Are you speaking of
this page? It is wrong (
permalink to incorrect section in incorrect version). I will apply for wiki editing rights to correct it.
A Bitcoin private key is always exactly 256 bits, no more and no less. I infer that the editor who wrote the incorect text was confusing private keys with HD seed values, or something of that nature. On a brief glance,
this page and
this page seem correct.
Yes, that's exactly what I was asking about, thanks!
Indeed, this part:
In Bitcoin, a private key is usually a 256-bit number (some newer wallets may use between 128 and 512 bits)
got me confused a bit, since I'm not very familiar with ECDSA.
But I think my question can be repeated for wallet seeds: how long would 128 bit seeds be secure against QC, and how do you think Bitcoin community will react if/when someone will start claiming coins from those wallets that were considered to be lost (I'm assuming that most holders will move their funds to new wallets before quantum brute force will become feasible). Of course it's a far smaller threat than the complete failure of public key cryptography, but still I'm curious.