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AK: Implement SipHash as the default hash algorithm for most use cases

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SipHash is highly HashDoS-resistent, initialized with a random seed at
startup (i.e. non-deterministic) and usable for security-critical use
cases with large enough parameters. We just use it because it's
reasonably secure with parameters 1-3 while having excellent properties
and not being significantly slower than before.
This commit is contained in:
kleines Filmröllchen 2023-09-21 00:14:35 +02:00 • committed by Ali Mohammad Pur
parent 5e15c29e22
commit 9a026fc8d5
9 changed files with 282 additions and 11 deletions
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51
Tests/AK/TestHashFunctions.cpp
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@ -7,6 +7,7 @@
#include <LibTest/TestCase.h>
#include <AK/HashFunctions.h>
#include <AK/SipHash.h>
#include <AK/Types.h>
TEST_CASE(int_hash)
@ -53,3 +54,53 @@ TEST_CASE(constexpr_ptr_hash)
// "ptr_hash" test binds the result.
static_assert(ptr_hash(FlatPtr(42)));
}
// Testing concrete hash results is not possible due to SipHash's non-determinism.
// We instead perform some sanity checks and try to hit any asserts caused by programming errors.
TEST_CASE(sip_hash)
{
EXPECT_EQ(standard_sip_hash(42), standard_sip_hash(42));
EXPECT_EQ(secure_sip_hash(42), secure_sip_hash(42));
EXPECT_NE(standard_sip_hash(42), secure_sip_hash(42));
}
TEST_CASE(sip_hash_bytes)
{
constexpr Array<u8, 8> short_test_array { 1, 2, 3, 4, 5, 6, 7, 8 };
constexpr Array<u8, 16> common_prefix_array { 1, 2, 3, 4, 5, 6, 7, 8, 0, 0, 0, 0, 0, 0, 0, 0 };
EXPECT_EQ((sip_hash_bytes<1, 3>(short_test_array.span())), (sip_hash_bytes<1, 3>(short_test_array.span())));
EXPECT_NE((sip_hash_bytes<1, 3>(short_test_array.span())), (sip_hash_bytes<1, 3>(common_prefix_array.span())));
for (size_t prefix_length = 1; prefix_length < 8; ++prefix_length) {
EXPECT_NE((sip_hash_bytes<1, 3>(short_test_array.span().trim(prefix_length))), (sip_hash_bytes<1, 3>(short_test_array.span())));
EXPECT_EQ((sip_hash_bytes<1, 3>(short_test_array.span().trim(prefix_length))), (sip_hash_bytes<1, 3>(common_prefix_array.span().trim(prefix_length))));
}
}
template<typename HashFunction>
requires(IsCallableWithArguments<HashFunction, unsigned, u64>)
static void run_benchmark(HashFunction hash_function)
{
for (size_t i = 0; i < 1'000'000; ++i) {
auto a = hash_function(i);
AK::taint_for_optimizer(a);
auto b = hash_function(i);
AK::taint_for_optimizer(b);
EXPECT_EQ(a, b);
}
}
BENCHMARK_CASE(deterministic_hash)
{
run_benchmark(u64_hash);
}
BENCHMARK_CASE(fast_sip_hash)
{
run_benchmark(standard_sip_hash);
}
BENCHMARK_CASE(secure_sip_hash)
{
run_benchmark(secure_sip_hash);
}