Public-key cryptography, developed in the mid-1970s, established the foundations on which the modern internet was built. It provided two fundamental capabilities: confidentiality, which keeps information secret from those who should not read it, and authenticity, which verifies that a message comes from its claimed source. These capabilities underpin most secure internet operations today, including web traffic, software distribution and the certificates that authenticate digital identities.
The prospect of large-scale quantum computers threatens these foundations. Over the past decade, the international cryptographic community has responded through a coordinated standardization effort, led by the US National Institute of Standards and Technology (NIST), to identify and standardize post-quantum algorithms that run on today’s classical hardware but resist attack by adversaries with quantum capability. The first standards were finalized in August 2024. Further selections remain in progress, and national migration programs, including the UAE’s, are underway.
Standards, however, define algorithms; they do not resolve every question about how those algorithms will work in practice and they do not exhaust what cryptography must provide. Modern digital systems increasingly require capabilities that reach beyond encryption and authentication — the ability to prove properties without revealing them, to authenticate anonymously while still detecting duplication, to prove possession of a secret key without exposing it. These capabilities are the subject of active research and will shape the next generation of secure digital infrastructure.
This whitepaper sets out how work at the Technology Innovation Institute’s Cryptography Research Center is contributing to that frontier. It provides a brief overview of the standards baseline, articulates the class of capabilities that extend beyond it, and examines three recent research contributions from the center — in certificate infrastructure for post-quantum key exchange, anonymous authentication with programmable linkability, and ring signatures that preserve anonymity while catching duplicate signers — as illustrations of what frontier work looks like today.
1. Introduction: The Standards Baseline
The standardization of post-quantum cryptography is the most consequential development in applied cryptography of the past decade. Following NIST’s multi-year selection process, the first three post-quantum standards were finalized in August 2024, covering key exchange and digital signature schemes. A fifth standard, HQC (a code-based key exchange mechanism, valued for its independent mathematical foundations) was selected in March 2025. Further selections remain in progress.
Researchers at the Technology Innovation Institute’s Cryptography Research Center have contributed to this process from its early stages, participating in the design, analysis, benchmarking, and refinement of multiple candidate schemes.
These standards address the two foundational cryptographic capabilities on which the modern internet was built. Confidentiality (encryption that prevents unauthorized parties from reading data) and authenticity (signatures that prove a message has not been altered and comes from its claimed source) are now provided with post-quantum security. Together, these capabilities cover most of what happens on the internet today, from securing web traffic to authenticating software updates and verifying identities in defense communications and financial infrastructure.
Alongside standardization, national migration programs are underway. Multiple jurisdictions have issued regulations requiring migration timelines for critical infrastructure. The UAE migration is anchored in a national cryptography law with a phased approach coordinated by the Cyber Security Council.
These efforts ensure that the confidentiality and authenticity of digital systems can survive the arrival of quantum computers. They do not address — and are not designed to address — the broader cryptographic capabilities that modern digital systems increasingly require.
The third capability
Encryption keeps information secret. Signatures prove that it comes from a particular party and has not been altered. Almost every secure operation on the internet is built from these two primitives.
A third capability has become central to how modern digital systems are designed. It is the ability to prove properties without revealing them: to demonstrate that a claim holds without disclosing the underlying data on which it rests.
Consider a voter in an electronic voting system who needs to prove that they are eligible to vote as they hold credentials from an authorized register without revealing their identity or their vote. Or a regulated entity that must demonstrate compliance with a sectoral rule while keeping its commercial data private. Or a party requesting a digital certificate for a new post-quantum key exchange algorithm — one for which the traditional signing-based proof of key ownership does not work — and needs to prove they hold the corresponding secret key.
Each of these operations sits outside what encryption and signatures can achieve. Encryption hides content and signatures identify signers. Neither can conceal an identity while proving something about it and neither can support selective, controlled disclosure. The third capability supplies what they cannot.
In classical cryptography, many of these capabilities are well-studied, with mature constructions available for practical use. In the post-quantum setting, the picture is different. Each capability must be reconstructed against a new threat model, often from different mathematical foundations, with different trade-offs, and with performance characteristics that must be tested, not assumed.
Attribute-based signatures allow authentication based on credentials without revealing which credentials. Ring signatures allow group authentication without identifying which member signed. Proofs of possession allow demonstration of secret-key ownership without exposing the key itself. Each has a distinct mathematical structure. Each is the subject of active research. And each has direct implications for the systems being designed today: for identity, regulation, defense, and the privacy-preserving public infrastructure that increasingly underpins the digital economy.
2. Three Contributions at the Frontier
Three recent research contributions from the Cryptography Research Center, produced in collaboration with international partners, illustrate what frontier work in post-quantum cryptography looks like in practice. The first addresses the deployability of the standard algorithms themselves. The second and third extend cryptographic capability beyond what the standards cover, into the terrain of privacy-preserving authentication.
Making the Standards Deployable: Proof-of-Possession for HQC
Every certificate on the modern internet — the certificates that authenticate web servers, sign software updates, and underpin trust across the digital economy — is issued through a specific mechanism. When a party requests a certificate from a certificate authority, they must demonstrate ownership of the private key corresponding to the public key they are presenting. In today’s cryptography, this proof is a signature.
That mechanism does not translate to the new generation of post-quantum key exchange algorithms. Schemes like HQC (Hamming Quasi-Cyclic) provide operations for generating and exchanging keys, but they do not provide a signing operation that can be used to prove key ownership. Without a compatible proof-of-possession mechanism, the certificate infrastructure that the modern internet depends on cannot issue certificates for post-quantum keys at scale.
The consequence is practical and immediate. Automated certificate issuance protocols (most notably ACME, the protocol behind mass certificate issuance across the web) depend on the signing-based mechanism. In the absence of an alternative that preserves both cryptographic soundness and protocol compatibility, migration to post-quantum key exchange at internet scale is blocked, however well the algorithms themselves are standardized.
Several proof-of-possession approaches for post-quantum keys have been proposed. Each carries a trade-off. Some are computationally faster but require modifications to key generation that break compliance with the NIST standard. Some preserve compliance but require interactive protocols that break compatibility with ACME. Others impose proof sizes that create real-world performance problems under the unstable network conditions of the actual internet.
The Cryptography Research Center’s contribution proposes a non-interactive proof-of-possession construction for HQC that keeps compliance with the emerging NIST standard, remains compatible with the ACME protocol as deployed, and produces smaller proofs than competing approaches. Empirical testing under simulated unstable network conditions demonstrates that the smaller proof size translates into competitive performance in the deployment conditions where alternative approaches degrade.
Rather than building a new cryptographic capability, it removes an obstacle to the deployment of a capability the standards process has otherwise cleared for adoption.
Programmable Anonymity: Conditionally Linkable Attribute-Based Signatures
Attribute-based signatures allow a party to prove that they satisfy a policy — that they hold credentials from an authorized organization, that they belong to a defined sector, that they meet particular regulatory criteria — without revealing which specific credentials they hold or who they are. The signer proves compliance; the verifier learns nothing else. This is a foundational primitive for privacy-preserving authentication.
Existing attribute-based signature schemes share a structural limitation. They treat anonymity as all-or-nothing: Signatures are always either unlinkable (meaning that two submissions by the same signer cannot be recognized as such) or always linkable, meaning that the correlation is universal and the anonymity commensurately weakened.
Neither position captures what real systems need. A voting system may need to detect when the same participant votes twice within a single election, while keeping votes across different elections unlinkable. A regulatory framework may require entities within a defined class to be publicly consistent in their filings while keeping other entities fully private. A verifiable credential system may need to allow correlation within a specific audit context and nowhere else. In each case, the requirement is neither universal anonymity nor universal linkability, but a controlled, declared correlation that arises only under specific circumstances.
The contribution introduces Conditionally Linkable Attribute-Based Signatures (CLABS), a framework in which linkability is programmable and context-dependent. Each signer declares, at registration, the specific contexts in which their signatures may be publicly correlated. Two signatures become linkable only when both signers have opted into the same context and their credentials match under a publicly defined rule. Outside those declared contexts, signatures remain fully unlinkable. The public can determine which contexts are subject to correlation; it cannot determine anything else about the signers.
The framework was designed to be modular. The researchers first defined it in general terms, so that it could be built from a range of underlying cryptographic ingredients. They then produced a specific working version, built on the branch of post-quantum mathematics known as lattice-based cryptography, and proved that it holds up against attack by a quantum adversary.
The framework fits systems that need to correlate some actions and not others under explicit rules — anonymous consultations that must catch duplicate submissions within a single round or credentials that can linked within one service session but not across services, for example.
Anonymous Authentication with Duplicate Detection: Linkable Ring Signatures
Ring signatures allow a signer to authenticate a message as coming from a group — a ring — without revealing which member signed. The signer chooses the ring; no group manager is required and no prior enrollment is needed. This makes ring signatures a foundational tool for anonymous authentication, with applications ranging from whistleblowing platforms to anonymous credential systems to electronic voting.
For many of these applications, anonymity alone is insufficient. A voting system must detect when the same participant votes twice, even if both votes are anonymous. An anonymous consultation must catch duplicate submissions. A privacy-preserving credential system must prevent double-use of single-use credentials. Linkability makes this possible: the ability to determine, given two signatures, whether they were produced by the same signer, without determining who that signer is.
Post-quantum linkable ring signatures have been an active research area. Several existing constructions rely on a common mechanism, in which the signer’s secret key is reused for both the signature and the linkability tag. That mechanism turned out to be too fragile, as recent cryptanalysis has shown that constructions of this form, when applied to certain post-quantum settings, either fail to achieve linkability or introduce correctness problems. The elegance that made these schemes attractive made them insecure.
The contribution introduces a new framework that allows linkable ring signatures to be constructed without the vulnerable key-reuse mechanism. In its place, the framework uses two distinct secret keys, related by an equivalence relation, one for signing and one for the linkability tag. This separation removes the class of attacks that undermined earlier constructions while preserving both the anonymity and linkability properties.
3. Building Beyond the Standards
The three contributions described in this whitepaper sit at the research frontier and together they illustrate the shape of the territory now being explored. One removes a deployment obstacle for algorithms already progressing through standardization. Two extend cryptographic capability into terrain the standards do not cover.
Cryptography for the post-quantum era is not a single problem to be solved by a single standards process. It is a stack of interrelated problems at the algorithm level, infrastructure level and capability level, and each layer requires its own research at the frontier.
At the algorithm level, the standards are close to complete. The international effort has produced deployable schemes that will underpin the next generation of secure digital systems.
At the infrastructure level, work of the kind exemplified by the HQC proof-of-possession construction determines whether standardized algorithms deploy or stall at the boundary between cryptographic theory and internet-scale operations. Without deployability work, standardization produces algorithms that cannot be issued in certificates, integrated into existing protocols or scaled into production.
At the capability level, the second and third contributions determine what the next generation of privacy-preserving digital infrastructure will be able to do — whether verifiable credentials, sectoral audits, anonymous consultations, and privacy-preserving regulatory frameworks are built on cryptography that can support them or built on approximations.
None of this work is pursued alone. Post-quantum cryptography is a globally distributed research effort and progress depends on the shared body of knowledge that the international research community generates and refines together.
For the UAE, this matters at two levels. As a national capability question, sovereign strength in the technologies underpinning the digital economy of the next decade requires research capability at the frontier, not only implementation capacity for the standards downstream. And as a contribution to the international commons, the UAE’s presence in frontier post-quantum research is part of the country’s positioning as a serious participant in the applied science that will shape the coming decades of digital infrastructure.