In a zkTLS protocol, a user proves to a third party a property of data obtained from an online service over TLS, revealing nothing beyond the statement proven. Each existing scheme, however, comes with its own security model, written for that scheme alone, so the schemes are not proven secure against a common definition. The root cause is a mismatch of levels: existing models are stated at the level of TLS and therefore reflect how each construction handles it. Yet TLS is only the transport,...

The rapid expansion of quantum computing threatens the security foundations of classical public-key cryptography, including RSA and ECC, both vulnerable to Shor's algorithm. For the automotive industry, where secure communication underpins critical functions such as over-the-air (OTA) updates, secure boot, firmware signing, PKI validation, and vehicle-to-everything (V2X) connectivity, this threat demands early and informed migration planning. This paper presents a cross-platform performance...

Post-quantum migration of Transport Layer Security (TLS) is often described as replacing a classical key-exchange algorithm with a post-quantum alternative. This framing is incomplete: TLS distributes security across key establishment, authentication, resumption and pre-shared keys (PSKs), traffic-secret evolution, and the X.509/PKIX ecosystem. These functions have different security objectives, failure modes, lifecycle dependencies, and deployment constraints. This Systematization of...

Organisations are upgrading their cryptographic infrastructure to become quantum‑safe before large‑scale quantum computers materialise. Post‑quantum cryptography (PQC) standards now exist for key‑exchange and digital signatures, but the urgent question for adopters is how to operationalise PQC in complex environments with confidence. In banking, Transport Layer Security (TLS), for example, protects data‑in‑transit across public‑facing channels and internal services, and is terminated at many...

Post-quantum migration in Transport Layer Security (TLS) requires evidence-aware measurements that distinguish session negotiation, endpoint capability, certificate-chain evidence, and the provenance of missing observations. This distinction is essential under TLS 1.3 encryption, resumption, mutual TLS, trace truncation, fragmentation, coalescing, active certificate retrieval, and temporal drift. We present a multi-surface framework for post-quantum TLS observability. The framework...

When using Transport Layer Security (TLS), web users can connect to a server and trust that they are sending and receiving data with the intended web server. This guarantee, however, is not transferable: there is no immediate way for a client to convince an external party that a transcript or message originated from a particular server. Beginning with the DECO protocol of Zhang et al., there has been a line of work on "TLS oracles"—cryptographic protocols that allow a client to commit to,...

Transport Layer Security (TLS) attestation protocols are a key building block for decentralized applications that require authenticated off-chain data. However, existing Designed Commitment TLS (DCTLS) constructions rely on designated verifiers, which prevents public verifiability and enables prover--verifier collusion in on-chain settings. To address these limitations, we propose a collusion-minimized TLS attestation framework $\Pi_{\mathrm{coll\text{-}min}}$ that extends existing DCTLS...

Among standardization efforts for space and interplanetary network security, the Internet Engineering Task Force (IETF) is driv- ing work on space network security, accounting for the unique proper- ties 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...

The rapid advancement of quantum computing threatens the security of widely deployed public-key cryptosystems, creating an urgent need for practical migration to post-quantum cryptographic (PQC) standards. Although the U.S. National Institute of Standards and Technology (NIST) and Korea’s KpqC initiative have recently standardized PQC algorithms, integrating them into Transport Layer Security (TLS)~1.3 remains operationally challenging. Larger certificates, higher handshake costs, and...

Mutual Transport Layer Security (mTLS) under- pins authenticated, confidential communication across modern service meshes, but its deployment stance in machine-learning platforms is typically static—fixed cipher suites, certificate life- times, and re-authentication schedules chosen for worst-case threats rather than observed risk. Large Language Model (LLM) serving pipelines exacerbate this rigidity: traffic is bursty, topolo- gies reconfigure dynamically under autoscaling, and sensitive...

The advancement of quantum computing threatens traditional public-key cryptographic algorithms such as RSA and ECC, both vulnerable to Shor’s algorithm. As most Transport Layer Security (TLS) deployments still rely on these quantum-vulnerable algorithms for key exchange and digital signatures, the transition to Post-Quantum Cryptography (PQC), standardized by NIST, has become increasingly urgent. Given the critical role of TLS in securing Internet communications, identifying and...

Transport Layer Security (TLS) is the backbone of the web, allowing clients to establish secure and private channels with servers. DECO (CCS'20) and follow-up works proposed protocols that enable proving the provenance of a TLS response, i.e., that a payload came from a particular server, without needing server-side modifications. Unfortunately, these works are limited to proving Boolean statements over the payload (e.g., age $\ge$ 18) and cannot combine payloads from multiple clients. We...

Authenticated Key Exchange (AKE) between any two entities is one of the most important security protocols available for securing our digital networks and infrastructures. In PQCrypto 2023, Bruckner, Ramacher and Striecks proposed a novel hybrid AKE (HAKE) protocol dubbed Muckle+ that is particularly useful in large quantum-safe networks consisting of a large number of nodes. Their protocol is hybrid in the sense that it allows key material from conventional, post-quantum, and quantum...

To provide safe communication across an unprotected medium such as the internet, network protocols are being established. These protocols employ public key techniques to perform key exchange and authentication. Transport Layer Security (TLS) is a widely used network protocol that enables secure communication between a server and a client. TLS is employed in billions of transactions per second. Contemporary protocols depend on traditional methods that utilize the computational complexity of...

Transport Layer Security ( TLS ) is foundational for safeguarding client-server communication. However, it does not extend integrity guarantees to third-party verification of data authenticity. If a client wants to present data obtained from a server, it cannot convince any other party that the data has not been tampered with. TLS oracles ensure data authenticity beyond the client-server TLS connection, such that clients can obtain data from a server and ensure provenance to any third...

The Automatic Certificate Management Environment protocol (ACME) has significantly contributed to the widespread use of digital certificates in safeguarding the authenticity and privacy of Internet data. These certificates are required for implementing the Transport Layer Security (TLS) protocol. However, it is well known that the cryptographic algorithms employed in these certificates will become insecure with the emergence of quantum computers. This study assesses the challenges in...

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...

Web users can gather data from secure endpoints and demonstrate the provenance of sensitive data to any third party by using privacy-preserving TLS oracles. In practice, privacy-preserving TLS oracles remain limited and cannot selectively verify larger sensitive data sets. In this work, we introduce a new oracle protocol, which reaches new scales in selectively verifying the provenance of confidential web data. The novelty of our work is a construction which deploys an honest verifier...

Transport Layer Security (TLS) establishes an authenticated and confidential channel to deliver data for almost all Internet applications. A recent work (Zhang et al., CCS'20) proposed a protocol to prove the TLS payload to a third party, without any modification of TLS servers, while ensuring the privacy and originality of the data in the presence of malicious adversaries. However, it required maliciously secure Two-Party Computation (2PC) for generic circuits, leading to significant...

Transport Layer Security (TLS) 1.3 and the Signal protocol are very important and widely used security protocols. We show that the key update function in TLS 1.3 and the symmetric key ratchet in Signal can be modeled as non-additive synchronous stream ciphers. This means that the efficient Time Memory Tradeoff Attacks for stream ciphers can be applied. The implication is that TLS 1.3, QUIC, DTLS 1.3, and Signal offer a lower security level against TMTO attacks than expected from the key...

OPAQUE is an Asymmetric Password-Authenticated Key Exchange (aPAKE) protocol being standardized by the IETF (Internet Engineering Task Force) as a more secure alternative to the traditional ``password-over-TLS'' mechanism prevalent in current practice. OPAQUE defends against a variety of vulnerabilities of password-over-TLS by dispensing with reliance on PKI and TLS security, and ensuring that the password is never visible to servers or anyone other than the client machine where the password...

The TLS (Transport Layer Security) protocol is the most important, most attacked, most analysed and most used cryptographic protocol in the world today. TLS is critical to the integrity of the Internet, and if it were to be broken e-commerce would become impossible, with very serious implications for the global economy. Furthermore TLS is likely to assume even greater significance in the near future with the rapid growth of an Internet of Things (IoT) -- a multiplicity of internet connected...

The DECentralized Oracle (DECO) protocol enables the verifiable provenance of data from Transport Layer Security (TLS) connections through secure two-party computation and zero-knowledge proofs. In this paper, we present PECO, an extension of DECO that enhances privacy features through the integration of two new private three-party handshake protocols (P3P-HS). PECO allows any web user to prove to a verifier the properties of data from TLS connections without disclosing the identity of the...

TLS is ubiquitous in modern computer networks. It secures transport for high-end desktops and low-end embedded devices alike. However, the public key cryptosystems currently used within TLS may soon be obsolete as large-scale quantum computers, once realized, would be able to break them. This threat has led to the development of post-quantum cryptography (PQC). The U.S. standardization body NIST is currently in the process of concluding a multi-year search for promising post-quantum...

Adopting Post-Quantum Cryptography (PQC) in network protocols is a challenging subject. Larger PQC public keys and signatures can significantly slow the Transport Layer Security (TLS) protocol. In this context, KEMTLS is a promising approach that replaces the handshake signatures by using PQC Key Encapsulation Mechanisms (KEMs), which have, in general, smaller sizes. However, for broad PQC adoption, hybrid cryptography has its advantages over PQC-only approaches, mainly about the confidence...

The pre-shared key (PSK) handshake modes of TLS 1.3 allow for the performant, low-latency resumption of previous connections and are widely used on the Web and by resource-constrained devices, e.g., in the Internet of Things. Taking advantage of these performance benefits with optimal and theoretically-sound parameters requires tight security proofs. We give the first tight security proofs for the TLS 1.3 PSK handshake modes. Our main technical contribution is to address a gap in prior...

Cache systems are crucial for reducing communication overhead on the Internet. The importance of communication privacy is being increasingly and widely recognized; therefore, we anticipate that nearly all end-to-end communication will be encrypted via secure sockets layer/transport layer security (SSL/TLS) in the near future. Herein we consider a catch-22 situation, wherein the cache server checks whether content has been cached or not, i.e., the cache server needs to observe it, thereby...

The emergence of cloud-computing has raised important privacy questions about the data that users share with remote servers. While data in transit is protected using standard techniques like Transport Layer Security (TLS), most cloud providers have unrestricted plaintext access to user data at the endpoint. Fully Homomorphic Encryption (FHE) offers one solution to this problem by allowing for arbitrarily complex computations on encrypted data without ever needing to decrypt it....

The Transport Layer Security (TLS) protocol is a fundamental building block for ensuring security on Internet. It provides an easy to use framework for the purposes of establishing an authenticated and secure channel between two parties that have never physically met. Nevertheless, TLS only provides a simple cryptographic functionality compared to more advanced protocols such as protocols for secure multiparty computation (MPC). In this work, we provide a framework for efficiently...

The threat of a cryptographically relevant quantum computer contributes to an increasing interest in the field of post-quantum cryptography (PQC). Compared to existing research efforts regarding the integration of PQC into the Transport Layer Security (TLS) protocol, industrial communication protocols have so far been neglected. Since industrial cyber-physical systems (CPS) are typically deployed for decades, protection against such long-term threats is needed. In this work, we propose two...

Transport Layer Security (TLS) constitutes one of the most widely used protocols for securing Internet communications and has also found broad acceptance in the Internet of Things (IoT) domain. As we progress toward a security environment resistant to quantum computer attacks, TLS needs to be transformed to support post-quantum cryptography. However, post-quantum TLS is still not standardised, and its overall performance, especially in resource-constrained, IoT-capable, embedded devices, is...

Large-scale quantum computers will be able to efficiently solve the underlying mathematical problems of widely deployed public key cryptosystems in the near future. This threat has sparked increased interest in the field of Post-Quantum Cryptography (PQC) and standardization bodies like NIST, IETF, and ETSI are in the process of standardizing PQC schemes as a new generation of cryptography. This raises the question of how to ensure a fast, reliable, and secure transition to upcoming PQC...

KEMTLS is a novel alternative to the Transport Layer Security (TLS) handshake that integrates post-quantum algorithms. It uses key encapsulation mechanisms (KEMs) for both confidentiality and authentication, achieving post-quantum security while obviating the need for expensive post-quantum signatures. The original KEMTLS paper presents a security analysis, Rust implementation, and benchmarks over emulated networks. In this work, we provide full Go implementations of KEMTLS and other...

While server-only authentication with certificates is the most widely used mode of operation for the Transport Layer Security (TLS) protocol on the world wide web, there are many applications where TLS is used in a different way or with different constraints. For example, embedded Internet-of-Things clients may have a server certificate pre-programmed and be highly constrained in terms of communication bandwidth or computation power. As post-quantum algorithms have a wider range of...

By design, TLS (Transport Layer Security) is a 2-party, end-to-end protocol. Yet, in practice, TLS delegation is often deployed: that is, middlebox proxies inspect and even modify TLS traffic between the endpoints. Recently, industry-leaders (e.g., Akamai, Cloudflare, Telefonica, Ericcson), standardization bodies (e.g., IETF, ETSI), and academic researchers have proposed numerous ways of achieving safer TLS delegation. We present LURK the LURK (Limited Use of Remote Keys) extension for...

The threat of a cryptographically relevant quantum computer contributes to an increasing interest in the field of post-quantum cryptography (PQC). Compared to existing research efforts regarding the integration of PQC into the Transport Layer Security (TLS) protocol, industrial communication protocols have so far been neglected. Since industrial cyber-physical systems (CPS) are typically deployed for decades, protection against such long-term threats is needed. In this work, we propose two...

We analyze the handshake protocol of the Transport Layer Security (TLS) protocol, version 1.3. We address both the full TLS 1.3 handshake (the one round-trip time mode, with signatures for authentication and (elliptic curve) Diffie–Hellman ephemeral ((EC)DHE) key exchange), and the abbreviated resumption/"PSK" mode which uses a pre-shared key for authentication (with optional (EC)DHE key exchange and zero round-trip time key establishment). Our analysis in the reductionist security framework...

We consider the theoretically-sound selection of cryptographic parameters, such as the size of algebraic groups or RSA keys, for TLS 1.3 in practice. While prior works gave security proofs for TLS 1.3, their security loss is quadratic in the total number of sessions across all users, which due to the pervasive use of TLS is huge. Therefore, in order to deploy TLS 1.3 in a theoretically-sound way, it would be necessary to compensate this loss with unreasonably large parameters that would be...

The common approach in secure communication channel protocols is to rely on ciphertexts arriving in-order and to close the connection upon any rogue ciphertext. Cryptographic security models for channels generally reflect such design. This is reasonable when running atop lower-level transport protocols like TCP ensuring in-order delivery, as for example is the case with TLS or SSH. However, protocols like QUIC or DTLS which run over a non-reliable transport such as UDP, do not---and in fact...

We present KEMTLS, an alternative to the TLS 1.3 handshake that uses key-encapsulation mechanisms (KEMs) instead of signatures for server authentication. Among existing post-quantum candidates, signature schemes generally have larger public key/signature sizes compared to the public key/ciphertext sizes of KEMs: by using an IND-CCA-secure KEM for server authentication in post-quantum TLS, we obtain multiple benefits. A size-optimized post-quantum instantiation of KEMTLS requires less than...

If two or more identical HTTPS clients, located at different geographic locations (regions), make an HTTPS request to the same domain (e.g. example.com), on the same day, will they receive the same HTTPS security guarantees in response? Our results give evidence that this is not always the case. We conduct scans for the top 250000 most visited domains on the Internet, from clients located at five different regions: Australia, Brazil, India, the UK, and the US. Our scans gather data from both...

Post-quantum cryptographic primitives have a range of trade-offs compared to traditional public key algorithms, either having slower computation or larger public keys and ciphertexts/signatures, or both. While the performance of these algorithms in isolation is easy to measure and has been a focus of optimization techniques, performance in realistic network conditions has been less studied. Google and Cloudflare have reported results from running experiments with post-quantum key exchange...

An elliptic curve known as Curve448 defined over the finite field $\mathbb{F}_p$, where $p=2^{448}-2^{224}-1$, has been proposed as part of the Transport Layer Security (TLS) protocol, version 1.3. Elements of $\mathbb{F}_p$ can be represented using 7 limbs where each limb is a 64-bit quantity. This paper describes efficient algorithms for reduction modulo $p$ that are required for performing field arithmetic in $\mathbb{F}_p$ using 7-limb representation. A key feature of our work is that we...

Within the Transport Layer Security (TLS) Protocol Version 1.3, RFC 7748 specifies elliptic curves targeted at the 128-bit and the 224-bit security levels. For the 128-bit security level, the Montgomery curve Curve25519 and its birationally equivalent twisted Edwards curve Ed25519 are specified; for the 224-bit security level, the Montgomery curve Curve448, the Edwards curve Edwards448 (which is isogenous to Curve448) and another Edwards curve which is birationally equivalent to Curve448...

A number of important real-world protocols including the Transport Layer Security (TLS) protocol have the ability to negotiate various security-related choices such as the protocol version and the cryptographic algorithms to be used in a particular session. Furthermore, some insecure application-layer protocols such as the Simple Mail Transfer Protocol (SMTP) negotiate the use of TLS itself on top of the application protocol to secure the communication channel. These protocols are often...

Experience shows that most researchers and developers tend to treat plain-domains (those that are not prefixed with “www” sub-domains, e.g. “example.com”) as synonyms for their equivalent www-domains (those that are prefixed with “www” sub-domains, e.g. “www.example.com”). In this paper, we analyse datasets of nearly two million plain-domains against their equivalent www-domains to answer the following question: Do plain-domains and their equivalent www-domains differ in TLS security...

Once algorithms for quantum-resistant key exchange and digital signature schemes are selected by standards bodies, adoption of post-quantum cryptography will depend on progress in integrating those algorithms into standards for communication protocols and other parts of the IT infrastructure. In this paper, we explore how two major Internet security protocols, the Transport Layer Security (TLS) and Secure Shell (SSH) protocols, can be adapted to use post-quantum cryptography. First, we...

TLS (Transport Layer Security) is a widely deployed protocol that plays a vital role in securing Internet trafic. Given the numerous known attacks for TLS 1.2, it was imperative to change and even redesign the protocol in order to address them. In August 2018, a new version of the protocol, TLS 1.3, was standardized by the IETF (Internet Engineering Task Force). TLS 1.3 not only benefits from stronger security guarantees, but aims to protect the identities of the server and client by...

Secure channel establishment protocols such as Transport Layer Security (TLS) are some of the most important cryptographic protocols, enabling the encryption of Internet traffic. Reducing latency (the number of interactions between parties before encrypted data can be transmitted) in such protocols has become an important design goal to improve user experience. The most important protocols addressing this goal are TLS 1.3, the latest TLS version standardized in 2018 to replace the widely...

Concerns about the impact of quantum computers on currently deployed public key cryptography have instigated research into not only quantum-resistant cryptographic primitives but also how to transition applications from classical to quantum-resistant solutions. One approach to mitigate the risk of quantum attacks and to preserve common security guarantees are hybrid schemes, which combine classically secure and quantum-resistant schemes. Various academic and industry experiments and draft...

Secure channels are one of the most pivotal building blocks of cryptography today. Internet connections, secure messaging, protected IoT data, etc., all rely upon the security of the underlying channel. In this work we define channel protocols, as well as security for channels constructed from stateful length-hiding authenticated encryption (stLHAE) schemes. Furthermore, we initiate the concept of secure termination where, upon receipt of a signifying message, a receiver is guaranteed to...

Secure channel protocols protect data transmission over a network from being overheard or tampered with. In the common abstraction, cryptographic models for channels involve a single key for ensuring the central security notions of confidentiality and integrity. The currently developed next version of the Transport Layer Security protocol, TLS 1.3, however introduces a key updating mechanism in order to deploy a sequence of multiple, possibly independent encryption keys in its channel...

We investigate security of key exchange protocols supporting so-called zero round-trip time (0-RTT), enabling a client to establish a fresh provisional key without interaction, based only on cryptographic material obtained in previous connections. This key can then be already used to protect early application data, transmitted to the server before both parties interact further to switch to fully secure keys. Two recent prominent examples supporting such 0-RTT modes are Google's QUIC protocol...

The record layer is the main bridge between TLS applications and internal sub-protocols. Its core functionality is an elaborate authenticated encryption: streams of messages for each sub-protocol (hand- shake, alert, and application data) are fragmented, multiplexed, and encrypted with optional padding to hide their lengths. Conversely, the sub-protocols may provide fresh keys or signal stream termination to the record layer. Compared to prior versions, TLS 1.3 discards obsolete schemes in...

Designing public key cryptosystems that resist attacks by quantum computers is an important area of current cryptographic research and standardization. To retain confidentiality of today's communications against future quantum computers, applications and protocols must begin exploring the use of quantum-resistant key exchange and encryption. In this paper, we explore post-quantum cryptography in general and key exchange specifically. We review two protocols for quantum-resistant key...

We investigate how to safely export additional cryptographic keys from secure channel protocols, modeled with the authenticated and confidential channel establishment (ACCE) security notion. For example, the EAP-TLS protocol uses the Transport Layer Security (TLS) handshake to output an additional shared secret which can be used for purposes outside of TLS, and the RFC 5705 standard specifies a general mechanism for exporting keying material from TLS. We show that, for a class of ACCE...

We analyze the handshake protocol of TLS 1.3 draft-ietf-tls-tls13-10 (published October 2015). This continues and extends our previous analysis (CCS 2015, Cryptology ePrint Archive 2015) of former TLS 1.3 drafts (draft-ietf-tls-tls13-05 and draft-ietf-tls-tls13-dh-based). Here we show that the full (EC)DHE Diffie-Hellman-based handshake of draft-10 is also secure in the multi-stage key exchange framework of Fischlin and Günther which captures classical Bellare-Rogaway key secrecy for key...

Authentication and authenticated encryption with associated data (AEAD) are applied in cryptographic protocols to provide message integrity. The definitions in the literature and the constructions used in practice all protect against forgeries, but offer varying levels of protection against replays, reordering, and drops. As a result of the lack of a systematic hierarchy of authentication and AEAD security notions, gaps have arisen in the literature, specifically in the provable security...

The Internet Engineering Task Force (IETF) is currently developing the next version of the Transport Layer Security (TLS) protocol, version 1.3. The transparency of this standardization process allows comprehensive cryptographic analysis of the protocols prior to adoption, whereas previous TLS versions have been scrutinized in the cryptographic literature only after standardization. Here we look at two related, yet slightly different candidates which were in discussion for TLS 1.3 at the...

Real-world cryptographic protocols such as the widely used Transport Layer Security (TLS) protocol support many different combinations of cryptographic algorithms (called ciphersuites) and simultaneously support different versions. Recent advances in provable security have shown that most modern TLS ciphersuites are secure authenticated and confidential channel establishment (ACCE) protocols, but these analyses generally focus on single ciphersuites in isolation. In this paper we extend...

Secure protocols for password-based user authentication are well-studied in the cryptographic literature but have failed to see wide-spread adoption on the Internet; most proposals to date require extensive modifications to the Transport Layer Security (TLS) protocol, making deployment challenging. Recently, a few modular designs have been proposed in which a cryptographically secure password-based mutual authentication protocol is run inside a confidential (but not necessarily...

Compression is desirable for network applications as it saves bandwidth; however, when data is compressed before being encrypted, the amount of compression leaks information about the amount of redundancy in the plaintext. This side channel has led to successful CRIME and BREACH attacks on web traffic protected by the Transport Layer Security (TLS) protocol. The general guidance in light of these attacks has been to disable compression, preserving confidentiality but sacrificing bandwidth....

Lattice-based cryptographic primitives are believed to offer resilience against attacks by quantum computers. We demonstrate the practicality of post-quantum key exchange by constructing ciphersuites for the Transport Layer Security (TLS) protocol that provide key exchange based on the ring learning with errors (R-LWE) problem; we accompany these ciphersuites with a rigorous proof of security. Our approach ties lattice-based key exchange together with traditional authentication using RSA or...

We select a set of elliptic curves for cryptography and analyze our selection from a performance and security perspective. This analysis complements recent curve proposals that suggest (twisted) Edwards curves by also considering the Weierstrass model. Working with both Montgomery-friendly and pseudo-Mersenne primes allows us to consider more possibilities which help to improve the overall efficiency of base field arithmetic. Our Weierstrass curves are backwards compatible with current...

The Secure Shell (SSH) protocol is widely used to provide secure remote access to servers, making it among the most important security protocols on the Internet. We show that the signed-Diffie--Hellman SSH ciphersuites of the SSH protocol are secure: each is a secure authenticated and confidential channel establishment (ACCE) protocol, the same security definition now used to describe the security of Transport Layer Security (TLS) ciphersuites. While the ACCE definition suffices to...

In this paper, we perform a review of elliptic curve cryptography (ECC), as it is used in practice today, in order to reveal unique mistakes and vulnerabilities that arise in implementations of ECC. We study four popular protocols that make use of this type of public-key cryptography: Bitcoin, secure shell (SSH), transport layer security (TLS), and the Austrian e-ID card. We are pleased to observe that about 1 in 10 systems support ECC across the TLS and SSH protocols. However, we find that...

The most widely used secure Internet communication standard TLS (Transport Layer Security) has an optional client certificate authentication feature that in theory has significant security advantages over HTML form-based password authentication. In this paper we discuss practical security and usability issues related to TLS client certificate authentication stemming from the server-side and browser implementations. In particular, we analyze Apache's mod_ssl implementation on the server side...

Since its introduction in 1994 the Secure Socket Layer (SSL) protocol (later renamed to Transport Layer Security (TLS)) evolved to the de facto standard for securing the transport layer. SSL/TLS can be used for ensuring data confidentiality, integrity and authenticity during transport. A main feature of the protocol is its flexibility. Modes of operation and security aims can easily be configured through different cipher suites. During its evolutionary development process several flaws were...

The Transport Layer Security (TLS) protocol is the most widely used security protocol on the Internet. It supports negotiation of a wide variety of cryptographic primitives through different cipher suites, various modes of client authentication, and additional features such as renegotiation. Despite its widespread use, only recently has the full TLS protocol been proven secure, and only the core cryptographic protocol with no additional features. These additional features have been the...

We present a security analysis of the complete TLS protocol in the Universal Composable security framework. This analysis evaluates the composition of key exchange functionalities realized by the TLS handshake with the message transmission of the TLS record layer to emulate secure communication sessions and is based on the adaption of the secure channel model from Canetti and Krawczyk to the setting where peer identities are not necessarily known prior the protocol invocation and may remain...

We study the security of the widely deployed Secure Session Layer/Transport Layer Security (TLS) key agreement protocol. Our analysis identifies, justifies, and exploits the modularity present in the design of the protocol: the {\em application keys} offered to higher level applications are obtained from a {\em master key}, which in turn is derived, through interaction, from a {\em pre-master key}. Our first contribution consists of formal models that clarify the security level enjoyed by...

This paper introduces a chosen-plaintext vulnerability in the Secure Sockets Layer (SSL) and Trasport Layer Security (TLS) protocols which enables recovery of low entropy strings such as can be guessed from a likely set of 2--1000 options. SSL and TLS are widely used for securing communication over the Internet. When utilizing block ciphers for encryption, the SSL and TLS standards mandate the use of the cipher block chaining (CBC) mode of encryption which requires an initialization vector...