Click to edit Present’s Name Three Attacks, Many Process Variations and One Expansive Countermeasure International Workshop on Cybersecurity Darshana Jayasinghe, Angelo Ambrose, Aleks Ignjatovic, Sri Parameswaran

Representation of Money 600 AD – Paper drafts representing the value of coins in China Coins represented by the intrinsic value of the material Today – Money is represented by strings of 1s and 0s Adapted from Prof Yasuura’s talk 2008

School of Computer Science and Engineering AES Unprotected AES Circuit 3 Plaintext Key SubByte ShiftRows Mix Columns Add Round Key SubByte ShiftRows Add Round Key Ciphertext N-1 Plaintext 128 bits ; Key 128, 192 or 256 bits AES N=10 AES - 192N=12 AES - 256N=14

School of Computer Science and Engineering Power Analysis Attacks Often non-intrusive and invasive First proposed by Kocher in 1998 – Simple power analysis – Differential power analysis – Correlation power analysis – Mutual information analysis Many more ….. Power consumption Plaintext, Key, Ciphertext Plaintext, Key, Ciphertext

School of Computer Science and Engineering Simple Power Analysis Widely used against Asymmetric-key algorithms embedded.com RSA Implementation

School of Computer Science and Engineering Differential Power Analysis Attacks - DPA PtKeyPtkeyBinaryμWμW 3F003F E006E B300B M 0 = M 1 = Key 0255 |R| PtKeyPtkeyBinaryμWμW 3F013E E016F B301B PtKeyPtkeyBinaryμWμW 3F053A E D C B305b

School of Computer Science and Engineering PtKeyPtkeyHW(S(Ptkey))μWμW 3F003F550 6E006E B300B PtKeyPtkeyHW(S(Ptkey))μWμW 3F013E450 6E016F B301B PtKeyPtkeyHW(S(Ptkey))μWμW 3F053A150 6E D C436 B305b Correlation Power Analysis Attacks - CPA

School of Computer Science and Engineering Attack on Standard AES Circuit

School of Computer Science and Engineering CPA can only detect linear dependencies Shannon's entropy is used to calculate the mutual information Often the key convergence rate falls behind the CPA Mutual Information Analysis Attacks 9 Hypothetical power consumption Observed power consumption Source: Wikipedia

School of Computer Science and Engineering Logic 1Logic 2 Yokohama 06 Basics of Algorithmic Balancing CMOSWDDL by Tiri 07 AES

School of Computer Science and Engineering Balancing : MUTE AES Proposed by Ambrose for a processor based environment

School of Computer Science and Engineering Back to AES Circuit Assume:

School of Computer Science and Engineering State 2 2 Way Balancing State 1

School of Computer Science and Engineering 4-way or Quadruple Balancing State 1 State 2 Can prove the same for timing

School of Computer Science and Engineering QuadSeal-4

School of Computer Science and Engineering QuadSeal-uni 512 bits 8 bits 32 bits

School of Computer Science and Engineering Attack on QuadSeal Visible Key bytes

School of Computer Science and Engineering Process Variation Path imbalances Aging effects. Process Variation Inter-dieIntra-die 18

School of Computer Science and Engineering …,L6,L5,L4,L3,L2,L1.,L6,L5,L4,L3, L2,L1 19 P1, P2, P3, P4, P5, P6, …..

School of Computer Science and Engineering QuadSeal Against Process Variation Each core (Din, Kin), (Din, Kin), (Din,Kin) and (Din,Kin) 24 inputs combinations 63-bit LFSR repetition time of ( ) Running at 50 MHz, (5, 849 years more precise) 20 Enable Signal

School of Computer Science and Engineering 21

School of Computer Science and Engineering CPA attacks

School of Computer Science and Engineering How Efficient is the swapping? 23

School of Computer Science and Engineering CPA attacks

School of Computer Science and Engineering Software Implementation of QuadSeal Microblaze is a 32 bit soft processor by Xilinx 32 bit input 32 bit output; 2 32 entries (4 GB) But only 256 entries will be used Composite SubByte table as a Hardware IP Pre-clear ? –After each table lookup, data lines are refreshed by loading 00000…0 (32’h0) Throughput X/4 25 Microblaze Control FPGA SASEBO GII Virtex V PC

School of Computer Science and Engineering Devices we target and attacks we prevent! DEVICES – ASIC – FPGA – Software on 32-bit Processors – Extensible Processors ATTACKS WE PREVENT – Differential Power Analysis Attacks (DPA) – Correlation Power Analysis (CPA) – Mutual Analysis Attacks

School of Computer Science and Engineering An Example Attack Setup

School of Computer Science and Engineering Thank you!