Support for [bcrypt]

[Vlix]

Just found this library and it's not bad (surprised the password name wasn't used before), but would like to see more from this library for convenience.

bcrypt is still widely used and shouldn't be too difficult to add (we have an implementation of it very similar to this library)
Maybe a good idea to move functions specific to a certain encryption to their own modules so that it's easier to know what you're using. e.g.:

import Data.Password (Pass)
import qualified Data.Password.Scrypt as Scrypt
import qualified Data.Password.Bcrypt as Bcrypt

myCheck :: Pass -> Either Scrypt.PassHash Bcrypt.PassHash -> PassCheck
myCheck pass = either (Scrypt.checkPass pass) (Bcrypt.checkPass pass)

[cdepillabout]

This sounds like a good idea. I'd definitely accept a PR adding this.

Although I think it would probably just be easier to keep everything in Data.Password and just have checkPassScrypt, checkPassBcrypt, etc functions.

[cdepillabout]

Now that I think about this, you'd also need corresponding hashing functions for both Scrypt and Bcrypt, so maybe adding them to different modules would be easier!

Although I do think that Data.Password.Bcrypt and Data.Password.Scrypt should re-export everything from Data.Password (which should really only contain the Pass and PassHash types, and related functions). That way the end user generally won't have to import both Data.Password and Data.Password.Bcrypt.

[Vlix]

Yes, it'd be more user friendly to re-export the common data types too, though I'd opt for having the PassHash data type be changed to ScryptHash and BcryptHash, so just in case anyone uses both algorithms, you can't mix them up by using a Bcrypt-hashed PassHash in a check for Scrypt.

Might even be nice to also add PBKDF2, since then you'd have all 3 "generally" accepted standards of password hashing.

[cdepillabout]

I'd opt for having the PassHash data type be changed to ScryptHash and BcryptHash

I was thinking that just having phantom types on PassHash would be fine.

So we could have PassHash Scrypt and PassHash Bcrypt.

If anyone wanted to write instances for PassHash, they'd generally just have to write them for PassHash a and have them apply to both PassHash Scrypt and PassHash Bcrypt.

Might even be nice to also add PBKDF2, since then you'd have all 3 "generally" accepted standards of password hashing.

This definitely sounds like a good idea too!