package spectre

import "golang.org/x/crypto/scrypt"

func userKey(name, secret string, scoper Scoper) ([]byte, error) {
	nameBytes := []byte(name)
	secretBytes := []byte(secret)
	keyScope := []byte(scoper.Scope(Authentication))

	nameBytesLen := len(nameBytes)
	keySalt := append(keyScope,
		byte(nameBytesLen>>24),
		byte(nameBytesLen>>16),
		byte(nameBytesLen>>8),
		byte(nameBytesLen),
	)
	keySalt = append(keySalt, nameBytes...)

	return scrypt.Key(secretBytes, keySalt, 32768, 8, 2, 64)
}