How to solve some strange hash of hack.chat

[Snoopy]

This is not something hashcat can do. Also the first 6 bytes of base64 only gives you the first 4 bytes of the hash. So you lose 224 bits of info about the hash. This will result in *a lot* of false positives for the password+SALT combination resulting in those 4 bytes.

I doubt this is worth your time.

Oh I just need to get one possible answer of the password.

do you know the salt and the 6 bytes? if yes, implement this "algorithm" in any programming/scripting language and feed this with bruteforce generated strings and break when this algo hits your 6 bytes (feeding incrementing numbers only maybe also work) well this sounds like a funny "give it a try" project for tomorrow (i will try to find a collision with numbers for sha(string+SALT)