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// Copyright 2020 The Gogs Authors. All rights reserved.
// Use of this source code is governed by a MIT-style
// license that can be found in the LICENSE file.
package cryptoutil
import (
"crypto/aes"
"crypto/cipher"
"crypto/rand"
"errors"
)
// AESGCMEncrypt encrypts plaintext with the given key using AES in GCM mode.
func AESGCMEncrypt(key, plaintext []byte) ([]byte, error) {
block, err := aes.NewCipher(key)
if err != nil {
return nil, err
}
gcm, err := cipher.NewGCM(block)
if err != nil {
return nil, err
}
nonce := make([]byte, gcm.NonceSize())
if _, err := rand.Read(nonce); err != nil {
return nil, err
}
ciphertext := gcm.Seal(nil, nonce, plaintext, nil)
return append(nonce, ciphertext...), nil
}
// AESGCMDecrypt decrypts ciphertext with the given key using AES in GCM mode.
func AESGCMDecrypt(key, ciphertext []byte) ([]byte, error) {
block, err := aes.NewCipher(key)
if err != nil {
return nil, err
}
gcm, err := cipher.NewGCM(block)
if err != nil {
return nil, err
}
size := gcm.NonceSize()
if len(ciphertext)-size <= 0 {
return nil, errors.New("ciphertext is empty")
}
nonce := ciphertext[:size]
ciphertext = ciphertext[size:]
return gcm.Open(nil, nonce, ciphertext, nil)
}
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