Encrypt TOTP secret before saving to database

encryption/encryption.go

@@ -0,0 +1,76 @@
+package encryption
+
+import (
+	"crypto/aes"
+	"crypto/cipher"
+	"crypto/rand"
+	"encoding/base64"
+	"fmt"
+	"github.com/fossyy/filekeeper/types"
+	"github.com/fossyy/filekeeper/utils"
+)
+
+type aesEncryption struct{}
+
+func NewAesEncryption() types.Encryption {
+	return &aesEncryption{}
+}
+
+func (e *aesEncryption) Encrypt(enc string) (string, error) {
+	secret := utils.Getenv("ENCRYPTION_SECRET")
+
+	aesCipher, err := aes.NewCipher([]byte(secret))
+
+	if err != nil {
+		return "", err
+	}
+
+	gcm, err := cipher.NewGCM(aesCipher)
+	if err != nil {
+		return "", err
+	}
+
+	nonce := make([]byte, gcm.NonceSize())
+	_, err = rand.Read(nonce)
+	if err != nil {
+		return "", err
+	}
+
+	ciphertext := gcm.Seal(nonce, nonce, []byte(enc), nil)
+
+	ciphertextBase64 := base64.StdEncoding.EncodeToString(ciphertext)
+
+	return ciphertextBase64, nil
+}
+
+func (e *aesEncryption) Decrypt(dec string) (string, error) {
+	ciphertext, err := base64.StdEncoding.DecodeString(dec)
+	if err != nil {
+		return "", err
+	}
+
+	secret := utils.Getenv("ENCRYPTION_SECRET")
+	if len(secret) != 16 && len(secret) != 24 && len(secret) != 32 {
+		return "", fmt.Errorf("invalid SECRET length: must be 16, 24, or 32 bytes")
+	}
+
+	aesCipher, err := aes.NewCipher([]byte(secret))
+	if err != nil {
+		return "", err
+	}
+
+	gcm, err := cipher.NewGCM(aesCipher)
+	if err != nil {
+		return "", err
+	}
+
+	nonceSize := gcm.NonceSize()
+	nonce, ciphertext := ciphertext[:nonceSize], ciphertext[nonceSize:]
+
+	plaintext, err := gcm.Open(nil, nonce, ciphertext, nil)
+	if err != nil {
+		return "", fmt.Errorf("message authentication failed: %v", err)
+	}
+
+	return string(plaintext), nil
+}