diff --git a/include/ndn-cpp-dev/security/key-chain.hpp b/include/ndn-cpp-dev/security/key-chain.hpp
index fffa05d..c5df5db 100644
--- a/include/ndn-cpp-dev/security/key-chain.hpp
+++ b/include/ndn-cpp-dev/security/key-chain.hpp
@@ -153,6 +153,22 @@
     return certificate;
   }
 
+  /**
+   * Fetch the private key for keyName and sign the data, and set the signature block of the data packet.
+   * Throw Error if signing fails.
+   * @param data Reference to the input data packet.
+   * @param keyName The name of the signing key.
+   * @param digestAlgorithm the digest algorithm.
+   */  
+  void
+  signInTpm(Data &data, const Name& keyName, DigestAlgorithm digestAlgorithm)
+  {
+    data.setSignatureValue
+      (Tpm::signInTpm(data.wireEncode().value(),
+                      data.wireEncode().value_size() - data.getSignature().getValue().size(),
+                      keyName, digestAlgorithm));
+  }
+
   void
   sign(Data &data)
   {
@@ -184,7 +200,7 @@
     data.setSignature(signature);
 
     // For temporary usage, we support RSA + SHA256 only, but will support more.
-    Tpm::signInTpm(data, cert->getPublicKeyName(), DIGEST_ALGORITHM_SHA256);
+    signInTpm(data, cert->getPublicKeyName(), DIGEST_ALGORITHM_SHA256);
   }
 
   void
@@ -195,7 +211,7 @@
     data.setSignature(signature);
 
     // For temporary usage, we support RSA + SHA256 only, but will support more.
-    Tpm::signInTpm(data, certificate.getPublicKeyName(), DIGEST_ALGORITHM_SHA256);
+    signInTpm(data, certificate.getPublicKeyName(), DIGEST_ALGORITHM_SHA256);
   }
   
   /**
@@ -296,7 +312,7 @@
     cert.setSignature(signature);
 
     // For temporary usage, we support RSA + SHA256 only, but will support more.
-    Tpm::signInTpm(cert, cert.getPublicKeyName(), DIGEST_ALGORITHM_SHA256);
+    signInTpm(cert, cert.getPublicKeyName(), DIGEST_ALGORITHM_SHA256);
   }