Abstract

There is a great need for entropy in the running kernel, as well as in user-space. The kernel needs to randomise TCP sequences, seed keys for IPSec, randomise PIDs, and so on. Starvation of these random numbers is a critical problem. Users need random keys, random filenames, nondeterministic games, random numbers for Monte-Carlo simulation and so on.

Kelsey, Schneier and Ferguson proposed an improved algorithm for providing statistically random numbers, at the same time cryptographically protecting their sequence and state. This is the Yarrow algorithm.

This work presents an implementation of this algorithm as the entropy device (/dev/random) in FreeBSD's kernel.

• View the full text of this paper in HTML, PDF, and PostScript. Until February 2003, you will need your USENIX membership identification in order to access the full papers.
  The Proceedings are published as a collective work, © 2002 by the USENIX Association. All Rights Reserved. Rights to individual papers remain with the author or the author's employer. Permission is granted for the noncommercial reproduction of the complete work for educational or research purposes. USENIX acknowledges all trademarks within this paper.

• If you need the latest Adobe Acrobat Reader, you can download it from Adobe's site.

• To become a USENIX Member, please see our Membership Information.