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Commons library for easy and safe encryption/decryption
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/*
 * Copyright 2014 Michael Bock
 * 
 * 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
 *
 *      http://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 de.mibos.commons.crypt;

import javax.annotation.Nonnull;
import javax.crypto.Cipher;
import javax.crypto.CipherInputStream;
import java.io.ByteArrayInputStream;
import java.io.FilterInputStream;
import java.io.InputStream;
import java.io.SequenceInputStream;

/**
 * An input stream for the specified {@link Crypt} which encrypts a plaintext input stream.

 * This is simply an extension to the standard {@link javax.crypto.CipherInputStream}, which additionally
 * provides the initialization vector as first input.

 *
 * @author Michael Bock
 * @version 1.5
 * @since 1.5
 * $Id: PlainInputStream.java 88 2014-12-05 00:00:29Z michaels-apps $
 */
public class PlainInputStream extends FilterInputStream {

    /**
     * An input stream for the specified {@link Crypt} which encrypts a plaintext input stream.

     * This is simply an extension to the standard {@link javax.crypto.CipherInputStream}, which additionally
     * provides the initialization vector as first input.

     *
     * @param crypt    the used {@link Crypt} object
     * @param input    the cipher input stream
     * @param password the password
     * @throws de.mibos.commons.crypt.CryptoInitializationProblem in case of a {@link CryptoInitializationProblem} problem
     */
    public PlainInputStream(@Nonnull final Crypt crypt, @Nonnull final InputStream input, @Nonnull final CharSequence password) {
        //noinspection ConstantConditions
        super(null);
        final byte[] passwordBytes = crypt.getHashedEncryptionKey(password);
        initCipher(crypt, input, passwordBytes);
        crypt.resetPasswordBytes(passwordBytes);
    }

    /**
     * An input stream for the specified {@link Crypt} which encrypts a plaintext input stream.

     * This is simply an extension to the standard {@link javax.crypto.CipherInputStream}, which additionally
     * provides the initialization vector as first input.

     *
     * @param crypt         the used {@link Crypt} object
     * @param input         the cipher input stream
     * @param passwordBytes the password bytes
     * @throws de.mibos.commons.crypt.CryptoInitializationProblem in case of a {@link CryptoInitializationProblem} problem
     */
    public PlainInputStream(@Nonnull final Crypt crypt, @Nonnull final InputStream input, @Nonnull final byte[] passwordBytes) {
        //noinspection ConstantConditions
        super(null);
        initCipher(crypt, input, passwordBytes);
    }

    /**
     * Initializes the underlying {@link javax.crypto.CipherInputStream}
     *
     * @param crypt         the used {@link Crypt} object
     * @param input         the cipher input stream
     * @param passwordBytes the password bytes
     * @throws de.mibos.commons.crypt.CryptoInitializationProblem in case of a {@link CryptoInitializationProblem} problem
     */
    private void initCipher(@Nonnull Crypt crypt, @Nonnull InputStream input, @Nonnull byte[] passwordBytes) {
        final Cipher cipher = crypt.getEncryptionCipher(passwordBytes);
        final byte[] iv = cipher.getIV();
        final ByteArrayInputStream ivInputStream = new ByteArrayInputStream(iv);
        this.in = new SequenceInputStream(ivInputStream, new CipherInputStream(input, cipher));
    }
}