mirror of
https://github.com/SerenityOS/serenity
synced 2024-07-01 11:59:23 +00:00
9a026fc8d5
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.
57 lines
1.4 KiB
C++
57 lines
1.4 KiB
C++
/*
|
|
* Copyright (c) 2018-2021, the SerenityOS developers.
|
|
*
|
|
* SPDX-License-Identifier: BSD-2-Clause
|
|
*/
|
|
|
|
#pragma once
|
|
|
|
#include <AK/Types.h>
|
|
|
|
namespace AK {
|
|
|
|
// FIXME: This hashing algorithm isn't well-known and may not be good at all.
|
|
// We can't use SipHash since that depends on runtime parameters,
|
|
// but some string hashes like IPC endpoint magic numbers need to be deterministic.
|
|
// Maybe use a SipHash with a statically-known key?
|
|
constexpr u32 string_hash(char const* characters, size_t length, u32 seed = 0)
|
|
{
|
|
u32 hash = seed;
|
|
for (size_t i = 0; i < length; ++i) {
|
|
hash += static_cast<u32>(characters[i]);
|
|
hash += (hash << 10);
|
|
hash ^= (hash >> 6);
|
|
}
|
|
hash += hash << 3;
|
|
hash ^= hash >> 11;
|
|
hash += hash << 15;
|
|
return hash;
|
|
}
|
|
|
|
constexpr u32 case_insensitive_string_hash(char const* characters, size_t length, u32 seed = 0)
|
|
{
|
|
// AK/CharacterTypes.h cannot be included from here.
|
|
auto to_lowercase = [](char ch) -> u32 {
|
|
if (ch >= 'A' && ch <= 'Z')
|
|
return static_cast<u32>(ch) + 0x20;
|
|
return static_cast<u32>(ch);
|
|
};
|
|
|
|
u32 hash = seed;
|
|
for (size_t i = 0; i < length; ++i) {
|
|
hash += to_lowercase(characters[i]);
|
|
hash += (hash << 10);
|
|
hash ^= (hash >> 6);
|
|
}
|
|
hash += hash << 3;
|
|
hash ^= hash >> 11;
|
|
hash += hash << 15;
|
|
return hash;
|
|
}
|
|
|
|
}
|
|
|
|
#if USING_AK_GLOBALLY
|
|
using AK::string_hash;
|
|
#endif
|