Ten years ago I built his first version of this. It didn't have code for outputting the data to a file so I wrote that in python. It worked. He has done an update and I assume that it will work since his first version worked. He mentions drift. I used a bit of software "correction" to the hardware bias to maintain a nominal distribution in the output over time. If you want to experiment with it this is a good place to start. http://robseward.com/misc/RNG2/

For encryption, XOR is the norm. You might want to used cypher block chaining while you are at it. As mentioned by others, physical security is the weakness.