Search

This document specifies the Simple Certificate Enrolment Protocol (SCEP), a PKI protocol that leverages existing technology by using CMS (formerly known as PKCS #7) and PKCS #10 over HTTP. SCEP is the evolution of the enrolment protocol sponsored by Cisco Systems, which enjoys wide support in both client and server implementations, as well as being relied upon by numerous other industry standards that work with certificates.

SSL and TLS are two secure protocols for creating secure connections over the Internet. X.509 certificate validation is important for security and needs to be performed before an SSL/TLS connection is established. However, state-of-the-art testing techniques, such as frankencert and mucert, have revealed, through randomly mutating Internet accessible certificates, that there exist unexpected, sometimes critical, validation differences among different SSL/TLS implementations. Despite these strong efforts, certificate validation is still not thoroughly tested and more effective techniques are needed as this work shows.To this end, this paper introduces transcert, a novel approach for effectively guiding fuzzing to perform deep testing of X.509 certificate validation. The goal of transcert is to generate certificates that trigger diverse executions; it achieves this goal by introducing the concept of a coverage transfer graph to efficiently, precisely abstract program executions. In particular, it records the execution of how a given certificate is validated by a reference SSL/TLS implementation. It then constructs a coverage transfer graph to model the coverage transfer from a test certificate (seed) to its mutated certificates (mutants), and explores the coverage transfer graph by iteratively sampling and mutating certificates.We have implemented transcert and evaluated it against frankencert and mucert on four state-of-the-art SSL/TLS implementations. The evaluation results clearly show the strengths of transcert— during 10,000 iterations, transcert has revealed 3,469 validation differences, 8× as many as those revealed by frankencert and mucert. We have identified 11 root causes of validation differences, all of which have been confirmed and five have never been reported previously. We also found that the primary goal of certificate chain validation is stated ambiguously in the widely-adopted PKI standard RFC 5280.

The Transport Layer Security (TLS) protocol aims to provide confidentiality and integrity of data. It is based on X.509 Certificates. Our previous research showed that popular Web Browsers exhibit non-standardized behaviour with respect to the certificate validation process [1]. This paper extends that work by examining their handling of OCSP Stapling. We also examine several popular HTTPS interception products, including proxies and anti-virus tools, regarding their certificate validation processes. We analyse and compare their behaviour to that described in the relative standards. Finally, we propose a system that allows the automation of certificate validation tests.

Public key infrastructures (PKIs) are the cornerstone for the security of the communication layer of online services relying on certificate-based authentication, such as e-commerce, e-government, online banking, cloud services, and many others. A PKI is an infrastructure based on a hierarchical model, but the use of PKIs in non-hierarchical contexts has exposed them to many types of attacks. Here, we discuss weaknesses exploited in past attacks and we propose a solution based on an original consensus algorithm developed for use on blockchain technology. In this implementation we retain the full functionality around X.509 certificates, i.e., for the triad (server name, server address, X.509 server certificate), and demonstrate a mechanism for obtaining fast consensus. The main properties of the solution are that a consensus may be reached even when not all members of the involved PKI participate in a transaction, and that no advanced trust agreement among PKIs is needed. The proposed solution is able to detect PKI attacks and can distinguish errors from attacks, allowing precise management of anomalies.

The security of cryptographic communication protocols that use X.509 certificates depends on the correctness of those certificates. This paper proposes a system that helps to ensure the correct operation of an X.509 certification authority and its registration authorities. We achieve this goal by enforcing a policy-defined, multi-party validation and authorization workflow of certificate signing requests. Besides, our system offers full accountability for this workflow for forensic purposes. As a foundation for our implementation, we leverage the distributed ledger and smart contract framework Hyperledger Fabric. Our implementation inherits the strong tamper-resistance of Fabric which strengthens the integrity of the computer processes that enforce the validation and authorization of the certificate signing request, and of the metadata collected during certificate issuance.

Certificates are the foundation of secure communication over the internet as of today. While certificates can be issued with long validity periods, there is always a risk of having them compromised during their lifetime. A good practice is therefore to use shorter validity periods. However, this limits the certificate lifetime and gives less flexibility in the timing of certificate replacements. In this thesis, we use publicly available network logs from Rapid7's Project Sonar to provide an overview of the current state of certificate usage behavior. Specifically, we look at the Let's Encrypt mass revocation event in March 2020, where millions of certificates were revoked with just five days notice. In general, we show how this kind of datasets can be used, and as a deeper exploration we analyze certificate validity, lifetime and use of certificates with overlapping validity periods, as well as discuss how our findings relate to industry standard and current security trends. Specifically, we isolate automated certificate services such as Let's Encrypt and cPanel to see how their certificates differ in characteristics from other certificates in general. Based on our findings, we propose a set of rules to help improve the trust in certificate usage and strengthen security online, introducing an Always secure policy aligning certificate validity with revocation time limits in order to replace revocation requirements and overcoming the fact that mobile devices today ignore this very important security feature. To round things off, we provide some ideas for further research based on our findings and what we see possible with datasets such as the one researched in this thesis.

In this paper a design and an implementation of a configurable system for managing the X509 certificates is described. The X509 certificates are one of the most important standards used today in a large number of different authentication mechanisms. As such, they represent one of the important topics at the Computer Security course at the School of Electrical Engineering, University of Belgrade. The system described in this paper has been used within the practical project at the Computer Security course. It provides the ability to generate, sign, and manipulate X509 certificates and it’s implemented in such a way that the graphical user interface (GUI) is completely separated from the logic. This way of implementation relaxes the students from GUI programming and enables them to concentrate on programming the part related to the certificates – security part of the project. The system has been successfully used at the course in the previous school year and the new and improved version is going to be used in this school year.

PDF Encryption is a content security mechanism developed and used by Adobe in their products. In this paper, we have checked a theoretical security level of a variant that uses public key infrastructure and X.509 certificates. We have described a basis of this mechanism and we have performed a simple security analysis. Then, we have showed possible tweaks and security improvements. At the end, we have given some recommendations that can improve security of a content secured with PDF Encryption based on X.509 certificates. Keywords: DRM, cryptography, security level, PDF Encryption, Adobe, X.509

For the purpose of securing mutual communication, Internet of Things (IoT) applications should establish a security association in advance for two or more sensor devices acting as the roles of sensors and actuators. Even though the X-509-based public key certificate can be a viable solution for such purpose, it is not efficient to employ in the IEEE 802.15.4 network, since it is too large to be loaded in IEEE 802.15.4 frames. So, the elliptic-curve Qu–Vanstone (ECQV) implicit certificate has been employed for lightweight security association establishment for the IoT environment. However, it is mandatory to secure the transaction between the sensor device requesting the certificate and the certificate authority. The previous ECQV certificate issuance protocol has several weaknesses, in terms of security and efficiency. In this paper, we propose a new ECQV certificate issuance protocol that addresses the security problems of the previous protocol. Our protocol design is based on integration into the secure join protocol of the IEEE 802.15.4, where we employ a cryptographically generated address for security bootstrapping to secure the join and certificate issuance protocol. We extensively analyze and compare our protocol with the previous protocol in terms of security and performance.

Public-key infrastructure (PKI) is based on public-key certificates and is the most widely used mechanism for trust and key management. However, standard PKI validation and revocation mechanisms are considered major reasons for its unsuitability for delay/disruption tolerant networking (DTN). DTN requires mechanism to authenticate messages at each node before forwarding it in the network. So, certificate revocation lists (CRLs) being distributed in DTN network will need to be authenticated and validated for issuer certificate authority (CA) at each node. In this study, the authors propose new validation and revocation mechanism which is compliant with DTN semantics and protocols. This study also proposes a new design for CRL in compliance with standard PKI X.509 standard to make the proposed mechanism easy to implement for DTN. The new designed CRL is of reduced size as it contains fewer entries as compared with standard X.509 CRL and also arranges the revocation list in the form of hash table (map) to increase the searching efficiency.

Information Centric Networking (ICN) leverages in-network caching to provide efficient data distribution and better performance by replicating contents in multiple nodes to bring content nearer the users. Since contents are stored and replicated into node caches, the content validity must be assured end-to-end. Each content object carries a digital signature to provide a proof of its integrity, authenticity, and provenance. However, the use of digital signatures requires a key management infrastructure to manage the key life cycle. To perform a proper signature verification, a node needs to know whether the signing key is valid or it has been revoked. This paper discusses how to retrieve up-to-date signing keys in the ICN scenario. In the usual public key infrastructure, the Certificate Revocation Lists (CRL) or the Online Certificate Status Protocol (OCSP) enable applications to obtain the revocation status of a certificate. However, the push-based distribution of Certificate Revocation Lists and the request/response paradigm of Online Certificate Status Protocol should be fit in the mechanism of named-data. We consider three possible approaches to distribute up-to-date keys in a similar way to the current CRL and OCSP. Then, we suggest a fourth protocol leveraging a set of distributed notaries, which naturally fits the ICN scenario. Finally, we evaluate the number and size of exchanged messages of each solution, and then we compare the methods considering the perceived latency by the end nodes and the throughput on the network links.

In the last couple of years, we have been actively developing the Dynamic On-Demand Analysis Service (DODAS) as an enabling technology to deploy container-based clusters over any Cloud infrastructure with almost zero effort. The DODAS engine is driven by high-level templates written in the TOSCA language, that allows to abstract the complexity of many configuration details. DODAS is particularly suitable for harvesting opportunistic computing resources; this is why several scientific communities already integrated their computing use cases into DODAS-instantiated clusters automating the instantiation, management and federation of HTCondor batch system. The increasing demand, availability and utilization of HPC by and for multidisciplinary user community, often mandates the possibility to transparently integrate, manage and mix HTC and HPC resources. In this paper, we discuss our experience extending and using DODAS to connect HPC and HTC resources in the context of a distributed Italian regional infrastructure involving multiple sites and communities. In this use case, DODAS automatically generates HTCondor-based clusters on-demand, dynamically and transparently federating sites that may also include HPC resources managed by SLURM; DODAS allows user workloads to make opportunistic and automated use of both HPC and HTC resources, thus effectively maximizing and optimizing resource utilization. We also report on our experience of using and federating HTCondor batch systems exploiting the JSON Web Token capabilities introduced in recent HTCondor versions, replacing the traditional X509 certificates in the whole chain of workload authorization. In this respect we also report on how we integrated HTCondor using OAuth with the INDIGO IAM service.

In the recent past, there has been a series of security incidents leading to increasing concern regarding the trust model currently employed by public key infrastructures. One of the key criticisms is the architecture’s implicit assumption that certificate authorities (CAs) are trustworthy a priori. This work proposes a metric to compensate this assumption by a differentiating assessment of a CA’s individual trustworthiness based on objective criteria. The metric utilizes a wide range of factors derived from existing policies, technical guidelines, and research. It consists of self-contained submetrics allowing the simple extension of the existing set of criteria. The focus is thereby on aspects which can be assessed by employing practically applicable methods of independent data collection. The metric is meant to help organizations, individuals, and service providers deciding which CAs to trust or distrust. For this, the modularized submetrics are clustered into coherent submetric groups covering a CA’s different properties and responsibilities. By applying individually chosen weightings to these submetric groups, the metric’s outcomes can be adapted to tailored protection requirements according to an exemplifying attacker model., In der jüngeren Vergangenheit führte eine Reihe von Sicherheitsvorfällen zu Skepsis bezüglich des momentan etablierten Vertrauensmodells von Public-Key-Infrastrukturen. Einer der Hauptkritikpunkte ist dabei die implizite Annahme, dass Zertifizierungsstellen (CAs) a priori vertrauenswürdig sind. Diese Arbeit stellt eine Metrik vor, welche diese Annahme durch eine differenzierte Beurteilung der individuellen Vertrauenswürdigkeit einer CA auf Basis objektiver Kriterien kompensieren soll. Hierfür bedient sie sich einer Vielzahl verschiedener Faktoren aus technischen Richtlinien und Forschungsarbeiten. Die Metrik besteht aus in sich abgeschlossenen Submetriken. Diese ermöglichen eine einfache Erweiterung des bestehenden Kriterienkatalogs. Der Fokus liegt dabei auf Aspekten, welche durch praktisch anwendbare, unabhängige Methoden der Datenerhebung beurteilt werden können. Die Metrik ist dafür vorgesehen, Organisationen, Dienstleistern und Einzelpersonen bei der Entscheidung zu helfen, welchen CAs sie trauen und welchen sie nicht trauen sollten. Die modularisierten Submetriken sind dafür in themenverwandte Gruppen unterteilt, welche verschiedene Eigenschaften und Aufgaben der CAs abdecken. Durch eine individuelle Gewichtung der einzelnen Submetrik-Gruppen kann die Metrik an Hand eines beispielhaften Angreifer-Modells an maßgeschneiderte Schutzbedarfe angepasst werden.

The migration of signing algorithms is a process which can be used to move from signing algorithms which are regarded as less safe to algorithms which are regarded as safer. The safety of cryptographic algorithms has been compromised before, algorithms such as SHA-1 has been proven to be broken. The goal of this study was to find criteria that could define a successful migration as well as evaluating a method to perform a migration. The criteria were found by evaluating related works found in an RFC document as well as in a Springer conference paper. The criteria that was found was the following: backwards compatibility, no downtime, no need for mass revocation, no need for strict scheduling and no extra overhead. The evaluated method utilized a construct called a multiple key certificate; it was chosen because it conformed to most of the found criteria. The multiple key certificate utilized two different key pairs, one generated from a conventional algorithm and the other using an alternative algorithm, it also conformed to the x.509 standard. The alternative algorithm could be chosen to be a post quantum algorithm. The prototype was tested for time overhead, memory overhead and backward compatibility. The results of testing to sign and verify 10 000 certificates as well as examining the file size of the certificate showed that the choice of alternative algorithm heavily affects the time overhead of the prototype certificate. The multiple key certificate also proved to be backwards compatible with widely used applications. This solution has proven itself to act in accordance to all the newly established criterion except for the criterion regarding overhead however, alternative algorithms could be strategically chosen to minimize overhead. The multiple key certificate seems to be a successful way to migrate signing algorithms. Migration av signeringsalgoritmer som används i certifikat är en process som kan behövas när en signeringsalgoritm som är mindre säker ska ersättas med en som är mer säker. Säkerheten som återfinns hos kryptografiska algoritmer har brutits förut, algoritmer såsom SHA-1 har bevisats vara osäkra. Målet med denna studie var att ta fram kriterier som kan definiera en lyckad migration samt evaluera en metod som kan användas för att utföra en migration. Kriterierna togs fram genom att studera tidigare arbeten inom migration av signeringsalgoritmer, dessa arbeten återfinns hos RFC dokument samt konferensrapporter från Springer. Kriterierna som togs fram var följande: kompatibilitet med äldre system, ingen nertid, inget behov av massrevokering, inget behov av strikta tidsscheman samt ingen extra omkostnad. Metoden som utvärderades kallas för flernyckels certifikat. Den valdes för att den följde flest av de nyfunna kriterierna. Lösningen utnyttjar två olika nyckelpar, nämligen ett nyckelpar som har genererats med en konventionell algoritm samt ett nyckelpar som har genererats med en alternativ algoritm. Lösningen följer även x.509 standarden. Den alternativa algoritmen kan väljas så att den är postkvantum. Prototypen testades för omkostnad i tid samt minne genom att signera och verifiera 10 000 certifikat samt att titta på certifikatens filstorlek. Prototypen testades även för kompatibilitet med kända applikationer. Resultaten visade att valet av alternativa algoritmer hade stor påverkan på omkostnaderna. Tester visade att prototypen var kompatibel med applikationer som används i stor utsträckning. Lösningen verkade följa alla nyfunna kriterier förutom kriteriet angående omkostnad men den alternativa algoritmen kan strategiskt väljas för att minimera omkostnaden. Prototypen verkar vara ett lyckat sätt att migrera signeringsalgoritmer.

Trabalho de projecto de mestrado, Engenharia Informática (Arquitetura, Sistemas e Redes de Computadores) Universidade de Lisboa, Faculdade de Ciências, 2019 Submitted by Teresa Boa (tdboa@fc.ul.pt) on 2019-09-20T14:22:40Z No. of bitstreams: 1 ulfc125537_tm_Hermínio_Tavares.pdf: 2491683 bytes, checksum: f55ed33b591482b65f086f8dccf0a1ea (MD5) Made available in DSpace on 2019-09-20T14:22:57Z (GMT). No. of bitstreams: 1 ulfc125537_tm_Hermínio_Tavares.pdf: 2491683 bytes, checksum: f55ed33b591482b65f086f8dccf0a1ea (MD5) Previous issue date: 2019

In recent years, we observed a growth of cybersecurity threats, especially due to the ubiquitous of connected and autonomous devices commonly defined as Internet of things (IoT). These devices, designed to handle basic operations, commonly lack security measurements. In this paper, we want to tackle how we could, by design, apply static and dynamic security solutions for those devices and define security measurements without degrading overall the performance.

In this work, we assessed the impact of post-quantum (PQ) cryptography on public key infrastructure (PKI). First, we modified a commercially available certification authority (CA) to issue 'hybrid'...

Rogue certificates are valid certificates issued by a legitimate certificate authority (CA) that are nonetheless untrustworthy; yet trusted by web browsers and users. With the current public key infrastructure, there exists a window of vulnerability between the time a rogue certificate is issued and when it is detected. Rogue certificates from recent compromises have been trusted for as long as weeks before detection and revocation. Previous proposals to close this window of vulnerability require changes in the infrastructure, Internet protocols, or end user experience. We present a method for detecting rogue certificates from trusted CAs developed from a large and timely collection of certificates. This method automates classification by building machine-learning models with Deep Neural Networks (DNN). Despite the scarcity of rogue instances in the dataset, DNN produced a classification method that is proven both in simulation and in the July 2014 compromise of the India CCA. We report the details of the classification method and illustrate that it is repeatable, such as with datasets obtained from crawling. We describe the classification performance under our current research deployment.

Bolstering public key authentication of networking entities, digital certificates are an entrenched part of Internet security. A digital certificate is an electronic document signed by a certificate authority (CA), vouching that the identified subject owns the declared public key (and the corresponding private key). In general, CAs are also responsible for certificate revocation as well as reissue, and certificates by nature are considered independent of each other. In this paper, we address the problem of certificate management and propose a flexible framework to create correlated certificates. We then apply it to implement the so-called multi-certificate public key infrastructure, which supports user self services, such as certificates’ spontaneous substitution as well as self-reissue after self-revocation. To the best of our knowledge, this is the first scheme for certificate users to achieve self-reissue. Another application of the proposed framework is the so-called anonymous digital certificate, which still binds a user’s identity to her public key, but in an anonymous yet user-controllable manner. That is, a user can reveal her identity-key binding only to her specified communication peers, while remaining anonymous to the general public, achieving privacy as these certificates are generally unlinkable.

We can share mobile certificates securely without modification of X.509 certificate.The certificate sharing system is implemented on a virtual private network.The certificate sharing system provides strong data security on physical devices.The certificate sharing system significantly improves convenience for users.The certificate sharing system provides a flexible and extensible system. As mobile and Internet technologies evolve, mobile services (e.g., Internet banking, social commerce) continuously expand and diversify. In order to use these mobile services, it is essential that security services, especially distribution certificates (e.g., bank certificates), relevant to mobile devices be provided. Some approaches to providing distribution certificates between a user's mobile device and a personal computer (PC) have been proposed. However, the existing approaches do not guarantee that the certificate in the mobile devices same with the issued one from the PC, causing constraints on mobile services such as mobile phone banking and mobile commerce (M-commerce).In this paper, we propose a novel approach that shares certificates securely without modification of the existing standard certificate format between a smartphone and a PC. We also implemented the certificate sharing system (CSS) in a virtual private network (VPN). The CSS provides strong end-to-end data security for the certificate with a key size of 192-bits which is able to guarantee an expiration date of three years. It also provides strong data security on physical devices with the use of device ID. The certificate that is shared between devices is available only through the CSS's authorization process. In addition, the CSS provides a flexible and extensible system for sharing certificates in enterprise environments. The CSS module of a PC was implemented by way of a standard web language, and the CSS module of a smartphone was developed with the assistance of mobile applications with a small size of 1210KB.

The deployment of any security policy requires the definition of a trust model that defines who trusts who and how. There is a host of research efforts in the trustworthy area to securing mobile ad hoc networks. Among the most used approaches are based on public-key certificates and gave birth to miscellaneous trust models ranging from centralized models to web-of-trust and distributed certification authorities. Certificates management in mobile ad hoc networks is a veritable challenge because of constrictions imposed by the nature of the network. The freedom of nodes mobility involves some constraints when designing reliable certification systems. In this paper, we address this issue and we propose a secure and reliable certificate chains recovery protocol for mobile ad hoc networks. Our proposal is based on web-of-trust in which the users ensure themselves the role of the certification service by issuing and managing the public-key certificates. The shortest and the safest certificate chains are selected in order to reduce the communication overhead and resist against compromised nodes which can generate false certificates. An analytical model is developed and simulations are performed in order evaluate the performances of our protocol, in which it demonstrates interesting results.

Mobile agent systems (MASs) that travel autonomously through a computer network in order to perform some computation or gather information on behalf of a human user or an application. business applications. In most applications, the security of mobile agents is of the utmost importance. this paper, we propose a MAS environment.Public key infrastructure is used in authentication. Policy-based security management has become a growing research area for mobile agent security. To ensure authorization in used to grant privileges to agents according to their roles. X.509 certificate is the most widely used data format for public key certificates. information in its OU (organization unit) field, to make sure environment are given access to certain data or resources according to their roles. may be tampered by malicious agent to misuse its privileges. To ensure agent’s integrity, agent code encrypted, signedand added in X.509 certificate to be checked before agent execution. confidentiality, information that needs to be protected from disclosure like agent’s shopping list is encrypted while travelling through communication channels to preven eavesdropping.

X.509 certificates underpin the security of the Internet economy, notably secure web servers, and they need to be revoked promptly and reliably once they are compromised. The original revocation method specified in the X.509 standard, to distribute certificate revocation lists (CRLs), is both old and untrustworthy. CRLs are susceptible to attacks such as Man-in-the-Middle and Denial of Service. The newer Online Certificate Status Protocol (OCSP) and OCSP-stapling approaches have well-known drawbacks as well.The primary contribution of this paper is Secure Revocation as a Peer Service (SCRaaPS). SCRaaPS is an alternative, reliable way to support X.509 certificate revocation via the Scrybe secure provenance system. The blockchain support of Scrybe enables the creation of a durable, reliable revocation service that can withstand Denial-of-Service attacks and ensures non-repudiation of certificates revoked. We provide cross-CA-revocation information and address the additional problem of intermediate-certificate revocation with the knock-on effects on certificates derived thereof.A Cuckoo filter provides quick, communication-free testing by servers and browsers against our current revocation list (with no false negatives). A further contribution of this work is that the revocation service can fit in as a drop-in replacement for OCSP-stapling with superior performance and coverage both for servers and browsers. Potential revocation indicated by our Cuckoo filter is backed up by rigorous service query to eliminate false positives. Cuckoo filter parameters are also stored in our blockchain to provide open access to this algorithmic option for detection.We describe the advantages of using a blockchain-based system and, in particular, the approach to distributed ledger technology and lightweight mining enabled by Scrybe, which was designed with secure provenance in mind.

X.509 Certificates are used by a wide range of technologies to verify identities, while the SSL protocol is used to provide a secure encrypted tunnel through which data can be sent over a public network. Combined both of these technologies provides the basis of the public key infrastructure (PKI). While the concept of PKI is a good idea, the different implementation of the technologies in different operating system and clients often lead to weaknesses. This paper proposes a methodology to automate the testing of SSL clients by generating both bogus and malformed certificates in order to evaluate the client's response and identify potential threats to network infrastructures.

With the popular use of SSL/TLS, more and more web applications, such as online banking, e-mail, and ecommerce, turn to secured channels for communication, which rely on X.509 certificate for authentication. Generally, every certificate has a theoretical validity period when it is issued. However, the used period in practice is often different from the theoretical validity, namely, before or after the validity, for a long or short time. If a certificate is expired, it is easily to be exploited by cyber-attackers, leading to web users’ personal information at risk. To explore the security flaws of the SSL/TLS certificate, we conduct a large-scale measurement study of X.509 certificate life cycle from the view of leaf certificates. Based on a passive data set collected over one year, we investigate the certificate validity period in a fine-grained manner, and uncover that the actual usage of the certificates are not satisfactory. Meanwhile, we discover several security-related issues that may leave the web communication at risk. The recommendations are summarized to ensure the long-term security for certificate use in practice. We believe that the work will be beneficial to web security and improve the certificate utilization in the future.

X.509 certificate parsing and validation is a critical task which has shown consistent lack of effectiveness, with practical attacks being reported with a steady rate during the last 10 years. In this work we analyze the X.509 standard and provide a grammar description of it amenable to the automated generation of a parser with strong termination guarantees, providing unambiguous input parsing. We report the results of analyzing a 11M X.509 certificate dump of the HTTPS servers running on the entire IPv4 space, showing that 21.5% of the certificates in use are syntactically invalid. We compare the results of our parsing against 7 widely used TLS libraries showing that 631k to 1,156k syntactically incorrect certificates are deemed valid by them (5.7%--10.5%), including instances with security critical mis-parsings. We prove the criticality of such mis-parsing exploiting one of the syntactic flaws found in existing certificates to perform an impersonation attack.

This demonstration presents a low cost, low power object based on Arduino board, whose security is enforced by a secure element. Most of IoT devices are built over a General Purpose Unit (GPU) associated to a radio System on Chip (SoC), and controlling multiple sensors and/or actuators. We designed a similar architecture, in which communications are secured by a TLS server running in a secure element. This secure chip performs strong mutual authentication with remote clients dealing with X509 certificates, and acts as an identity module.

X.509 is the de facto digital certificate standard used in building the Public Key Infrastructure (PKI) on the Internet. However, traditional X.509 certificates are too heavy for battery powered or energy harvesting Internet of Things (IoT) devices where it is crucial that energy consumption and memory footprints are as minimal as possible.

The public key cryptography (PKC) is essential for securing many applications in smart grid. For the secure use of the PKC, certificate revocation schemes tailored to smart grid applications should be adopted. However, little work has been done to study certificate revocation in smart grid. In this paper, we first explain different motivations that necessitate revoking certificates in smart grid. We also identify the applications that can be secured by PKC and thus need certificate revocation. Then, we explain existing certificate revocation schemes and define several metrics to assess them. Based on this assessment, we identify the applications that are proper for each scheme and discuss how the schemes can be modified to fully satisfy the requirements of its potential applications. Finally, we study certificate revocation in pseudonymous public key infrastructure (PPKI), where a large number of certified public/private keys are assigned for each node to preserve privacy. We target vehicles-to-grid communications as a potential application. Certificate revocation in this application is a challenge because of the large number of certificates. We discuss an efficient certificate revocation scheme for PPKI, named compressed certificate revocation lists (CRLs). Our analytical results demonstrate that one revocation scheme cannot satisfy the overhead/security requirements of all smart grid applications. Rather, different schemes should be employed for different applications. Moreover, we used simulations to measure the overhead of the schemes.

Transport Layer Security (TLS) and its predecessor, SSL, are important cryptographic protocol suites on the Internet. They both implement public key certificates and rely on a group of trusted certificate authorities (i.e., CAs) for peer authentication. Unfortunately, the most recent research reveals that, if any one of the pre-trusted CAs is compromised, fake certificates can be issued to intercept the corresponding SSL/TLS connections. This security vulnerability leads to catastrophic impacts on SSL/TLS-based HTTPS, which is the underlying protocol to provide secure web services for e-commerce, e-mails, etc. To address this problem, we design an attribute dependency-based detection mechanism, called SSLight. SSLight can expose fake certificates by checking whether the certificates contain some attribute dependencies rarely occurring in legitimate samples. We conduct extensive experiments to evaluate SSLight and successfully confirm that SSLight can detect the vast majority of fake certificates issued from any trusted CAs if they are compromised. As a real-world example, we also implement SSLight as a Firefox add-on and examine its capability of exposing existent fake certificates from DigiNotar and Comodo, both of which have made a giant impact around the world.

Each public key infrastructure needs an efficient certificate status validation method to exclude the revoked certificates from network. In this paper, we present a novel certificate validation scheme called E-ADOPT or Enhanced-ADOPT which utilizes a new kind of certificate status information. In this solution, we modify the OCSP response messages to carry information about the accusations issued against the certificate and this additional security information helps the client nodes to tune the OCSP results refresh rate more intelligently. As a result, client node can mitigate the certificate status information inconsistency problem with lower overheads and conduct more effective certificate status validations in MANET. Simulation results demonstrate that by appending accusation-related information to the OCSP responses, our solution achieves better results.

This article discusses two strategies for managing sensing resources in the cloud and providing them as a service. The first strategy follows the data-centric model, where the cloud offers environmental data to its clients as a service, without any knowledge of how data are measured and processed. The second strategy adopts the device-centric model, which enables the cloud clients to use a virtual sensing infrastructure that they can customize for specific purposes. They can access sensed data and customize one or more virtual devices. The article also presents a cloud framework, called Cloud4Sens, that combines both the data-centric and device-centric models, enabling the end-user to choose which type of cloud service he needs. The proposed solution was designed according to the Sensor Web Enablement (SWE) specifications defined by the Open Geospatial Consortium and exploits well known technologies, such as XMPP (Extensible Messaging and Presence Protocol) communications and X509 certificates.

When is it better to use a self-signed rather than a public certificate authority to sign your certificates? If you aren't sure, you're not alone. The reasons many companies make the wrong choice and the factors to be considered when choosing a certificate solution are discussed.

The X509 certification is one of the most important standards used today in a large number of different authentication mechanisms. As such, they represent one of the important topics at the Computer Security course at the School of Electrical Engineering, University of Belgrade. This paper describes a configurable system for handling X509 certificates, which has been used within the practical project at the Computer Security course. The system provides the ability to generate, sign, and manipulate X509 certificates. The system was implemented in such a way that the graphical user interface (GUI) is completely separated from the logic, which relaxes the students from GUI programming and enables them to concentrate on programming the part related to the certificates. The system has been successfully used at the course in the previous school year.

We present a certificate access management system to support the USDOT's proposed rule on Vehicle-to-Vehicle (V2V) communications, Federal Motor Vehicle Safety Standard (FMVSS) No. 150. Our proposal, which we call Binary Hash Tree based Certificate Access Management (BCAM) eliminates the need for vehicles to have bidirectional connectivity with the Security Credential Management System (SCMS) for certificate update. BCAM significantly improves the ability of the SCMS to manage large-scale software and/or hardware compromise events. Vehicles are provisioned at the start of their lifetime with all the certificates they will need. However, certificates and corresponding private key reconstruction values are provided to the vehicle encrypted, and the keys to decrypt them are only made available to the vehicles shortly before the start of the validity periods of those certificates. Vehicles that are compromised can be effectively removed from the V2V system by preventing them from decrypting the certificates. We demonstrate that the system is feasible with a broadcast channel for decryption keys and other revocation information, even if that channel has a relatively low capacity.Reproducibility VM download link: https://drive.google.com/open?id=0B4ozf__jZFRs7VmhqampHczhBTkU

Digital certificates are one of the key components to ensure secure network communications. The complexity of the certificate standard, ITU-R-X.509, has led to a number of breaches in the TLS protocol security due to certificate misinterpretation by TLS libraries. We argue that the root cause of such an issue is the complexity of the certificate structure, which can be gauged with the framework of formal language theory: the language describing digital certificates is context sensitive. Such a complexity led to handcrafted X.509 parsers, resulting in implementations which are not guaranteed to perform correct language recognition. We highlight the issues in X.509, and propose a new format for digital certificates, designed to be parsed effectively and efficiently, while retaining the same semantic expressiveness. The certificate format can be deployed gradually, is fully specified as a regular language, and is specified as a formal grammar from which a provably correct parser can be automatically derived. We validate the effectiveness of our proposal, and the linear running time provided by the approach, generating an instance of the parser with a production grade lexer/parser generation framework.