diff --git a/router/java/src/net/i2p/router/tunnel/BuildMessageProcessor.java b/router/java/src/net/i2p/router/tunnel/BuildMessageProcessor.java
index 9b77b88d9d41ba53120456337e0f6fef2a6fc117..4240407904b385d166bee331ca1bb41703be11cc 100644
--- a/router/java/src/net/i2p/router/tunnel/BuildMessageProcessor.java
+++ b/router/java/src/net/i2p/router/tunnel/BuildMessageProcessor.java
@@ -1,6 +1,7 @@
 package net.i2p.router.tunnel;
 
 import net.i2p.I2PAppContext;
+import net.i2p.crypto.EncType;
 import net.i2p.data.Base64;
 import net.i2p.data.DataFormatException;
 import net.i2p.data.DataHelper;
@@ -88,6 +89,10 @@ public class BuildMessageProcessor {
      * @return the current hop's decrypted record or null on failure
      */
     public BuildRequestRecord decrypt(TunnelBuildMessage msg, Hash ourHash, PrivateKey privKey) {
+        // TODO proposal 152
+        if (privKey.getType() != EncType.ELGAMAL_2048)
+            return null;
+
         BuildRequestRecord rv = null;
         int ourHop = -1;
         long beforeActualDecrypt = 0;