docs: def from_passphrase(cls, email, passphrase):
          """
          This performs key derivation from an email address and passphrase according
          to the miniLock specification.
          
          Specifically, the passphrase is digested with a standard blake2s 32-bit digest,
          then it is passed through scrypt with the email address as salt value using
          N = 217, r = 8, p = 1, L = 32.
          
          The 32-byte digest from scrypt is then used as the Private Key from which
          the public key is derived.
          """
          pp_blake = pyblake2.blake2s(cls.ensure_bytes(passphrase)).digest()
          #pp_scrypt = scrypt.hash(pp_blake, cls.ensure_bytes(email), 2**17, 8, 1, 32)
          pp_scrypt = pylibscrypt.scrypt(pp_blake, cls.ensure_bytes(email), 2**17, 8, 1, 32)
          key = nacl.public.PrivateKey(pp_scrypt)
          return cls(key.public_key, key)