Add AES GCM encryption provider

services/secrets/encryption_aes.go

@@ -0,0 +1,89 @@
+// Copyright 2021 The Gitea 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 secrets
+
+import (
+	"crypto/aes"
+	"crypto/cipher"
+	"crypto/rand"
+	"encoding/base64"
+	"fmt"
+	"io"
+)
+
+type aesEncryptionProvider struct {
+}
+
+func NewAesEncryptionProvider() EncryptionProvider {
+	return &aesEncryptionProvider{}
+}
+
+func (e *aesEncryptionProvider) Encrypt(secret, key []byte) ([]byte, error) {
+	block, err := aes.NewCipher(key)
+	if err != nil {
+		return nil, err
+	}
+
+	c, err := cipher.NewGCM(block)
+	if err != nil {
+		return nil, err
+	}
+
+	nonce := make([]byte, c.NonceSize(), c.NonceSize()+c.Overhead()+len(secret))
+	if _, err = io.ReadFull(rand.Reader, nonce); err != nil {
+		return nil, err
+	}
+	out := c.Seal(nil, nonce, secret, nil)
+
+	return append(nonce, out...), nil
+}
+
+func (e *aesEncryptionProvider) EncryptString(secret string, key []byte) (string, error) {
+	out, err := e.Encrypt([]byte(secret), key)
+	if err != nil {
+		return "", err
+	}
+	return base64.StdEncoding.EncodeToString(out), nil
+}
+
+func (e *aesEncryptionProvider) Decrypt(enc, key []byte) ([]byte, error) {
+	block, err := aes.NewCipher(key)
+	if err != nil {
+		return nil, err
+	}
+
+	c, err := cipher.NewGCM(block)
+	if err != nil {
+		return nil, err
+	}
+
+	if len(enc) < c.NonceSize() {
+		return nil, fmt.Errorf("encrypted value too short")
+	}
+
+	nonce := enc[:c.NonceSize()]
+	ciphertext := enc[c.NonceSize():]
+
+	out, err := c.Open(nil, nonce, ciphertext, nil)
+	if err != nil {
+		return nil, err
+	}
+
+	return out, nil
+}
+
+func (e *aesEncryptionProvider) DecryptString(enc string, key []byte) (string, error) {
+	encb, err := base64.StdEncoding.DecodeString(enc)
+	if err != nil {
+		return "", err
+	}
+
+	out, err := e.Encrypt(encb, key)
+	if err != nil {
+		return "", err
+	}
+
+	return string(out), nil
+}