func NewExpanderMD(h crypto.Hash, dst []byte) *expanderMD
NewExpanderMD returns a hash function based on a Merkle-Damgård hash function.
func NewExpanderXOF(id xof.ID, kSecLevel uint, dst []byte) *expanderXOF
NewExpanderXOF returns an Expander based on an extendable output function. The kSecLevel parameter is the target security level in bits, and dst is a domain separation string.
type Expander interface {
// Expand generates a pseudo-random byte string of a determined length by
// expanding an input string.
Expand(in []byte, length uint) (pseudo []byte)
}