International Conference on Education, Management, Computer and Society (EMCS 2016) Application Of KEELOQ Algorithm In PEPS System Dan Li Yi Wang1,2 * Dept. of Physics & Electronic Science Guizhou Normal University 1.Key Laboratory of special Automotive Electronics Guiyang,Guizhou,China technology of the Education Department of Guizhou e-mail:[email protected] Province Guiyang, Guizhou, China 2. Dept.of Physics & Electronic Science,Guizhou 1,2 Wen jun Xiao Normal University 1.Key Laboratory of special Automotive Electronics Guiyang,Guizhou,China e-mail:[email protected] technology of the Education Department of Guizhou Province *Corresponding Author Guiyang,Guizhou,China 2. Dept.of Physics & Electronic Science,Guizhou Normal University Guiyang,Guizhou,China e-mail:[email protected] Abstract—Passive Entry Passive Start(PEPS) because its system is developed on the basis of the remote access high security and easy to use which has become the main system is the latest security technology,it integrates the development trend in the field of the automotive remote access system and anti-theft lock check system electronics.For the security and reliability of PEPS (Immobilizer, IMMO) function,to a great extent,it satisfies system,my paper proposed a encryption and decryption the people to the requirements of access control system method based on KEELOQ algorithm.Compared with other security, The KEELOQ algorithm proposed in this paper to encryption algorithms,the proposed method increases the implement the encryption and decryption of PEPS system, synchronization,which makes each transmitted data is so as to ensure the safety of the car.KEELOQ algorithm is unique and does not repeat,and also increasing the difficulty a block cipher algorithm designed by South Africa of data decoding and interception,improving the security of WilleSmit,in the 1980s,it includes 32-bit block cipher and the system.This paper mainly use the KEELOQ algorithm encryption and decryption principle and process,the 64-bit key length,it is now widely used in automobiles working princeple of PEPS system,those program to discuss wireless door lock device[4]. the design of the intelligent key and the application of KEELOQ algorithm in PEPS system.in the end,the paper II. KEELOQ ALGORITHM PRINCIPLE also made a encoding and decoding experiments.The result KEELOQ block cipher is an unbalanced Feistel show that as long as the sended data made one change,the structure[5], the packet length is 32 bit,encryption for 528 result is changed more than half after the encryption of times,Each circle only change 1 bit,encryption key length KEELOQ algorithm.therefore,the method I researched in is 64 bits,and recycling in the encryption process.the core this paper can effectively improve the security and reliability idea KEELOQ algorithm is to use KEELOQ encryption of PEPS system. algorithm with 64 bit encryption key to encrypt 32 bit Keywords-PEPS;KEELOQ;intelligent key;KEELOQ tool; plaintext, finally get a 32 bit cipher text,at the receiving encryption algorithm end use the KEELOQ decryption algorithm decryption 32 bit cipher text,and restore the 32 bit plaintext,when I. INTRODUCTION decrypting need to learn the serial number, identification With the continuous improvement of people's living number and synchronization of the encoder count,can standard, People have higher requirements to property decod the encoded information effectively[6-7].The key of security,For example,the safety of the entrance guard KEELOQ algorithm is the synchronous counter,because in system[1]. Now in order to let people use more the receiver receives the data after decryption,to determine convenient,therefore,the security and reliability of the whether the synchronous counter match,only the entrance guard system has been the subject of the synchronous counter after the match,will process the researchers study[2]. Entrance guard system including received information.KEELOQ algorithm process has two visual entrance guard system, alarm,entrance guard steps they are encryption and decryption. system,fingerprint entrance guard system and entrance A. KEELOQ encryption process guard system of remote control,etc.,especially in the remote access system has been widely used,such as the It needs to define a data registers and key registers home gateway,garage door,door, corridor to the highway before encryption,used to store the 32 bit plaintext and 64 toll station,etc[3].Passive Entry Passive Start(PEPS) bit key, respectively.The encryption process is:(1)Define a © 2016. The authors - Published by Atlantis Press 796 nonlinear table has five input code, 1 output code;(2) In the NLF(,,,,) a b c d e abc abd ace ade de data register of evenly spaced take five: (1) cd be bc ae ac e d LLLLL31,,,, 26 20 9 1 Through the type(1) nonlinear L ... L ... L ... L ... L ... L operation (NLF) to produce an output code;(3) Get the 30 25 19 15 8 0 output code LL16, 0 and the key k0 in the register through NLF an exclusive or operation to get the first output;(4) Each generates an output code,data registers and the key registers to do shift processing, respectively,then repeat the k15 k ... k process above 528 times,can get a 32-bit cipher 63 0 text.KEELOQ encryption algorithm process is shown in the Fig .1 below. Figure 2. KEELOQ decryption algorithm process Mathematical expression of the encryption algorithm is as follows: III. PEPS SYSTEM COMPOSITION AND i i i i i i i i WORKING PRINCIPLE NLFLLLLL(,,,,)31 26 20 9 1 L16 L0 kimod 64 A. PEPS system structure LLLi1 ( i ,i,) ..., i 31 1 i from 0 to 527 The development of the car door,has experienced three Type of NLF for nonlinear function stages,total mechanical locks,remote control door lock and NLF(,,,,) a b c d e abc abd ace ade de PEPS system so far. （1） PEPS system consists of PEPS ECU 、 Electrical cd be bc ae ac e d Steering Colum Lock(ESCL) 、 SWITCH 、 Immobi- lizer(IMMO) 、 ANTENNA 、 intelligent key 、 body L ... L ... L ... L ... L ... L L 31 26 20 16 9 1 0 control module(BCM) 、 engine control moduleand the inductive switch and other components.Very high NLF requirements for hardware and security and it is very expensive,abroad mainly in high middle-grade automobile and domestic development of low cost and high security of PEPS system[8], The system removes trouble is that start the vehicle by inserting the key,improve the ride k63 ... k0 comfort[9-10]. B. PEPS system working principle Figure 1. KEELOQ encryption algorithm process Principle of PEPS system are shown in Fig .3 below.Between PEPS ECU and BCM,ECM,ESCL through B. KEELOQ decryption process CAN bus communication,and the information obtained The method of decryption process and encryption from the bus through CAN bus and the ECM,ESCL process almost the same,just bits of operational data authentication. changed.Decryption process is:(1)Define a nonlinear table It consists of Passive Entry Passive Start two parts,in has five input code,1 output code;(2)In the data register of PE section,when the user has a valid intelligent key near the door handle within one meter,PEPS controller by low evenly spaced take five: LLLLL30,,,, 25 19 8 0 Through frequency antenna to send instruction to intelligent key,and the type (1) nonlinear operation (NLF) to produce an then validated, after verification the received information output code;(3)Get the output code LL31, 15 and the key by the KEELOQ algorithm for data encryption,and the k in the register through an exclusive or operation to get encrypted data is returned to the PEPS controller, the 15 PEPS control will sent unlock instructions to BCM via the first output;(4) Each generates an output code,data CAN bus controller,and then complete the unlock door registers and the key registers to do shift processing, lock operation.In PS section,under the condition of the respectively,then repeat the process above 528 times,can interior has a valid intelligent key,only requires the user to get a 32-bit plaintext.KEELOQ decryption algorithm press the ignition switch,PEPS ECU send low frequency process is shown in the Fig .2 below. signal by low frequency antenna to intelligent key,Then Mathematical expression of the decryption algorithm is intelligent key compare the received signal with the storing as follows: information and authentication,if authentication complete,t i NLFLLLLL(,,,,)i i i i i L i L i k he PEPS ECU will connecte the powe immediately,with 30 25 19 8 0 15 31 i-1m od 64 i i the ESCL,EMS through the CAN bus communication LLLi 1- ( ,..., ， i ) authentication and unlock,after unlocked,PEPS ECU will 30 0 i from 528 to 1 receive the brake pedal signal is connected with the ECM Type of NLF for nonlinear function starter relay,so as to make the engine start. 797 PEPS ECU VCC Power supply Power supply by iron module MCU Backup the door open signal Low Low frequency frequency driver antenna The left front door knob signal module Right front doors hand signal Signal input interface The brake switch signal The left front door state signals BCM The right front door status signals Gear switch signal The left back door status signals Signal input RF RFA receiving UID The right back door status signals module Switch input Switch and Trunk status signals Switch and indicator the indicator Switch the light output light Hood lock state signals light Door control The left front door motor lock Alarm output power Relay feedback signals driver The The right front door motor module IMMO IMMO power LIN communication manage power supply The left back door motor ment enable signal Relay module box The right rear door motor CAN starter Trunk motor ESCL CAN EMS Relay control M CAN communication Figure 3.