Browsers can detect malicious websites that are provisioned with forged or fake TLS SSL certificates. However, they are not so good at detecting malicious websites if they are provisioned with mistakenly issued certificates or certificates that have been issued by a compromised certificate authority. Google proposed certificate transparency which is an open framework to monitor and audit certificates in real time. Thereafter, a few other certificate transparency schemes have been proposed which can even handle revocation. All currently known constructions use Merkle hash trees and have proof size logarithmic in the number of certificates domain owners. We present a new certificate transparency scheme with short (constant size) proofs. Our construction makes use of dynamic bilinear-map accumulators. The scheme has many desirable properties like efficient revocation, low verification cost and update costs comparable to the existing schemes. We provide proofs of security and evaluate the performance of our scheme.
Recently, Dowling @cite_33 proposed a formal framework of secure logging in general. Formal security proofs for secure logging have been presented. The underlying framework consider Google's framework and does not support revocation of domain owners. However, only the proof of presence has been considered in this work. A different line of work is accountable PKI (APKI) @cite_10 @cite_31 , which has been used to address the decrease in trust on CAs. APKI efficiently handles revocation and is still a tree-based protocol. Deployment challenges for log based PKI enhancements have been presented in @cite_8 . Accountability in future internet has been discussed in @cite_28 . Key transparency is another closely related line of work. It differs from the certificate transparency in that, in key transparency, there is a requirement to protect the secrecy of the public keys of the domain owners. Coniks @cite_29 is an example of a key transparency scheme.
@cite_33 @cite_8 @cite_28 @cite_29 @cite_31 @cite_10
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Log-based PKI enhancements propose to improve the current TLS PKI by creating public logs to monitor CA operations, thus providing transparency and accountability. In this paper we take the first steps in studying the deployment process of log-based PKI enhancements in two ways. First, we model the influences that parties in the PKI have to incentivize one another to deploy a PKI enhancement, and determine that potential PKI enhancements should focus their initial efforts on convincing browser vendors to deploy. Second, as a promising vendor-based solution we propose deployment status filters, which use a Bloom filter to monitor deployment status and efficiently defend against downgrade attacks from the enhanced protocol to the current TLS PKI. Our results provide promising deployment strategies for log-based PKI enhancements and raise additional questions for further fruitful research. We present CONIKS, an end-user key verification service capable of integration in end-to-end encrypted communication systems. CONIKS builds on transparency log proposals for web server certificates but solves several new challenges specific to key verification for end users. CONIKS obviates the need for global third-party monitors and enables users to efficiently monitor their own key bindings for consistency, downloading less than 20 kB per day to do so even for a provider with billions of users. CONIKS users and providers can collectively audit providers for non-equivocation, and this requires downloading a constant 2.5 kB per provider per day. Additionally, CONIKS preserves the level of privacy offered by today's major communication services, hiding the list of usernames present and even allowing providers to conceal the total number of users in the system. We present ARPKI, a public-key infrastructure that ensures that certificate-related operations, such as certificate issuance, update, revocation, and validation, are transparent and accountable. ARPKI is the first such infrastructure that systematically takes into account requirements identified by previous research. Moreover, ARPKI is co-designed with a formal model, and we verify its core security property using the Tamarin prover. We present a proof-of-concept implementation providing all features required for deployment. ARPKI efficiently handles the certification process with low overhead and without incurring additional latency to TLS. ARPKI offers extremely strong security guarantees, where compromising n-1 trusted signing and verifying entities is insufficient to launch an impersonation attack. Moreover, it deters misbehavior as all its operations are publicly visible. Recent trends in public-key infrastructure research explore the tradeoff between decreased trust in Certificate Authorities (CAs), resilience against attacks, communication overhead (bandwidth and latency) for setting up an SSL TLS connection, and availability with respect to verifiability of public key information. In this paper, we propose AKI as a new public-key validation infrastructure, to reduce the level of trust in CAs. AKI integrates an architecture for key revocation of all entities (e.g., CAs, domains) with an architecture for accountability of all infrastructure parties through checks-and-balances. AKI efficiently handles common certification operations, and gracefully handles catastrophic events such as domain key loss or compromise. We propose AKI to make progress towards a public-key validation infrastructure with key revocation that reduces trust in any single entity.