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Fig 24. Block diagram of RNG module
10.2.1 PRNG digital core
The module delivers an 8-bit random number. The Pseudo Random Number Generator
consists of an 80-bit LFSR with a feedback polynomial and an S-Box substitution for the
output of the PRNG.
The feedback polynomial of the LFSR is:
x
The feedback polynomial is XOR with the TRNG input when a new seed is loaded.
Some bits in the LFSR feeds an S-BOX lookup-table, taken from the DES Specification
and the output of the SBOX is XOR with the feedback value from the LFSR.
10.2.2 RNG analog core (TRNG)
The basic function of TRNG is to provide a seed for the PRNG. The TRNG needs supply
and references from the PMU. The TRNG consists of 2 comparators which monitor an
analog signal to choose which offset has to be applied to this signal. The outputs of these
2 comparators are combined to generate the random number.
The TRNG generates an input random bit
or 1's as PRNG seed value.
UM10858
User manual
COMPANY PUBLIC
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All information provided in this document is subject to legal disclaimers.
Rev. 1.4 — 14 May 2018
stream, which
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UM10858
PN7462 family HW user manual
is xored to avoid continuous 0's
© NXP B.V. 2018. All rights reserved.
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