/**
* Copyright (C) 2014-2016 Open Whisper Systems
*
* Licensed according to the LICENSE file in this repository.
*/
package org.whispersystems.signalservice.api.messages;
import com.google.protobuf.ByteString;
import org.whispersystems.libsignal.InvalidVersionException;
import org.whispersystems.libsignal.logging.Log;
import org.whispersystems.libsignal.util.guava.Optional;
import org.whispersystems.signalservice.api.push.SignalServiceAddress;
import org.whispersystems.signalservice.api.util.UuidUtil;
import org.whispersystems.signalservice.internal.push.SignalServiceProtos.Envelope;
import org.whispersystems.signalservice.internal.util.Hex;
import org.whispersystems.util.Base64;
import java.io.IOException;
import java.security.InvalidAlgorithmParameterException;
import java.security.InvalidKeyException;
import java.security.NoSuchAlgorithmException;
import java.util.Arrays;
import javax.crypto.BadPaddingException;
import javax.crypto.Cipher;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.Mac;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;
/**
* This class represents an encrypted Signal Service envelope.
*
* The envelope contains the wrapping information, such as the sender, the
* message timestamp, the encrypted message type, etc.
*
* @author Moxie Marlinspike
*/
public class SignalServiceEnvelope {
private static final String TAG = SignalServiceEnvelope.class.getSimpleName();
private static final int SUPPORTED_VERSION = 1;
private static final int CIPHER_KEY_SIZE = 32;
private static final int MAC_KEY_SIZE = 20;
private static final int MAC_SIZE = 10;
private static final int VERSION_OFFSET = 0;
private static final int VERSION_LENGTH = 1;
private static final int IV_OFFSET = VERSION_OFFSET + VERSION_LENGTH;
private static final int IV_LENGTH = 16;
private static final int CIPHERTEXT_OFFSET = IV_OFFSET + IV_LENGTH;
private final Envelope envelope;
/**
* Construct an envelope from a serialized, Base64 encoded SignalServiceEnvelope, encrypted
* with a signaling key.
*
* @param message The serialized SignalServiceEnvelope, base64 encoded and encrypted.
* @param signalingKey The signaling key.
* @throws IOException
* @throws InvalidVersionException
*/
public SignalServiceEnvelope(String message, String signalingKey, boolean isSignalingKeyEncrypted)
throws IOException, InvalidVersionException
{
this(Base64.decode(message), signalingKey, isSignalingKeyEncrypted);
}
/**
* Construct an envelope from a serialized SignalServiceEnvelope, encrypted with a signaling key.
*
* @param input The serialized and (optionally) encrypted SignalServiceEnvelope.
* @param signalingKey The signaling key.
* @throws InvalidVersionException
* @throws IOException
*/
public SignalServiceEnvelope(byte[] input, String signalingKey, boolean isSignalingKeyEncrypted)
throws InvalidVersionException, IOException
{
if (!isSignalingKeyEncrypted) {
this.envelope = Envelope.parseFrom(input);
} else {
if (input.length < VERSION_LENGTH || input[VERSION_OFFSET] != SUPPORTED_VERSION) {
throw new InvalidVersionException("Unsupported version!");
}
SecretKeySpec cipherKey = getCipherKey(signalingKey);
SecretKeySpec macKey = getMacKey(signalingKey);
verifyMac(input, macKey);
this.envelope = Envelope.parseFrom(getPlaintext(input, cipherKey));
}
}
public SignalServiceEnvelope(int type, Optional<SignalServiceAddress> sender, int senderDevice, long timestamp, byte[] legacyMessage, byte[] content, long serverTimestamp, String uuid) {
Envelope.Builder builder = Envelope.newBuilder()
.setType(Envelope.Type.valueOf(type))
.setSourceDevice(senderDevice)
.setTimestamp(timestamp)
.setServerTimestamp(serverTimestamp);
if (sender.isPresent()) {
if (sender.get().getUuid().isPresent()) {
builder.setSourceUuid(sender.get().getUuid().get().toString());
}
if (sender.get().getNumber().isPresent()) {
builder.setSourceE164(sender.get().getNumber().get());
}
}
if (uuid != null) {
builder.setServerGuid(uuid);
}
if (legacyMessage != null) builder.setLegacyMessage(ByteString.copyFrom(legacyMessage));
if (content != null) builder.setContent(ByteString.copyFrom(content));
this.envelope = builder.build();
}
public SignalServiceEnvelope(int type, long timestamp, byte[] legacyMessage, byte[] content, long serverTimestamp, String uuid) {
Envelope.Builder builder = Envelope.newBuilder()
.setType(Envelope.Type.valueOf(type))
.setTimestamp(timestamp)
.setServerTimestamp(serverTimestamp);
if (uuid != null) {
builder.setServerGuid(uuid);
}
if (legacyMessage != null) builder.setLegacyMessage(ByteString.copyFrom(legacyMessage));
if (content != null) builder.setContent(ByteString.copyFrom(content));
this.envelope = builder.build();
}
public String getUuid() {
return envelope.getServerGuid();
}
public boolean hasUuid() {
return envelope.hasServerGuid();
}
/**
* @return True if either a source E164 or UUID is present.
*/
public boolean hasSource() {
return envelope.hasSourceE164() || envelope.hasSourceUuid();
}
/**
* @return The envelope's sender as an E164 number.
*/
public Optional<String> getSourceE164() {
return Optional.fromNullable(envelope.getSourceE164());
}
/**
* @return The envelope's sender as a UUID.
*/
public Optional<String> getSourceUuid() {
return Optional.fromNullable(envelope.getSourceUuid());
}
public String getSourceIdentifier() {
return getSourceUuid().or(getSourceE164()).orNull();
}
public boolean hasSourceDevice() {
return envelope.hasSourceDevice();
}
/**
* @return The envelope's sender device ID.
*/
public int getSourceDevice() {
return envelope.getSourceDevice();
}
/**
* @return The envelope's sender as a SignalServiceAddress.
*/
public SignalServiceAddress getSourceAddress() {
return new SignalServiceAddress(UuidUtil.parseOrNull(envelope.getSourceUuid()), envelope.getSourceE164());
}
/**
* @return The envelope content type.
*/
public int getType() {
return envelope.getType().getNumber();
}
/**
* @return The timestamp this envelope was sent.
*/
public long getTimestamp() {
return envelope.getTimestamp();
}
public long getServerTimestamp() {
return envelope.getServerTimestamp();
}
/**
* @return Whether the envelope contains a SignalServiceDataMessage
*/
public boolean hasLegacyMessage() {
return envelope.hasLegacyMessage();
}
/**
* @return The envelope's containing SignalService message.
*/
public byte[] getLegacyMessage() {
return envelope.getLegacyMessage().toByteArray();
}
/**
* @return Whether the envelope contains an encrypted SignalServiceContent
*/
public boolean hasContent() {
return envelope.hasContent();
}
/**
* @return The envelope's encrypted SignalServiceContent.
*/
public byte[] getContent() {
return envelope.getContent().toByteArray();
}
/**
* @return true if the containing message is a {@link org.whispersystems.libsignal.protocol.SignalMessage}
*/
public boolean isSignalMessage() {
return envelope.getType().getNumber() == Envelope.Type.CIPHERTEXT_VALUE;
}
/**
* @return true if the containing message is a {@link org.whispersystems.libsignal.protocol.PreKeySignalMessage}
*/
public boolean isPreKeySignalMessage() {
return envelope.getType().getNumber() == Envelope.Type.PREKEY_BUNDLE_VALUE;
}
/**
* @return true if the containing message is a delivery receipt.
*/
public boolean isReceipt() {
return envelope.getType().getNumber() == Envelope.Type.RECEIPT_VALUE;
}
public boolean isUnidentifiedSender() {
return envelope.getType().getNumber() == Envelope.Type.UNIDENTIFIED_SENDER_VALUE;
}
private byte[] getPlaintext(byte[] ciphertext, SecretKeySpec cipherKey) throws IOException {
try {
byte[] ivBytes = new byte[IV_LENGTH];
System.arraycopy(ciphertext, IV_OFFSET, ivBytes, 0, ivBytes.length);
IvParameterSpec iv = new IvParameterSpec(ivBytes);
Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
cipher.init(Cipher.DECRYPT_MODE, cipherKey, iv);
return cipher.doFinal(ciphertext, CIPHERTEXT_OFFSET,
ciphertext.length - VERSION_LENGTH - IV_LENGTH - MAC_SIZE);
} catch (NoSuchAlgorithmException | NoSuchPaddingException | InvalidKeyException | InvalidAlgorithmParameterException | IllegalBlockSizeException e) {
throw new AssertionError(e);
} catch (BadPaddingException e) {
Log.w(TAG, e);
throw new IOException("Bad padding?");
}
}
private void verifyMac(byte[] ciphertext, SecretKeySpec macKey) throws IOException {
try {
Mac mac = Mac.getInstance("HmacSHA256");
mac.init(macKey);
if (ciphertext.length < MAC_SIZE + 1)
throw new IOException("Invalid MAC!");
mac.update(ciphertext, 0, ciphertext.length - MAC_SIZE);
byte[] ourMacFull = mac.doFinal();
byte[] ourMacBytes = new byte[MAC_SIZE];
System.arraycopy(ourMacFull, 0, ourMacBytes, 0, ourMacBytes.length);
byte[] theirMacBytes = new byte[MAC_SIZE];
System.arraycopy(ciphertext, ciphertext.length-MAC_SIZE, theirMacBytes, 0, theirMacBytes.length);
Log.w(TAG, "Our MAC: " + Hex.toString(ourMacBytes));
Log.w(TAG, "Thr MAC: " + Hex.toString(theirMacBytes));
if (!Arrays.equals(ourMacBytes, theirMacBytes)) {
throw new IOException("Invalid MAC compare!");
}
} catch (NoSuchAlgorithmException | InvalidKeyException e) {
throw new AssertionError(e);
}
}
private SecretKeySpec getCipherKey(String signalingKey) throws IOException {
byte[] signalingKeyBytes = Base64.decode(signalingKey);
byte[] cipherKey = new byte[CIPHER_KEY_SIZE];
System.arraycopy(signalingKeyBytes, 0, cipherKey, 0, cipherKey.length);
return new SecretKeySpec(cipherKey, "AES");
}
private SecretKeySpec getMacKey(String signalingKey) throws IOException {
byte[] signalingKeyBytes = Base64.decode(signalingKey);
byte[] macKey = new byte[MAC_KEY_SIZE];
System.arraycopy(signalingKeyBytes, CIPHER_KEY_SIZE, macKey, 0, macKey.length);
return new SecretKeySpec(macKey, "HmacSHA256");
}
}
