and return the first half of the vector // Part 3: transform back and zero the top half
C_KZG_RET toeplitz_part_3(blst_p1 *out, const blst_p1 *h_ext_fft, uint64_t length, const FK20SingleSettings *fk) { C_KZG_RET toeplitz_part_3(blst_p1 *out, const blst_p1 *h_ext_fft, uint64_t n2, const FK20SingleSettings *fk) {
ASSERT(fft_g1(out, h_ext_fft, true, length, fk->ks->fs) == C_KZG_OK, C_KZG_ERROR); uint64_t n = n2 / 2;
blst_p1 identity_g1;
ASSERT(fft_g1(out, h_ext_fft, true, n2, fk->ks->fs) == C_KZG_OK, C_KZG_ERROR);
// Zero the second half of h
blst_p1_from_affine(&identity_g1, &identity_g1_affine);
for (uint64_t i = n; i < n2; i++) {
out[i] = identity_g1;
}
return C_KZG_OK; return C_KZG_OK;
} }
@ -130,36 +139,24 @@ void toeplitz_coeffs_step(poly *out, const poly *in) {
// The upper half of the polynomial coefficients is always 0, so we do not need to extend to twice the size // The upper half of the polynomial coefficients is always 0, so we do not need to extend to twice the size
// for Toeplitz matrix multiplication // for Toeplitz matrix multiplication
C_KZG_RET fk20_single_da_opt(blst_p1 *out, const poly *p, FK20SingleSettings *fk) { C_KZG_RET fk20_single_da_opt(blst_p1 *out, const poly *p, FK20SingleSettings *fk) {
uint64_t n2 = p->length, n = n2 / 2; uint64_t n = p->length, n2 = n * 2;
blst_p1 *h, *h_ext_fft, identity_g1; blst_p1 *h, *h_ext_fft;
poly reduced_poly, toeplitz_coeffs; poly toeplitz_coeffs;
C_KZG_RET ret; C_KZG_RET ret;
ASSERT(n2 <= fk->ks->fs->max_width, C_KZG_BADARGS); ASSERT(n2 <= fk->ks->fs->max_width, C_KZG_BADARGS);
ASSERT(is_power_of_two(n2), C_KZG_BADARGS); ASSERT(is_power_of_two(n), C_KZG_BADARGS);
for (uint64_t i = n; i < n2; i++) {
ASSERT(fr_is_zero(&p->coeffs[i]), C_KZG_BADARGS);
}
// The first half of the input polynomial
reduced_poly.coeffs = p->coeffs;
reduced_poly.length = n;
ASSERT(init_poly(&toeplitz_coeffs, n2) == C_KZG_OK, C_KZG_MALLOC); ASSERT(init_poly(&toeplitz_coeffs, n2) == C_KZG_OK, C_KZG_MALLOC);
toeplitz_coeffs_step(&toeplitz_coeffs, &reduced_poly); toeplitz_coeffs_step(&toeplitz_coeffs, p);
ASSERT(c_kzg_malloc((void **)&h_ext_fft, toeplitz_coeffs.length * sizeof *h_ext_fft) == C_KZG_OK, C_KZG_MALLOC); ASSERT(c_kzg_malloc((void **)&h_ext_fft, toeplitz_coeffs.length * sizeof *h_ext_fft) == C_KZG_OK, C_KZG_MALLOC);
ASSERT((ret = toeplitz_part_2(h_ext_fft, &toeplitz_coeffs, fk)) == C_KZG_OK, ASSERT((ret = toeplitz_part_2(h_ext_fft, &toeplitz_coeffs, fk)) == C_KZG_OK,
ret == C_KZG_MALLOC ? ret : C_KZG_ERROR); ret == C_KZG_MALLOC ? ret : C_KZG_ERROR);
ASSERT(c_kzg_malloc((void **)&h, toeplitz_coeffs.length * sizeof *h) == C_KZG_OK, C_KZG_MALLOC); ASSERT(c_kzg_malloc((void **)&h, toeplitz_coeffs.length * sizeof *h) == C_KZG_OK, C_KZG_MALLOC);
ASSERT(toeplitz_part_3(h, h_ext_fft, n2, fk) == C_KZG_OK, C_KZG_ERROR); ASSERT(toeplitz_part_3(h, h_ext_fft, n2, fk) == C_KZG_OK, C_KZG_ERROR);
blst_p1_from_affine(&identity_g1, &identity_g1_affine);
for (uint64_t i = n; i < n2; i++) {
h[i] = identity_g1;
}
ASSERT(fft_g1(out, h, false, n2, fk->ks->fs) == C_KZG_OK, C_KZG_ERROR); ASSERT(fft_g1(out, h, false, n2, fk->ks->fs) == C_KZG_OK, C_KZG_ERROR);
free(h); free(h);
@ -170,25 +167,13 @@ C_KZG_RET fk20_single_da_opt(blst_p1 *out, const poly *p, FK20SingleSettings *fk
C_KZG_RET da_using_fk20_single(blst_p1 *out, const poly *p, FK20SingleSettings *fk) { C_KZG_RET da_using_fk20_single(blst_p1 *out, const poly *p, FK20SingleSettings *fk) {
uint64_t n = p->length, n2 = n * 2; uint64_t n = p->length, n2 = n * 2;
poly extended_poly;
ASSERT(n2 <= fk->ks->fs->max_width, C_KZG_BADARGS); ASSERT(n2 <= fk->ks->fs->max_width, C_KZG_BADARGS);
ASSERT(is_power_of_two(n), C_KZG_BADARGS); ASSERT(is_power_of_two(n), C_KZG_BADARGS);
ASSERT(init_poly(&extended_poly, n2) == C_KZG_OK, C_KZG_MALLOC); ASSERT(fk20_single_da_opt(out, p, fk) == C_KZG_OK, C_KZG_ERROR);
for (uint64_t i = 0; i < n; i++) {
extended_poly.coeffs[i] = p->coeffs[i];
}
for (uint64_t i = n; i < n2; i++) {
extended_poly.coeffs[i] = fr_zero;
}
ASSERT(fk20_single_da_opt(out, &extended_poly, fk) == C_KZG_OK, C_KZG_ERROR);
ASSERT(reverse_bit_order(out, sizeof out[0], n2) == C_KZG_OK, C_KZG_ERROR); ASSERT(reverse_bit_order(out, sizeof out[0], n2) == C_KZG_OK, C_KZG_ERROR);
free_poly(&extended_poly);
return C_KZG_OK; return C_KZG_OK;
} }
@ -204,7 +189,7 @@ C_KZG_RET new_fk20_single_settings(FK20SingleSettings *fk, uint64_t n2, KZGSetti
fk->x_ext_fft_len = n2; fk->x_ext_fft_len = n2;
ASSERT(c_kzg_malloc((void **)&x, n * sizeof *x) == C_KZG_OK, C_KZG_MALLOC); ASSERT(c_kzg_malloc((void **)&x, n * sizeof *x) == C_KZG_OK, C_KZG_MALLOC);
ASSERT(c_kzg_malloc((void **)&fk->x_ext_fft, n2 * sizeof *fk->x_ext_fft) == C_KZG_OK, C_KZG_MALLOC); ASSERT(c_kzg_malloc((void **)&fk->x_ext_fft, fk->x_ext_fft_len * sizeof *fk->x_ext_fft) == C_KZG_OK, C_KZG_MALLOC);
for (uint64_t i = 0; i < n - 1; i++) { for (uint64_t i = 0; i < n - 1; i++) {
x[i] = ks->secret_g1[n - 2 - i]; x[i] = ks->secret_g1[n - 2 - i];

2
src/fk20_proofs.h
View File

@ -40,7 +40,7 @@ uint32_t reverse_bits_limited(uint32_t length, uint32_t value);
C_KZG_RET reverse_bit_order(void *values, size_t size, uint64_t n); C_KZG_RET reverse_bit_order(void *values, size_t size, uint64_t n);
C_KZG_RET toeplitz_part_1(blst_p1 *out, const blst_p1 *x, uint64_t n, KZGSettings *ks); C_KZG_RET toeplitz_part_1(blst_p1 *out, const blst_p1 *x, uint64_t n, KZGSettings *ks);
C_KZG_RET toeplitz_part_2(blst_p1 *out, const poly *toeplitz_coeffs, const FK20SingleSettings *fk); C_KZG_RET toeplitz_part_2(blst_p1 *out, const poly *toeplitz_coeffs, const FK20SingleSettings *fk);
C_KZG_RET toeplitz_part_3(blst_p1 *out, const blst_p1 *h_ext_fft, uint64_t length, const FK20SingleSettings *fk); C_KZG_RET toeplitz_part_3(blst_p1 *out, const blst_p1 *h_ext_fft, uint64_t n2, const FK20SingleSettings *fk);
C_KZG_RET fk20_single_da_opt(blst_p1 *out, const poly *p, FK20SingleSettings *fk); C_KZG_RET fk20_single_da_opt(blst_p1 *out, const poly *p, FK20SingleSettings *fk);
C_KZG_RET da_using_fk20_single(blst_p1 *out, const poly *p, FK20SingleSettings *fk); C_KZG_RET da_using_fk20_single(blst_p1 *out, const poly *p, FK20SingleSettings *fk);
C_KZG_RET new_fk20_single_settings(FK20SingleSettings *fk, uint64_t n2, KZGSettings *ks); C_KZG_RET new_fk20_single_settings(FK20SingleSettings *fk, uint64_t n2, KZGSettings *ks);