1 files changed, 78 insertions, 0 deletions
diff --git a/modules/secret/secret.go b/modules/secret/secret.go
new file mode 100644
index 0000000..e70ae18
--- /dev/null
+++ b/modules/secret/secret.go
@@ -0,0 +1,78 @@
+// Copyright 2019 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package secret
+
+import (
+	"crypto/aes"
+	"crypto/cipher"
+	"crypto/rand"
+	"crypto/sha256"
+	"encoding/base64"
+	"encoding/hex"
+	"errors"
+	"fmt"
+	"io"
+)
+
+// AesEncrypt encrypts text and given key with AES.
+func AesEncrypt(key, text []byte) ([]byte, error) {
+	block, err := aes.NewCipher(key)
+	if err != nil {
+		return nil, fmt.Errorf("AesEncrypt invalid key: %v", err)
+	}
+	b := base64.StdEncoding.EncodeToString(text)
+	ciphertext := make([]byte, aes.BlockSize+len(b))
+	iv := ciphertext[:aes.BlockSize]
+	if _, err = io.ReadFull(rand.Reader, iv); err != nil {
+		return nil, fmt.Errorf("AesEncrypt unable to read IV: %w", err)
+	}
+	cfb := cipher.NewCFBEncrypter(block, iv)
+	cfb.XORKeyStream(ciphertext[aes.BlockSize:], []byte(b))
+	return ciphertext, nil
+}
+
+// AesDecrypt decrypts text and given key with AES.
+func AesDecrypt(key, text []byte) ([]byte, error) {
+	block, err := aes.NewCipher(key)
+	if err != nil {
+		return nil, err
+	}
+	if len(text) < aes.BlockSize {
+		return nil, errors.New("AesDecrypt ciphertext too short")
+	}
+	iv := text[:aes.BlockSize]
+	text = text[aes.BlockSize:]
+	cfb := cipher.NewCFBDecrypter(block, iv)
+	cfb.XORKeyStream(text, text)
+	data, err := base64.StdEncoding.DecodeString(string(text))
+	if err != nil {
+		return nil, fmt.Errorf("AesDecrypt invalid decrypted base64 string: %w", err)
+	}
+	return data, nil
+}
+
+// EncryptSecret encrypts a string with given key into a hex string
+func EncryptSecret(key, str string) (string, error) {
+	keyHash := sha256.Sum256([]byte(key))
+	plaintext := []byte(str)
+	ciphertext, err := AesEncrypt(keyHash[:], plaintext)
+	if err != nil {
+		return "", fmt.Errorf("failed to encrypt by secret: %w", err)
+	}
+	return hex.EncodeToString(ciphertext), nil
+}
+
+// DecryptSecret decrypts a previously encrypted hex string
+func DecryptSecret(key, cipherHex string) (string, error) {
+	keyHash := sha256.Sum256([]byte(key))
+	ciphertext, err := hex.DecodeString(cipherHex)
+	if err != nil {
+		return "", fmt.Errorf("failed to decrypt by secret, invalid hex string: %w", err)
+	}
+	plaintext, err := AesDecrypt(keyHash[:], ciphertext)
+	if err != nil {
+		return "", fmt.Errorf("failed to decrypt by secret, the key (maybe SECRET_KEY?) might be incorrect: %w", err)
+	}
+	return string(plaintext), nil
+}