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Cryptography

There are two kinds of cryptosystems: symmetric and asymmetric. Symmetric cryptosystems use the same key (the secret key) to encrypt and decrypt a message, and asymmetric cryptosystems use one key (the public key) to encrypt a message and a different key (the private key) to decrypt it. Assymetric cryptosystems are also called public key cryptosystems.

Symmetric cryptosystems have a problem: how do you transport the secret key from the sender to the recipient securely and in a tamperproof fashion? If you could send the secret key securely, then, in theory, you wouldn't need the symmetric cryptosystem in the first place -- because you would simply use that secure channel to send your message. Frequently, trusted couriers are used as a solution to this problem. Another, more efficient and reliable solution is a public key cryptosystem, such as RSA, which is used in the popular security tool PGP.

sci.crypt and sci.crypt.research are two USENET newsgroups that deal exclusively with cryptography. The latter is a moderated group.

Cryptography Web Sites, Publications, FAQs, and References

Bruce Schneier's Applied Cryptography (2nd Ed.) is the crypto Bible for the professional engineer and interested layman. It's a good survey of the state of the art in crypto techniques and protocols. You can also subscribe to and read back issues of Crypto-Gram, Bruce Schneier's monthly newsletter about cryptography.

FAQS and References

• The Cryptography FAQ
• RSA Labs Cryptography FAQ
• Cryptography References (part 10 of the sci.crypt FAQ)
• Bruce Schneier's Index of Cryptography Papers Online
• The Snake Oil FAQ (Snake Oil Warning Signs: Encryption Software to Avoid)
• The sci.crypt.research newsgroup FAQ

Recurring Publications

• Crypto-gram is a monthly email newletter published by Bruce Schneier
• CrytpoBytes, a technical newsletter on cryptography from RSA Laboratories

Books

• Applied Cryptography (2nd Ed.) by Bruce Schneier (includes an errata sheet)
• Handbook of Applied Cryptography by Alfred Menezes, Paul van Oorschot and Scott Vanstone
• Building in Big Brother: The Cryptographic Policy Debate edited by Lance Hoffman

Cryptography Web Sites and Organizations

• The Center for Democracy and Technology Cryptography Page
• The Crypto Policy Archive at the Electronic Privacy Information Center (EPIC)
• John Gilmore's Cryptography Export Control Archives
• Crypto.com is Matt Blaze's Cryptography information Web site
• Cryptography World has introductory information for beginners
• International Association for Cryptologic Research (IACR)
• The National Security Agency
• The North American Cryptography Archives
• Paul Leyland's cryptography FTP archive
• The Public Key Cryptography Standards (PKCS) Archive at RSADSI
• Ron Rivest's Cryptography and Security Page
• Quadralay's Cryptography Archive
• Vince Cate's Cryptorebel/Cypherpunk Page

Online Documents

• Chaffing and Winnowing: Confidentiality without Encryption by Ron Rivest
• Computer Generated Random Numbers by David W. Deley
• The Crypto Anarchist Manifesto by Tim C. May
• Diceware for Passphrase Generation and Other Cryptographic Applications by Arnold G. Reinhold
• The Dining Cryptographers Problem: Unconditional Sender and Recipient Untraceability by David Chaum, J. Cryptology (1988)
• The Magic Words are Squeamish Ossifrage by D. Atkins, M. Graff, A. Lenstra, and P. Leyland
  (This document is in PostScript format only.)
• The Mathematical Guts of RSA Encryption by Francis Litterio
• One-Time Pad FAQ
• Online Cash Checks by David Chaum
• P=?NP Doesn't Affect Cryptography by Arnold G. Reinhold
• Survey on PGP Passphrase Usage by Arnold G. Reinhold
• TEMPEST in a Teapot by Grady Ward (1993)
• Untraceable Electronic Mail, Return Addresses, and Digital Pseudonyms by David Chaum, Communications of the ACM
• Why Are One-Time Pads Perfectly Secure? by Fran Litterio
• Why Cryptography is Harder Than It Looks by Bruce Schneier

Anonymous E-Mail Remailers

• Sending anonymous email via the Web
• Global Internet Liberty Campaign Anonymous Remailer
• Riot Anonymous Remailer (secure Web site)

Copyright © Francis Litterio