Argon2

[NIIBE Yutaka]

Hello,

Jussi, if you have any idea about implementing Argon2 in libgcrypt,
please let us know.

Let me explain the background of mine.

Use of Argon2 in OpenPGP message were discussed sometimes.

   - 2015-10-18 about Argon2i:
   https://mailarchive.ietf.org/arch/browse/openpgp/?gbt=1&index=IORjkQR17EURj9HQaKCqoQ2TKkI

   - These days: Proposed change including S2K with Argon2id:
   https://gitlab.com/openpgp-wg/rfc4880bis/-/merge_requests/72/diffs

For GnuPG, it's not that important, I suppose.  Probably, we won't use.
Perhaps, at maximum, it will be (only) for interoperability to other
OpenPGP implementation exchanging secret keys.

For libgcrypt, on the other hand, I think that it's good if we support
Argon2 as crypto library.  When KDF supports Argon2, it's good.


So, I wonder about how we add Argon2 into libgcrypt.

Now, I looked at this code:

   https://github.com/P-H-C/phc-winner-argon2
   CC0 or Apache Public License 2.0

Any ideas?
--