Algorithm 1 GSR-TRNG.

1:  procedure Pre-processing($GS{R}^{raw}$)

2:  Down-sampling to 128 Hz

3:  Low-pass filter ($[0-60Hz]$)

4:  procedure GetEntropy($GS{R}^{cleaned}$)

5:  Split $GS{R}^{cleaned}$ into N-seconds $GSR$-$windows$ (N=4 in our experiments)

6:  for each GSR-window($x^{\left(j\right)}\left(t\right)$) do

7:    Hilbert Transform: $y^{\left(j\right)}\left(t\right)=h\left(t\right)\ast x^{\left(j\right)}\left(t\right)$

8:    Entropy Extraction: $g^{\left(j\right)}{\left(t\right)}_{(0,\dots ,7)}=uint8(\left(uint32\left(abs(y^{\left(j\right)}\left(t\right)\ast {10}^2)\right)\right)>>24)$