1 Montgomery Modular Multiplication in Hard- ware

FEI KEMT
Figure 6 – 10 Amount of sampled ones during 1000 sampling periods for TRNG with configuration
A (detail of the raising edge).
an impact on the parameters of the generated sequence and therefore should initiate
an alarm signal inside the TRNG.
From measured data it is possible to estimate the jitter parameters and draw the
probability histograms. In the Figure 6 – 14 we compare the histograms of TRNG
working in configuration A and B which differ in loop filter bandwidth. In both cases
the jitter has normal Gaussian distribution. As it can be observed, the configuration
A includes jitter with lower deviation while the jitter in configuration B has almost
three times higher value.
What we find crucial in our measurements is the observation of jitter parameters
with changing temperature. The jitter in the PLL circuitry becomes different with
freezing the chip what can be observed as a change in number of sampled ones
at critical samples positions. In Figure 6 – 15 we depicted the difference in those
numbers when comparing the values by boundary temperatures −40 ◦ C and +30 ◦ C
in both configurations. The difference has the Gaussian normal distribution as well
as in case of the previously discussed jitter by the room temperature. The standard
deviation of the additional jitter is identical to its values for measurements at stable
temperature. As a result we can conclude that by changing the chip temperature
the amplitude of the jitter changes, too.
In case of PLL-TRNG the bigger are the changes of jitter amplitude the bigger
are changes in the histogram of jitter and that has direct impact on statistical
properties of the generated sequence. In case of configuration A the changes in
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