194 lines
6.8 KiB
Java
194 lines
6.8 KiB
Java
/**
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* Copyright (C) 2014 Open 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.whispersystems.textsecure.api.messages;
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import android.util.Log;
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import com.google.protobuf.ByteString;
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import org.whispersystems.libaxolotl.InvalidVersionException;
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import org.whispersystems.textsecure.internal.push.PushMessageProtos.IncomingPushMessageSignal;
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import org.whispersystems.textsecure.internal.util.Base64;
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import org.whispersystems.textsecure.internal.util.Hex;
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import java.io.IOException;
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import java.security.InvalidAlgorithmParameterException;
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import java.security.InvalidKeyException;
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import java.security.NoSuchAlgorithmException;
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import java.util.Arrays;
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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.IvParameterSpec;
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import javax.crypto.spec.SecretKeySpec;
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public class TextSecureEnvelope {
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private static final String TAG = TextSecureEnvelope.class.getSimpleName();
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private static final int SUPPORTED_VERSION = 1;
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private static final int CIPHER_KEY_SIZE = 32;
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private static final int MAC_KEY_SIZE = 20;
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private static final int MAC_SIZE = 10;
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private static final int VERSION_OFFSET = 0;
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private static final int VERSION_LENGTH = 1;
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private static final int IV_OFFSET = VERSION_OFFSET + VERSION_LENGTH;
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private static final int IV_LENGTH = 16;
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private static final int CIPHERTEXT_OFFSET = IV_OFFSET + IV_LENGTH;
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private final IncomingPushMessageSignal signal;
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public TextSecureEnvelope(String message, String signalingKey)
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throws IOException, InvalidVersionException
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{
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byte[] ciphertext = Base64.decode(message);
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if (ciphertext.length < VERSION_LENGTH || ciphertext[VERSION_OFFSET] != SUPPORTED_VERSION)
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throw new InvalidVersionException("Unsupported version!");
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SecretKeySpec cipherKey = getCipherKey(signalingKey);
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SecretKeySpec macKey = getMacKey(signalingKey);
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verifyMac(ciphertext, macKey);
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this.signal = IncomingPushMessageSignal.parseFrom(getPlaintext(ciphertext, cipherKey));
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}
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public TextSecureEnvelope(int type, String source, int sourceDevice,
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String relay, long timestamp, byte[] message)
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{
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this.signal = IncomingPushMessageSignal.newBuilder()
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.setType(IncomingPushMessageSignal.Type.valueOf(type))
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.setSource(source)
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.setSourceDevice(sourceDevice)
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.setRelay(relay)
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.setTimestamp(timestamp)
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.setMessage(ByteString.copyFrom(message))
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.build();
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}
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public String getSource() {
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return signal.getSource();
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}
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public int getSourceDevice() {
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return signal.getSourceDevice();
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}
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public int getType() {
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return signal.getType().getNumber();
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}
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public String getRelay() {
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return signal.getRelay();
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}
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public long getTimestamp() {
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return signal.getTimestamp();
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}
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public byte[] getMessage() {
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return signal.getMessage().toByteArray();
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}
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public boolean isWhisperMessage() {
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return signal.getType().getNumber() == IncomingPushMessageSignal.Type.CIPHERTEXT_VALUE;
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}
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public boolean isPreKeyWhisperMessage() {
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return signal.getType().getNumber() == IncomingPushMessageSignal.Type.PREKEY_BUNDLE_VALUE;
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}
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public boolean isPlaintext() {
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return signal.getType().getNumber() == IncomingPushMessageSignal.Type.PLAINTEXT_VALUE;
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}
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public boolean isReceipt() {
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return signal.getType().getNumber() == IncomingPushMessageSignal.Type.RECEIPT_VALUE;
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}
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private byte[] getPlaintext(byte[] ciphertext, SecretKeySpec cipherKey) throws IOException {
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try {
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byte[] ivBytes = new byte[IV_LENGTH];
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System.arraycopy(ciphertext, IV_OFFSET, ivBytes, 0, ivBytes.length);
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IvParameterSpec iv = new IvParameterSpec(ivBytes);
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Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
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cipher.init(Cipher.DECRYPT_MODE, cipherKey, iv);
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return cipher.doFinal(ciphertext, CIPHERTEXT_OFFSET,
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ciphertext.length - VERSION_LENGTH - IV_LENGTH - MAC_SIZE);
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} catch (NoSuchAlgorithmException | NoSuchPaddingException | InvalidKeyException | InvalidAlgorithmParameterException | IllegalBlockSizeException e) {
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throw new AssertionError(e);
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} catch (BadPaddingException e) {
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Log.w(TAG, e);
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throw new IOException("Bad padding?");
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}
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}
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private void verifyMac(byte[] ciphertext, SecretKeySpec macKey) throws IOException {
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try {
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Mac mac = Mac.getInstance("HmacSHA256");
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mac.init(macKey);
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if (ciphertext.length < MAC_SIZE + 1)
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throw new IOException("Invalid MAC!");
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mac.update(ciphertext, 0, ciphertext.length - MAC_SIZE);
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byte[] ourMacFull = mac.doFinal();
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byte[] ourMacBytes = new byte[MAC_SIZE];
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System.arraycopy(ourMacFull, 0, ourMacBytes, 0, ourMacBytes.length);
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byte[] theirMacBytes = new byte[MAC_SIZE];
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System.arraycopy(ciphertext, ciphertext.length-MAC_SIZE, theirMacBytes, 0, theirMacBytes.length);
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Log.w(TAG, "Our MAC: " + Hex.toString(ourMacBytes));
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Log.w(TAG, "Thr MAC: " + Hex.toString(theirMacBytes));
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if (!Arrays.equals(ourMacBytes, theirMacBytes)) {
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throw new IOException("Invalid MAC compare!");
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}
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} catch (NoSuchAlgorithmException | InvalidKeyException e) {
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throw new AssertionError(e);
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}
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}
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private SecretKeySpec getCipherKey(String signalingKey) throws IOException {
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byte[] signalingKeyBytes = Base64.decode(signalingKey);
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byte[] cipherKey = new byte[CIPHER_KEY_SIZE];
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System.arraycopy(signalingKeyBytes, 0, cipherKey, 0, cipherKey.length);
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return new SecretKeySpec(cipherKey, "AES");
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}
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private SecretKeySpec getMacKey(String signalingKey) throws IOException {
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byte[] signalingKeyBytes = Base64.decode(signalingKey);
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byte[] macKey = new byte[MAC_KEY_SIZE];
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System.arraycopy(signalingKeyBytes, CIPHER_KEY_SIZE, macKey, 0, macKey.length);
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return new SecretKeySpec(macKey, "HmacSHA256");
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}
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}
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