Silently switch to hardened SHA1

[SoniEx2]

Hardened SHA1 is mostly backwards-compatible, so this shouldn't be much of an issue. (2^-90 probability of breaking compatibility with any given hash. you only have a handful on a torrent, it'll be fine.)

[ckerr]

I guess my question is, it a torrent client switched to hardened SHA1, does that cause issues when communicating with other peers that aren't using it?

[SoniEx2]

yes, with a very low probability. it's good enough tho. ideally they'd also switch, or there'd be a new protocol version that uses something better than SHA1.

[ckerr]

I 100% agree with the usefulness of avoiding torrent hash collisions. Since the BitTorrent spec version 2 uses SHA2-256, and is the standard, IMO that is the right way of solving this problem.

The issue to track BitTorrent spec version 2 is #458

I'm closing this issue since 458 will be the fix, but I appreciate the suggestion. It's a good idea.