Android Open Source - conceal Native G C M Cipher Output Stream

From Project

Back to project page conceal.

License

The source code is released under:

BSD License For Conceal software Copyright (c) 2014, Facebook, Inc. All rights reserved. Redistribution and use in source and binary forms, with or without modification, are permitted provided that...

If you think the Android project conceal listed in this page is inappropriate, such as containing malicious code/tools or violating the copyright, please email info at java2s dot com, thanks.

Java Source Code

/*
 *  Copyright (c) 2014, Facebook, Inc./*from ww  w .ja  va  2 s.  c o  m*/
 *  All rights reserved.
 *
 *  This source code is licensed under the BSD-style license found in the
 *  LICENSE file in the root directory of this source tree. An additional grant
 *  of patent rights can be found in the PATENTS file in the same directory.
 *
 */

package com.facebook.crypto.streams;

import com.facebook.crypto.cipher.NativeGCMCipher;

import java.io.IOException;
import java.io.OutputStream;
import java.lang.ArrayIndexOutOfBoundsException;

/**
 * This class is used to encapsulate encryption using GCM. On writes, bytes are first encrypted
 * before actually being written out to the delegate stream.
 */
public class NativeGCMCipherOutputStream extends OutputStream {

  private static final int UPDATE_BUFFER_SIZE = 256;

  private final OutputStream mCipherDelegate;
  private final NativeGCMCipher mCipher;
  private final byte[] mUpdateBuffer;
  private final byte[] mTag = new byte[NativeGCMCipher.TAG_LENGTH];

  /**
   * Creates a new output stream to write to.
   *
   * @param cipherDelegate The stream to write encrypted bytes to.
   * @param cipher The cipher used to encrypt the bytes.
   */
  public NativeGCMCipherOutputStream(OutputStream cipherDelegate,
      NativeGCMCipher cipher) {
    mCipherDelegate = cipherDelegate;
    mCipher = cipher;
    mUpdateBuffer = new byte[UPDATE_BUFFER_SIZE + mCipher.getCipherBlockSize()];
  }

  @Override
  public void close() throws IOException {
    try {
      mCipher.encryptFinal(mTag, mTag.length);
      mCipherDelegate.write(mTag);
    } finally {
      try {
        mCipher.destroy();
      } finally {
        mCipherDelegate.close();
      }
    }
  }

  @Override
  public void flush() throws IOException {
    mCipherDelegate.flush();
  }

  @Override
  public void write(byte[] buffer) throws IOException {
    write(buffer, 0, buffer.length);
  }

  @Override
  public void write(byte[] buffer, int offset, int count)
      throws IOException {
    if (buffer.length < offset + count) {
      throw new ArrayIndexOutOfBoundsException(offset + count);
    }

    int times = count / UPDATE_BUFFER_SIZE;
    int remainder = count % UPDATE_BUFFER_SIZE;

    for (int i = 0; i < times; ++i) {
      int written = mCipher.update(buffer, offset, UPDATE_BUFFER_SIZE, mUpdateBuffer);
      mCipherDelegate.write(mUpdateBuffer, 0, written);
      offset += UPDATE_BUFFER_SIZE;
    }

    if (remainder > 0) {
      int written = mCipher.update(buffer, offset, remainder, mUpdateBuffer);
      mCipherDelegate.write(mUpdateBuffer, 0, written);
    }
  }

  @Override
  public void write(int oneByte) throws IOException {
    byte[] data = new byte[1];
    data[0] = (byte) oneByte;
    write(data, 0, 1);
  }
}

Java Source Code List