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c-kzg-4844
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Merge pull request #9 from ethereum/3093 

Update Fiat-Shamir protocol to match specs
This commit is contained in:
Ramana Kumar 2022-11-27 19:38:59 +00:00 committed by GitHub
parent 8a6f9f5b7c b69104859f
commit 1a30272d14
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GPG Key ID: 4AEE18F83AFDEB23
1 changed files with 28 additions and 31 deletions
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src/c_kzg_4844.c
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@ -1091,13 +1091,14 @@ static void bytes_of_uint64(uint8_t out[8], uint64_t n) {
}
}
static C_KZG_RET hash_to_bytes(uint8_t out[32],
static C_KZG_RET compute_challenges(BLSFieldElement *out, BLSFieldElement r_powers[],
const Polynomial polys[], const KZGCommitment comms[], uint64_t n) {
size_t i; uint64_t j;
size_t ni = 32; // len(FIAT_SHAMIR_PROTOCOL_DOMAIN) + 8 + 8
size_t np = ni + n * FIELD_ELEMENTS_PER_BLOB * 32;
const size_t ni = 32; // len(FIAT_SHAMIR_PROTOCOL_DOMAIN) + 8 + 8
const size_t np = ni + n * BYTES_PER_BLOB;
const size_t nb = np + n * 48;
uint8_t* bytes = calloc(np + n * 48, sizeof(uint8_t));
uint8_t* bytes = calloc(nb + (n == 0), sizeof(uint8_t)); // need at least 1 byte more than ni for hash later
if (bytes == NULL) return C_KZG_MALLOC;
memcpy(bytes, FIAT_SHAMIR_PROTOCOL_DOMAIN, 16);
@ -1111,7 +1112,20 @@ static C_KZG_RET hash_to_bytes(uint8_t out[32],
for (i = 0; i < n; i++)
bytes_from_g1(&bytes[np + i * 48], &comms[i]);
hash(out, bytes, np + n * 48);
uint8_t hash_output[32] = {0};
hash(hash_output, bytes, nb);
memcpy(bytes, hash_output, 32);
bytes[32] = 0x0;
hash(hash_output, bytes, 33);
if (n > 0) {
if (n > 1) bytes_to_bls_field(&r_powers[1], hash_output);
compute_powers(r_powers, n);
}
bytes[32] = 0x1;
hash(hash_output, bytes, 33);
bytes_to_bls_field(out, hash_output);
free(bytes);
return C_KZG_OK;
@ -1121,30 +1135,18 @@ static C_KZG_RET compute_aggregated_poly_and_commitment(Polynomial poly_out, KZG
const Polynomial polys[],
const KZGCommitment kzg_commitments[],
size_t n) {
if (n == 0) return C_KZG_BADARGS;
BLSFieldElement* r_powers = calloc(n, sizeof(BLSFieldElement));
if (0 < n && r_powers == NULL) return C_KZG_MALLOC;
C_KZG_RET ret;
uint8_t* hash = calloc(32, sizeof(uint8_t));
if (hash == NULL) return C_KZG_MALLOC;
ret = hash_to_bytes(hash, polys, kzg_commitments, n);
if (ret != C_KZG_OK) { free(hash); return ret; }
BLSFieldElement* r_powers = calloc(n + 1, sizeof(BLSFieldElement));
if (r_powers == NULL) { free(hash); return C_KZG_MALLOC; }
bytes_to_bls_field(&r_powers[1], hash);
free(hash);
compute_powers(r_powers, n + 1);
*chal_out = r_powers[n];
ret = compute_challenges(chal_out, r_powers, polys, kzg_commitments, n);
if (ret != C_KZG_OK) { if (r_powers != NULL) free(r_powers); return ret; }
poly_lincomb(poly_out, polys, r_powers, n);
g1_lincomb(comm_out, kzg_commitments, r_powers, n);
free(r_powers);
if (r_powers != NULL) free(r_powers);
return C_KZG_OK;
}
@ -1152,16 +1154,11 @@ C_KZG_RET compute_aggregate_kzg_proof(KZGProof *out,
const Blob blobs[],
size_t n,
const KZGSettings *s) {
if (n == 0) {
*out = g1_identity;
return C_KZG_OK;
}
KZGCommitment* commitments = calloc(n, sizeof(KZGCommitment));
if (commitments == NULL) return C_KZG_MALLOC;
if (0 < n && commitments == NULL) return C_KZG_MALLOC;
Polynomial* polys = calloc(n, sizeof(Polynomial));
if (polys == NULL) { free(commitments); return C_KZG_MALLOC; }
if (0 < n && polys == NULL) { free(commitments); return C_KZG_MALLOC; }
for (size_t i = 0; i < n; i++) {
poly_from_blob(polys[i], blobs[i]);
@ -1173,8 +1170,8 @@ C_KZG_RET compute_aggregate_kzg_proof(KZGProof *out,
BLSFieldElement evaluation_challenge;
C_KZG_RET ret;
ret = compute_aggregated_poly_and_commitment(aggregated_poly, &aggregated_poly_commitment, &evaluation_challenge, polys, commitments, n);
free(commitments);
free(polys);
if (commitments != NULL) free(commitments);
if (polys != NULL) free(polys);
if (ret != C_KZG_OK) return ret;
return compute_kzg_proof(out, aggregated_poly, &evaluation_challenge, s);