1 files changed, 56 insertions, 0 deletions
diff --git a/internal/cryptoutil/aes.go b/internal/cryptoutil/aes.go
new file mode 100644
index 00000000..ec037b64
--- /dev/null
+++ b/internal/cryptoutil/aes.go
@@ -0,0 +1,56 @@
+// 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)
+}