SipHash.java — netty Source File

Source Code

/*
 * Copyright 2025 The Netty Project
 *
 * The Netty Project licenses this file to you under the Apache License,
 * version 2.0 (the "License"); you may not use this file except in compliance
 * with the License. You may obtain a copy of the License at:
 *
 *   https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations
 * under the License.
 */
package io.netty.handler.codec.quic;

import io.netty.util.internal.ObjectUtil;

import java.nio.ByteBuffer;
import java.nio.ByteOrder;

/**
 * <a href="https://www.aumasson.jp/siphash/siphash.pdf">Siphash implementation</a>.
 */
final class SipHash {

    static final int SEED_LENGTH = 16;

    // Make this class allocation free as soon as its constructed.
    private final int compressionRounds;
    private final int finalizationRounds;

    // As specified in https://www.aumasson.jp/siphash/siphash.pdf
    private static final long INITIAL_STATE_V0 = 0x736f6d6570736575L; // "somepseu"
    private static final long INITIAL_STATE_V1 = 0x646f72616e646f6dL; // "dorandom"
    private static final long INITIAL_STATE_V2 = 0x6c7967656e657261L; // "lygenera"
    private static final long INITIAL_STATE_V3 = 0x7465646279746573L;  // "tedbytes"

    private final long initialStateV0;
    private final long initialStateV1;
    private final long initialStateV2;
    private final long initialStateV3;

    private long v0;
    private long v1;
    private long v2;
    private long v3;

    SipHash(int compressionRounds, int finalizationRounds, byte[] seed) {
        if (seed.length != SEED_LENGTH) {
            throw new IllegalArgumentException("seed must be of length " + SEED_LENGTH);
        }
        this.compressionRounds = ObjectUtil.checkPositive(compressionRounds, "compressionRounds");
        this.finalizationRounds = ObjectUtil.checkPositive(finalizationRounds, "finalizationRounds");

        // Wrap the seed to extract two longs that will be used to generate the initial state.
        // Use little-endian as in the paper.
        ByteBuffer keyBuffer = ByteBuffer.wrap(seed).order(ByteOrder.LITTLE_ENDIAN);
        final long k0 = keyBuffer.getLong();
// ... (91 more lines)