ELECTRONICS DEPARTMENT

Transcription

1 ELECTRONICS DEPARTMENT By Eng. 28 th Mar MUSTAFA 2012 M. Efficient SHIPLEImplementation of AES Algorithm Immune to DPA Attack

2 Cryptography processing plaintext cipher text format Block Cipher Stream Cipher Explicit Hidden Steganography Cryptography Schemes Number of keys Transforming plaintext to cipher text Symmetric Private Key Asymmetric Public Key substitution transposition

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4 Classical Ciphers (Substitution ) Caesar substitution

5 Classical Ciphers (Substitution ) Monoalphabetic substitution

6 Classical Ciphers (Substitution ) Polyalphabetic substitution

7 Classical Ciphers (Diffusion )

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9 Invisible Ink Write with lemon juice and a toothpick/ cotton swab. Let the paper dry. Heat the paper with an iron to reveal the hidden message.

10 Steganography Fishing freshwater bends and saltwater coasts rewards anyone feeling stressed. Resourceful anglers usually find masterful leapers fun and admit swordfish rank overwhelming any day. Send lawyers, guns, and money.

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12 Block cipher Vs. Stream cipher A sequence of blocks are encrypted by the same key A sequence of blocks are encrypted by a sequence of keys

13 Stream Cipher

14 Block Cipher Some examples: DES IDEA SAFER CAST AES Rijndael Blowfish RC6 MARS SERPENT

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16 Classification of Cryptographic Secret key cryptography There is a key shared by both sender and receiver Sender encrypts and Receiver decrypts messages using the shared key. Public key cryptography Each user has his/her own public key and private key Public key is made public but private key is kept secret Public key is used for encryption but private key for decryption

17 Symmetric Cryptography K A K A plaintext message, m encryption algorithm ciphertext K A (m) decryption algorithm plaintext m = K ( K (m) ) A A Total number of keys = n(n-1)/2 Difficult to management and quite insecure

18 Asymmetric Cryptography K B + Bob s public key K B - Bob s private key plaintext message, m encryption algorithm ciphertext + K (m) B decryption algorithm plaintext message - + m = K (K (m)) B B very slow.

19 History of Modern Cryptology National Bureau of Standards (NBS) National Institute of Standards and Technology (NIST) 1. The algorithm must provide a high level of security 2. The security should not depend on the secrecy of the algorithm. 3. The algorithm must be available to all users. 4. The algorithm must be economically implementable in electronic devices. LUCIFER DES (DEA)

20 Game Over Electronic Frontier Foundation EEF

21 Introduction to Cryptanalysis

22 Invasive attack Monitoring the entire signals. Reading memory blocks. Editing the chip architecture. **Source: Fraunhofer Institute for Integrated Circuits

23 Semi-Invasive Attack

24 Non-invasive attack The leakage information by: The radiated electromagnetic waves The processed time Consumed power

25 Differential Power Analysis Unknown Cipher key DUA N Plaintext Cipher power consumption Model Cipher key Array M Nx1 NxM

26 Consumed power N= 2000 M= 256 Unknown Cipher key DUA N Plaintext Cipher power consumption Model Cipher key Array M Nx1 NxM

27 Power models Assumptions: HD (0 1) = HD (1 0) HD (0 0) = HD (1 1) = 0 w HD (v 0, v1) = HW (v 0 XOR v1)

28 DPA for pipeline Architecture Plain text Key AddRoundKey Latch (1) SBox Latch (2) Shift Latch (3) MixCol Latch (4) Cipher text

29 DPA for pipeline Architecture Plaintext : 2000 random sequence Cipher Key: 0855B47080B7CDD AD8E0C42a

30 Results under spot the histogram of MSB of plaintext Mean value=9.7 standard value = 7.4 var = 2.7

31 Similar work 1. Power equalizations 2. Adding nonlinear blocks (masking technique)

32 The proposed Idea Key Plain text Random AddRoundKey MUX B Histogram of the produced noise Latch (1) SBox Latch (2) MUX A Latch (1') Latch (2') Mean noise = Var noise = SNR= 0.23 MUX A Shift Latch (3) Latch (3') MUX A MixCol Latch (4) Latch (4') MUX A Cipher text

33 Results under spot

34 Summary and conclusion This paper provides : A counter measurements solution against the DPA. A solution has not impact on AES security itself. Use the existed hardware and add a little overhead hardware.

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