Raspberry Pi
From wiki
Entropy
The Raspberry Pi contains a hardware random number generator. It is activated by default in newer Raspbian versions. You can test it by checking the presence of the file /dev/hwrng.
However is is not used by default to fill the Linux kernel entropy. To use it install the package rng-tools.
$ sudo apt install rng-tools
You can then test the available entropy using
$ cat /proc/sys/kernel/random/entropy_avail
1856
