Masking schemes are key in thwarting side-channel attacks due to their robust theoretical foundation. Transitioning from Boolean to arithmetic (B2A) masking is a necessary step in various cryptography schemes, including hash functions, ARX-based ciphers, and lattice-based cryptography. While there exists a significant body of research focusing on B2A software implementations, studies pertaining to hardware implementations are quite limited, with the majority dedicated solely to creating...

The conversion between arithmetic and Boolean masking representations (A2B \& B2A) is a crucial component for side-channel resistant implementations of lattice-based (post-quantum) cryptography. In this paper, we first propose novel $d$-order algorithms for the secure addition (SecADDChain$_q$) and B2A (B2X2A). Our secure adder is well-suited for repeated ('chained') executions, achieved through an improved method for repeated masked modular reduction. The optimized B2X2A gadget removes a...

We present novel and improved high-order masking gadgets for Dilithium, a post-quantum signature scheme that has been standardized by the National Institute of Standards and Technologies (NIST). Our proposed gadgets include the ShiftMod gadget, which is used for efficient arithmetic shifts and serves as a component in other masking gadgets. Additionally, we propose a new algorithm for Boolean-to-arithmetic masking conversion of a $\mu$-bit integer $x$ modulo any integer $q$, with a...

Arithmetic to Boolean masking (A2B) conversion is a crucial technique in the masking of lattice-based post-quantum cryptography. It is also a crucial part of building a masked comparison which is one of the hardest to mask building blocks for active secure lattice-based encryption. We first present a new method, called one-hot conversion, to efficiently convert from higher-order arithmetic masking to Boolean masking using a variant of the higher-order table-based conversion of Coron et al....

Masking is a popular secret-sharing technique that is used to protect cryptographic implementations against physical attacks like differential power analysis. So far, most research in this direction has focused on finding efficient Boolean masking schemes for well-known symmetric cryptographic algorithms like AES and Keccak. However, especially with the advent of post-quantum cryptography (PQC), arithmetic masking has received increasing attention from the research community. In practice,...

Masking is a popular technique to protect cryptographic implementations against side-channel attacks and comes in several variants including Boolean and arithmetic masking. Some masked implementations require conversion between these two variants, which is increasingly the case for masking of post-quantum encryption and signature schemes. One way to perform Arithmetic to Boolean (A2B) mask conversion is a table-based approach first introduced by Coron and Tchulkine, and later corrected and...

Physical attacks, especially side-channel attacks, are threats to IoT devices which are located everywhere in the field. For these devices, the authentic functionality is important so that the IoT system becomes correct, and securing this functionality against side-channel attacks is one of our emerging issues. Toward that, Coron et al. gave an efficient arithmetic-to-Boolean mask conversion algorithm which enables us to protect cryptographic algorithms including arithmetic operations, such...

Masking is a very common countermeasure against side channel attacks. When combining Boolean and arithmetic masking, one must be able to convert between the two types of masking, and the conversion algorithm itself must be secure against side-channel attacks. An efficient high-order Boolean to arithmetic conversion scheme was recently described at CHES 2017, with complexity independent of the register size. In this paper we describe a simplified variant with fewer mask refreshing, and still...

Converting a Boolean mask to an arithmetic mask, and vice versa, is often required in implementing side-channel resistant instances of cryptographic algorithms that mix Boolean and arithmetic operations. In this paper, we describe a method for converting a Boolean mask to an arithmetic mask that runs in constant time for a fixed order. We propose explicit algorithms for a second-order secure Boolean-to-arithmetic mask conversion that uses 31 instructions and for a third-order secure mask...