docs: def scrypt(password, salt, N=SCRYPT_N, r=SCRYPT_r, p=SCRYPT_p, olen=64):
      """Returns a key derived using the scrypt key-derivarion function
  
      N must be a power of two larger than 1 but no larger than 2 ** 63 (insane)
      r and p must be positive numbers such that r * p < 2 ** 30
  
      The default values are:
      N -- 2**14 (~16k)
      r -- 8
      p -- 1
  
      Memory usage is proportional to N*r. Defaults require about 16 MiB.
      Time taken is proportional to N*p. Defaults take <100ms of a recent x86.
  
      The last one differs from libscrypt defaults, but matches the 'interactive'
      work factor from the original paper. For long term storage where runtime of
      key derivation is not a problem, you could use 16 as in libscrypt or better
      yet increase N if memory is plentiful.
      """
      check_args(password, salt, N, r, p, olen)
  
      if _scrypt_ll:
          out = ctypes.create_string_buffer(olen)
          if _scrypt_ll(password, len(password), salt, len(salt),
                        N, r, p, out, olen):
              raise ValueError
          return out.raw
  
      if len(salt) != _scrypt_salt or r != 8 or (p & (p - 1)) or (N*p <= 512):
          return scr_mod.scrypt(password, salt, N, r, p, olen)
  
      s = next(i for i in range(1, 64) if 2**i == N)
      t = next(i for i in range(0, 30) if 2**i == p)
      m = 2**(10 + s)
      o = 2**(5 + t + s)
      if s > 53 or t + s > 58:
          raise ValueError
      out = ctypes.create_string_buffer(olen)
      if _scrypt(out, olen, password, len(password), salt, o, m) != 0:
          raise ValueError
      return out.raw