This package of tools can encrypt and decrypt any file type, you can use you own key so no one can decrypt it. Unless they know the key. Note** you can only decrypt files that are encrypted that you did not create if you know the key for it, you cant randomly create a key and try to use it to decrypt it. There is and example folder inside the download too
How to:
Encrypter:
<Encrypter.exe> <input> <output> : <The Key you want>
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Decrypter:
<Decrypter.exe> <input> <output> : <The Key you entered in the encryptor>
Note -- if the file has and extension on it ex: example.txt, you must add the .txt.
The Decrypter will say it was decrypted successfully but if you did not enter the right key you will get a file damage error, So enter the right key (One you use to encrypt the file with)