The Yarrow algorithm is a cryptographically secure pseudorandom number generator. The name is taken from the yarrow plant, the stalks of which are dried and used as a randomising agent in I Ching divination.

It was designed by Bruce Schneier, John Kelsey, and Niels Ferguson of Counterpane Labs (Kelsey et. al, 1999). The Yarrow algorithm is explicitly unpatented and royalty-free; no license is required to use it. Yarrow is incorporated in Mac OS X and FreeBSD for their /dev/random devices.

An improved design from Ferguson and Schneier, Fortuna, is described in their book, Practical Cryptography.

External links

• Yarrow algorithm page
• ''Yarrow-160: Notes on the Design and Analysis of the Yarrow Cryptographic Pseudorandom Number Generator'', J. Kelsey, B. Schneier, and N. Ferguson

de:Yarrow (Algorithmus) es:Yarrow fr:Yarrow pt:Algoritmo Yarrow