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// Copyright 2016 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package secretbox_test
import (
"crypto/rand"
"encoding/hex"
"fmt"
"io"
"golang.org/x/crypto/nacl/secretbox"
)
func Example() {
// Load your secret key from a safe place and reuse it across multiple
// Seal calls. (Obviously don't use this example key for anything
// real.) If you want to convert a passphrase to a key, use a suitable
// package like bcrypt or scrypt.
secretKeyBytes, err := hex.DecodeString("6368616e676520746869732070617373776f726420746f206120736563726574")
if err != nil {
panic(err)
}
var secretKey [32]byte
copy(secretKey[:], secretKeyBytes)
// You must use a different nonce for each message you encrypt with the
// same key. Since the nonce here is 192 bits long, a random value
// provides a sufficiently small probability of repeats.
var nonce [24]byte
if _, err := io.ReadFull(rand.Reader, nonce[:]); err != nil {
panic(err)
}
// This encrypts "hello world" and appends the result to the nonce.
encrypted := secretbox.Seal(nonce[:], []byte("hello world"), &nonce, &secretKey)
// When you decrypt, you must use the same nonce and key you used to
// encrypt the message. One way to achieve this is to store the nonce
// alongside the encrypted message. Above, we stored the nonce in the first
// 24 bytes of the encrypted text.
var decryptNonce [24]byte
copy(decryptNonce[:], encrypted[:24])
decrypted, ok := secretbox.Open([]byte{}, encrypted[24:], &decryptNonce, &secretKey)
if !ok {
panic("decryption error")
}
fmt.Println(string(decrypted))
// Output: hello world
}
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