Concept for true random number generators

designrandom number

I have an idea. Lets say we have an unpowered TTL set-reset flip flop with both inputs tied to 5v(logic high). When we apply power to the flip flop, it goes into a quiescent state, so there is no telling what the output would be. Basically, we have a one bit random number generator.

Now for my question. Modern processors and microcontrollers have the ability to generate pseudo-random numbers. Of course, these aren't truly random. But if my flip flop scenario generates true-random numbers, then why don't designers use this concept, but with more flip flops?

Best Answer

They don't use that concept because, unfortunately, it doesn't work-- the start-up state of a FF won't be very random at all.

Quoting from "Cryptographic Hardware and Embedded Systems -- CHES 2003: 5th International Workshop Volume 5"

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Making a truly random number generator is not easy.