mcf51jf128 Freescale Semiconductor, Inc, mcf51jf128 Datasheet - Page 608

• Manufacturer Part Number: mcf51jf128
• Description: Mcf51jf128 Reference Manual
• Manufacturer: Freescale Semiconductor, Inc

Modes of Operation
27.1.2 Features
The RNG includes these distinctive features:
27.2 Modes of Operation
The RNGB operates in the following modes.
27.2.1 Self Test Mode
In this mode the RNGB performs a self test of the statistical counters and the PRNG
algorithm to verify that the hardware is functioning properly. The self test takes ~29,000
cycles to complete. When self test completes an interrupt may be generated, if there are
no outstanding commands in the command register. This mode is entered by setting the
RNG_CMD[ST] bit. When self test mode completes, the RNGB remains idle until seed
mode is requested or the RNGB transitions to seed mode if automatic seeding is enabled.
27.2.2 Seed Generation Mode
During seed generation, the RNGB adds entropy generated in the TRNG to the 256-bit
XKEY register. The PRNG algorithm executes 20,000 times sampling the entropy from
the TRNG to create an initial seed for random number generation. At the same time, the
TRNG runs simple statistical tests on its output.
When seed generation is complete, the TRNG reports the pass/fail result of the tests
through RNG_ESR. If the new seed passes the statistical tests, RNG_SR[SDN] is set,
signalling that the RNG is ready to compute secure pseudo-random data. The RNG then
transitions to random number generation mode.
608
• National Institute of Standards and Technology (NIST)-approved pseudo-random
• Supports the key generation algorithm defined in the Digital Signature Standard
• Integrated entropy sources capable of providing the PRNG with entropy for its seed.
number generator
• http://csrc.nist.gov
• http://www.itl.nist.gov/fipspubs/fip186.htm
MCF51JF128 Reference Manual, Rev. 2, 03/2011
Preliminary
Freescale Semiconductor, Inc.