On 25 Feb 2010, at 01:41, Greg Parker wrote: > On Feb 24, 2010, at 5:27 PM, Graham Lee wrote: >> On 24 Feb 2010, at 22:57, Michael A. Crawford wrote: >>> Part of your response suggests that if there was an existing framework that >>> was openly available, it wouldn't do me any good because the bad guys would >>> have the source code. >> >> I disagree. If it's based on a tried and tested (and occasionally formally >> verified) crypto system, knowing the algorithm doesn't lead to a crack. >> Weaknesses would come through bugs in the framework (or incorrect >> application of it), and the more people who can see the source the greater >> chance there is that good people as well as bad can find the issues. Good >> people fix 'em. > > Except in the standalone piracy-prevention case, the algorithm is already > known to be broken. Formally, the attacker already has in hand all of the > information they need: they have the executable and all of the data accessed > by the executable. The only information the attacker lacks is the algorithm. > Once they know the algorithm, they know how to rewrite your executable to > bypass the protection system.
They don't even need to know the algorithm, if they have access to kernel memory - at some point the code has to end up in a state the OS can execute. Believing that DRM provides confidentiality is the most common "incorrect application" I come across :-) Graham. -- Graham Lee http://blog.securemacprogramming.com/ http://www.mac-developer-network.com/category/columns/security/ _______________________________________________ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
