1 Montgomery Modular Multiplication in Hard- ware

FEI KEMT
Figure 6 – 13 Amount of sampled ones during 1000 sampling periods according to temperature
for chosen sample positions in TRNG with configuration B.
tistical independence between the critical samples. The model was confirmed in
empirical way and is valid for small number of critical samples, however, in case
of higher number the model is less precise. In order to achieve a better adjusted
model we propose for future research to monitor and analyse the bit sequence at
the output of the sampling gate, before XOR operation. This kind of measurements
may uncover a possible dependency between the samples.
In the last part of the chapter we presented results of experiments with change-
able temperature of chip with the PLL-TRNG. As a result we propose additional
requirements for the generator design that need to be met in order to achieve a
robustness of the design. We can conclude that configurations with more than 10
highly critical samples per edge behave reliably even in changing environment. The
bigger are the changes of jitter amplitude the bigger are changes in the histogram of
jitter and that has direct negative impact on statistical properties of the generated
sequence.
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