Is it possible to...?

[PityOnU]

I was wondering if there is a program out there that can use a set of known keys to determine possible other keys. For example, if the program is given the keys AAAAA, BBBBB, and CCCCC, it will analyze the keys and suggest the possible key of DDDDD & etc.

I figure that encryption like this is kinda what computers were made for, so there must be some way to do something like this... right? Obviously the keys I'm trying to generate are a bit more complex that DDDDD, but it's the same principle. Right?

Do any of you know of anywhere I could find a program like this or how I would go about making one myself?

Thanks in advance! Any time and effort you put into your rsponse is much appreciated!

[phkninja]

Are you trying to recover a second key from the first or are you just trying to generate keys.

If its the latter then the answer to your question its called brute force password generation. Not going to provide links but if you search the web. There are alot of programs that can do this, but its a time consuming method of breaking encryption.

If its the first one then your out of luck. Unless the encryption algorithm is totally insecure you cannot find any similarity between keys (like public key, both keys are generated using complex algorithms but neither can be derived from the other).

[electroglyph]

i don't think there are many programs at all that can do this. fact is, i think it would require some seriously impressive math skills to write an efficient program to do it. simply put, there's no practical way to do it.

probably only feasible with an FPGA or NVidia GPU + SDK. but it would be a cool project to undertake.

there is only one program i can think of that does this: THC-Shagg, but it's only for check digit algorithms.

the quickest method will always be reverse engineering...input an invalid key and debug the application to see how it checks the key. however, any system which uses a third party for key verification is probably not using "generated" keys at all. with online gaming for instance keys could be randomly generated, placed on a list, and then simply checked to see whether they were issued or not.

Edited October 27, 2007 by Yzöwl
pointless swearing removed

[phkninja]

you still havent specified what kind of key you are trying to discover.

You mention encryption (thats why i gave the first post) thats only one use of a key, as electroglyph said keys are used in gaming (or in other software) to allow you to install or to run a program.

If we knew the context then we might be able to help more

[PityOnU]

I was going to try and figure out the encryption key for Zune Marketplace Free Trial cards. I figured it would be pretty cool to do, but I have since abandonned the effort.

In case you were wondering, the keys were something like BDHWY-8PMG6-X9432-HHPJ8-G4XV8 , so I figure I don't stand much of a chance.

Thanks for the help though.

[electroglyph]

I can pretty much guarantee those are completely random. There is no way to generate more because Microsoft simply keeps a master list of their randomly generated keys and when you enter the code online Microsoft checks to see whether it was issued or not.

Generated keys are typically found in shareware or trial versions of software.

I've also been thinking more on the subject, and I think it would be nearly impossible to make such a program anyways. The biggest bottleneck would be testing the generated keys. You would need many many many sample keys to work with and you'd still generate tons of incorrect keys. This would force you to develop an interface between the key generator and the target software so that keys could be tested programmatically. Since there would be custom programming required for each different target to make it even remotely feasible your time would probably be much better spent reverse engineering the target software to begin with.