Argon2 output does not conform to the specs

[jdoe0000000]

According to the specs, = should be omitted from the b64 encoded parts of the output string. Currently, the Argon2 module includes =s in the b64 encoded parts.

>>> let salt = Salt "abcdefghijklmnop"
>>> hashPasswordWithSalt defaultParams salt (mkPassword "foobar")
PasswordHash {unPasswordHash = "$argon2id$v=19$m=65536,t=2,p=1$YWJjZGVmZ2hpamtsbW5vcA==$BztdyfEefG5V18ZNlztPrfZaU5duVFKZiI6dJeWht0o="}

In contrast, the reference implementation produces the following output string for the same input.

$ echo -n foobar | argon2 abcdefghijklmnop -id -t 2 -k 65536 -l 32
Type:		Argon2id
Iterations:	2
Memory:		65536 KiB
Parallelism:	1
Hash:		073b5dc9f11e7c6e55d7c64d973b4fadf65a53976e545299888e9d25e5a1b74a
Encoded:	$argon2id$v=19$m=65536,t=2,p=1$YWJjZGVmZ2hpamtsbW5vcA$BztdyfEefG5V18ZNlztPrfZaU5duVFKZiI6dJeWht0o
0.072 seconds
Verification ok

Moreover, checkPassword will not accept hash strings without padding =s.

>>> checkPassword (mkPassword "foobar") (PasswordHash "$argon2id$v=19$m=65536,t=2,p=1$YWJjZGVmZ2hpamtsbW5vcA$BztdyfEefG5V18ZNlztPrfZaU5duVFKZiI6dJeWht0o")
PasswordCheckFail

But the same string with padding =s works fine.

>>> checkPassword (mkPassword "foobar") (PasswordHash "$argon2id$v=19$m=65536,t=2,p=1$YWJjZGVmZ2hpamtsbW5vcA==$BztdyfEefG5V18ZNlztPrfZaU5duVFKZiI6dJeWht0o=")
PasswordCheckSuccess

[Vlix]

@jdoe0000000 Thanks for bringing this up!
I think I've either overlooked this detail or mistakenly implemented it incorrectly.
I can't remember what I used as a reference, tbh. The Argon2 specification doesn't describe the "required" format for printing a hash AFAICT. Is this format official, or just how every other library does it?

Regardless, it'd be a good idea to accept technically correct hashes.
(I was already planning on doing more with hashing formats: #11)

Do you want to make a PR for this? If not, I'll pick this up before the version 3.0.0.0 release.

[jdoe0000000]

@Vlix Thank you for looking into this.

tbh. The Argon2 specification doesn't describe the "required" format for printing a hash AFAICT. Is this format official, or just how every other library does it?

The specs I linked is just for the PHC string format. The specs is official AFAICT.

I guess the PHC format is technically not the official format for Argon2 since it's not in its specs, but it has a special status since it's what the reference implementation uses.

[Vlix]

Merged and will be included in the 3.0.0.0 release