Thread: File Encryption

I am not sure if this post belongs in this forum or not... but... I am planing on creating a program that provides the features of a text editor, but also lets you encrypt a file. I plan to do this in the wxWidgets GUI toolkit, to which I am fairly comfortable with. Does anyone have any tips or ideas for how to encrypt a file? I know very little about encyption, but I wasn't planing on using or creating a complex encryption style, just enough to keep a group of un-educated people out of my files. I was thinking of simply adding 3 to all Unicode characters (so the character originally inputed would be 3+ whatever it was;For example, A would be D) but that seemed much to simple to use.

I was thinking of simply adding 3 to all Unicode characters...

I think that will work for plain text. (For general purpose file encryption, you can run into overflow problems when you add to the values.)

But, you probably shouldn't try to invent you own encryption scheme. A lot of smart people have done lots of work on encryption methods already. Do a little research to see what you can find.

The simplest encryption technique is probably XOR encryption. It's easy to do because it uses the same key and the same algorithm for encryption & decription... Run the data through once and it's encrypted. Run it through again, and it's decrypted.

The only difficult thing about XOR encryption is that binary bit-manipulation can be confusing for beginners. Since binary isn't built into cin and cout, its difficult to "see" what you are doing.

You're saving in UTF-16 Unicode, right? If the goal is merely to obfuscate the output to prevent any CASUAL attempt to decrypt it, then an easy method would be to just swap the upper and lower bytes of each Unicode character.

If you want real encryption there are several free, easy to use libraries available.

>I was thinking of simply adding 3 to all Unicode characters

That's called a Ceaser Cypher. And overflow isn't a problem with it, the numbers just wrap around.. so long as they unoverflow when you reverse the cypher.

If you want to overdo it you should look up trap door functions. I have a book on them somewhere around here... I wonder where I put it.

Trap door functions? Never heard of that sounds interesting.

>That's called a Ceaser Cypher

Wow, I didn't think it would actually have a name. Cool.

I may decide to have an option of different encryption methods. In the encrypted file, I'll put a signifier so the program can tell how it was encrypted, but for passkeys, I'll probably have to make the user remember those, or encrypt them in the file with the same algorithm.

Hmmm. Good point. I just didn't want to burden the user with passwords,giving people too much to remember can annoy some people. But, I suppose there is no way around it if I want my app secure.

I think trapdoor functions are functions that allow you to "bypass" the passkey or encryption method. Which is of course making your application "unsecure" to anyone who knows about the trapdoor.

I think your thinking of 'backdoor'.

So, what if I wanted to use hashes to encrypt files? Only problem is, I cant decrypt them.