I'm 12 year boi and I've just developed a simple java programm with GUI on Swing It's Encryptor
it can encrypt and decrypt messages with numbers, latin and cyrillic characters.
It's all packed in runnable .jar file and ready to use, you only need to have java on your PC and you can run it. Rare it please, I can give it to you with a link
From budgets to cutbacks...