C Language, Good ways to obfuscate/mangle strings?

Good ways to obfuscate/mangle strings?

Author	Message
Bill Schonga #1 / 8	Good ways to obfuscate/mangle strings? Howdy.. I'm trying to hide about 50 strings (with < 100 characters each) so that the ASCII data isn't viewable in a hex editor, and was curious to see if there's already a method folks here would recommend for doing it. The strings change frequently between compiles (they're being passed to a script interpreter), so I'm wondering if I should just make an external string parser that converts them all into strings of ASCII values and embeds them in the code. Thanks for any ideas.. -Bill
Sun, 10 Dec 2000 03:00:00 GMT

User9230 #2 / 8	Good ways to obfuscate/mangle strings? Read their FAQ. -- C-FAQ ftp sites: ftp://ftp.eskimo.com ftp://rtfm.mit.edu Hypertext C-FAQ: http://www.eskimo.com/~scs/C-faq/top.html C-FAQ Book: ISBN 0-201-84519-9. Want Software? Algorithms? Pubs? http://www.infoseek.com
Sun, 10 Dec 2000 03:00:00 GMT

Richard Sta #3 / 8	Good ways to obfuscate/mangle strings? Quote: > I'm trying to hide about 50 strings (with < 100 characters each) so >that the ASCII data isn't viewable in a hex editor, and was curious to >see if there's already a method folks here would recommend for doing it. It depends whether you just want to hide the strings from a casual observer, or protect them from a concerted attack. If the former then the simplest approach is probably just to xor each character with a fixed value. If the latter then, as Dann has already commented, you're into the domain of cryptography and you'd probably do best to ask in sci.crypt. Quote: >The strings change frequently between compiles (they're being passed >to a script interpreter), so I'm wondering if I should just make an >external string parser that converts them all into strings of ASCII >values and embeds them in the code. That sounds like the simplest approach to getting the munged strings into your program -- it shouldn't be too hard to write a little program which converts the strings and generates a .c file containing, say, an array of the results. Your program could then unscramble the strings when it starts running, and subsequently access the plain versions by indexing into the array. Cheers, Richard -- Richard Stamp Churchill College, Cambridge
Sun, 10 Dec 2000 03:00:00 GMT

Will Ro #4 / 8	Good ways to obfuscate/mangle strings? : Howdy.. : I'm trying to hide about 50 strings (with < 100 characters each) so : that the ASCII data isn't viewable in a hex editor, and was curious to : see if there's already a method folks here would recommend for doing it. : The strings change frequently between compiles (they're being passed : to a script interpreter), so I'm wondering if I should just make an : external string parser that converts them all into strings of ASCII : values and embeds them in the code. I've mostly seen NAND used for this. It seems pretty simple to convert to and from the encrypted version, but anyone who can use a hex editor is probably smart enough to figure it out. If it's just to avoid messing up a game, not a problem; otherwise you probably need to use real encryption. Will
Sun, 10 Dec 2000 03:00:00 GMT

Alan Cur #5 / 8	Good ways to obfuscate/mangle strings? Quote: >That sounds like the simplest approach to getting the munged strings >into your program -- it shouldn't be too hard to write a little program >which converts the strings and generates a .c file containing, say, an >array of the results. Your program could then unscramble the strings >when it starts running, and subsequently access the plain versions by >indexing into the array. It'll never get to the point of accessing them, because right after the unscrambling is when I print the results and exit the de{filter}.
Mon, 11 Dec 2000 03:00:00 GMT

Richard Sta #6 / 8	Good ways to obfuscate/mangle strings? Quote: >>Your program could then unscramble the strings >>when it starts running, and subsequently access the plain versions by >>indexing into the array. >It'll never get to the point of accessing them, because right after the >unscrambling is when I print the results and exit the de{filter}. As I said, Alan, it depends on whether you're just trying to hide the strings from a casual observer or make them secure against a serious attack. If the latter, I think my advice to XOR the characters with a fixed pattern is much dodgier than the bit you've quoted above. :-) Cheers, Richard -- Richard Stamp Churchill College, Cambridge
Mon, 11 Dec 2000 03:00:00 GMT

Bill Schonga #7 / 8	Good ways to obfuscate/mangle strings? Quote: > >>Your program could then unscramble the strings > >>when it starts running, and subsequently access the plain versions by > >>indexing into the array. > >It'll never get to the point of accessing them, because right after the > >unscrambling is when I print the results and exit the de{filter}. > As I said, Alan, it depends on whether you're just trying to hide the > strings from a casual observer or make them secure against a serious > attack. If the latter, I think my advice to XOR the characters with > a fixed pattern is much dodgier than the bit you've quoted above. :-) The goal is just to make it harder than cutting&pasting the strings from a hex editor, like I can now with the binary. With the current code, pumping the characters through an XOR or NAND definitely seems like the best way to go about it. Thanks for the feedback! -Bill
Mon, 11 Dec 2000 03:00:00 GMT

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