Author: Eugene Nalimov
Date: 08:22:24 03/26/99
Go up one level in this thread
On March 26, 1999 at 07:50:36, Robert Hyatt wrote: >On March 25, 1999 at 23:49:20, Eugene Nalimov wrote: > >>On March 25, 1999 at 23:01:48, Ed Schröder wrote: >> >>>On March 25, 1999 at 22:37:58, Robert Hyatt wrote: >>> >>>>On March 25, 1999 at 10:02:37, Eugene Nalimov wrote: >>>> >>>>>On March 25, 1999 at 08:05:45, Robert Hyatt wrote: >>>>> >>>>>>On March 25, 1999 at 07:08:57, Robert Ericsson wrote: >>>>>> >>>>>>>I have just read at Gambit-SOFT News that Crafty will not be for free >>>>>>>download anymore. >>>>>>> >>>>>>>I can understand Dr. Hyatt's decision and all I can say is a BIG thank you >>>>>>>to Bob for all previous free downloads of Crafty!! >>>>>>> >>>>>>>I enjoy Crafty very much. I hope we will hear from you here at CCC though. >>>>>>>Good luck with your future programming! >>>>>>> >>>>>>>Yours sincerely, >>>>>>>Robert Ericsson >>>>>> >>>>>> >>>>>>Crafty will continue to be available. Just not via anonymous ftp, so that I >>>>>>can maintain some sort of control over it. I don't know how it will be done >>>>>>just yet, but details will be posted here soon. >>>>> >>>>>Maybe you can distribute executables by anonymous FTP. My guess >>>>>is that at least 80% of Crafty users will be happy with it. >>>>> >>>>>Eugene >>>> >>>>That doesn't solve the 'drafty' problem.. because it is not terribly hard to >>>>use a hex editor to find the various strings in crafty and change them to some >>>>sort of profanity. >>> >>>You can add a checksum to the Crafty executable. I have done this myself >>>in every Rebel release. If one byte is changed then it is exit program. >>>It's also a good protection against a virus. >>> >>>Ed Schroder >> >> >>I can write some Win32-specific code - I know structure of the >>executables very well (before moving to MS I wrote Win32 linker). >>Of course, that can be broken, too, but at least some assembly >>knowledge is required. >> >>Bob, please write to me if you are interested. >> >>Eugene > >I'm interested. What I am thinking of is using argv[0] to get the name of >the program, then simply opening that file and checksumming it. I could do it >on what is in memory, but that would be a bit harder and make it so system >dependent that it would probably be a headache. > >seem ok like that? > >Bob That will work, too. I thought about more complicated schema, that will give more troubles to hackers. In your schema it's possible to set breakpoint to fopen() (or deeper, in the corresponding API level - then symbol information is not necessary) and easily detect the place where checksum is calculated. No one schema is bulletproof, and maybe yours will be sufficient. BTW, Crafty are already has functions that calculate CRC32. Please look in the file tbdecode.c. If you decide to use them, just replace 'static' by 'extern "C"'. Eugene >> >>>>Tablebases and the PGN game collections are 'up' still. And crafty will be >>>>again once I find a way to exert some control over it. IE the license agreement >>>>will likely change, although the cost will _always_ be what it is today. :)
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