src/test/java/org/apache/commons/crypto/examples/CipherByteBufferExample.java

 /*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF 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 org.apache.commons.crypto.examples;

import java.nio.ByteBuffer;
import java.nio.charset.StandardCharsets;
import java.util.Arrays;
import java.util.Properties;

import javax.crypto.Cipher;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;

import org.apache.commons.crypto.cipher.CryptoCipher;
import org.apache.commons.crypto.utils.AES;
import org.apache.commons.crypto.utils.Utils;

/**
 * Example showing the CryptoCipher API using a ByteBuffer
 */
public class CipherByteBufferExample {

    /**
     * Converts ByteBuffer to String
     *
     * @param buffer input byte buffer
     * @return the converted string
     */
    private static String asString(final ByteBuffer buffer) {
        final ByteBuffer copy = buffer.duplicate();
        final byte[] bytes = new byte[copy.remaining()];
        copy.get(bytes);
        return new String(bytes, StandardCharsets.UTF_8);
    }

    /**
     * Converts String to UTF8 bytes
     *
     * @param input the input string
     * @return UTF8 bytes
     */
    private static byte[] getUTF8Bytes(final String input) {
        return input.getBytes(StandardCharsets.UTF_8);
    }

    public static void main(final String[] args) throws Exception {
        final SecretKeySpec key = AES.newSecretKeySpec(getUTF8Bytes("1234567890123456"));
        final IvParameterSpec iv = new IvParameterSpec(getUTF8Bytes("1234567890123456"));
        final Properties properties = new Properties();
        //Creates a CryptoCipher instance with the transformation and properties.
        final String transform = AES.CBC_PKCS5_PADDING;
        final ByteBuffer outBuffer;
        final int bufferSize = 1024;
        final int updateBytes;
        final int finalBytes;
        try (CryptoCipher encipher = Utils.getCipherInstance(transform, properties)) {

            final ByteBuffer inBuffer = ByteBuffer.allocateDirect(bufferSize);
            outBuffer = ByteBuffer.allocateDirect(bufferSize);
            inBuffer.put(getUTF8Bytes("hello world!"));

            inBuffer.flip(); // ready for the cipher to read it
            // Show the data is there
            System.out.println("inBuffer=" + asString(inBuffer));

            // Initializes the cipher with ENCRYPT_MODE, key and iv.
            encipher.init(Cipher.ENCRYPT_MODE, key, iv);
            // Continues a multiple-part encryption/decryption operation for byte buffer.
            updateBytes = encipher.update(inBuffer, outBuffer);
            System.out.println(updateBytes);

            // We should call do final at the end of encryption/decryption.
            finalBytes = encipher.doFinal(inBuffer, outBuffer);
            System.out.println(finalBytes);
        }

        outBuffer.flip(); // ready for use as decrypt
        final byte [] encoded = new byte[updateBytes + finalBytes];
        outBuffer.duplicate().get(encoded);
        System.out.println(Arrays.toString(encoded));

        // Now reverse the process
        try (CryptoCipher decipher = Utils.getCipherInstance(transform, properties)) {
            decipher.init(Cipher.DECRYPT_MODE, key, iv);
            final ByteBuffer decoded = ByteBuffer.allocateDirect(bufferSize);
            decipher.update(outBuffer, decoded);
            decipher.doFinal(outBuffer, decoded);
            decoded.flip(); // ready for use
            System.out.println("decoded="+asString(decoded));
        }
    }

}