On the Ineffectiveness of Internal Encodings - Revisiting the DCA Attack on White-Box Cryptography

Bock, Estuardo Alpírez; Brzuska, Chris; Michiels, Wil; Treff, Alexander

doi:10.1007/978-3-319-93387-0_6

Cited by 11 publications

(1 citation statement)

References 15 publications

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“…The publication of these papers sparked more interest in the topic of whitebox cryptography, with many new constructions based on DES [31] and AES [40,28,41,29,2] appearing over the years. Unfortunately, all of these implementations have been broken, using both algebraic attacks [39,26,34,22,30,24] and attacks based on side-channel analysis [16,13,12]. All of these designs improved upon or were inspired by the CEJO framework.…”

Section: Introductionmentioning

confidence: 99%

A White-Box Speck Implementation Using Self-equivalence Encodings

Vandersmissen¹,

Ranea²,

Preneel³

2022

Applied Cryptography and Network Security

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In 2002, Chow et al. initiated the formal study of white-box cryptography and introduced the CEJO framework. Since then, various white-box designs based on their framework have been proposed, all of them broken. Ranea and Preneel proposed a different method in 2020, called self-equivalence encodings and analyzed its security for AES. In this paper, we apply this method to generate the first academic whitebox speck implementations using self-equivalence encodings. Although we focus on speck in this work, our design could easily be adapted to protect other add-rotate-xor (ARX) ciphers. Then, we analyze the security of our implementation against key-recovery attacks. We propose an algebraic attack to fully recover the master key and external encodings from a white-box speck implementation, with limited effort required. While this result shows that the linear and affine self-equivalences of speck are insecure, we hope that this negative result will spur additional research in higher-degree self-equivalence encodings for white-box cryptography. Finally, we created an open-source Python project implementing our design, publicly available at https://github.com/jvdsn/ white-box-speck. We give an overview of five strategies to generate output code, which can be used to improve the performance of the whitebox implementation. We compare these strategies and determine how to generate the most performant white-box speck code. Furthermore, this project could be employed to test and compare the efficiency of attacks on white-box implementations using self-equivalence encodings.

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