Description
In the white-box attack context, i.e., the setting where an implementation of a cryptographic algorithm is executed on an untrusted open platform, the adversary has full access to the implementation and its execution environment. As a result, the adversary is much more powerful than in a traditional black-box environment in which the adversary has only access to the inputs and outputs of a cryptographic algorithm. For example, the adversary can make use of widely available tools such as disassemblers and debuggers with breakpoint functionality. An example of a white-box environment is a digital content protection system in which the client is implemented in software and executed on a PC, tablet, set-top box or a mobile phone. A malicious end-user may attempt to extract a secret key used for content decryption from the software. Next, the end-user may distribute this key to non-entitled end-users, or the end-user may use this key to decrypt the content directly, circumventing content usage rules. White-box cryptography aims to protect the confidentiality of the secret key of a cryptographic algorithm in a white-box environment. In particular, it is a technique to construct software implementations of a cryptographic algorithm that are sufficiently secure against a white-box attacker. These implementations are referred to as white-box implementations.<br/> In this talk, we elaborate on white-box cryptography in general (e.g., what are the main white-box security objectives and the typical attacker¿s goals in the white-box environment) and we discuss its application to AES. We start with the design of the first published white-box AES implementation by Chow et al. in 2002, and the efficient attack on this implementation by Billet et al. in 2004. Next, we discuss the design of two new white-box AES implementations claimed to be resistant against Billet et al.¿s attack, and we present practical attacks showing that none of these proposed countermeasures actually achieve white-box security. To conclude, we discuss a novel white-box technique proposed by Michiels and Gorissen in 2010 and share some thoughts about the future of white-box cryptography.
Next sessions
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On the average hardness of SIVP for module lattices of fixed rank
Speaker : Radu Toma - Sorbonne Université
In joint work with Koen de Boer, Aurel Page, and Benjamin Wesolowski, we study the hardness of the approximate Shortest Independent Vectors Problem (SIVP) for random module lattices. We use here a natural notion of randomness as defined originally by Siegel through Haar measures. By proving a reduction, we show it is essentially as hard as the problem for arbitrary instances. While this was[…] -
Attacks and Remedies for Randomness in AI: Cryptanalysis of PHILOX and THREEFRY
Speaker : Yevhen Perehuda - Ruhr-University Bochum
In this work, we address the critical yet understudied question of the security of the most widely deployed pseudorandom number generators (PRNGs) in AI applications. We show that these generators are vulnerable to practical and low-cost attacks. With this in mind, we conduct an extensive survey of randomness usage in current applications to understand the efficiency requirements imposed in[…]-
Cryptography
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Lightweight (AND, XOR) Implementations of Large-Degree S-boxes
Speaker : Marie Bolzer - LORIA
The problem of finding a minimal circuit to implement a given function is one of the oldest in electronics. In cryptography, the focus is on small functions, especially on S-boxes which are classically the only non-linear functions in iterated block ciphers. In this work, we propose new ad-hoc automatic tools to look for lightweight implementations of non-linear functions on up to 5 variables for[…]-
Cryptography
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Symmetrical primitive
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Implementation of cryptographic algorithm
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Algorithms for post-quantum commutative group actions
Speaker : Marc Houben - Inria Bordeaux
At the historical foundation of isogeny-based cryptography lies a scheme known as CRS; a key exchange protocol based on class group actions on elliptic curves. Along with more efficient variants, such as CSIDH, this framework has emerged as a powerful building block for the construction of advanced post-quantum cryptographic primitives. Unfortunately, all protocols in this line of work are[…] -
Endomorphisms via Splittings
Speaker : Min-Yi Shen - No Affiliation
One of the fundamental hardness assumptions underlying isogeny-based cryptography is the problem of finding a non-trivial endomorphism of a given supersingular elliptic curve. In this talk, we show that the problem is related to the problem of finding a splitting of a principally polarised superspecial abelian surface. In particular, we provide formal security reductions and a proof-of-concept[…]-
Cryptography
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