OpenPGP, an IETF Proposed Standard based on PGP application, has its own Public Key Infrastructure (PKI) architecture which is different from the one based on X.509, another standard from ITU. This paper describes the OpenPGP PKI; the historical perspective as well as its current use. The current OpenPGP PKI issues include the capability of a PGP keyserver and its performance. PGP keyservers have been developed and operated by volunteers since the 1990s. The keyservers distribute, merge, and expire the OpenPGP public keys. Major keyserver managers from several countries have built the globally distributed network of PGP keyservers. However, the current PGP Public Keyserver (pksd) has some limitations. It does not support fully the OpenPGP format so that it is neither expandable nor flexible, without any cluster technology. Finally we introduce the project on the next generation OpenPGP public keyserver called the OpenPKSD, lead by Hironobu Suzuki, one of the authors, and funded by Japanese Information-technology Promotion Agency(IPA).
OpenPGP PKI itself can be described as the superset of PKI @cite_27 , however, combining OpenPGP PKI with other authentication system is challenging work in both theoretical and operational field. Formal study of trust relationship of PKI started in the late 1990s @cite_7 @cite_14 and GnuPG development version in December 2002 started to support its trust calculation with GnuPGP's trust signature.
@cite_27 @cite_14 @cite_7
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The Public Key Infrastructure (PKI) in use today on the Internet to secure communications has several drawbacks arising from its centralised and non-transparent design. In the past there has been instances of certificate authorities publishing rogue certificates for targeted attacks, and this has been difficult to immediately detect as certificate authorities are not transparent about the certificates they issue. Furthermore, the centralised selection of trusted certificate authorities by operating system and browser vendors means that it is not practical to untrust certificate authorities that have issued rogue certificates, as this would disrupt the TLS process for many other hosts. SCPKI is an alternative PKI system based on a decentralised and transparent design using a web-of-trust model and a smart contract on the Ethereum blockchain, to make it easily possible for rogue certificates to be detected when they are published. The web-of-trust model is designed such that an entity or authority in the system can verify (or vouch for) fine-grained attributes of another entity's identity (such as company name or domain name), as an alternative to the centralised certificate authority identity verification model. The public key infrastructure (PKI) based authentication protocol provides the basic security services for vehicular ad-hoc networks (VANETs). However, trust and privacy are still open issues due to the unique characteristics of vehicles. It is crucial for VANETs to prevent internal vehicles from broadcasting forged messages while simultaneously protecting the privacy of each vehicle against tracking attacks. In this paper, we propose a blockchain-based anonymous reputation system (BARS) to break the linkability between real identities and public keys to preserve privacy. The certificate and revocation transparency is implemented efficiently using two blockchains. We design a trust model to improve the trustworthiness of messages relying on the reputation of the sender based on both direct historical interactions and indirect opinions about the sender. Experiments are conducted to evaluate BARS in terms of security and performance and the results show that BARS is able to establish distributed trust management, while protecting the privacy of vehicles. The current Transport Layer Security (TLS) Public-Key Infrastructure (PKI) is based on a weakest-link security model that depends on over a thousand trust roots. The recent history of malicious and compromised Certification Authorities has fueled the desire for alternatives. Creating a new, secure infrastructure is, however, a surprisingly challenging task due to the large number of parties involved and the many ways that they can interact. A principled approach to its design is therefore mandatory, as humans cannot feasibly consider all the cases that can occur due to the multitude of interleavings of actions by legitimate parties and attackers, such as private key compromises (e.g., domain, Certification Authority, log server, other trusted entities), key revocations, key updates, etc. We present ARPKI, a PKI architecture that ensures that certificate-related operations, such as certificate issuance, update, revocation, and validation, are transparent and accountable. ARPKI efficiently supports these operations, and gracefully handles catastrophic events such as domain key loss or compromise. Moreover ARPKI is the first PKI architecture that is co-designed with a formal model, and we verify its core security property using the TAMARIN prover. We prove that ARPKI offers extremely strong security guarantees, where compromising even n 1 trusted signing and verifying entities is insufficient to launch a man-in-the-middle attack. Moreover, ARPKI’s use deters misbehavior as all operations are publicly visible. Finally, we present a proof-of-concept implementation that provides all the features required for deployment. Our experiments indicate that ARPKI efficiently handles the certification process with low overhead. It does not incur additional latency to TLS, since no additional round trips are required. Traditional PKIs face a well-known vulnerability that caused by compromised Certificate Authorities (CA) issuing bogus certificates. Several solutions like AKI and ARPKI have been proposed to address this vulnerability. However, they require complex interactions and synchronization among related entities, and their security has not been validated with wide deployment. We propose an accountable, flexible and efficient decentralized PKI to achieve the same goal using the blockchain technology of Bitcoin, which has been proven to be secure and reliable. The proposed scheme, called BKI, realizes certificate issuance, update and revocation with transactions on a special blockchain that is managed by multiple trusted maintainers. BKI achieves accountability and is easy to check certificate validity, and it is also more secure than centralized PKIs. Moreover, the certificate status update interval of BKI is in seconds, significantly reducing the vulnerability window. In addition, BKI is more flexible than AKI and ARPKI in that the number of required CAs to issue certificates is tunable for different applications. We analyze BKI’s security and performance, and present details on implementation of BKI. Experiments using Ethereum show that certificate issuance update revocation cost 2.38 ms 2.39 ms 1.59 ms respectively.