A Radio-Frequency-Identification (RFID) tag is a small and inexpensive device that consists of an IC chip and an antenna which communicate by radio frequency. It emits an ID in response to a query from a radio communication device called as a reader. For this reason, the RFID tag is used for management of goods and it is used as a substitute for a bar code. However, RFID system may infringe on a consumer's privacy because it has a strong tracing ability. In this paper we describe problems of previous works on RFID security protocols and specify several known attacks and introduce PPP(Privacy Protection Protocol) for a RFID security protocol which serves as a proof of concept for authentication an RFID tag to a reader device using the vernam and standard encryption as a cryptographic primitive. To verify our protocol, we use model checking methodology, that is, Casper(A Compiler for Security Protocol), CSP(Communicating Sequential Processes) and then verify security properties such as secrecy and authentication using FDR(Failure Divergence Refinement) tool.