package main

import (
	"encoding/base64"
	"encoding/binary"
)

// ed25519Line is a public key line with a well-formed ed25519 blob.
func ed25519Line(seed byte, comment string) string {
	blob := []byte{}
	for _, part := range [][]byte{[]byte("ssh-ed25519"), make([]byte, 32)} {
		part2 := append([]byte(nil), part...)
		if len(part2) == 32 {
			part2[0] = seed
		}
		l := make([]byte, 4)
		binary.BigEndian.PutUint32(l, uint32(len(part2)))
		blob = append(append(blob, l...), part2...)
	}
	return "ssh-ed25519 " + base64.StdEncoding.EncodeToString(blob) + " " + comment
}