I've made a USB TRNG device acording to information found at XR232USB and everything is working as stated by the author.
Only difference between my device and original is the speed of delivery of random data, and I'm guessing it has to do with the fact that I've rearanged the physical placement of el. components on pcb. I've spent a couple of months reeducating myself on basic electronics concepts, searched this and other forums in order to understand the concept of noise generation proposed by author and finaly decided to ask for help and guidance.
Since I'm using the same MCU and I haven't changed anything in MCU code provided by author , I would like to focus on noise generation part of the circuit. I've tried to run a simulation in LTSpice with no success (bad LM393 model, or just my lack of knowledge).
My main goal is to speed up the random data delivery (currently it's arround 72kbps, I've simply measured the time needed for storing 1MB of received random data into file, it takes 113 seconds and I've done it 100 of times). The device is visible as COM port and the port settings are "230400, 8, n, 1".
I dont have an oscilloscope at the moment, but I think that output from "oscilator" part of comparator was arround 150kHz - what limits the bandwidth?
I would realy apreciate any advice, thought or suggestion regarding the whole concept or just a part of circuit.
I think that this kind of device is ideal for testing a couple of cryptoanalisys concepts I have in mind (asuming that the device can produce only good keys) and to test generated data with a kind of novel randomness test (my coleague just mentioned something about this, I don;t have a clue what's on his mind).
Thanks in advance!
Igor
Only difference between my device and original is the speed of delivery of random data, and I'm guessing it has to do with the fact that I've rearanged the physical placement of el. components on pcb. I've spent a couple of months reeducating myself on basic electronics concepts, searched this and other forums in order to understand the concept of noise generation proposed by author and finaly decided to ask for help and guidance.
Since I'm using the same MCU and I haven't changed anything in MCU code provided by author , I would like to focus on noise generation part of the circuit. I've tried to run a simulation in LTSpice with no success (bad LM393 model, or just my lack of knowledge).
My main goal is to speed up the random data delivery (currently it's arround 72kbps, I've simply measured the time needed for storing 1MB of received random data into file, it takes 113 seconds and I've done it 100 of times). The device is visible as COM port and the port settings are "230400, 8, n, 1".
I dont have an oscilloscope at the moment, but I think that output from "oscilator" part of comparator was arround 150kHz - what limits the bandwidth?
I would realy apreciate any advice, thought or suggestion regarding the whole concept or just a part of circuit.
I think that this kind of device is ideal for testing a couple of cryptoanalisys concepts I have in mind (asuming that the device can produce only good keys) and to test generated data with a kind of novel randomness test (my coleague just mentioned something about this, I don;t have a clue what's on his mind).
Thanks in advance!
Igor
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