Randomness Requirements for Security

Summary

Network Working Group D. Eastlake, 3rd Request for : 4086 Motorola Laboratories BCP: 106 J. Schiller Obsoletes: 1750 MIT Category: Best Current Practice S. Crocker June 2005 Randomness Requirements for Security Status of This Memo This document specifies an Internet Best Current Practices for the Internet Community, and requests discussion and suggestions for improvements. Distribution of this memo is unlimited. Copyright Notice Copyright (C) The Internet Society (2005). Abstract Security systems are built on strong cryptographic algorithms that foil pattern analysis attempts. However, the security of these systems is dependent on generating secret quantities for passwords, cryptographic keys, and similar quantities. The use of pseudo-random processes to generate secret quantities can result in pseudo- security. A sophisticated attacker may find it easier to reproduce the environment that produced the secret quantities and to search the resulting small set of possibilities than to locate the quantities in the whole of the potential number space. Choosing random quantities to foil a resourceful and motivated adversary is surprisingly difficult. This document points out many pitfalls in using poor entropy sources or traditional pseudo-random number generation techniques for generating such quantities. It recommends the use of truly random hardware techniques and shows that the existing hardware on many systems can be used for this purpose. It provides suggestions to ameliorate the problem when a hardware solution is not available, and it gives examples of how large such quantities need to be for some applications. Eastlake, et al. Standards Track [Page 1] RFC 4086 Randomness Requirements for Security June 2005 Table of Contents 1. Introduction and Overview .......................................3 2. General Requirements ............................................4 3. Entropy Sources .................................................7 3.1. Volume Required ................