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View Full Version : One time encryption


devilassassin
February 4th, 2004, 02:04 AM
I am looking for a program that will encrypt something, a word document in paticular so that after the document is decrypted once it will delete itself or encrypt itself with a different password. This is because I have notes dictated to me from school and then I type them out when I get home so its easier for me to read. I soon discovered there was a market for this type of thing in my class so I handed out copies the file- hoping my classmates would be honest and not sell them off to other people and stealing my hard work. But it turns out people weren't so honest. So this year I was thinking that if I could find a program that after encryption only could decrypt once I would be able to stop this "theft" so I alone benefit from my work financially.

Ollie Snowie
February 4th, 2004, 02:41 AM
Well you wouldn't need very strong encryption would you?
I was thinking along the lines of a batch file with "echo ___" distributed around with lots of "___>nul" commands in just to make it more difficult to copy & paste. Then just put "del ___" at the end. It's very easy to crack but it would take a long time to copy & paste all those lines. I can't see anyonwe being particularly bothered to do that. It would take a fair time to do the encryption though. To stop someone just getting rid of the "del ___" at the end, you could hide it in a self extracting zip file and include a command to delete the zip file as well.

GibboNet
February 5th, 2004, 03:30 AM
Could you hand out printed copies ? Not many people are going to scan / ocr them though some will find a photocopier.

You could use PGP, and the 'secure viewer' option, so they can read it on screen, but never copy it or print it.

Rhadon
February 5th, 2004, 08:09 AM
You could use PGP, and the 'secure viewer' option, so they can read it on screen, but never copy it or print it. They could still take screenshots and print these afterwards, but it would be a bothersome process if it's a long text.

A better idea than encryption is to make different versions of your text by applying minor but unique changes to it which nobody takes notice of (double spaces, etc.). It's not much work and every person you give the text to gets a unique one. If it spreads afterwards and you see a "published" version of what you wrote, all you have to do is to search for the unique change you hid and you know who published it.

devilassassin
February 5th, 2004, 07:41 PM
I had thought of the printing idea but that will go through a hell of a lot of ink and if I raised the price I doubt many people will buy it. As for double space thing, most people would leave their notes at home so it would be hard for me to find out but I would see the occasional one. Anyway if I did see who did it, what am I supposed to do beat him up- Im not exactly the tallest or stongest person of the bunch. Its better to try and prevent it. And Ollie Snowie I have no idea what your post means. But thanks for the ideas so far guys.