hi friends, I'm back!!! Encrypt and decrypt text in a file!

So, here is my question:

I need to write encrypted text in a file, and read decrypted text again from this file! Of course, finally this text should be identical!

Please, write your ideas, which ways exist for this? How to apply different encryption methods!

I've found this topic here, but may be you have other, or better solutions!

http://forums.cgsociety.org/archive/index.php/t-704912.html

Thank you so much!!!