IACR's ePrint A database of cryptographic papers.

Light blue touchpaper A blog of the Security group at the University of Cambridge.

Matrix news Our very simple concentrator of security-related RSS feeds.

Encyclopedies of Cryptography

The Codebreakers (The Story of Secret Writing) - David Kahn (pdf file)

Military Cryptoanalysis Part I - William F. Friedman (pdf file)

Codes - The Guide To Secrecy From Acient To Modern Times - Richard A. Mollin (pdf file)