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aes.go
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aes.go
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/*
Copyright SecureKey Technologies Inc. All Rights Reserved.
SPDX-License-Identifier: Apache-2.0
*/
package dataprotect
import (
"crypto/aes"
"crypto/cipher"
"crypto/rand"
"errors"
"io"
)
const (
keySizeDiv = 8
)
type AES struct {
keyLength int
}
func NewAES(keyLength int) *AES {
return &AES{
keyLength: keyLength,
}
}
func (a *AES) Encrypt(data []byte) ([]byte, []byte, error) {
key, err := a.generateAESKey()
if err != nil {
return nil, nil, err
}
block, err := aes.NewCipher(key)
if err != nil {
return nil, nil, err
}
gcm, err := cipher.NewGCM(block)
if err != nil {
return nil, nil, err
}
nonce := make([]byte, gcm.NonceSize())
if _, err = io.ReadFull(rand.Reader, nonce); err != nil {
return nil, nil, err
}
ciphertext := gcm.Seal(nonce, nonce, data, nil)
return ciphertext, key, nil
}
func (a *AES) Decrypt(data []byte, key []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
}
if len(data) < gcm.NonceSize() {
return nil, errors.New("ciphertext too short")
}
nonce, ciphertext := data[:gcm.NonceSize()], data[gcm.NonceSize():]
plaintext, err := gcm.Open(nil, nonce, ciphertext, nil)
if err != nil {
return nil, err
}
return plaintext, nil
}
func (a *AES) generateAESKey() ([]byte, error) {
key := make([]byte, a.keyLength/keySizeDiv)
_, err := io.ReadFull(rand.Reader, key)
if err != nil {
return nil, err
}
return key, nil
}