def fingerprint(public_key, username)
      LoginUser.fingerprint(public_key) if public_key
    rescue Exception => e
      Log.error("Failed to create public key fingerprint for user #{username}", e)
      nil
    end
def fingerprint(public_key, username)
      LoginUser.fingerprint(public_key) if public_key
    rescue Exception => e
      Log.error("Failed to create public key fingerprint for user #{username}", e)
      nil
    end
Create fingerprint for public key

 == Parameters:
 @param [String] RSA public key
 @param [String] Name of user owning this key

 == Return:
 @return [String] Fingerprint for key if it could create it
 @return [NilClass] if it could not create it