use sodium_hex2bin() and _bin2hex() to resist timing / side channel a…

…ttacks

src/Threema/MsgApi/Encryptor/SodiumEncryptor.php

@@ -83,6 +83,35 @@ public function getDescription()
  return 'Sodium implementation ' . SODIUM_LIBRARY_VERSION;
  }
 
+ /**
+ * Converts a binary string to an hexadecimal string.
+ *
+ * This is the same as PHP s bin2hex() implementation, but it is resistant to
+ * timing attacks.
+ *
+ * @param string $binaryString The binary string to convert
+ * @return string
+ */
+ public function bin2hex($binaryString)
+ {
+ return sodium_bin2hex($binaryString);
+ }
+
+ /**
+ * Converts an hexadecimal string to a binary string.
+ *
+ * This is the same as PHP s hex2bin() implementation, but it is resistant to
+ * timing attacks.
+ *
+ * @param string $hexString The hex string to convert
+ * @param string|null $ignore (optional) Characters to ignore
+ * @return string
+ */
+ public function hex2bin($hexString, $ignore = null)
+ {
+ return sodium_hex2bin($hexString, $ignore);
+ }
+
  /**
  * @param string $data
  * @param string $nonce