123 lines
3.6 KiB
Java
123 lines
3.6 KiB
Java
/**
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* Copyright (C) 2011 Whisper Systems
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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package org.thoughtcrime.securesms.crypto;
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import java.io.File;
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import java.io.FileNotFoundException;
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import java.io.FileOutputStream;
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import java.io.IOException;
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import java.security.InvalidKeyException;
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import java.security.NoSuchAlgorithmException;
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import javax.crypto.BadPaddingException;
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import javax.crypto.Cipher;
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import javax.crypto.IllegalBlockSizeException;
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import javax.crypto.Mac;
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import javax.crypto.NoSuchPaddingException;
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import javax.crypto.spec.SecretKeySpec;
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import android.util.Log;
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/**
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* A class for streaming an encrypted MMS "part" to disk.
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*
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* @author Moxie Marlinspike
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*/
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public class EncryptingPartOutputStream extends FileOutputStream {
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private Cipher cipher;
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private Mac mac;
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private boolean closed;
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public EncryptingPartOutputStream(File file, MasterSecret masterSecret) throws FileNotFoundException {
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super(file);
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try {
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mac = initializeMac(masterSecret.getMacKey());
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cipher = initializeCipher(mac, masterSecret.getEncryptionKey());
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closed = false;
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} catch (IOException ioe) {
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Log.w("EncryptingPartOutputStream", ioe);
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throw new FileNotFoundException("Couldn't write IV");
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} catch (InvalidKeyException e) {
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throw new AssertionError(e);
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} catch (NoSuchAlgorithmException e) {
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throw new AssertionError(e);
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} catch (NoSuchPaddingException e) {
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throw new AssertionError(e);
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}
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}
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@Override
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public void write(byte[] buffer) throws IOException {
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this.write(buffer, 0, buffer.length);
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}
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@Override
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public void write(byte[] buffer, int offset, int length) throws IOException {
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byte[] encryptedBuffer = cipher.update(buffer, offset, length);
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if (encryptedBuffer != null) {
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mac.update(encryptedBuffer);
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super.write(encryptedBuffer, 0, encryptedBuffer.length);
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}
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}
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@Override
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public void close() throws IOException {
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try {
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if (!closed) {
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byte[] encryptedRemainder = cipher.doFinal();
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mac.update(encryptedRemainder);
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byte[] macBytes = mac.doFinal();
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super.write(encryptedRemainder, 0, encryptedRemainder.length);
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super.write(macBytes, 0, macBytes.length);
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closed = true;
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}
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super.close();
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} catch (BadPaddingException bpe) {
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throw new AssertionError(bpe);
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} catch (IllegalBlockSizeException e) {
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throw new AssertionError(e);
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}
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}
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private Mac initializeMac(SecretKeySpec key) throws NoSuchAlgorithmException, InvalidKeyException {
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Mac hmac = Mac.getInstance("HmacSHA1");
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hmac.init(key);
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return hmac;
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}
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private Cipher initializeCipher(Mac mac, SecretKeySpec key) throws IOException, InvalidKeyException, NoSuchAlgorithmException, NoSuchPaddingException {
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Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
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cipher.init(Cipher.ENCRYPT_MODE, key);
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byte[] ivBytes = cipher.getIV();
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mac.update(ivBytes);
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super.write(ivBytes, 0, ivBytes.length);
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return cipher;
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}
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}
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