security: Adding delete methods in KeyChain

Change-Id: I8e3bbbf6e911b43189c510c56118d291f8932df4
diff --git a/src/security/sec-tpm.hpp b/src/security/sec-tpm.hpp
index dd9a55e..3336a32 100644
--- a/src/security/sec-tpm.hpp
+++ b/src/security/sec-tpm.hpp
@@ -35,6 +35,13 @@
    */
   virtual void 
   generateKeyPairInTpm(const Name& keyName, KeyType keyType, int keySize) = 0;
+  
+  /**
+   * Delete a key pair of asymmetric keys.
+   * @param keyName The name of the key pair.
+   */
+  virtual void
+  deleteKeyPairInTpm(const Name &keyName) = 0;
 
   /**
    * Get the public key