This is the reference C implementation of Argon2, the password-hashing
function that won the Password Hashing Competition (PHC).

You should use Argon2 whenever you need to hash passwords for
credential storage, key derivation, or other applications.

There are two main versions of Argon2, Argon2i and Argon2d. Argon2i
is the safest against side-channel attacks, while Argon2d provides
the highest resistance against GPU cracking attacks.

Argon2i and Argon2d are parametrized by

* A time cost, which defines the amount of computation realized
  and therefore the execution time, given in number of iterations
* A memory cost, which defines the memory usage, given in kibibytes
* A parallelism degree, which defines the number of parallel threads