simple-scrypt provides a convenience wrapper around Go's existing scrypt
 package that makes it easier to securely derive strong keys ("hash user
 passwords"). This library allows you to:
    - Generate a scrypt derived key with a crytographically secure salt and
 sane default parameters for N, r and p.
    - Upgrade the parameters used to generate keys as hardware improves by
 storing them with the derived key (the scrypt spec. doesn't allow for this
 by default).
    - Provide your own parameters (if you wish to). The API closely mirrors
 Go's bcrypt (https://golang.org/x/crypto/bcrypt) library in an effort to
 make it easy to migrate—and because it's an easy to grok API.