With the development of quantum computers and quantum algorithms, many of our classical public-key cryptographic systems will be compromised. To circumvent this, one approach is to take our classical cryptographic systems and design them on mathematically hard problems for which no known quantum algorithms can provide a speedup. Our work revolves around one such cryptographic system, the anonymous credential protocol. In this thesis, we implement a post-quantum anonymous credential scheme, and extend it to include additional features like the disclosure of properties of attributes. We implement the protocol in Python, run a series of correctness tests, and then compare our work with implementations from the literature. We also outline a more complete picture of what adversarial models are needed for post-quantum security. The motivation behind our work is to build more usable, feature-intensive anonymous credential systems that are resistant to adversaries with quantum computing capabilities. We present our work as a step towards providing more easily accessiblesoftware for a larger audience to extend.
With the development of quantum computers and quantum algorithms, many of our classical public-key cryptographic systems will be compromised. To circumvent this, one approach is to take our classical cryptographic systems and design them on mathematically hard problems for which no known quantum algorithms can provide a speedup. Our work revolves around one such cryptographic system, the anonymous credential protocol. In this thesis, we implement a post-quantum anonymous credential scheme, and extend it to include additional features like the disclosure of properties of attributes. We implement the protocol in Python, run a series of correctness tests, and then compare our work with implementations from the literature. We also outline a more complete picture of what adversarial models are needed for post-quantum security. The motivation behind our work is to build more usable, feature-intensive anonymous credential systems that are resistant to adversaries with quantum computing capabilities. We present our work as a step towards providing more easily accessiblesoftware for a larger audience to extend.
Authentication on the Internet usually has the drawback of leaking the identity of the users, or at least allowing to trace them from a server to another. Anonymous credentials overcome this issue, by allowing users to reveal the attributes necessary for the authentication, without revealing any other information (in particular not their identity). In this article, we provide a generic framework to construct anonymous credential schemes and use it to give a concrete construction of post-quantum (lattice-based) anonymous credential protocol. Our protocol thus allows for long-term security even when one considers the emergence of quantum computers able to break widely used traditional computational assumptions, such as RSA, the discrete logarithm or Diffie-Hellman. We also give a concrete implementation of our protocol, which is only one order of magnitude slower and bandwidth consuming than previous anonymous credentials that are not post-quantum.
Anonymous credential (AC) systems are privacy-preserving authentication mech-anisms that allow users to prove that they have valid credentials anonymously. These systems provide a powerful tool for several practical applications, such as anonymous pay-ment systems in e-commerce, preserving robust privacy protection for users. Most existing AC systems are constructed using traditional number-theoretic approaches, making them insecure under quantum attacks. With four decades of research in anonymous credential systems, there is a need for a comprehensive review that identifies the design structures of AC systems, organizes the research trends, and highlights unaddressed gaps for the future development of AC, especially bringing AC to post-quantum cryptography. This work is a complete study describing AC systems, as well as their architecture, components, security, and performance. Additionally, real-world implementations of various applications are identified, analyzed, and compared according to the design structure. Lastly, the challenges hindering the shift toward the quantumly secure lattice-based AC designs are discussed.
The impending arrival of viable quantum computing is a major worry to modern-day identity management systems that mainly depend on classical public-key cryptography techniques such as RSA and elliptic curve. Such systems are the basis of secure infrastructure in digital identities such as authentication, digital signature and trust models based on certificates. These cryptographic primitives can be broken using quantum algorithms like Shor and Grover, compromising the privacy of credentials and sessions stored and authenticated on digital ecosystems. The paper provides the necessity of the transition of identity management systems to post-quantum cryptographic (PQC) algorithms that will be resistant to quantum attacks. It gives a general overview of quantum-exposed identity protocols, as well as a look at the up-and-coming PQC algorithms under development, with a special call to digital signature algorithms capable of identity provision, authentication, and credential lifecycle management. Moreover, the paper isolates the problems of integration which include key size overhead, legacy system compatibility and performance trade-offs and suggests integration to take place through the use of hybrid and decentralized framework to allow a secure migration. This study will form part of a strategic plan to a post-quantum identity infrastructure, with the long term reliability, validity, and withstanding of quantum-era vulnerabilities.
Anonymous credential schemes are a key application in modern cryptography. Recent research has advanced these schemes by incorporating issuer-hiding capabilities, which prevent the disclosure of the credential issuer’s identity. While several issuer-hiding anonymous credential schemes exist, none offer resilience against quantum computing adversaries. To address this gap, we propose a post-quantum issuer-hiding anonymous credential scheme, building on the recent work known as ring referral (S&P ’25), which allows anonymous signatures from third-party signers. Ring referral is an integration of ring signature and anonymous credential schemes, enabling issuer-hiding anonymous credentials. In this paper, we present an efficient lattice-based ring referral scheme, which supports quantum-resistant security. Our scheme extends a recent lattice-based credential scheme (CCS ’24) via LNP proof system (CRYPTO ’22).
Public-key cryptography is indispensable in maintaining the security and integrity of digital data. The most widely used current public-key cryptography is based on the integer factorization problem and the elliptic-curve discrete logarithm problem, which are vulnerable against an adversary with large-scale quantum computers. Fortunately, post-quantum cryptography (PQC) can provide security against both classical and quantum adversaries. Due to rapid advancement in quantum computer development, the transition from classical public-key cryptography to PQC has become imperative. A watershed moment in this transition is the recent publication of a set of PQC schemes by the National Institute of Standards and Technology (NIST). Although it is a significant step, the research and development in PQC is quite immature compared to several decades-old classical public-key cryptographic schemes. Therefore, several open problems, such as physical attack analysis and their countermeasures, application-specific modifications, lightweight implementations for resource-constrained devices, integration into different secure protocols, etc., need to be addressed before the widespread deployment of PQC in real-world applications. This dissertation aims to address some of these problems in order to bridge the gap between the theory and practice of PQC.
The advent of quantum computing poses a significant threat to the foundational cryptographic algorithms that secure modern digital communications. [27]. Protocols such as HTTPS, digital certificates, and public key infrastructures (PKIs) heavily rely on cryptographic primitives like RSA, ECC, and Diffie-Hellman, which are vulnerable to quantum attacks—most notably Shor’s algorithm. [18]. This paper presents a comprehensive comparative analysis between classical cryptographic algorithms currently in widespread use and emerging post-quantum cryptographic schemes designed to withstand quantum adversaries. [24]. We review the cryptographic mechanisms underpinning modern internet security, outline the mathematical foundations of quantum attacks, and evaluate the security, performance, and implementation feasibility of quantum-resistant alternatives such as Kyber, Dilithium, and Falcon. [25]. Additionally, we assess the hybrid approaches currently being explored by institutions and tech companies to enable a smooth transition to post-quantum cryptography. [23]. By providing an in-depth comparison, this study aims to guide researchers, developers, and policymakers in understanding the critical implications of quantum computing on cryptographic infrastructures and the necessary steps for securing communications in the quantum era. [16].