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9ca52a4cbe
Replaces standalone `SipHashUint256` with an `operator()` overload in `PresaltedSipHasher`. Updates all hasher classes (`SaltedUint256Hasher`, `SaltedTxidHasher`, `SaltedWtxidHasher`) to use `PresaltedSipHasher` internally, enabling the same constant-state caching optimization while keeping behavior unchanged. Benchmark was also adjusted to cache the salting part.
66 lines
2.1 KiB
C++
66 lines
2.1 KiB
C++
// Copyright (c) 2016-present The Bitcoin Core developers
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// Distributed under the MIT software license, see the accompanying
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// file COPYING or http://www.opensource.org/licenses/mit-license.php.
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#ifndef BITCOIN_CRYPTO_SIPHASH_H
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#define BITCOIN_CRYPTO_SIPHASH_H
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#include <cstdint>
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#include <span>
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class uint256;
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/** SipHash-2-4 */
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class CSipHasher
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{
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private:
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uint64_t v[4];
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uint64_t tmp;
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uint8_t count; // Only the low 8 bits of the input size matter.
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public:
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static constexpr uint64_t C0{0x736f6d6570736575ULL};
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static constexpr uint64_t C1{0x646f72616e646f6dULL};
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static constexpr uint64_t C2{0x6c7967656e657261ULL};
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static constexpr uint64_t C3{0x7465646279746573ULL};
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/** Construct a SipHash calculator initialized with 128-bit key (k0, k1) */
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CSipHasher(uint64_t k0, uint64_t k1);
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/** Hash a 64-bit integer worth of data
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* It is treated as if this was the little-endian interpretation of 8 bytes.
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* This function can only be used when a multiple of 8 bytes have been written so far.
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*/
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CSipHasher& Write(uint64_t data);
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/** Hash arbitrary bytes. */
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CSipHasher& Write(std::span<const unsigned char> data);
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/** Compute the 64-bit SipHash-2-4 of the data written so far. The object remains untouched. */
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uint64_t Finalize() const;
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};
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/**
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* Optimized SipHash-2-4 implementation for uint256.
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*
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* This class caches the initial SipHash v[0..3] state derived from (k0, k1)
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* and implements a specialized hashing path for uint256 values, with or
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* without an extra 32-bit word. The internal state is immutable, so
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* PresaltedSipHasher instances can be reused for multiple hashes with the
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* same key.
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*/
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class PresaltedSipHasher
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{
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uint64_t v[4];
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public:
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explicit PresaltedSipHasher(uint64_t k0, uint64_t k1) noexcept {
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v[0] = CSipHasher::C0 ^ k0;
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v[1] = CSipHasher::C1 ^ k1;
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v[2] = CSipHasher::C2 ^ k0;
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v[3] = CSipHasher::C3 ^ k1;
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}
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uint64_t operator()(const uint256& val) const noexcept;
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uint64_t operator()(const uint256& val, uint32_t extra) const noexcept;
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};
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#endif // BITCOIN_CRYPTO_SIPHASH_H
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