A small library for computing modular group operations efficiently with BC. For information about BC, see Keith Mattews’ excellent site. It implements modulo exponentiation (modexp) and modulo inverse (modinv), as well as LCM, GCD and bits (which returns the length, in bits, of an integer). This is everything you need to do basic RSA and Elgamal style cryptographic operations (see for example my OpenSSL RSA exponent 3 vulnerability exploit).
Perl script for jamming a Web log. There is balance to be made between logging for security purposes (yang) and respecting user privacy (yin). My intention with this script was simply to expose the problem.