Secure Programming Cookbook for C and C++

11.8. Getting Entropy or Pseudo-Randomness Using EGADS

Problem

You want to use a library-level interface to EGADS for gathering entropy or getting cryptographically strong pseudo-random data. For example, you may need entropy on a system such as Microsoft Windows, where there is no built-in API for getting it.

Solution

Use the EGADS API as described in the following Section 11.8.3.

Discussion

EGADS, the Entropy Gathering and Distribution System, is capable of performing many functions related to random numbers. First, it provides a high-level interface for getting random values, such as integers, numbers in a particular range, and so on. Second, EGADS does its own entropy collection, and has a library-level API for accessing the collector, making it a simple API to use for any of your randomness needs.

EGADS supports a variety of Unix variants, including Darwin, FreeBSD, Linux, OpenBSD, and Solaris. In addition, it supports Windows NT 4.0, Windows 2000, and Windows XP. Unfortunately, EGADS does not support Windows 95, Windows 98, or Windows ME because it runs as a service (which is a subsystem that does not exist on these versions of Windows). EGADS is available from http://www.securesoftware.com/egads.

EGADS is a good solution for the security-minded because it is conservative. It contains a conservative entropy collector and a conservative pseudo-random number generator. Both of these components have provable security properties that rely only on the strength of the AES cryptographic ...