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All of them, more or less. There are a few marker bits but the rest are pure data. There is no error correct or redundancy.


I didn't think v4 uuid's were completely random over that 128bit space for some reason, and this was wrong, but interestingly.

for a uuid like 414c1bde-b676-4242-be35-887f01a24f10, if I take its suffix 887f01a24f10 (12 chars, 48 bits) there are still 19 chars (76 bits) to the left of it. (barring the constant 13th char identifier 4)

There still are 2^76 uuid's with that suffix to search through. It made sense with ipv6 addresses and cryptography, but for some reason I had this idea that uuid's didn't use an CRNG that covered the whole 128 bit space. A lot of wrong stuff rattling around in my memory for some reason, thanks for clarifying.


There are 6 fixed bits. The other two are in the 17th hex character.

But overall you have that right. Every bit is either completely random or fixed. There are no reduced-randomness patterns unless you generated it wrong.




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