Add a fuzz test for Num3072 multiplication and inversion

This commit is contained in:
Pieter Wuille 2021-12-01 14:19:08 -05:00
parent a7a7cfa3e8
commit 030c9edf5b
2 changed files with 159 additions and 0 deletions

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@ -229,3 +229,7 @@ arith_uint256 UintToArith256(const uint256 &a)
b.pn[x] = ReadLE32(a.begin() + x*4);
return b;
}
// Explicit instantiations for base_uint<6144> (used in test/fuzz/muhash.cpp).
template base_uint<6144>& base_uint<6144>::operator*=(const base_uint<6144>& b);
template base_uint<6144>& base_uint<6144>::operator/=(const base_uint<6144>& b);

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@ -2,13 +2,168 @@
// Distributed under the MIT software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.
#include <arith_uint256.h>
#include <crypto/muhash.h>
#include <span.h>
#include <uint256.h>
#include <test/fuzz/FuzzedDataProvider.h>
#include <test/fuzz/fuzz.h>
#include <test/fuzz/util.h>
#include <array>
#include <vector>
namespace {
/** Class to represent 6144-bit numbers using arith_uint256 code.
*
* 6144 is sufficient to represent the product of two 3072-bit numbers. */
class arith_uint6144 : public base_uint<6144> {
public:
arith_uint6144(uint64_t x) : base_uint{x} {}
/** Construct an arith_uint6144 from any multiple of 4 bytes in LE notation,
* up to 768 bytes. */
arith_uint6144(Span<const uint8_t> bytes) : base_uint{}
{
assert(bytes.size() % 4 == 0);
assert(bytes.size() <= 768);
for (unsigned i = 0; i * 4 < bytes.size(); ++i) {
pn[i] = ReadLE32(bytes.data() + 4 * i);
}
}
/** Serialize an arithm_uint6144 to any multiply of 4 bytes in LE notation,
* on the condition that the represented number fits. */
void Serialize(Span<uint8_t> bytes) {
assert(bytes.size() % 4 == 0);
assert(bytes.size() <= 768);
for (unsigned i = 0; i * 4 < bytes.size(); ++i) {
WriteLE32(bytes.data() + 4 * i, pn[i]);
}
for (unsigned i = bytes.size() / 4; i * 4 < 768; ++i) {
assert(pn[i] == 0);
}
};
};
/** The MuHash3072 modulus (2**3072 - 1103717) as 768 LE8 bytes. */
constexpr std::array<const uint8_t, 768> MODULUS_BYTES = {
155, 40, 239, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
};
const arith_uint6144 ZERO{0};
const arith_uint6144 ONE{1};
const arith_uint6144 MODULUS{MODULUS_BYTES};
/** Update value to be the modulus of the input modulo MODULUS. */
void Reduce(arith_uint6144& value)
{
arith_uint6144 tmp = value;
tmp /= MODULUS;
tmp *= MODULUS;
value -= tmp;
}
} // namespace
FUZZ_TARGET(num3072_mul)
{
// Test multiplication
FuzzedDataProvider provider{buffer.data(), buffer.size()};
// Read two 3072-bit numbers from fuzz input, and construct arith_uint6144
// and Num3072 objects with the read values.
uint16_t data_a_len = provider.ConsumeIntegralInRange(0, 384);
uint8_t data_a[384] = {0};
provider.ConsumeData(data_a, data_a_len);
arith_uint6144 a_uint{data_a};
Num3072 a_num{data_a};
uint8_t data_b[384] = {0};
provider.ConsumeData(data_b, 384);
arith_uint6144 b_uint{data_b};
Num3072 b_num{data_b};
// Multiply the first number with the second, in both representations.
a_num.Multiply(b_num);
a_uint *= b_uint;
Reduce(a_uint);
// Serialize both to bytes and compare.
uint8_t buf_num[384], buf_uint[384];
a_num.ToBytes(buf_num);
a_uint.Serialize(buf_uint);
assert(Span(buf_num) == Span(buf_uint));
}
FUZZ_TARGET(num3072_inv)
{
// Test inversion
FuzzedDataProvider provider{buffer.data(), buffer.size()};
// Read a 3072-bit number from fuzz input, and construct arith_uint6144
// and Num3072 objects with the read values.
uint8_t data[384] = {0};
provider.ConsumeData(data, 384);
Num3072 num{data};
arith_uint6144 uint{data};
// Bail out if the number has no inverse.
if ((uint == ZERO) || (uint == MODULUS)) return;
// Compute the inverse of the Num3072 object.
Num3072 inv;
inv.SetToOne();
inv.Divide(num);
// Convert the computed inverse to arith_uint6144.
uint8_t buf[384];
inv.ToBytes(buf);
arith_uint6144 uint_inv{buf};
// Multiply the original and the inverse, and expect 1.
uint *= uint_inv;
Reduce(uint);
assert(uint == ONE);
}
FUZZ_TARGET(muhash)
{
FuzzedDataProvider fuzzed_data_provider{buffer.data(), buffer.size()};