Utilities for secure password hashing via the argon2 algorithm. It is a
relatively new hashing algorithm and is believed to be very secure. The
'argon2' implementation included in the package is the reference
implementation. The package also includes some utilities that should be
useful for digest authentication, including a wrapper of 'blake2b'. For
similar R packages, see sodium and 'bcrypt'. See
<https://en.wikipedia.org/wiki/Argon2> or
<https://eprint.iacr.org/2015/430.pdf> for more information.
