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).
A web of trust'' used in PGP is referred in several researches including the peer-to-peer authentication @cite_9 , trust computation @cite_7 @cite_14 , and privacy enhanced technology @cite_6 . However, there are few description on PGP keyserver. It might be because PGP keyserver mechanism is too simple. It is not a CA but just a pool of public keys. From users' viewpoint, PGP keyserver has a large amount of OpenPGP public keys that provide the interesting material for social analysis of network community. For example, OpenPGP keyserver developer Jonathan McDowell also developed Experimental PGP key path finder'' @cite_20 that searches and displays the chain of certification between the users.
@cite_14 @cite_7 @cite_9 @cite_6 @cite_20
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Most currently deployed public key infrastructures (PKIs) are hierarchically oriented and rely on a centralized design. Hierarchical PKIs may be appropriate solutions for many usage-scenarios, but there exists the viable alternative of the 'Web of Trust'. In a web of trust, each user of the system can choose for himself whom he elects to trust, and whom not. After contrasting the properties of web-of-trust based PKIs to those of hierarchical PKIs, an introduction to webs of trust and to quantitative trust calculations is given. The paper concludes with the presentation of an efficient, sub-exponential algorithm that allows heuristic computations of trust paths in a web of trust. CRYPTOGRAPHIC PROTOCOLS. Protocol Building Blocks. Basic Protocols. Intermediate Protocols. Advanced Protocols. Esoteric Protocols. CRYPTOGRAPHIC TECHNIQUES. Key Length. Key Management. Algorithm Types and Modes. Using Algorithms. CRYPTOGRAPHIC ALGORITHMS. Data Encryption Standard (DES). Other Block Ciphers. Other Stream Ciphers and Real Random-Sequence Generators. Public-Key Algorithms. Special Algorithms for Protocols. THE REAL WORLD. Example Implementations. Politics. SOURCE CODE.source Code. References. From the Publisher: If gou've ever made a secure purchase with your credit card online, you have seen cryptography, or "crypto," in action. From Steven Levy -- the author who made "hackers" a household word -- comes this account of a revolution that will affect every citizen in the twenty-first century. Crypto tells the inside story of how a group of "crypto rebels" -- nerds and visionaries turned freedom fighters -- teamed up with corporate interests to beat Big Brother and ensure our privacy on the Internet. From Whitfield Diffie's discovery of public key encryption in the mid-1970s to the Phil Zimmerman-led "cypherpunks'" recent fight to distribute encryption power freely to the masses, Levy's history of one of the most controversial and important topics of the digital age reads like the best futuristic fiction. From the Publisher: Use of the Internet is expanding beyond anyone's expectations. As corporations, government offices, and ordinary citizens begin to rely on the information highway to conduct business, they are realizing how important it is to protect their communications -- both to keep them a secret from prying eyes and to ensure that they are not altered during transmission. Encryption, which until recently was an esoteric field of interest only to spies, the military, and a few academics, provides a mechanism for doing this. PGP, which stands for Pretty Good Privacy, is a free and widely available encryption program that lets you protect files and electronic mail. Written by Phil Zimmermann and released in 1991, PGP works on virtually every platform and has become very popular both in the U.S. and abroad. Because it uses state-of-the-art public key cryptography, PGP can be used to authenticate messages, as well as keep them secret. With PGP, you can digitally "sign" a message when you send it. By checking the digital signature at the other end, the recipient can be sure that the message was not changed during transmission and that the message actually came from you. PGP offers a popular alternative to U.S. government initiatives like the Clipper Chip because, unlike Clipper, it does not allow the government or any other outside agency access to your secret keys. PGP: Pretty Good Privacy by Simson Garfinkel is both a readable technical user's guide and a fascinating behind-the-scenes look at cryptography and privacy. Part I, "PGP Overview," introduces PGP and the cryptography that underlies it. Part II, "Cryptography History and Policy," describes the history of PGP -- its personalities, legal battles, and other intrigues; it also provides background on the battles over public key cryptography patents and the U.S. government export restrictions, and other aspects of the ongoing public debates about privacy and free speech. Part III, "Using PGP," describes how to use PGP: protecting files and email, creating and using keys, signing messages, certifying and distributing keys, and using key servers. Part IV, "Appendices," describes how to obtain PGP from Internet sites, how to install it on PCs, UNIX systems, and the Macintosh, and other background information. The book also contains a glossary, a bibliography, and a handy reference card that summarizes all of the PGP commands, environment variables, and configuration variables.