Make it possible to deserialize SenderKeyDistributionMessages

1 files changed, 46 insertions, 6 deletions

diff --git a/java/src/main/java/org/whispersystems/libaxolotl/protocol/SenderKeyDistributionMessage.java b/java/src/main/java/org/whispersystems/libaxolotl/protocol/SenderKeyDistributionMessage.java
index 424dd87c..35f9e218 100644
--- a/java/src/main/java/org/whispersystems/libaxolotl/protocol/SenderKeyDistributionMessage.java
+++ b/java/src/main/java/org/whispersystems/libaxolotl/protocol/SenderKeyDistributionMessage.java
@@ -1,7 +1,12 @@
 package org.whispersystems.libaxolotl.protocol;
 
 import com.google.protobuf.ByteString;
+import com.google.protobuf.InvalidProtocolBufferException;
 
+import org.whispersystems.libaxolotl.InvalidKeyException;
+import org.whispersystems.libaxolotl.InvalidMessageException;
+import org.whispersystems.libaxolotl.LegacyMessageException;
+import org.whispersystems.libaxolotl.ecc.Curve;
 import org.whispersystems.libaxolotl.ecc.ECPublicKey;
 import org.whispersystems.libaxolotl.util.ByteUtil;
 
@@ -15,17 +20,52 @@ public class SenderKeyDistributionMessage implements CiphertextMessage {
 
   public SenderKeyDistributionMessage(int id, int iteration, byte[] chainKey, ECPublicKey signatureKey) {
     byte[] version = {ByteUtil.intsToByteHighAndLow(CURRENT_VERSION, CURRENT_VERSION)};
+    byte[] protobuf = WhisperProtos.SenderKeyDistributionMessage.newBuilder()
+                                                                .setId(id)
+                                                                .setIteration(iteration)
+                                                                .setChainKey(ByteString.copyFrom(chainKey))
+                                                                .setSigningKey(ByteString.copyFrom(signatureKey.serialize()))
+                                                                .build().toByteArray();
 
     this.id           = id;
     this.iteration    = iteration;
     this.chainKey     = chainKey;
     this.signatureKey = signatureKey;
-    this.serialized   = WhisperProtos.SenderKeyDistributionMessage.newBuilder()
-                                                                  .setId(id)
-                                                                  .setIteration(iteration)
-                                                                  .setChainKey(ByteString.copyFrom(chainKey))
-                                                                  .setSigningKey(ByteString.copyFrom(signatureKey.serialize()))
-                                                                  .build().toByteArray();
+    this.serialized   = ByteUtil.combine(version, protobuf);
+  }
+
+  public SenderKeyDistributionMessage(byte[] serialized) throws LegacyMessageException, InvalidMessageException {
+    try {
+      byte[][] messageParts = ByteUtil.split(serialized, 1, serialized.length - 1);
+      byte     version      = messageParts[0][0];
+      byte[]   message      = messageParts[1];
+
+      if (ByteUtil.highBitsToInt(version) < CiphertextMessage.CURRENT_VERSION) {
+        throw new LegacyMessageException("Legacy message: " + ByteUtil.highBitsToInt(version));
+      }
+
+      if (ByteUtil.highBitsToInt(version) > CURRENT_VERSION) {
+        throw new InvalidMessageException("Unknown version: " + ByteUtil.highBitsToInt(version));
+      }
+
+      WhisperProtos.SenderKeyDistributionMessage distributionMessage = WhisperProtos.SenderKeyDistributionMessage.parseFrom(message);
+
+      if (!distributionMessage.hasId()        ||
+          !distributionMessage.hasIteration() ||
+          !distributionMessage.hasChainKey()  ||
+          !distributionMessage.hasSigningKey())
+      {
+        throw new InvalidMessageException("Incomplete message.");
+      }
+
+      this.serialized   = serialized;
+      this.id           = distributionMessage.getId();
+      this.iteration    = distributionMessage.getIteration();
+      this.chainKey     = distributionMessage.getChainKey().toByteArray();
+      this.signatureKey = Curve.decodePoint(distributionMessage.getSigningKey().toByteArray(), 0);
+    } catch (InvalidProtocolBufferException | InvalidKeyException e) {
+      throw new InvalidMessageException(e);
+    }
   }
 
   @Override