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A S CRAMBLER FOR A K EYLESS E NTRY S YSTEM

A S CRAMBLER FOR A K EYLESS E NTRY S YSTEM. Kaushik Roy and Anne Woo University of Illinois at Urbana-Champaign Department of Electrical Engineering Senior Design, ECE345 November 30, 2001. Introduction to the KES. Consumer uses for a K eyless E ntry S ystem (KES) Garage doors Cars

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A S CRAMBLER FOR A K EYLESS E NTRY S YSTEM

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  1. A SCRAMBLERFORA KEYLESS ENTRY SYSTEM Kaushik Roy and Anne Woo University of Illinois at Urbana-Champaign Department of Electrical Engineering Senior Design, ECE345 November 30, 2001

  2. Introduction to the KES • Consumer uses for a Keyless Entry System (KES) • Garage doors • Cars • Other security purposes • Diagram of a KES

  3. Diagram of a KES Transmitter: Key Encryption RF Transmitter (mod- ulator, antenna) Numeric Key Code Generated Receiver: RF Receiver (an- tenna, demodulator) Key Recovery and Verification Key Decryption

  4. Motivation for Project • Current KES are insecure • Uses one unique code per system • Code grabbers can be easily assembled and purchased from electronic shops • Other communication devices utilize spread spectrum technology • Cordless phones • Interested in DSP and Communications

  5. Project Goals Develop a scrambler and descrambler for KES • More difficult for signal reproduction when using a cyclic code instead of one unique code. • Utilizes government standards for encryption • Code grabber is useless when implementing the spread spectrum system

  6. Original Design • Used TI DSP boards • Three components • Cyclic Algorithm • Advanced Encryption System • Spread Spectrum • Scrambler components implemented using C-code • System operated at 2 MHz

  7. Labview Implementation • Spread spectrum signal transmitted between National Instrument DAQ cards through cable • Each block implemented individually using Labview virtual instruments • System operated at 1 kHz

  8. Labview Software Program

  9. Cyclic Algorithm Utilizes an algorithm and seed to produce 128 unique codes

  10. Advanced Encryption System • National Institute for Standards and Technology (NIST) standard • Used to avoid insecure transmission of raw data bits • Distributes all bit sequences evenly

  11. Performance of AES

  12. Spread Spectrum System • Used by the government to resist jamming and interference • Looks like noise to the environment • Spreads out narrowband signal over a wider bandwidth • Direct Sequence Spread Spectrum • Unique PN Sequence

  13. How Spread Spectrum Works PN Sequence Data bits Transmitted bits Reproduced from “Transmitter/Receiver Pair Using CDMA Encoding.”

  14. PN Sequence • M-sequences • Kasami Codes • Gold Codes widely used • Low autocorrelation for equal spreading • Ones and zeros are balanced • http://www.associatedpro.com/pn_sim/pnsim.html

  15. Tolerance Analysis of PN Length

  16. Final Transmitter Design Lock/Unlock Operation To Receiver Cyclic Algorithm Advanced Encryption System Spread Spectrum From Receiver “Ack” signal

  17. Final Receiver Design Cyclic Algorithm From Trans- mitter Spread Spectrum Advanced Encryption System Verification of Proper Algorithm Lock/Unlock Action To Transmitter “Ack” signal

  18. Tests Performed 1. Normal transmission between transmitter (TX) and receiver (RX). SIGNAL ACK

  19. Tests Performed Cont. 2. TX unable to communicate to RX.

  20. Tests Performed Cont. 3. RX unable to communicate to TX. SIGNAL

  21. Tests Performed Cont. 4. TX battery failure occurs and system is reset.

  22. Tests Performed Cont. 5. TX and RX have different PN codes. SIGNAL

  23. Testing Hardware Transmitter Receiver Protoboard

  24. Performance • Achieved goal to have transmitter and receiver operate properly to handle various real life test situations • 1kHz sampling rate used (approximately 5 seconds per operation) • 128 unique codes from cyclic algorithm • Implemented spread spectrum with baseband signal

  25. Challenges • Utilizing TI-DSP boards • Receiving spread spectrum signal using Labview • Transmitter receiver synchronization

  26. Future Recommendations • Operate system at 2 MHz • Implement error correction bits • Distinguish between the superposition of signals • Complete RF portion of the scrambler system

  27. Acknowledgements Professor Douglas Jones Professor Richard Blahut Professor Gary Swenson Dave Crowe

  28. Thank YouQuestions…?

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