package protocol

import (
	"crypto/sha256"
	"encoding/hex"
	"strings"
)

// AuthenticationCode lets a person compare the browser's authorization request
// with the one they initiated in their app. It is a label, never a credential.
func AuthenticationCode(id string) string {
	sum := sha256.Sum256([]byte(id))
	code := strings.ToUpper(hex.EncodeToString(sum[:4]))
	return code[:4] + "-" + code[4:]
}