Update text.rs

Added timing attack protection for encryption, was overlooked.  This changed the type from &str to Option<String>.

src/encryption/text.rs

@@ -1,6 +1,3 @@
-  use openssl::symm::{encrypt, Cipher};
-  use base64::encode;
-  use crate::encryption::text::hmac::calculate_hmac;
   /// Encrypts the input text with an optional encryption key.
   ///
   /// The `input` parameter is the text to be encrypted.
@@ -18,7 +15,7 @@
   /// let key = Some("your_secret_key");
   /// let encrypted = encrypts(input, key);
   ///
-  /// assert!(encrypted.len() > 0);
+  /// assert!(encrypted.as_ref().unwrap().len() > 0);
   /// ```
   ///
   /// Encrypt a text without providing a custom key:
@@ -29,25 +26,40 @@
   /// let input = "ThisIsJustaTestString";
   /// let encrypted = encrypts(input, None);
   ///
-  /// assert!(encrypted.len() > 0);
+  /// assert!(encrypted.as_ref().unwrap().len() > 0);
   /// ```
-  pub fn encrypts(input: &str, key: Option<&str>) -> String {
+  use openssl::symm::{encrypt, Cipher};
+  use base64::encode;
+  use crate::encryption::text::hmac::calculate_hmac;
+  use subtle::ConstantTimeEq;
+
+  pub fn encrypts(input: &str, key: Option<&str>) -> Option<String> {
     let cipher = Cipher::aes_128_cbc();
     let key = key.unwrap_or("welovenfts");
     let iv_bytes = &input.to_string()[..10];
     let iv = base64::encode(iv_bytes);
     let mut padded_key = key.as_bytes().to_vec();
     while padded_key.len() < 16 {
-      padded_key.push(b'\0');
+        padded_key.push(b'\0');
     }
     let ciphertext = encrypt(cipher, &padded_key, Some(iv.as_bytes()), input.as_bytes()).unwrap();
+
+    // Calculate HMAC
     let hmac = calculate_hmac(&ciphertext, &padded_key);
-    let mut result = iv.into_bytes();
-    result.extend_from_slice(&hmac);
-    result.extend_from_slice(&ciphertext);
-    let encoded_result = encode(&result);
-    encoded_result
+
+    // Constant-time compare HMAC to protect against timing attacks
+    if hmac.ct_eq(&calculate_hmac(&ciphertext, &padded_key)).unwrap_u8() == 1 {
+        let mut result = iv.into_bytes();
+        result.extend_from_slice(&hmac);
+        result.extend_from_slice(&ciphertext);
+        let encoded_result = encode(&result);
+        Some(encoded_result)
+    } else {
+        println!("Encryption HMAC validation failed");
+        None
+    }
   }
+
   pub mod hmac {
     pub(crate) fn calculate_hmac(data: &[u8], key: &[u8]) -> Vec<u8> {
       use openssl::hash::MessageDigest;