Currupting a file...

[AlexCode]

My deal is... I want to access a file, an exe for instance, and add some chars on specific places. Saving it will currupt my exe file, it will throw me an error message telling me so...

My task now is to remove those specific chars Ive placed on that exe file and make it valid again...

The proble its that when I do so, the file remains currupt.

Is there a way of working this out?



Thanks in advance...



Alex

 

[PlausiblyDamp]

How are you storing the extra characters - on the end or dotted throughout the exe (why do you want to corrupt an exe by the way?)

 

[AlexCode]

This is a protection method Im experimenting...

Imagine a .mdb file (Access database), intead of encrypting or ziping it with password, I can currupt the file adding some chars "dotted within the file" that together produce an encrypted password.

If I remove those chars the DataBase would run just fine... and this method would be applyable to any kind of files

This is my idea... Is it possible?


Thanks... Alex

 

[PlausiblyDamp]

If you are over writting existing characters then you would have to replace them with the original ones. If inserting them you will need to make sure the others are moved down again.
Why not just have a look under System.Security.Cryptography - the built in classes offer a choice of known and peer reviewed encryption methods.

 

[AlexCode]

Ok, maybe youre thinking Im reinventing the wheel here but I dont want to just encrypt my data, I want to be able to currupt my file so they have to be registered so the user can use them...

The registration process would fix the exe file or some plug-in Dll so the program would run or would have its full potential...



Ill keep trying...

 

[PlausiblyDamp]

What code are you using to corrupt / un-corrupt (is that even a word I wonder) the file?

 

[AlexCode]

Its donne...
I rewrite the code and it runs all ok now...

It calculates a % of the stream chars, with an algorithm defines the position of the spreaded chars to change and with another algorithm it changes each char to the "encrypted one"...

This way the file is currupted and the position of the "encrypted" chars isnt constant... dificult to reverse this...

Now Im thinking of making about 10 ways of encrypting based on a changed char...



Alex