Passports, identity cards and travel visas are examples of machine readable travel documents (MRTDs) or eMRTDs for their electronic variants. The security of the data exchanged between these documents and a reader is secured with a standardized password authenticated key exchange (PAKE) protocol known as PACE. A new world-wide protocol migration is expected with the arrival of post-quantum cryptography (PQC) standards. In this paper, we focus on the impact of this migration on constrained embedded devices as used in eMRTDs. We present a feasibility study of a candidate post-quantum secure PAKE scheme as the replacement for PACE on existing widely deployed resource-constrained chips. In a wider context, we study the size, performance and security impact of adding post-quantum cryptography with a focus on chip storage and certificate chains for existing eMRTDs. We show that if the required post-quantum certificates for the eMRTD fit in memory, the migration of existing eMRTD protocols to their post-quantum secure equivalent is already feasible but a performance penalty has to be paid. When using a resource constrained SmartMX3 P71D600 smart card, designed with classical cryptography in mind, then execution times of a post-quantum secure PAKE algorithm using the recommended post-quantum parameter of the new PQC standard ML-KEM can be done in under a second. This migration will be aided by future inclusion of dedicated hardware accelerators and increased memory to allow storage of larger keys and improve performance.
Discovering, managing, and reporting on cryptographic assets is a critical step for the transition to quantum-safe systems and applications. Cryptography Bills of Materials (CBOMs) have been proposed as an aid to cryptographic inventory, agility, and compliance with guidelines to create more secure software and services. Writing policies and automating compliance checks for cryptography is a valuable but complex task. We present a prototype framework for automated evaluation of cryptographic compliance extending existing CBOM tools with a policy-driven engine that classifies cryptographic assets according to customizable rules and compliance levels. Machine-readable policies enable flexible adaptation to different guidelines while supporting analysts in performing semi-automatic assessments. The prototype is validated through experiments on both synthetic and real-world software. Results show that the system correctly identifies deprecated and disallowed primitives, producing clear compliance reports. While we highlight some difficulties common to automating compliance checks, our findings demonstrate the potential of CBOM-based approaches to enhance visibility, governance, and readiness for the post-quantum cryptography transition.
eIDAS 2.0 (electronic IDentification, Authentication and trust Services) is a very ambitious regulation aimed at equipping European citizens with a personal digital identity wallet (EU Digital Identity Wallet) on a mobile phone that not only needs to achieve a high level of security, but also needs to be available as soon as possible for a large number of citizens and respect their privacy (as per GDPR - General Data Protection Regulation). In this paper, we introduce the foundations of a digital identity wallet solution that could help move closer to this objective by leveraging the proven anonymous credentials system BBS (Eurocrypt 2023), also known as BBS+, but modifying it to avoid the limitations that have hindered its widespread adoption, especially in certified infrastructures requiring trusted hardware implementation. In particular, the solution we propose, which we call BBS# , does not rely, contrary to BBS/BBS+, on bilinear maps and pairing-friendly curves (which are not supported by existing hardware) and only depends on the hardware implementation of well-known digital signature schemes such as ECDSA (ISO/IEC 14888-3) or ECSDSA (also known as ECSchnorr, ISO/IEC 14888-3) using classical elliptic curves. More precisely, BBS# can be rolled out without requiring any change in existing hardware or the algorithms that hardware supports. BBS# , which is proven secure in the algebraic group and random oracle models (AGM+ROM), retains the well-known security property (unforgeability of the credentials under the (gap) q-SDH assumption) and anonymity properties (multi-show full unlinkability and statistical anonymity of presentation proofs) of BBS/BBS+. By implementing BBS# on several smartphones using different secure execution environments, we show that it is possible to achieve eIDAS 2.0 transactions which are not only efficient (around 70 ms on Android StrongBox), secure and certifiable at the highest level but which would also provide strong (optimal) privacy protection for all European ID Wallet users.
Accessing online services requires users to choose from a growing set of identity providers, including social logins (e.g., Google), national eID providers (e.g., CIE), and recently, under the revised electronic Identification, Authentication and Trust Services regulation (eIDAS 2.0), “Log in with Digital Wallet”. In self sovereign identity settings, this choice worsens the “NASCAR problem”: users must select among many wallets, while relying parties face significant integration and maintenance costs. The W3C Digital Credentials API shifts selection from the wallet to the specific credential required by the relying parties, enabling a simpler and more interoperable user journey. To achieve this, the API mediates requests and responses through both web and operating system interfaces. Yet this multi-party, cross layer architecture, which spans user agents, operating systems, and wallets, expands the attack surface. This paper presents a preliminary threat model for the Digital Credentials API to identify and mitigate potential threats, thereby supporting a secure, privacy preserving, and interoperable self sovereign identity ecosystem.
Digital identity wallets are currently being developed around the globe, aiming to provide user-centric and secure authentication. Realizing this in a privacy-preserving manner is paramount, and even mandated in Europe which is developing the European Digital Identity Wallet with planned release in 2026. Current proposals to build these wallets are based on classic signature schemes such as ECDSA, but would benefit greatly from the use of anonymous credentials. Thus, there is currently a strong interest in developing the necessary standards to bring these cryptographic concepts into the real world. This work aims to inform ongoing standardization efforts by providing an overview of the most prominent solutions, and the remaining open challenges. We split our overview among two fundamental architectural approaches: (1) dedicated multi-message signature schemes that allow for efficient ZKPs, and (2) general-purpose ZKPs used on top of legacy ECDSA. We also provide a comprehensive summary of the broad feature set that anonymous credentials can provide for identity wallets, in order to demonstrate that upgrading to these systems is a worthwhile endeavor and help to design standards that can leverage the rich existing body of work.
Overhead costs associated with post quantum (PQ) algorithms, especially digital signatures, create a significant barrier to incorporation and adoption of post quantum cryptographic protocols in various settings. To counter this, the working group for the Messaging Layer Security (MLS) protocol under the Internet Engineering Task Force has proposed an approach where traditional and PQ sessions of the protocol are strategically combined in such a way as to amortize PQ-associated overhead, i.e., an Amortized Post Quantum (APQ) combiner. In this work, we implement and benchmark APQ using standardized NIST algorithms (ML-KEM and ML-DSA) integrated into OpenMLS with native Rust cryptographic libraries, presenting the first comprehensive performance evaluation of APQ to include PQ authenticity. Our evaluation encompasses execution run-time, message size, and memory consumption across various security levels and amortization ratios to compare and contrast MLS with traditional-only, APQ confidentiality-only, APQ confidentiality+authenticity, and an alternative hybrid ciphersuite. We demonstrate that APQ achieves exponential improvements in message size and memory efficiency as amortization traditional:PQ ratios decrease from 1:1 to 1:100, with optimal performance observed around 1:50 ratios. These findings establish APQ as a practical solution for deploying post quantum security in resource constrained settings.
We report on our experiences with the ongoing European standardisation efforts related to the EU Cyber Resilience Act (CRA) and provide interim (November 2025) estimates on the direction that European cryptography regulation may take, particularly concerning the algorithm “allow list” and PQC transition requirements in products. The CRA has a wide-ranging set of security requirements, including security patching and the use of cryptography (data integrity, confidentiality for data at rest and data in transit). However, the Cyber Resilience Act itself is a legal text devoid of technical detail – it does not specify the type of cryptography deemed appropriate to satisfy its requirements. The technical implications of CRA are being detailed in approximately 40 new standards from the three European standardisation organisations, CEN, CENELEC, and ETSI. While the resulting ETSI standards can be expected to be available for free even in the drafting stage, the CEN and CENELEC standards will probably require a per-reader license fee. This, despite recent legal rulings asserting that product security and safety standards are part of EU law due to their legal effects. We outline some of the risks associated with the partially closed standardisation process, including active impact minimisation by vendors concerned with engineering costs, a lack of public review leading to lower technical quality, and an increased potential for backdoors. Taking a recent (2024) example of cryptographic requirements in such standards, we observe that the definitions and language in the Radio Equipment Directive (RED DA) harmonised standard (EN 18031 series) may allow vendors to take an approach where weak cryptography is considered “best practice” right until exploitation is feasible. Recognising recent developments such as the EU Post-Quantum Cryptography transition roadmap, many CRA standardisation working groups are moving towards a “State-of-the-Art Cryptography” (SOTA Cryptography) model where approved mechanism listings are published by the European Cybersecurity Certification Group (ECCG). CRA-compliant products may still support other cryptographic mechanisms, but only SOTA is permitted as a safe default for Internet-connected products.
Anonymous credentials enable the unlinkable presentation of previously attested information, or even only predicates thereof. They are a versatile tool and currently enjoy attention in various real-world applications, ranging from the European Digital Identity project to Privacy Pass. While each application usually requires their own tailored variant of anonymous credentials, they all share the same common blueprint. So far, this has not been leveraged though, and currently several proposals either targeting monolithic variants of core components such as BBS signatures, or application-specific protocols undergo standardization. This is clearly not optimal, as the same work gets repeated multiple times, while still risking ending up with many slight modifications of the same main idea and protocols. In this work we present our vision to use a modular approach to build anonymous credential systems: they are built from a core component – consisting of a commitment, signature and NIZK scheme – that can be extended with additional commitment-based modules in a plug-and-play manner. We sketch modules for pseudonyms, range proofs and device binding. Importantly, apart from the committed input, all modules are entirely independent of each other. We use this modularity to propose a concrete instantiation that uses BBS signatures for the core component and ECDSA signatures for device binding, addressing the need to bind modern credential schemes to legacy signatures in secure hardware elements.
Among standardization efforts for space and interplanetary network security, the Internet Engineering Task Force (IETF) is driving work on space network security, accounting for the unique properties of space environments that make space communication challenging. This includes long, variable-length delays, packet loss, and intermittent end-to-end connectivity. Within these efforts, there is a focus on using IP-based protocols for security, and in particular the use of the QUIC protocol. This is unsurprising given QUIC’s growing popularity and offer of optimization intended for reducing latency. However, QUIC uses the Transport Layer Security (TLS) key exchange handshake protocol, which was originally designed for ‘connect and forget’ style Internet connections at scale. It is also session-based, where protocol participants require reestablishment of the session for each reconnection – a costly maneuver in the space setting. Furthermore, TLS by default does not achieve strong post-compromise security properties within sessions, exhibiting a risk under long-lived connections, and need for synchronous handshakes to counteract this are in functional contrast to the space environment, which has intermittent end-to-end connectivity. We address both drawbacks of QUIC by introducing QUIC-MLS: a variant of QUIC which replaces the session-based, synchronous TLS handshake with the standardized continuous key agreement protocol, Messaging Layer Security (MLS), which achieves asynchronous forward secrecy and post-compromise security. In addition to the design itself, we implement our design and provide benchmarks, and analyze our new construction in a formal cryptographic model.
As a case study in cryptographic binding, we present a formal-methods analysis of the cryptographic channel binding mechanisms in the Fast IDentity Online (FIDO) Universal Authentication Framework (UAF) authentication protocol, which seeks to reduce the use of traditional passwords in favor of authentication devices. First, we show that UAF's channel bindings fail to mitigate protocol interaction by a Dolev-Yao adversary, enabling the adversary to transfer the server's authentication challenge to alternate sessions of the protocol. As a result, in some contexts, the adversary can masquerade as a client and establish an authenticated session with a server (e.g., possibly a bank server). Second, we implement a proof-of-concept man-in-the-middle attack against eBay's open source FIDO UAF implementation. Third, we propose and formally verify improvements to UAF. The weakness we analyze is similar to the vulnerability discovered in the Needham-Schroeder protocol over 25 years ago. That this vulnerability appears in the FIDO UAF standard highlights the strong need for protocol designers to bind messages properly and to analyze their designs with formal-methods tools. To our knowledge, we are first to carry out a formal-methods analysis of channel binding in UAF and first to exhibit details of an attack on UAF that exploits the weaknesses of UAF's channel binding. Our case study illustrates the importance of cryptographically binding context to protocol messages to prevent an adversary from misusing messages out of context.
Blockchain builds a trustworthy service among parties that do not have to trust each other. In recent years, blockchain applications have exploded, ranging from financial services to governmental applications. In this article, we review blockchain consensus, the crucial building block for blockchains to achieve security goals. By selectively discussing the trade-offs made by each type of consensus protocol and conducting a review of blockchain-related standards, we discuss why we need to standardize blockchain consensus and what challenges are yet to be solved before or even after blockchain consensus is standardized.
Secure multi-party computation (SMPC) enables the output of an intended function to be computed, while it keeps the individual inputs confidential. Thus, SMPC will play an important role in the data industry to protect privacy, and promote data flow to produce values in privacy-sensitive scenarios. Before SMPC has been widely adopted and applied in real-world information systems, related technical standards are imperative to coordinate developers, manufacturers, service providers, and users. This paper proposes a vision of SMPC technical standards. The proposed SMPC technical framework is composed of four layers, namely, the SMPC protocol layer, the SMPC device layer, the SMPC system layer, and the layer of common supporting function (CSF). Each layer includes several standards specifying some aspects of SMPC technologies and applications: (a) the SMPC protocol layer specifies different types of protocols and also protocol components; (b) the device layer defines various SMPC devices, each of which runs independently and implements a certain set of SMPC protocol operations; (c) the system layer specifies function requirements of an SMPC system, such as computation function, configuration and coordination, and security requirements, such as authentication, privilege management, data authorization, communication security, storage security, and log; and (d) the CSF layer defines typical common supporting functions for popular applications, such as joint data aggregation, joint modeling/prediction, privacy-preserving information retrieval, and sample alignment.
The Key Encapsulation Mechanism (KEM) is one of the most important foundational cryptographic primitives. It can be used to construct Public Key Encryption (PKE), Key Exchange, and Authenticated Key Exchange. With the continuing advances in quantum computing (e.g., Shor’s algorithm), traditional KEMs based on RSA and ECC will eventually become insecure. As the NIST Post-Quantum Cryptography (PQC) Standardization progresses, exploring the construction of post-quantum secure KEMs has become a highly relevant topic. This paper presents a comprehensive survey of general constructions of post-quantum secure KEMs in both the random oracle model (ROM) and quantum random oracle model (QROM), focusing on their security definitions, general constructions, and practical applications. We examine key security notions for KEMs, such as OW-CPA, IND-CPA, IND-1CCA, and IND-CCA, as well as their general construction from CPA-secure PKE schemes alongside applications in real-world protocols, including TLS 1.3, KEMTLS, Signal, and Noise. Specifically, we examine the FO and modular variants for IND-CCA KEMs, three distinct T-transforms for IND-1CCA KEMs, and the CPA transform for CPA-secure KEMs derived from CPA-secure PKEs. We further discuss the security requirements of KEMs within various protocols and highlight that IND-1CCA KEMs can be used to construct practical protocols such as KEMTLS, Signal, and Noise. In particular, CPA-secure KEMs can be employed in constructing post-quantum TLS 1.3.
Recent reports on the timeline of quantum threats suggest that large, scalable quantum computers will likely become a reality in the near future. This impending technological advancement has increased the urgency for standardisation of and migration to Post-Quantum Cryptography (PQC), making it a critical focus for information and cybersecurity experts. In this document, we will provide an overview of the current state of standardisation efforts in the field of PQC and explore its implications across various sectors, including industry, academic research, open-source development, and government agencies. Additionally, we will address some future work that remains unaddressed within existing standardisation initiatives, offering insights into the areas that require further attention and development.
To deal with the potential threat of quantum computers, both industry and academia have started to deploy schemes that are composition of classically secure and quantum-secure constructions. In particular, the IETF has proposed three composite encryption modes that establish a shared key using a combination of public key encryption, key encapsulation, and key exchange primitives. However, no security proofs are provided. As a complement to their proposals, this work first defines various quantum CPA-security that capture the capability of adversary during the transition to the fully quantum world. Towards this goal, we follow the footprint by Bindel et al. (PQCrypto 2017, PQCrypto 2019) to categorize the adversaries according to whether the adversaries have a quantum computer and whether they have quantum access to the challenge queries. We then observe that our security definitions coincide with those defined by Gagliardoni (Thesis 2017), which could be of independent interest. Finally, we prove the quantum CPA-security of the first two composite encryption modes in the IETF draft. The results show that the composite schemes are secure as long as at least one of its components is secure.
IP cameras have become a popular option in residential spaces, especially for family members, pet owners, and others who wish to monitor their home from afar, providing both security and peace of mind. The ease of use, the ability to stream real-time data and the affordable price make them an attractive choice not just in homes, but also in commercial environment. However, just like any other IoT devices, any misconfiguration during the manufacturing or deployment process can result in an insecure device and privacy leakage. In this study, we compared and analysed different legislation related to IoT devices across the globe. We have identified multiple privacy and security implications by accessing and evaluating 281 footage from publicly accessible Internet Protocol cameras (IP cameras) available on Shodan in the UK. We evaluate such risks by using ChatGPT, in addition to a manual assessment. Our results show that general large language models such as ChatGPT are highly accurate in detecting the content of such footage e.g., detecting the presence of people in those images. Our findings highlight the need of security awareness among the users and manufacturers, as well as addressing the inconsistencies across different legislation worldwide.
We present Scloud^+ , an LWE-based key encapsulation mechanism (KEM). The key feature of Scloud^+ is its use of the unstructured-LWE problem (i.e., without algebraic structures such as rings or modules) and its incorporation of ternary secrets and lattice coding to enhance performance. A notable advantage of the unstructured-LWE problem is its resistance to potential attacks exploiting algebraic structures, making it a conservative choice for constructing high-security schemes. However, a key disadvantage of such schemes is their limited computational and communication efficiency. Scloud^+ utilizes ternary secrets and BW_32 lattice codes to enhance noise control and ensure robust error correction during decryption, enabling smaller parameters while maintaining low decryption failure probabilities. Equipped with these techniques, Scloud^+ exhibits a significant improvement in efficiency. When compared with FrodoKEM for parameter sets targeting 128, 192, and 256 bits of security respectively, Scloud^+ achieves practical performance with a public key size approximately 0.71 ∼ 0.87 x and a ciphertext size approximately 0.56 ∼ 0.78 x that of FrodoKEM. The encapsulation plus decapsulation time is approximately 0.74 ∼ 0.84 x that of FrodoKEM.
We present the first formal-methods analysis of the Session Binding Proxy (SBP) protocol, which mitigates theft of a server-issued authentication cookie from a client communicating with a vulnerable, legacy server. To protect the cookie, SBP cryptographically binds the cookie to an underlying Transport Layer Security (TLS) channel using the channel’s master secret and a secret key known only to a reverse proxy, which SBP introduces between the server and the client. An adversary who steals the bound cookie cannot reuse this cookie to create malicious requests on a separate connection because the cookie’s channel binding will not match the adversary’s channel. Because SBP does not modify the client or server software, it renders the client and server “oblivious protocol participants” that are not aware of the SBP session. Our analysis verifies that SBP mitigates cookie theft under the client’s cryptographic assumptions but fails to authenticate the client under the proxy’s assumptions: the proxy lacks assurance that the client generates a fresh TLS pre-master secret, and the legacy server relies on usernames and passwords to authenticate the client. Our analysis of this obscure protocol sheds insight into the role and limitations of TLS channel bindings when augmenting legacy protocols.
Cryptographic algorithms are vital components ensuring the privacy and security of computer systems. They have constantly improved and evolved over the years following new developments, attacks, breaks, and lessons learned. A recent example is that of quantum-resistant cryptography, which has gained a lot of attention in the last decade and is leading to new algorithms being standardized today. These algorithms, however, present a real challenge: they come with strikingly different size and performance characteristics than their classical counterparts. At the same time, common foundational aspects of our transport protocols have lagged behind as the Internet remains a very diverse space in which different use-cases and parts of the world have different needs. This vision paper motivates more research and possible standards updates related to the upcoming quantum-resistant cryptography migration. It stresses the importance of amplification reflection attacks and congestion control concerns in transport protocols and presents research and standardization takeaways for assessing the impact and the efficacy of potential countermeasures. It emphasizes the need to go beyond the standardization of key encapsulation mechanisms in order to address the numerous protocols and deployments of public-key encryption while avoiding pitfalls. Finally, it motivates the critical need for research in anonymous credentials and blind signatures at the core of numerous deployments and standardization efforts aimed at providing privacy-preserving trust signals.
