I'm trying to create a program for encrypting/decrypting different files. I have not problems with the code, I just don't know how to save the password for every file, which was encrypted through my program.

A user can encrypt his file using a password, and when he tries to decrypt it, there must be a message which informs him about the incorrect password, because, when he uses an incorrect password, the program will produce a decrypted file, which will still be unreadable.