User's Manual

Random Numbers
14 RSA BSAFE Crypto-C Intel Hardware User’s Guide
The Intel Random Number Generator
The Intel Random Number Generator is dedicated hardware that harnesses system
thermal noise to generate random values. The generator is free-running,
accumulating random bits of data until a 32-bit buffer is filled.
Whitening Hardware Results
The bits the Intel RNG supplies to the application have been whitened by the
hardware; that is, a post-processing algorithm has been applied to reduce patterns in
the hardware bits and make them less predictable. The advantage of performing
whitening in software as well as hardware is that an attacker must modify the
hardware and the software to make the HRNG leak secret information.
If you are seeding a pseudo-random number generator, you can use the random
number without whitening for optimal performance. If you plan to use the random
numbers directly, you may wish to apply additional whitening. Since the Intel RNG
performs its own whitening, performing additional whitening may reduce the
performance of your application.
Using the Intel RNG
The Intel RNG enables your application to get the seed bits that are needed to produce
cryptographic keys and challenges that in turn can protect vast quantities of data. In a
few milliseconds, the Intel RNG can produce all the random bits needed to seed an
application. This is significantly faster than the software mechanisms for gathering
unpredictable bits. Software mechanisms can take as long as ten seconds to gather a
seed and often require user input (for example, via the mouse or keyboard).
Unavailability of Hardware
If the Intel RNG is unavailable, then the appropriate action depends on the security
needs of the application. If the Intel RNG is not working at start-up, and thus there are
no seed bits available from hardware randomness, then an application with
exceptionally high security needs may want to inform the user and exit. Most
applications can simply notify the user and request a user-supplied seed.