Uhm, why this if we have GPG? I've never heard of Text Shredder and automatically distrust any new crypto (just look at Telegram), whereas GPG is very well known and much more battle tested.

Edit: The download button gives me some .exe file and the source code is Microsoft shit. Not gonna work.

Edit2: It seems to use AES ECB. Definitely secure... not https://en.wikipedia.org/wiki/File:Tux_ecb.jpg

Pseudocode of what it does:

    function EncryptBlock(data, password)
      encrpytedMessage = aes.Encrypt(data, passwd, salt, pbkdf2RoundsCount);
      return encrpytedMessage; // sic
    
    function aes.Encrypt(data, pwd, salt, pwd_rounds)
      hash = pbkdf2(pwd, salt, rounds);
      IV = hash.getBytes(16);
      passwd = hash.getBytes(32);
      encrypted = aes(data, passwd, IV);
      return encrypted;