An open-source utility for Linux that uses an attached webcam to seed the kernel's random number generator for cryptographic purposes.
An open source utility for Linux that seeds the kernel's random number generator with data pulled from an attached microphone.
A command line utility that calculates the amount of informational entropy in arbitrary fields of data. Useful for cryptanalysis and data compression research
Along with NIST SP800-22rev1 (statistical analysis of pseudo-random number generators), the Statistical Test Suite can be used to actually perform the tests outlined in this document. Runs under Windows, Linux, and Mac OSX. Written in C.
An in-depth description of how pseudorandom number generators work (specifically, in Linux and OpenBSD) and how to improve the entropy pools of systems. Includes instructions on testing the entropy available, running an entropy gathering daemon to keep the entropy pool full, and how to rig up a wireless network interface to seed the kernel entropy pool.
A daemon that adds noise to the Linux kernel's entropy pool to maintain a certain amount of randomness. Every little bit helps.
FOSS software that uses an RTL-SDR radio receiver as a cryptographic entropy generator. Pulls samples of RF noise, processes them, and seeds an RNG with it. Written in C.