Revocation Checking Research Articles

Shared group session key-based conditional privacy-preserving authentication protocol for VANETs

Vehicular Ad-Hoc Networks (VANETs) have significantly enhanced driving safety and comfort by leveraging vehicular wireless communication technology. Due to the open nature of VANETs, conditional privacy-preserving authentication protocol should be offered against potential attacks. Efficient and secure authentication among vehicles in VANETs are important requirements, but there are various limitations in the existing conditional privacy-preserving authentication protocols for securing VANETs. To cope with the inherent issues, we propose a conditional privacy-preserving authentication protocol based share group session key (SGSK) by integrating the self-healing key distribution technique, blockchain, and MTI/C0 protocol. In our protocol, we use SGSK instead of the time-consuming Certificate Revocation List (CRL) checking, and we revoke malicious vehicles by updating SGSK. It is shared among unrevoked vehicles within a domain and across-domain. As a result, when a malicious revoked vehicle enters a new domain, it is difficult for it to access the system and send false messages. Furthermore, our protocol can not only achieve computation efficiency by reducing the number of computing operations of bilinear pairing but also resist various attacks while keeping conditional privacy protection. We implement our protocol in the Hyperledger Fabric platform. The experimental results show that our protocol is available to revoke 180 malicious vehicles in across-domain scenarios within one second, and it can meet the requirement of verifying 600 messages per second easily. Moreover, our comprehensive performance evaluations demonstrates that our protocol outperforms other approaches in terms of vehicle revocation checking cost, computation overhead, and communication overhead. In addition, to show the feasibility and validity of our protocol, we use SUMO and NS2 to simulate the actual VANET scenario and validate the efficiency and performance of our protocol. Simulation results prove the practicability of our protocol for VANETs.

Verifying Certificate Revocation Status for Short Key Lengths in Vehicle Communication Systems

This paper proposes and analyzes a ticket-based OCSP protocol for efficient certificate revocation checking in vehicle communication systems. The IEEE WAVE standard for vehicular networks requires real-time processing of Basic Safety Messages (BSMs) exchanged between vehicles. Traditional OCSP revocation checking can introduce delays. The proposed approach distributes OCSP responses as tickets valid for a road section. Vehicles use shorter keys extracted from the tickets for faster cryptographic processing. Experiments compare processing times for signature generation and verification with different elliptic curves. The results show the proposed technique provides faster revocation checking. This allows time-critical vehicle-to-vehicle message processing at high rates under computational constraints. The ticket-based OCSP mechanism enhances security while meeting real-time requirements in vehicular networks.

Revocation Speedrun: How the WebPKI Copes with Fraudulent Certificates

The TLS ecosystem depends on certificates to bootstrap secure connections. Certificate Authorities (CAs) are trusted to issue these correctly. However, as a result of security breaches or attacks, certificates may be issued fraudulently and need to be revoked prematurely. Revocation, as a reactive measure, is fundamentally damage control and, as such, time is critical. Therefore, measuring reaction delay is the first step to identifying how well the revocation system functions. In this paper we attempt to characterize the current performance of the WebPKI in dealing with fraudulent certificates. We present measurements of each step in the revocation process: the detection of certificate issuance through Certificate Transparency (CT) monitoring, the administrative revocation process at popular CAs, and the revocation checking behavior of end-user clients, both in a controlled virtualized environment and in the wild. We perform two live measurements, in 2022 and 2023, respectively, to provide a longitudinal comparison. We find that detection and revocation of fraudulent certificates is quick and efficient when leveraging CT and can be completed within 6.5 hours on average. Furthermore, CT is being increasingly enforced by some browsers. However, ∼83% of the clients we observed, across popular browsers, brands and OSes, completely disregard a certificate's status, whileall of the studied browsers still display soft-fail behavior, making them vulnerable to attackers capable of interfering with the network. Of the clients that do check revocation, we find that 35% can be made to accept a revoked certificate through the use of OCSP Stapling. We expect this number to grow with client-side adoption of OCSP Stapling [RFC6961]. Current OCSP expiration times allow a revoked certificate to remain fully valid for up to 7 days for the majority of CAs, exposing clients to attacks.

BRT: An Efficient and Scalable Blockchain-Based Revocation Transparency System for TLS Connections.

Log-based public key infrastructure(PKI) refers to a robust class of CA-attack-resilient PKI that enhance transparency and accountability in the certificate revocation and issuance process by compelling certificate authorities (CAs) to submit revocations to publicly and verifiably accessible logs. However, log-based PKIs suffer from a reliance on centralized and consistent sources of information, rendering them susceptible to split-world attacks, and they regrettably fail to provide adequate incentives for recording or monitoring CA behavior. Blockchain-based PKIs address these limitations by enabling decentralized log audits through automated financial incentives. However, they continue to face challenges in developing a scalable revocation mechanism suited for lightweight clients. In this paper, we introduce BRT, a scalable blockchain-based system for certificate and revocation transparency. It serves to log, audit, and validate the status of certificates within the transport layer security (TLS)/secure sockets layer(SSL) PKI domain. We designed an audit-on-chain framework, coupled with an off-chain storage/computation system, to enhance the efficiency of BRT when operating in a blockchain environment. By implementing a blockchain-based prototype, we demonstrate that BRT achieves storage-efficient log recording with a peak compression rate reaching 8%, cost-effective log updates for large-scale certificates, and near-instantaneous revocation checks for users.

Edge-Cloud-Assisted Certificate Revocation Checking: An Efficient Solution Against Irresponsible Service Providers

Certificate revocation checking (CRC) is a fundamental requirement in certificate-based public-key cryptographic systems. Most existing CRC schemes are not tailored for edgecloud computing systems, and directly applying these schemes would cause security and efficiency problems. In this paper, we first propose a two-layer edge-cloud-assisted CRC framework, dubbed ECA-CRC, where edge nodes utilizing a probabilistic checking algorithm serve as a first layer, and the cloud server utilizing a deterministic checking algorithm serves as a second layer. Both the edge nodes and the cloud server collaboratively provide verifiable CRC services for devices. The most prominent manifestations of ECA-CRC are that (1) most CRC requests can be processed with the probabilistic checking layer, which reduces the checking delay significantly while providing an accurate CRC service; (2) devices can detect the irresponsible behavior of the service provider, including using an incorrect revoked certificate set (RCS) to compute checking results or procrastinating on updating the RCS, as soon as possible.We then propose an efficient instantiation of ECA-CRC, dubbed eECACRC, by utilizing a Merkle hash tree (MHT) based homomorphic signature, Cuckoo filter, and Othello. We formally prove the security of eECA-CRC against the irresponsible service provider under the random oracle model. We implement an eECA-CRC prototype and conduct a comprehensive performance evaluation based on a public certificate database. Our results show that 95% of CRC requests are completed on the edge nodes, and only 5% of CRC requests need to be handled by the cloud server.

Decentralized CRL Management for Vehicular Networks With Permissioned Blockchain

In vehicular networks, authentication technology provides a basic security means to achieve trusted communication between legitimate vehicles. Revocation checking for vehicle certificates is an indispensable procedure in the process of authentication to protect vehicular networks from attacks by non-legitimate vehicles. However, revocation checking introduces procedures that requires additional time to process which challenges latency-sensitive applications in vehicular networks. This challenge grows more evidently when considering the factor of privacy preservation. In this paper, we propose to offload partial revocation task to network edges to lighten the revocation process in vehicles. Particularly, we design a method to achieve decentralized Global Certificate Revocation List (GCRL) management in network edges using permissioned blockchain technologies. In the method, both tamper-proof property and quick synchronization of the GCRL are guaranteed. Besides, our method can detect illegal revocation behaviours by validation in vehicles. Finally, we build a prototype of our proposed solution based on Hyperledger Fabric, and compare with Proof-of-Work scheme in terms of blockchain synchronization latency performance.

Identity authentication for edge devices based on zero‐trust architecture

SummaryDevice identity authentication is the first line of defense for edge computing security mechanisms. Many authentication schemes are often accompanied by high communication and computational overhead. In addition, due to the continuous enhancement of network virtualization and dynamics, the security requirements for logical boundaries of many enterprise information systems “cloudification,” and the huge data security challenges faced by enterprise core assets, all make the original "one‐time authentication, all the way" trust model no longer reliable. Therefore, the paper proposes a local identity authentication and roaming identity authentication protocol based on a zero‐trust architecture. First, we propose a revocable group signature scheme, the expiration time is bound to the key of each edge terminal device. According to this solution, since the identity authentication token generated by the expired key is invalid, it does not need to be included in the revocation list, which improves the efficiency of revocation checking. Compared with the current identity authentication protocol, this article not only builds a model based on the zero trust architecture, effectively solves the shortcomings of the network security protection architecture, but also considers the unforgeability of the expiration time, and realizes effective revocation and more efficient identity authentication.

ESAR: Enhanced Secure Authentication and Revocation Scheme for Vehicular Ad Hoc Networks

Vehicle Ad Hoc Network (VANET) systems that use Public Key Infrastructure (PKI) experience significant delays when checking Certificate Revocation Lists (CRLs) and performing key pair-based asymmetric cryptographic operations. This paper offers a fast and secure mechanism for revocation checking, processing and PKI key pair updating called the Enhanced Secure Authentication and Revocation (ESAR) scheme for VANETs. The ESAR Vehicle-To-Vehicle (V2V) authentication method applies Keyed-Hash-based Message Authentication Code (H-MAC) cryptogram validation for On-Board-Unit (OBU) revocation checks instead of the CRL search. We examined the ESAR together with a similar VANET scheme and achieved better results. We selected the Expedite Message Authentication Protocol for Vehicular Ad Hoc Networks (EMAP), which, upon a review of the literature, was seen to offer fewer countermeasures to provide resistance to most attacks. In addition, we completed the missing parts of the EMAP scheme with performance improvements and we compared it with other schemes in terms of security. Our ESAR scheme includes the following improvements. (1) The unauthorized update protection of sensitive assets is handled by revocation key sender verification and revocation version validation. (2) Privacy concerns are addressed by the use of keyed trimmed H-MAC-based pseudo ID creation. (3) Reliable data transmission issues are resolved by including missing message identification tags. (4) Performance concerns are addressed by eliminating and combining network requests to offer fast security key revocation. We targeted system performance and durability and also attack resistance using anomaly detection improvements. We ran three simulations: the standard (using CRL only), the proposed (ESAR), and the existing (EMAP) methods. According to the findings of our simulation analysis, our proposed system was more efficient in terms of performance and network congestion than the other examined methods.

Physically Secure Lightweight and Privacy-Preserving Message Authentication Protocol for VANET in Smart City

Secure message transmission in vehicular communications in smart cities is still a challenging task. Most of the related work employed the Public Key Infrastructure, Certification Revocation Lists (CRLs) for ensuring security, privacy. However, these work suffered from some issues such as: 1) the time-consuming checking process, huge size of CRLs, 2) traceability attacks by linking unencrypted Basic Safety Messages (BSMs), 3) extracting secret keys from the storage of parked vehicles or road-side units (RSU) by an adversary. To address the aforementioned issues, we thus propose a physically secure privacy-preserving message authentication protocol using Physical Unclonable Function (PUF), Secret Sharing. The proposed protocol guarantees security, privacy against passive, active attacks even under memory leakage. The entities (i.e., vehicles, RSU) make use of their PUF to reconstruct a secret polynomial-share so that pairwise temporal secret keys (PTKs) can be established with other entities. Unlike existing protocols, BSMs are also encrypted in our protocol (by PTKs) to provide a higher level of security, thwart vehicles traceability attacks. To revoke a vehicle, RSU needs not broadcast CRLs. Instead, RSU distributes only a secure offset key using threshold Secret Sharing. Consequently, our revocation checking process has computation complexity <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\mathcal {O}(1)$</tex-math></inline-formula> . Our protocol also eliminates the need for a third party in Vehicle-to-Vehicle communication to ensure expeditious transmission. Security analysis, performance evaluation show that our proposed protocol outperforms existing schemes in terms of security features, computation, communication cost.

Design and Implementation of a Compressed Certificate Status Protocol

Trust in Secure Sockets Layer–based communications is traditionally provided by Certificate (or Certification) Authorities (CAs) in the form of signed certificates. Checking the validity of a certificate involves three steps: (i) checking its expiration date, (ii) verifying its signature, and (iii) ensuring that it is not revoked. Currently, such certificate revocation checks (i.e., step (iii) above) are done either via Certificate Revocation Lists (CRLs), or Online Certificate Status Protocol (OCSP) servers. Unfortunately, despite the existence of these revocation checks, sophisticated cyber-attackers can still trick web browsers to trust a revoked certificate, believing that it is still valid. Although frequently updated , nonced , and timestamped certificates can reduce the frequency and impact of such cyber-attacks, they add a huge burden to the CAs and OCSP servers. Indeed, CAs and/or OCSP servers need to timestamp and sign on a regular basis all the responses, for every certificate they have issued, resulting in a very high overhead. To mitigate this and provide a solution to the described cyber-attacks, we present CCSP : a new approach to provide timely information regarding the status of certificates, which capitalizes on a newly introduced notion called Signed Collections . In this article, we present in detail the notion of Signed Collections and the complete design, implementation, and evaluation of our approach. Performance evaluation shows that CCSP (i) reduces space requirements by more than an order of magnitude, (ii) lowers the number of signatures required by six orders of magnitude compared to OCSP-based methods, and (iii) adds only a few milliseconds of overhead in the overall user latency.

Fast-track message authentication protocol for DSRC using HMAC and group keys

The exchange of information between vehicle to vehicle and vehicle to infrastructure in vehicular ad hoc networks (VANET) should be secured to provide an intelligent transport system. VANET uses certificate revocation lists (CRL) and public key infrastructures (PKI) for its security. In any PKI algorithms validity of the messages received from the sender is executed by checking the senders certificate in current CRL and verify the authenticity of the signature and certificate of the sender. Checking the CRL and verifying the authenticity is time-consuming and affects system performance drastically. This paper offers an accelerated and secure authentication method that utilizes a hash message authentication code (HMAC) in combination with secret keys for the revocation checking process. By using HMAC and enhancing the CRL checking procedure, the algorithm provides improved performance of the system parameters like authentication delay, end-to-end delay, and packet delivery ratio. Also, this algorithm reduces the delay involved in vehicle authentication. This novel algorithm uses the random distribution of keys that enables the authenticated on-board unit to securely share and update a secret key. An authentication delay of 77.29 μs, end-to-end delay of 13.56 ms and packet delivery ratio of 81.2% is achieved.

Disposable dynamic accumulators: toward practical privacy-preserving mobile eIDs with scalable revocation

Providing methods to anonymously validate user identity is essential in many applications of electronic identity (eID) systems. A feasible approach to realize such a privacy-preserving eID is the usage of group signature protocols or pseudonym-based signatures. However, providing a revocation mechanism that preserves privacy is often the bottleneck for the scalability of such a system. In order to bridge this gap between practicability and privacy, we propose a new pseudonym-based mobile eID signature scheme suitable for smart cards and secure elements that also enables efficient and scalable revocation checks. By using a pseudorandom function, we derive one-time verification tokens used for identity verification as well as revocation checks and generate proofs of validity using a new method referred to as disposable dynamic accumulators. Our scheme preserves unlinkability and anonymity of the eID holder even beyond revocation and does not require online connectivity to a trusted party for verification and revocation checks.

Anonymous roaming authentication protocol for wireless network with backward unlinkability, exculpability and efficient revocation check

Secure seamless roaming in a wireless network is desirable in today’s highly dynamic world. Providing revocation and non-traceability in an efficient two-party roaming authentication protocol is a challenging task. Conventional two-party protocols utilize pseudo-identities or group signature with revocation tokens to support non-traceability and strong user anonymity. Among the group signature based authentication schemes, only Priauth scheme has non-traceability or backward/forward unlinkability and the mobile user does not have to do any computation after each revocation. Despite all the advantages, Priauth scheme does not support exculpability or in other words the home server knows the group signing key of the mobile user. In case of dispute, the mobile user can deny that it generated signature because the mobile user and the home server both know the signing key of the mobile user. Thus, the mobile user cannot be held accountable. Moreover, Priauth has high revocation cost due to pairing operation performed for each revoked token in the revocation list during revocation checking at the foreign server. In addition, the existing group signature based authentication schemes are not provably secure in the random oracle model. We propose a provably secure two-party authentication protocol using group signature scheme which overcomes the weaknesses of Priauth scheme by supporting exculpability, backward unlinkability and using exponential operation instead of costlier pairing operation during revocation checking.

Provably Secure Anonymous-yet-Accountable Crowdsensing with Scalable Sublinear Revocation

Abstract Group signature schemes enable anonymous-yet-accountable communications. Such a capability is extremely useful for applications, such as smartphone-based crowdsensing and citizen science. However, the performance of modern group signature schemes is still inadequate to manage large dynamic groups. In this paper, we design the first provably secure verifier-local revocation (VLR) - based group signature scheme that supports sublinear revocation, named Sublinear Revocation with Backward unlinkability and Exculpability (SRBE). To achieve this performance gain, SRBE introduces time bound pseudonyms for the signer. By introducing low-cost short-lived pseudonyms with sublinear revocation checking, SRBE drastically improves the efficiency of the group-signature primitive. The backward-unlinkable anonymity of SRBE guarantees that even after the revocation of a signer, her previously generated signatures remain unlinkable across epochs. This behavior favors the dynamic nature of real-world crowdsensing settings. We prove its security and discuss parameters that influence its scalability. Using SRBE, we also implement a prototype named GroupSense for anonymous-yet-accountable crowdsensing, where our experimental findings confirm GroupSense’s scalability. We point out the open problems remaining in this space.

Certificate Revocation List Distribution Based on Road Map Distance Protocol (RMDP) in Vanet

Vehicular ad-hoc networking can provide efficient traffic information, emergency warning, alert messages and infotainment dissemination. It takes a vital role in safety fields such as defense system, traffic system, etc. Even though, some advanced Public Key Infrastructure and digital signature method was used for security, intrusion detection is an inevitable challenge in networks. Prevention and detection of malicious vehicle from jeopardizing the safety of the other vehicle is focused in this paper by using region-based FBB (Flooding-Bilinear-Bloom Filter) authentication protocol. Authentication is performed in any PKI (Public Key Infrastructure) system by checking if the certificate of the sender is included in the CRL (Certificate Revocation List) and verifying the authenticity and checking the sign of the sender. Bilinear pairing method is used to create an anonymous Id for each vehicle. The CRL checking process has been done using Bloom Filter method which avoids false negative. CRL can be passed between vehicles by bi-directional flooding method which avoids network congestion. This paper focuses mainly the CRL dissemination using the bi-directional flooding method. It replaces the time-consuming CRL Checking process. It reduces message loss ratio by using fast revocation checking and CRL updating method as well as it needs very less memory space compared to other methods.

Time-Bound Anonymous Authentication for Roaming Networks

We propose an anonymous authentication protocol that supports time-bound credentials for an efficient revocation. It is especially suitable for large-scale network in roaming scenario. With our newly designed group signature scheme as a building block, a timestamp can be embedded to user secret key. No expired key can be used to authenticate, and hence naturally revoked users (e.g., due to contract expiration) are not required to be put into the revocation list. This makes our protocol much faster than previous roaming protocols in terms of revocation checking, which is a main part in verification.

EPA: An efficient and privacy-aware revocation mechanism for vehicular ad hoc networks

Security is vital for the reliable operation of vehicular ad hoc networks (VANETs). One of the critical security issues is the revocation of misbehaving vehicles. While essential, revocation checking can leak private information. In particular, repositories receiving the certificate status queries could infer the identity of the vehicles posing the query and the target of the query. An important loss of privacy results from this ability to tie the checking vehicle with the query’s target, due to their likely willingness to communicate. In this paper, we propose an Efficient and Privacy-Aware revocation Mechanism (EPA) based on the use of Merkle Hash Trees (MHT) and a Crowds-based anonymous protocol, which replaces the time-consuming certificate revocation lists checking process. EPA provides explicit, concise, authenticated and unforgeable information about the revocation status of each certificate while preserving the users’ privacy. Moreover, EPA reduces the security overhead for certificate status checking, and enhances the availability and usability of the revocation data. By conducting a detailed performance evaluation, EPA is demonstrated to be reliable, efficient, and scalable.

PPREM: Privacy Preserving REvocation Mechanism for Vehicular Ad Hoc Networks

One of the critical security issues of Vehicular Ad Hoc Networks (VANETs) is the revocation of misbehaving vehicles. While essential, revocation checking can leak potentially sensitive information. Road Side Units (RSUs) receiving the certificate status queries could infer the identity of the vehicles posing the query. An important loss of privacy results from the RSUs ability to tie the checking vehicle with the query's target. We propose a Privacy Preserving Revocation mechanism (PPREM) based on a universal one-way accumulator. PPREM provides explicit, concise, authenticated and unforgeable information about the revocation status of each certificate while preserving the users' privacy.

Can Jannie verify? Usability of display-equipped RFID tags for security purposes

The recent emergence of RFID tags capable of performing public key operations enables a number of new applications in commerce e.g., RFID-enabled credit cards and security e.g., ePassports and access-control badges. While the use of public key cryptography in RFID tags mitigates many difficult security issues, certain important usability-related issues remain, particularly when RFID tags are used for financial transactions or bearer identification.In this paper, we focus exclusively on techniques with user involvement for secure user-to-tag authentication, transaction verification, reader expiration and revocation checking, as well as pairing of RFID tags with other personal devices. Our approach is based on two factors: 1 recent advances in hardware and manufacturing have made it possible to mass-produce inexpensive passive display-equipped RFID tags, and 2 high-end RFID tags used in financial transactions or identification are attended by a human user typically, their owner. Our techniques rely on user involvement coupled with on-tag displays to achieve better security and privacy. Since user acceptance is a crucial factor in this context, we conducted comprehensive user studies to assess usability of all considered methods. This paper reports on our findings.

EMAP: Expedite Message Authentication Protocol for Vehicular Ad Hoc Networks

Vehicular ad hoc networks (VANETs) adopt the Public Key Infrastructure (PKI) and Certificate Revocation Lists (CRLs) for their security. In any PKI system, the authentication of a received message is performed by checking if the certificate of the sender is included in the current CRL, and verifying the authenticity of the certificate and signature of the sender. In this paper, we propose an Expedite Message Authentication Protocol (EMAP) for VANETs, which replaces the time-consuming CRL checking process by an efficient revocation checking process. The revocation check process in EMAP uses a keyed Hash Message Authentication Code ({HMAC}), where the key used in calculating the {HMAC} is shared only between nonrevoked On-Board Units (OBUs). In addition, EMAP uses a novel probabilistic key distribution, which enables nonrevoked OBUs to securely share and update a secret key. EMAP can significantly decrease the message loss ratio due to the message verification delay compared with the conventional authentication methods employing CRL. By conducting security analysis and performance evaluation, EMAP is demonstrated to be secure and efficient.