@quark@ferengi.one My money is on a SHA1SUM hash encoding to keep things much simpler:

$ echo -n "https://twtxt.net/user/prologic/twtxt.txt\n2020-07-18T12:39:52Z\nHello World! 😊" | sha1sum | head -c 11
87fd9b0ae4e

@prologic@twtxt.net Why sha1 in particular? There are known attacks on it. sha256 seems pretty widely supported if you’re worried about support.

@prologic@twtxt.net Wikipedia claims sha1 is vulnerable to a “chosen-prefix attack”, which I gather means I can write any two twts I like, and then cause them to have the exact same sha1 hash by appending something. I guess a twt ending in random junk might look suspcious, but perhaps the junk could be worked into an image URL like . If that’s not possible now maybe it will be later.

git only uses sha1 because they’re stuck with it: migrating is very hard. There was an effort to move git to sha256 but I don’t know its status. I think there is progress being made with Game Of Trees, a git clone that uses the same on-disk format.

I can’t imagine any benefit to using sha1, except that maybe some very old software might support sha1 but not sha256.