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A set of utilities for Java

There is a newer version: 3.0.0

package org.rx.net.shadowsocks.encryption.impl;

import io.netty.buffer.ByteBuf;
import lombok.SneakyThrows;
import org.bouncycastle.crypto.StreamCipher;
import org.bouncycastle.crypto.engines.ChaCha7539Engine;
import org.bouncycastle.crypto.engines.ChaChaEngine;
import org.rx.net.shadowsocks.encryption.CryptoSteamBase;

import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;
import java.security.InvalidAlgorithmParameterException;

public class ChaCha20Crypto extends CryptoSteamBase {
    public final static String CIPHER_CHACHA20 = "chacha20";
    public final static String CIPHER_CHACHA20_IETF = "chacha20-ietf";

    public ChaCha20Crypto(String name, String password) {
        super(name, password);
    }

    @Override
    public int getIVLength() {
        if (_name.equals(CIPHER_CHACHA20)) {
            return 8;
        } else if (_name.equals(CIPHER_CHACHA20_IETF)) {
            return 12;
        }
        return 0;
    }

    @Override
    public int getKeyLength() {
        if (_name.equals(CIPHER_CHACHA20) || _name.equals(CIPHER_CHACHA20_IETF)) {
            return 32;
        }
        return 0;
    }

    @Override
    protected SecretKey getKey() {
        return new SecretKeySpec(_ssKey.getEncoded(), "AES");
    }

    @SneakyThrows
    @Override
    protected StreamCipher getCipher(boolean isEncrypted) {
        if (_name.equals(CIPHER_CHACHA20)) {
            return new ChaChaEngine();
        } else if (_name.equals(CIPHER_CHACHA20_IETF)) {
            return new ChaCha7539Engine();
        }
        throw new InvalidAlgorithmParameterException(_name);
    }

    @Override
    protected void _encrypt(byte[] data, ByteBuf stream) {
        byte[] buffer = new byte[data.length];
        int noBytesProcessed = encCipher.processBytes(data, 0, data.length, buffer, 0);
        stream.writeBytes(buffer, 0, noBytesProcessed);
    }

    @Override
    protected void _decrypt(byte[] data, ByteBuf stream) {
        byte[] buffer = new byte[data.length];
        int BytesProcessedNum = decCipher.processBytes(data, 0, data.length, buffer, 0);
        stream.writeBytes(buffer, 0, BytesProcessedNum);
    }
}