Uli's Web Site
[ Zathras.de - Uli's Web Site ]
Other Sites: Stories
Abi 2000
Stargate: Resurgence
Lost? Site Map!
     home | blog | moose | programming | articles >> blog

 Blog Topics

15 Most Recent [RSS]

 Less work through Xcode and shell scripts
2011-12-16 @600
 iTunesCantComplain released
2011-10-28 @954
 Dennis Ritchie deceased
2011-10-13 @359
 Thank you, Steve.
2011-10-06 @374
 Cocoa Text System everywhere...
2011-03-27 @788
 Blog migration
2011-01-29 @520
 All you need to know about the Mac keyboard
2010-08-09 @488
 Review: Sherlock
2010-07-31 @978
 Playing with Objective C on Debian
2010-05-08 @456
 Fruit vs. Obst
2010-05-08 @439
 Mixed-language ambiguity
2010-04-15 @994
 Uli's 12:07 AM Law
2010-04-12 @881
 Uli's 1:24 AM Law
2010-04-12 @874
 Uli's 6:28 AM Law
2010-04-12 @869
 Uli's 3:57 PM Law
2010-04-12 @867


Nice article on serial numbers

Just stumbled across a neat (and, admittedly, old) article that explains how to use the OpenSSL library from code as a way of implementing licensing for an application you write.

OpenSSL keys aren't quite suitable for use as serial numbers (because a 1024-bit key is 128 characters long, and users wouldn't want to type that), but if you have a license URL scheme or a license file implementation, they'll do just fine. You just use your private key to encrypt some data about the license (i.e. user name, number of seats, expiration date), and the app can extract that using the public key. And factoring a private 1024-bit key currently still takes too long to be worthwhile.

This doesn't make your app un-crackable, but will keep key generators off the web. People will need binary patches to remove the licensing code or replace the public key. And whoever is stupid enough to use a binary patch from some shady web site is punished enough already, because they prolly also have lots of viruses and exploits on their machine anyway...

Reader Comments: (RSS Feed)
Kishor Patel writes:
Great pointer. Thanks very much.
Or E-Mail Uli privately.

Created: 2008-08-15 @000 Last change: 2018-03-22 @063 | Home | Admin | Edit
© Copyright 2003-2018 by M. Uli Kusterer, all rights reserved.