Attacks and Countermeasures for White-box Designs

Abstract

In traditional symmetric cryptography, the adversary has access only to the inputs and outputs of a cryptographic primitive. In the white-box model the adversary is given full access to the implementation. He can use both static and dynamic analysis as well as fault analysis in order to break the cryptosystem, e.g. to extract the embedded secret key. Implementations secure in such model have many applications in industry. However, creating such implementations turns out to be a very challenging if not an impossible task. Recently, Bos et al. [7] proposed a generic attack on white-box primitives called differential computation analysis (DCA). This attack was applied to many white-box implementations both from academia and industry. The attack comes from the area of side-channel analysis and the most common method protecting against such attacks is masking, which in turn is a form of secret sharing. In this paper we present multiple generic attacks against masked white-box implementations. We use the term "masking" in a very broad sense. As a result, we deduce new constraints that any secure white-box implementation must satisfy. Based on the new constraints, we develop a general method for protecting white-box implementations. We split the protection into two independent components: value hiding and structure hiding. Value hiding must provide protection against passive DCA-style attacks that rely on analysis of computation traces. Structure hiding must provide protection against circuit analysis attacks. In this paper we focus on developing the value hiding component. It includes protection against the DCA attack by Bos et al. and protection against a new attack called algebraic attack. We present a provably secure first-order protection against the new algebraic attack. The protection is based on small gadgets implementing secure masked XOR and AND operations. Furthermore, we give a proof of compositional security allowing to freely combine secure gadgets. We derive concrete security bounds for circuits built using our construction.

Defeating State-of-the-Art White-Box Countermeasures with Advanced Gray-Box Attacks

“…Although the exact location of the shares might not be obvious for the adversary because of some obfuscation or obscurity in the implementation structure, linear masking can be completely smashed using a simple gray-box attack. The so-called linear decoding analysis (LDA) was formally introduced in [GPRW18, GPRW20] -and also independently discussed in [BU18]-as an effective way to break linear masking (or any other linear encoding scheme) in white-box model.…”

“…The principle of shuffling is to randomly permute the order of several independent operations (possibly including dummy operations) in order to increase the noise in the instantaneous leakage on a sensitive variable. It was shown that an implementation solely protected with linear masking is vulnerable to a linear decoding analysis (LDA), which is able to recover the locations of shares by solving a linear system [GPRW18,GPRW20,BU18]. The authors of [BRVW19] analyze the combination of linear masking and shuffling and show that it can achieve some level of resistance against advanced gray-box attacks.…”

“…Three implementations (all due to Biryukov and Udovenko) were still alive at the deadline of the contest but were broken a few days or weeks afterward. 2 As explained in this paper, all three winning implementations were based on state-of-the-art white-box countermeasures, including a mix of linear and non-linear masking [BU18] together with shuffling and additional obfuscation. In this article, we give a thorough explanation of how we managed to break all three implementations with advanced gray-box attacks and our novel data-dependency analytic techniques (as well as a "lightweight" de-obfuscation).…”

Improvement on a Masked White-Box Cryptographic Implementation

“…For this reason, there were several approaches to preventing DPA and DPA variants on white-box cryptography. For example, applying masking [25], a standard countermeasure to DPA, was investigated [26], [27]. However, masking is vulnerable to higher-order DPA attacks, and this is also the case with masking applied to white-box cryptography [27].…”

Measuring Performances of a White-Box Approach in the IoT Context

“…In particular, new approaches to verify the security of a white-box implementation have been proposed in [44] where Bos et al present differential fault analysis (DFA) and differential computational analysis (DCA) attacks (further information on fault-injection and differential power analysis attacks can be found in [45,46] respectively). In addition, in [47,48] the authors explained more formally why DCA is effective against linear and nibble encoding, Rivain and Wang [43] provide an extensive analysis on the effectiveness of DCA, finally Biryukov and Udovenko [49] give a general protection method for white-box implementations against DCA.…”