Android Open Source - conceal Bouncy Castle Helper

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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...

Java Source Code

/*
 *  Copyright (c) 2014, Facebook, Inc./*ww  w.  jav a 2 s  . c om*/
 *  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;

import java.io.UnsupportedEncodingException;
import java.util.Arrays;

import android.annotation.TargetApi;
import android.os.Build;

import com.facebook.crypto.cipher.NativeGCMCipher;

import org.spongycastle.crypto.InvalidCipherTextException;
import org.spongycastle.crypto.engines.AESEngine;
import org.spongycastle.crypto.modes.GCMBlockCipher;
import org.spongycastle.crypto.params.AEADParameters;
import org.spongycastle.crypto.params.KeyParameter;

@TargetApi(Build.VERSION_CODES.GINGERBREAD)
public class BouncyCastleHelper {

  public static Result bouncyCastleEncrypt(byte[] data, byte[] key, byte[] iv, byte[] aadData)
      throws UnsupportedEncodingException, InvalidCipherTextException {
    GCMBlockCipher gcm = new GCMBlockCipher(new AESEngine());
    byte[] gcmOut = new byte[CryptoTestUtils.NUM_DATA_BYTES + NativeGCMCipher.TAG_LENGTH];
    KeyParameter keyParameter = new KeyParameter(key);

    // Add aad data.
    AEADParameters params = new AEADParameters(
          keyParameter,
          NativeGCMCipher.TAG_LENGTH * 8,
          iv,
          aadData);

    // Init encryption.
    gcm.init(true, params);
    int written = gcm.processBytes(data, 0, data.length, gcmOut, 0);
    written += gcm.doFinal(gcmOut, written);

    byte[] bouncyCastleOut = Arrays.copyOfRange(gcmOut, 0, written);
    byte[] cipherText =
        Arrays.copyOfRange(bouncyCastleOut, 0, CryptoTestUtils.NUM_DATA_BYTES);
    byte[] tag =
        Arrays.copyOfRange(bouncyCastleOut, CryptoTestUtils.NUM_DATA_BYTES, bouncyCastleOut.length);
    return new Result(cipherText, tag);
  }

  public static class Result {

    public final byte[] cipherText;
    public final byte[] tag;

    public Result(byte[] cipherText, byte[] tag) {
      this.cipherText = cipherText;
      this.tag = tag;
    }
  }
}

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