AesCodec.java

package com.ingotpowered.net.codec;

import io.netty.buffer.ByteBuf;
import io.netty.channel.ChannelHandlerContext;
import io.netty.handler.codec.ByteToMessageCodec;
import org.bouncycastle.crypto.BufferedBlockCipher;
import org.bouncycastle.crypto.engines.AESFastEngine;
import org.bouncycastle.crypto.modes.CFBBlockCipher;
import org.bouncycastle.crypto.params.KeyParameter;
import org.bouncycastle.crypto.params.ParametersWithIV;

import java.util.List;

public class AesCodec extends ByteToMessageCodec<ByteBuf> {

    private static final int bufferSize = 1024;

    private BufferedBlockCipher aesCipherDecoder = new BufferedBlockCipher(new CFBBlockCipher(new AESFastEngine(), 8));
    private BufferedBlockCipher aesCipherEncoder = new BufferedBlockCipher(new CFBBlockCipher(new AESFastEngine(), 8));
    private byte[] decoderIn;
    private byte[] decoderOut;
    private byte[] encoderIn;
    private byte[] encoderOut;

    public AesCodec(byte[] iv) {
        this.aesCipherDecoder.init(false, new ParametersWithIV(new KeyParameter(iv), iv, 0, 16));
        this.aesCipherEncoder.init(true, new ParametersWithIV(new KeyParameter(iv), iv, 0, 16));
        this.decoderIn = new byte[bufferSize];
        this.decoderOut = new byte[this.aesCipherDecoder.getOutputSize(bufferSize)];
        this.encoderIn = new byte[bufferSize];
        this.encoderOut = new byte[this.aesCipherEncoder.getOutputSize(bufferSize)];
    }

    protected void decode(ChannelHandlerContext context, ByteBuf in, List<Object> out) {
        ByteBuf buffer = context.alloc().buffer(this.aesCipherDecoder.getOutputSize(in.readableBytes()));
        int read;
        while (in.isReadable()) {
            if (in.readableBytes() > bufferSize) {
                read = bufferSize;
            } else {
                read = in.readableBytes();
            }
            in.readBytes(this.decoderIn, 0, read);
            read = this.aesCipherDecoder.processBytes(this.decoderIn, 0, read, this.decoderOut, 0);
            buffer.writeBytes(this.decoderOut, 0, read);
        }
        out.add(buffer);
    }

    protected void encode(ChannelHandlerContext context, ByteBuf in, ByteBuf out) throws Exception {
        int read;
        while (in.isReadable()) {
            if (in.readableBytes() > bufferSize) {
                read = bufferSize;
            } else {
                read = in.readableBytes();
            }
            in.readBytes(this.encoderIn, 0, read);
            read = this.aesCipherEncoder.processBytes(this.encoderIn, 0, read, this.encoderOut, 0);
            out.writeBytes(this.encoderOut, 0, read);
        }
    }
}