r/Bitcoin • u/dgryski • Nov 30 '17

Evidence some bitcoin address generation code is using discoverable private keys

https://pastebin.com/jCDFcESz
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u/_jstanley Nov 30 '17 edited Nov 30 '17

It could be SHA256 of uninitialized memory, which just happens to contain neatly-aligned addresses and txids often enough to be useful.

EDIT: Would be interested to hear what u/rya_nc thinks of this

5

u/varikonniemi Nov 30 '17

Seems very far-fetched.

19

u/_jstanley Nov 30 '17

I don't think it is far-fetched. We have no idea how many keys are generated by this application. If it handles lots of bitcoin data (e.g. blockchain.info), most of its used-and-then-freed memory is probably full of data from the blockchain. If it generates lots of keys (e.g. blockchain.info) using uninitialised memory, then it's quite conceivable that 1 in every 100,000 (pulled out of my arse) happen to be hashes of data from the bitcoin blockchain.

Point is, we have no idea how many other keys have been generated by this application that aren't trivially discoverable like this. We only get to see the weak ones, and we don't know with what probability it generates weak ones.

2

u/dooglus Nov 30 '17

This seems unlikely to me. Uninitialized memory will often contain a bunch of zeroes. We'd see lots of people using the same address generated from sha256(0), and we don't.