package keyring

import (

"crypto/rand"

"golang.org/x/crypto/nacl/secretbox"

)

// SecretKey for encrypting items.

type SecretKey *[32]byte

func randBytes(length int) []byte {

buf := make([]byte, length)

if _, err := rand.Read(buf); err != nil {

panic(err)

}

return buf

}

func rand24() *[24]byte {

b := randBytes(24)

var b24 [24]byte

copy(b24[:], b[:24])

return &b24

}

func rand32() *[32]byte {

b := randBytes(32)

var b32 [32]byte

copy(b32[:], b[:32])

return &b32

}

func bytes32(b []byte) *[32]byte {

if len(b) != 32 {

panic("not 32 bytes")

}

var b32 [32]byte

copy(b32[:], b)

return &b32

}

func secretBoxSeal(b []byte, secretKey SecretKey) []byte {

nonce := rand24()

encrypted := secretbox.Seal(nil, b, nonce, secretKey)

encrypted = append(nonce[:], encrypted...)

return encrypted

}

func secretBoxOpen(encrypted []byte, secretKey SecretKey) ([]byte, bool) {

if secretKey == nil {

return nil, false

}

if len(encrypted) < 24 {

return nil, false

}

var nonce [24]byte

copy(nonce[:], encrypted[:24])

encrypted = encrypted[24:]

return secretbox.Open(nil, encrypted, &nonce, secretKey)

}