Is hashing random numbers generated from a TRNG enough to create a key?

Question

Basically taking the output of something like a Lavarand and pass that through a hash function like sha-2.

I guess at the end of the day the core of my question is, can an hash function be used as a pseudorandom number generator?

We had recently a question about this and many. All questions are welcomed and searched questions are more accepted by the community. How to calculate the bias of cryptographic hash output from biased input? Using a Hash as a secure PRNG — kelalaka, Nov 07 '21 at 15:11
Just a little quirk re. terminology, but output from a decent TRNG can be used for keys as is. Lava lamps are just a entropy source, not a TRNG per se. — Paul Uszak, Nov 07 '21 at 22:22

score 0 · Answer 1 · answered Nov 08 '21 at 20:57

Yes, If you have a TRNG you can use the output from it when a random key is required for cryptographic purposes.

If you doubt your TRNG indeed has sufficient entropy and sufficiently small bias, a good strategy is to collect more bits than needed from your entropy source and hash them using a secure hash algorithm.

I believe Lavarand already does something similar it collects entropy and uses it to seed a PRNG. I did not actually review the internal so can't comment but if they do a reasonable job hashing the output would be redundant.

Is hashing random numbers generated from a TRNG enough to create a key?

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