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c-kzg-4844
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Bring compute_challenges() closer to the spec

This commit is contained in:
George Kadianakis 2022-11-28 14:00:01 +02:00
parent 1a30272d14
commit 94aa388055
1 changed files with 20 additions and 10 deletions
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src/c_kzg_4844.c
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@ -1098,34 +1098,44 @@ static C_KZG_RET compute_challenges(BLSFieldElement *out, BLSFieldElement r_powe
const size_t np = ni + n * BYTES_PER_BLOB;
const size_t nb = np + n * 48;
uint8_t* bytes = calloc(nb + (n == 0), sizeof(uint8_t)); // need at least 1 byte more than ni for hash later
uint8_t* bytes = calloc(nb, sizeof(uint8_t));
if (bytes == NULL) return C_KZG_MALLOC;
/* Copy domain seperator */
memcpy(bytes, FIAT_SHAMIR_PROTOCOL_DOMAIN, 16);
bytes_of_uint64(&bytes[16], FIELD_ELEMENTS_PER_BLOB);
bytes_of_uint64(&bytes[16 + 8], n);
/* Copy polynomials */
for (i = 0; i < n; i++)
for (j = 0; j < FIELD_ELEMENTS_PER_BLOB; j++)
bytes_from_bls_field(&bytes[ni + BYTES_PER_FIELD_ELEMENT * (i * FIELD_ELEMENTS_PER_BLOB + j)], &polys[i][j]);
/* Copy commitments */
for (i = 0; i < n; i++)
bytes_from_g1(&bytes[np + i * 48], &comms[i]);
uint8_t hash_output[32] = {0};
hash(hash_output, bytes, nb);
memcpy(bytes, hash_output, 32);
bytes[32] = 0x0;
hash(hash_output, bytes, 33);
/* Now let's create challenges! */
uint8_t hashed_data[32] = {0};
hash(hashed_data, bytes, nb);
uint8_t r[32] = {0};
uint8_t hash_input_0[33] = {0}; // hashed_data + b'\x00'
memcpy(hash_input_0, hashed_data, 32);
hash_input_0[32] = 0x0;
hash(r, hash_input_0, 33);
if (n > 0) {
if (n > 1) bytes_to_bls_field(&r_powers[1], hash_output);
if (n > 1) bytes_to_bls_field(&r_powers[1], r);
compute_powers(r_powers, n);
}
bytes[32] = 0x1;
hash(hash_output, bytes, 33);
bytes_to_bls_field(out, hash_output);
uint8_t eval_challenge[32] = {0};
uint8_t hash_input_1[33] = {0}; // hashed_data + b'\x01'
memcpy(hash_input_1, hashed_data, 32);
hash_input_1[32] = 0x1;
hash(eval_challenge, hash_input_1, 33);
bytes_to_bls_field(out, eval_challenge);
free(bytes);
return C_KZG_OK;