Handbook of Applied Cryptography
- Reference work available for free download (with restrictions) from the Web.
- http://www.cacr.math.uwaterloo.ca/hac/

A Cryptographic Compendium
- Outline of the various types of cipher systems that have been used historically and the relationships between them.
- http://www.quadibloc.com/crypto/intro.htm

MD5 Reverse Lookup
- Project to record and search for mappings of MD5 hashes to their original messages.
- http://md5.crysm.net

Crypto Machines
- Features machines and systems used in secure communications. Includes brief history on cryptography.
- http://www.jproc.ca/crypto/

Standard Cryptographic Algorithm Naming
- Provides references for a collection of cryptographic algorithms, assigning each an ASCII name and zero or more aliases.
- http://www.users.zetnet.co.uk/hopwood/crypto/scan/

An Overview of Cryptography by Gary C. Kessler
- Defines cryptographic terms and concepts, offers crypto scheme comparison, and provides some real world examples.
- http://www.garykessler.net/library/crypto.html

Why Cryptography Is Harder Than It Looks
- Essay on pitfalls of implementing and using secure systems.
- http://www.schneier.com/essay-037.html

Frode Weierud's Cryptology Page
- History of cryptography, cipher machines and their simulation, cryptanalysis and other code breaking techniques.
- http://frode.home.cern.ch/frode/crypto/

CryptoMX Tools
- Set of cryptography tools written entirely in JavaScript, designed to work on any computer with a JavaScript capable browser.
- http://cryptomx.sourceforge.net

The Cipher Challenge
- History of a code cracking competition. Challenge details, how it was solved, winners, essays and photo gallery.
- http://www.simonsingh.net/Cipher_Challenge.html

Randomness and the Netscape Browser
- Article about cracking the original Netscape encryption algorithm, and links to resources for generating crypto strength randomness.
- http://www.cs.berkeley.edu/~daw/netscape-randomness.html

Deschall
- Articles describing the first crack of a DES-encrypted message, with some source code and mailing list archives.
- http://www.interhack.net/projects/deschall/

International Cryptography Freedom
- Links to cryptography related downloads and information from around the world.
- http://www.piracy.com

Adam Back's Homepage: Cypherspace
- Find information on some cryptanalytic hacks, breaking weak cryptosystems and links to more cryptography related websites.
- http://cypherspace.org/adam/

Cryptonomicon
- Cryptography related articles, downloads, news, links and discussions.
- http://www.cryptonomicon.net/

Cryptography World
- Introduction to cryptography, including concepts, key management and application.
- http://www.cryptographyworld.com

Cryptography FAQ
- Ten part FAQ list that is essential reading for any newcomer to cryptography.
- http://www.faqs.org/faqs/cryptography-faq/

International Association for Cryptologic Research (IACR)
- Non-profit scientific organisation intended to further research in cryptology.
- http://www.iacr.org/

Crypto-Gram
- Free monthly email newsletter covering developments in cryptography and other computer security issues.
- http://www.counterpane.com/crypto-gram.html

Choosing a Good Password
- Tips on choosing a difficult to crack password and pitfalls in password selection.
- http://www.cs.umd.edu/faq/Passwords.shtml

Strong Cryptography Links on the Internet
- Dealing with cryptography, information security, cryptographers government, commercial, university, and personal sites, newsgroups, publications, programs and applications.
- http://www.c4i.org/erehwon/crypto.html

Cypherpunks
- Group, with mailing list, that is interested in privacy and cryptography.
- ftp://ftp.csua.berkeley.edu/pub/cypherpunks/mailing_list/index.html

The Munitions Maker Graphic
- Campaign to distribute image (rsa2d.gif) in protest of ITAR regulations that treat encryption as munitions.
- http://online.offshore.com.ai/arms-trafficker/rsa2d.html

Cyphernomicon
- Tim May's CryptoNotes, and an introduction to the Cypherpunks.
- http://www2.pro-ns.net/~crypto/cyphernomicon.html