Move publisherPublicKeyDigest and keyLocator from MetaInfo to Signature.
diff --git a/ndn-cpp/publisher-public-key-digest.hpp b/ndn-cpp/publisher-public-key-digest.hpp
index 3b8dd56..0a5a2c5 100644
--- a/ndn-cpp/publisher-public-key-digest.hpp
+++ b/ndn-cpp/publisher-public-key-digest.hpp
@@ -53,6 +53,14 @@
   { 
     setVector(publisherPublicKeyDigest_, publisherPublicKeyDigest, publisherPublicKeyDigestLength); 
   }
+  
+  /**
+   * Clear the publisherPublicKeyDigest.
+   */
+  void clear()
+  {
+    publisherPublicKeyDigest_.clear();
+  }
 
 private:
   std::vector<unsigned char> publisherPublicKeyDigest_;