Extensible Markup Language (XML) is one of the most popular serialization languages. Since many security protocols are built using XML, it also provides cryptographic functionality. A central framework in this area is the Security Assertion Markup Language (SAML). This standard is one of the most widely used options for implementing Single Sign-On (SSO), which allows users to authenticate to different service providers using the credentials from a single identity provider. Like all other security protocols currently in use, the security and privacy of XML-based frameworks such as SAML is threatened by the development of increasingly powerful quantum computers. In fact, future attackers with access to scalable quantum computers will be able to break the currently used cryptographic building blocks and thus undermine the security of the SAML SSO to illegally access sensitive private information. Post-quantum cryptography algorithms have been developed to protect against such quantum attackers. While many security protocols have been migrated into the quantum age by using post-quantum cryptography, no such solutions for XML and the security protocols based on it have been developed, let alone tested. We make the following contributions to fill this gap. We have designed post-quantum solutions for the cryptographic building blocks in XML and integrated them into the SAML SSO protocol. We implemented our solutions in the OpenSAML, Apache Santuario, and BouncyCastle libraries and extensively tested their performance for various post-quantum instantiations. As a result, we have created a comprehensive and solid foundation for post-quantum XML and post-quantum SAML SSO migration.
Extensible Markup Language (XML) is one of the most popular serialization languages. Since many security protocols are built using XML, it also provides cryptographic functionality. A central framework in this area is the Security Assertion Markup Language (SAML). This standard is one of the most widely used options for implementing Single Sign-On (SSO), which allows users to authenticate to different service providers using the credentials from a single identity provider. Like all other security protocols currently in use, the security and privacy of XML-based frameworks such as SAML is threatened by the development of increasingly powerful quantum computers. In fact, future attackers with access to scalable quantum computers will be able to break the currently used cryptographic building blocks and thus undermine the security of the SAML SSO to illegally access sensitive private information. Post-quantum cryptography algorithms have been developed to protect against such quantum attackers. While many security protocols have been migrated into the quantum age by using post-quantum cryptography, no such solutions for XML and the security protocols based on it have been developed, let alone tested. We make the following contributions to fill this gap. We have designed post-quantum solutions for the cryptographic building blocks in XML and integrated them into the SAML SSO protocol. We implemented our solutions in the OpenSAML, Apache Santuario, and BouncyCastle libraries and extensively tested their performance for various post-quantum instantiations. As a result, we have created a comprehensive and solid foundation for post-quantum XML and post-quantum SAML SSO migration.
In 1994, Peter Shor developed a quantum algorithm that can efficiently solve the factorization and discrete logarithm problems. These problems are the foundation of modern cryptographic algorithms and the existence of an efficient algorithm for solving them threatens their security. Although large-scale quantum computers capable of breaking current cryptographic algorithms are not yet available, advances in quantum technology and the risk of “store now, decrypt later” attacks make it essential to prepare for migration to quantum-safe cryptography today. For the past decade, the cryptographic community has been actively developing algorithms that are not exploitable by Shor’s algorithm; such algorithms are said to be “quantum-safe” or “post-quantum.” However, cryptographic algorithms do not exist in isolation—they are components of larger cryptographic systems, such as protocols or other cryptographic primitives. Migrating these systems to use quantum-safe algorithms is therefore a complex task. This thesis studies the migration of several widely used cryptographic systems to post-quantum cryptography. In particular, we consider the migration of the public-key infrastructure (PKI), the TLS protocol, the XML Encryption and XML Signature standards, the SAML security framework, the Advanced Electronic Signature (AdES) standard, and the password-authenticated public-key encryption (PAPKE) primitive. For each topic, we analyze how the presence of quantum adversaries affects the security of existing constructions and identify components that rely on cryptographic assumptions vulnerable to quantum attacks. Based on this analysis, we propose approaches for adapting these systems to use post-quantum cryptographic algorithms. The proposed solutions are considered in two main forms: purely post-quantum and hybrid post-quantum. Purely post-quantum approaches rely exclusively on post-quantum algorithms, while hybrid post-quantum approaches combine classical and post-quantum mechanisms in order to provide security as long as at least one of the underlying assumptions remains secure. Hybrid post-quantum approaches are primarily motivated by uncertainty regarding the security of post-quantum algorithms. For each proposal, we discuss the advantages and disadvantages of the design, including deployment complexity, compatibility with existing systems, and performance considerations. In several cases, we also provide proof-of-concept implementations and evaluate their performance through benchmarks. We study post-quantum public-key infrastructures, which form a fundamental component of many other cryptographic systems. We show that constructing a purely post-quantum PKI does not fundamentally differ from constructing a classical PKI. For hybrid deployments, we propose two approaches—the composite hybrid and the parallel hybrid—which differ primarily in their implementation complexity. We also survey and analyze existing proposals for post-quantum TLS. In contrast, systems such as XML encryption and XML signatures, the SAML security framework, and the eIDAS-related AdES standard have received little attention in the context of post-quantum migration. For these systems, we outline possible migration approaches and provide proof-of-concept implementations. In addition, we present an example migration plan for a Trust Service Provider that relies on all of the discussed cryptographic systems, together with the methodology used to develop it. Finally, we consider the migration of the cryptographic primitive PAPKE. We propose a novel construction that replaces an ideal cipher with a half-ideal cipher, resulting in more efficient quantum-safe constructions and motivating the study of a new public-key encryption property called decryption robustness.
Advancements in quantum computing create substantial risks for classical cryptographic systems, particularly RSA and Elliptic-Curve Cryptography, that underpin FIDO2 and WebAuthn authentication protocols. Shor's algorithm can compromise these systems by extracting private keys from their public counterparts when sufficiently powerful quantum computers exist. Passwordless authentication has grown increasingly prevalent, with FIDO2 and WebAuthn serving as core trust elements within digital identity architectures. Quantum-enabled attackers present serious challenges to both credential security and attestation validation processes. Organizations must adopt post-quantum cryptographic methods proactively to sustain authentication integrity while maintaining existing trust structures. The harvest-now-decrypt-later paradigm presents urgent risks where malicious entities intercept and store authentication traffic for future decryption upon quantum computer maturation. FIDO2 credentials embedded within authenticators or bound to user devices maintain long lifespans, often synchronized across cloud ecosystems as passkeys, creating extended vulnerability windows. Post-quantum migration represents both cryptographic enhancement and essential lifecycle management spanning authenticators, browsers, servers, and attestation authorities. This framework proposes a crypto-agile hybrid WebAuthn architecture integrating classical and post-quantum algorithms. Embedding ML-DSA for digital signatures and ML-KEM for key encapsulation within WebAuthn registration and authentication flows enables progressive credential rotation without disrupting trust chains. The architecture aligns with CBOR Object Signing and Encryption identifiers and emerging IETF post-quantum WebAuthn specifications, ensuring standards compliance.
Advancements in quantum computing create substantial risks for classical cryptographic systems, particularly RSA and Elliptic-Curve Cryptography, that underpin FIDO2 and WebAuthn authentication protocols. Shor's algorithm can compromise these systems by extracting private keys from their public counterparts when sufficiently powerful quantum computers exist. Passwordless authentication has grown increasingly prevalent, with FIDO2 and WebAuthn serving as core trust elements within digital identity architectures. Quantum-enabled attackers present serious challenges to both credential security and attestation validation processes. Organizations must adopt post-quantum cryptographic methods proactively to sustain authentication integrity while maintaining existing trust structures. The harvest-now-decrypt-later paradigm presents urgent risks where malicious entities intercept and store authentication traffic for future decryption upon quantum computer maturation. FIDO2 credentials embedded within authenticators or bound to user devices maintain long lifespans, often synchronized across cloud ecosystems as passkeys, creating extended vulnerability windows. Post-quantum migration represents both cryptographic enhancement and essential lifecycle management spanning authenticators, browsers, servers, and attestation authorities. This framework proposes a crypto-agile hybrid WebAuthn architecture integrating classical and post-quantum algorithms. Embedding ML-DSA for digital signatures and ML-KEM for key encapsulation within WebAuthn registration and authentication flows enables progressive credential rotation without disrupting trust chains. The architecture aligns with CBOR Object Signing and Encryption identifiers and emerging IETF post-quantum WebAuthn specifications, ensuring standards compliance.
The development of quantum computing poses a very real threat to traditional cryptography, especially these, which are number-theoretic like RSA and ECC. With the more and more development of quantum algorithms such as Shor and Grover, there is an immediate necessity to come up with cryptographic protocols that are resistant to quantum attacks. This paper reviews and discusses different quantum-resistant (post-quantum) cryptographic schemes, such as lattice-based, code-based, multivariate, hash-based, and isogeny-based cryptography. It compares these protocols on the assumptions of their security and their efficiency in their computation and the size of their keys as well as their possible integrations into the existing communication infrastructure. Moreover, we also evaluate the standardization process by NIST and the difficulties of moving towards post-quantum security in practical use. This paper proposes a scalable comparison system, which correlates the hypothetical security basis of postquantum cryptography with the ability to effectively operate in the real world. It has emphasized protocol interoperability, migration compatibility and trade-offs in performance that gives a viable roadmap towards quantum-resistant cryptographic protocols implementation into current communication infrastructures whilst also providing scalable and future secure communication systems. This study, by emphasizing the potential and the drawbacks of the existing post-quantum cryptography schemes, helps in a more precise idea of the directions to follow on the way to a secure, future-proof communications scheme.
The development of quantum computing poses a very real threat to traditional cryptography, especially these, which are number-theoretic like RSA and ECC.With the more and more development of quantum algorithms such as Shor and Grover, there is an immediate necessity to come up with cryptographic protocols that are resistant to quantum attacks.This paper reviews and discusses different quantum-resistant (post-quantum) cryptographic schemes, such as latticebased, code-based, multivariate, hash-based, and isogeny-based cryptography.It compares these protocols on the assumptions of their security and their efficiency in their computation and the size of their keys as well as their possible integrations into the existing communication infrastructure.Moreover, we also evaluate the standardization process by NIST and the difficulties of moving towards post-quantum security in practical use.This paper proposes a scalable comparison system, which correlates the hypothetical security basis of post-quantum cryptography with the ability to effectively operate in the real world.It has emphasized protocol interoperability, migration compatibility and trade-offs in performance that gives a viable roadmap towards quantum-resistant cryptographic protocols implementation into current communication infrastructures whilst also providing scalable and future secure communication systems.This study, by emphasizing the potential and the drawbacks of the existing post-quantum cryptography schemes, helps in a more precise idea of the directions to follow on the way to a secure, future-proof communications scheme.
Transport Layer Security (TLS) is the backbone security protocol of the Internet. As this fundamental protocol is at risk from future quantum attackers, many proposals have been made to protect TLS against this threat by implementing post-quantum cryptography (PQC). The widespread interest in post-quantum TLS has given rise to a large number of solutions over the last decade. These proposals differ in many aspects, including the security properties they seek to protect, the efficiency and trustworthiness of their post-quantum building blocks, and the application scenarios they consider, to name a few. Based on an extensive literature review, we classify existing solutions according to their general approaches, analyze their individual contributions, and present the results of our extensive performance experiments. Based on these insights, we identify the most reasonable candidates for post-quantum TLS, which research problems in this area have already been solved, and which are still open. Overall, our work provides a well-founded reference point for researching post-quantum TLS and preparing TLS in practice for the quantum age.