adding prekey='true' to omemo messages if applicable

2 files changed, 29 insertions, 11 deletions

diff --git a/src/main/java/eu/siacs/conversations/crypto/axolotl/XmppAxolotlMessage.java b/src/main/java/eu/siacs/conversations/crypto/axolotl/XmppAxolotlMessage.java
index 3fcd0fcf..2d6bba55 100644
--- a/src/main/java/eu/siacs/conversations/crypto/axolotl/XmppAxolotlMessage.java
+++ b/src/main/java/eu/siacs/conversations/crypto/axolotl/XmppAxolotlMessage.java
@@ -3,6 +3,8 @@ package eu.siacs.conversations.crypto.axolotl;
 import android.util.Base64;
 import android.util.Log;
 
+import org.whispersystems.libaxolotl.protocol.CiphertextMessage;
+
 import java.security.InvalidAlgorithmParameterException;
 import java.security.InvalidKeyException;
 import java.security.NoSuchAlgorithmException;
@@ -41,7 +43,7 @@ public class XmppAxolotlMessage {
 	private byte[] innerKey;
 	private byte[] ciphertext = null;
 	private byte[] iv = null;
-	private final Map<Integer, byte[]> keys;
+	private final Map<Integer, XmppAxolotlSession.AxolotlKey> keys;
 	private final Jid from;
 	private final int sourceDeviceId;
 
@@ -104,7 +106,8 @@ public class XmppAxolotlMessage {
 					try {
 						Integer recipientId = Integer.parseInt(keyElement.getAttribute(REMOTEID));
 						byte[] key = Base64.decode(keyElement.getContent().trim(), Base64.DEFAULT);
-						this.keys.put(recipientId, key);
+						boolean isPreKey =keyElement.getAttributeAsBoolean("prekey");
+						this.keys.put(recipientId, new XmppAxolotlSession.AxolotlKey(key,isPreKey));
 					} catch (NumberFormatException e) {
 						throw new IllegalArgumentException("invalid remote id");
 					}
@@ -199,7 +202,7 @@ public class XmppAxolotlMessage {
 	}
 
 	public void addDevice(XmppAxolotlSession session) {
-		byte[] key = session.processSending(innerKey);
+		XmppAxolotlSession.AxolotlKey key = session.processSending(innerKey);
 		if (key != null) {
 			keys.put(session.getRemoteAddress().getDeviceId(), key);
 		}
@@ -217,10 +220,13 @@ public class XmppAxolotlMessage {
 		Element encryptionElement = new Element(CONTAINERTAG, AxolotlService.PEP_PREFIX);
 		Element headerElement = encryptionElement.addChild(HEADER);
 		headerElement.setAttribute(SOURCEID, sourceDeviceId);
-		for (Map.Entry<Integer, byte[]> keyEntry : keys.entrySet()) {
+		for (Map.Entry<Integer, XmppAxolotlSession.AxolotlKey> keyEntry : keys.entrySet()) {
 			Element keyElement = new Element(KEYTAG);
 			keyElement.setAttribute(REMOTEID, keyEntry.getKey());
-			keyElement.setContent(Base64.encodeToString(keyEntry.getValue(), Base64.NO_WRAP));
+			if (keyEntry.getValue().prekey) {
+				keyElement.setAttribute("prekey","true");
+			}
+			keyElement.setContent(Base64.encodeToString(keyEntry.getValue().key, Base64.NO_WRAP));
 			headerElement.addChild(keyElement);
 		}
 		headerElement.addChild(IVTAG).setContent(Base64.encodeToString(iv, Base64.NO_WRAP));
@@ -232,7 +238,7 @@ public class XmppAxolotlMessage {
 	}
 
 	private byte[] unpackKey(XmppAxolotlSession session, Integer sourceDeviceId) {
-		byte[] encryptedKey = keys.get(sourceDeviceId);
+		XmppAxolotlSession.AxolotlKey encryptedKey = keys.get(sourceDeviceId);
 		return (encryptedKey != null) ? session.processReceiving(encryptedKey) : null;
 	}
 
diff --git a/src/main/java/eu/siacs/conversations/crypto/axolotl/XmppAxolotlSession.java b/src/main/java/eu/siacs/conversations/crypto/axolotl/XmppAxolotlSession.java
index 725757a3..773b6857 100644
--- a/src/main/java/eu/siacs/conversations/crypto/axolotl/XmppAxolotlSession.java
+++ b/src/main/java/eu/siacs/conversations/crypto/axolotl/XmppAxolotlSession.java
@@ -82,13 +82,13 @@ public class XmppAxolotlSession implements Comparable<XmppAxolotlSession> {
 	}
 
 	@Nullable
-	public byte[] processReceiving(byte[] encryptedKey) {
+	public byte[] processReceiving(AxolotlKey encryptedKey) {
 		byte[] plaintext = null;
 		FingerprintStatus status = getTrust();
 		if (!status.isCompromised()) {
 			try {
 				try {
-					PreKeyWhisperMessage message = new PreKeyWhisperMessage(encryptedKey);
+					PreKeyWhisperMessage message = new PreKeyWhisperMessage(encryptedKey.key);
 					if (!message.getPreKeyId().isPresent()) {
 						Log.w(Config.LOGTAG, AxolotlService.getLogprefix(account) + "PreKeyWhisperMessage did not contain a PreKeyId");
 						return null;
@@ -104,7 +104,7 @@ public class XmppAxolotlSession implements Comparable<XmppAxolotlSession> {
 					}
 				} catch (InvalidMessageException | InvalidVersionException e) {
 					Log.i(Config.LOGTAG, AxolotlService.getLogprefix(account) + "WhisperMessage received");
-					WhisperMessage message = new WhisperMessage(encryptedKey);
+					WhisperMessage message = new WhisperMessage(encryptedKey.key);
 					plaintext = cipher.decrypt(message);
 				} catch (InvalidKeyException | InvalidKeyIdException | UntrustedIdentityException e) {
 					Log.w(Config.LOGTAG, AxolotlService.getLogprefix(account) + "Error decrypting axolotl header, " + e.getClass().getName() + ": " + e.getMessage());
@@ -123,11 +123,11 @@ public class XmppAxolotlSession implements Comparable<XmppAxolotlSession> {
 	}
 
 	@Nullable
-	public byte[] processSending(@NonNull byte[] outgoingMessage) {
+	public AxolotlKey processSending(@NonNull byte[] outgoingMessage) {
 		FingerprintStatus status = getTrust();
 		if (status.isTrustedAndActive()) {
 			CiphertextMessage ciphertextMessage = cipher.encrypt(outgoingMessage);
-			return ciphertextMessage.serialize();
+			return new AxolotlKey(ciphertextMessage.serialize(),ciphertextMessage.getType() == CiphertextMessage.PREKEY_TYPE);
 		} else {
 			return null;
 		}
@@ -141,4 +141,16 @@ public class XmppAxolotlSession implements Comparable<XmppAxolotlSession> {
 	public int compareTo(XmppAxolotlSession o) {
 		return getTrust().compareTo(o.getTrust());
 	}
+
+	public static class AxolotlKey {
+
+
+		public final byte[] key;
+		public final boolean prekey;
+
+		public AxolotlKey(byte[] key, boolean prekey) {
+			this.key = key;
+			this.prekey = prekey;
+		}
+	}
 }