Office Jesus Posted January 3, 2015 Share Posted January 3, 2015 (edited) Hello, everyone!I want to present the next entry in my "Fun" series. This time it's a bit of crypto!Features of this keygenme: Coded (poorly) in MASM Not packed Not for beginners? Difficulty: 2-3/10 I hope you guys solve this and post tutorials (text, flash, anything) in this thread! As always, I fully expect ChOoKi to solve this within five minutes of downloading. I also expect him to half-ass his way through a tutorial and then not post it. Good luck, everyone! I look forward to your solutions! If you find any bugs, please report them so I can fix them.Cheers,Office Jesus fkgm2.zip Solutions Ragdog DimitarSerg ChOoKi Edited January 8, 2015 by Office Jesus 4 Link to comment Share on other sites More sharing options...
ChOoKi Posted January 3, 2015 Share Posted January 3, 2015 (edited) Has it been five minutes yet? @Office Jesus: Will pm my solution later to allow other members to enjoy it too Edited January 3, 2015 by ChOoKi 2 Link to comment Share on other sites More sharing options...
ragdog Posted January 3, 2015 Share Posted January 3, 2015 (edited) RagdogO**5-2**A3D48D1FA0701A8209C**2D683870 edit:Censored Edited January 3, 2015 by ragdog 1 Link to comment Share on other sites More sharing options...
ChOoKi Posted January 3, 2015 Share Posted January 3, 2015 What the...? I haven't even opened my eyes Oh well, I guess this is expected when members here are starved for a good kgm and for a long time 1 Link to comment Share on other sites More sharing options...
xSRTsect Posted January 3, 2015 Share Posted January 3, 2015 dude next time dont spoil the contents of the crackme on the description, lol. Link to comment Share on other sites More sharing options...
ragdog Posted January 3, 2015 Share Posted January 3, 2015 DUDE i didnt spoiled out anything otherwise i would have posted a working keygen be faster next time Link to comment Share on other sites More sharing options...
DimitarSerg Posted January 3, 2015 Share Posted January 3, 2015 (edited) it was easy (some logic, xor, sha, rsa) **DS** OJ15-37AFB60160FAD50C821C287CB08C7A42 Nice Modulus Office Jesus / iNFECTiON You don't know but you were one of my teachers in keygenning when I started my way in RE... in 2010 I learned your tuts with interest (An Exercise in RSA Reversal (RSA128 + MD5), Simple.MD5.kg-OJ(Perfect Uninstaller) and after that I keygenned a lot of commercial software and at this moment RE is my major job in my life. I want say Thanks for your work ! Edited January 3, 2015 by DimitarSerg 3 Link to comment Share on other sites More sharing options...
xSRTsect Posted January 3, 2015 Share Posted January 3, 2015 DUDE i didnt spoiled out anything otherwise i would have posted a working keygen be faster next time I dont mean you, I mean the OP. Link to comment Share on other sites More sharing options...
XorRanger Posted January 4, 2015 Share Posted January 4, 2015 am i blind or what?i see the sha1 vectors ( when initialized and used) , the RSA Public Key but i can't seem to find where it (the RSA Public Key) is been used for the Encryption Process. Link to comment Share on other sites More sharing options...
ChOoKi Posted January 4, 2015 Share Posted January 4, 2015 (edited) Maybe this will help (Warning: SPOILER!!!) 0040170A |. FF75 F0 PUSH DWORD PTR SS:[EBP-10] ; address to hold RSA public key bignum 0040170D |. 68 0FCE4000 PUSH 0040CE0F ; RSA public key string = "10001" 00401712 |. E8 292A0000 CALL 00404140 ; RSA public key string to bignum call 00401717 |. FF75 EC PUSH DWORD PTR SS:[EBP-14] ; address to hold ModExp result 0040171A |. FF75 F4 PUSH DWORD PTR SS:[EBP-0C] ; bignum1 address = You'll have to find out 0040171D |. FF75 F0 PUSH DWORD PTR SS:[EBP-10] ; bignum2 address = RSA public key bignum 00401720 |. FF75 FC PUSH DWORD PTR SS:[EBP-4] ; bignum3 address = You'll have to find out 00401723 |. E8 58380000 CALL 00404F80 ; bignum ModExp call 00401728 |. FF75 EC PUSH DWORD PTR SS:[EBP-14] ; ModExp result address 0040172B |. FF75 F8 PUSH DWORD PTR SS:[EBP-8] ; address for ??? 0040172E |. E8 7D290000 CALL 004040B0 ; bignum compare call = ModExp result <> address for ??? p.s: Making a tutorial on this kgm already and it will be posted here as soon as it's finished Cheers Edited January 4, 2015 by ChOoKi 4 Link to comment Share on other sites More sharing options...
ChOoKi Posted January 8, 2015 Share Posted January 8, 2015 (edited) ... I also expect him to half-ass his way through a tutorial and then not post it. Tutorial + Kg + Tools ~~ Package was updated (a silly bug in Kg.exe) ~~ OJ_Fun_KGM_#2_Package_Updated.7z Edited January 8, 2015 by ChOoKi 6 Link to comment Share on other sites More sharing options...
pnta Posted January 8, 2015 Share Posted January 8, 2015 Great tut, thanks my bro ChOoKi Link to comment Share on other sites More sharing options...
ChOoKi Posted January 8, 2015 Share Posted January 8, 2015 As a note, the package (above) was updated as soon as I detected a silly little bug in "Kg.exe". I think I'm gettng old for this stuff, time will tell 1 Link to comment Share on other sites More sharing options...
kao Posted January 8, 2015 Share Posted January 8, 2015 @ChOoKi: reversers don't get old, they get bored by easy stuff. Up your game a bit and choose harder targets in the future. 1 Link to comment Share on other sites More sharing options...
ChOoKi Posted January 8, 2015 Share Posted January 8, 2015 (edited) @kao: I think I was low on sugar earlier (not enough beer) In the last few years there has been a tremendous decline in number of kgms posted here, so chances are very slim at finding "harder targets", mind you that making a tutorial on one of them is futile to most beginners. Edited January 8, 2015 by ChOoKi 2 Link to comment Share on other sites More sharing options...
sama Posted January 8, 2015 Share Posted January 8, 2015 this was far to difficult for me, but the solution from ChOoKi is simple awesome thanks for the tutorial dude. and thanks to Office Jesus for the keygenme. Link to comment Share on other sites More sharing options...
XorRanger Posted January 8, 2015 Share Posted January 8, 2015 This was way beyond me i must confess but thanks to ChOoKi for this awesome tutorial and Office Jesus for this nice KeygenME. 1 Link to comment Share on other sites More sharing options...
DimitarSerg Posted January 8, 2015 Share Posted January 8, 2015 (edited) @kao: I think I was low on sugar earlier (not enough beer) In the last few years there has been a tremendous decline in number of kgms posted here, so chances are very slim at finding "harder targets", mind you that making a tutorial on one of them is futile to most beginners. It's not the problem... If you want more hard - look at commercial software... There are a lot of different interesting algorithmes and sometimes they are very complex and difficult with custom crypro, some hidden checks and tricks, interesting key structures and very rarely self-made virtual machines, etc. Edited January 8, 2015 by DimitarSerg Link to comment Share on other sites More sharing options...
xSRTsect Posted January 8, 2015 Share Posted January 8, 2015 (edited) It's not the problem... If you want more hard - look at commercial software... There are a lot of different interesting algorithmes and sometimes they are very complex and difficult with custom crypro, some hidden checks and tricks, interesting key structures and very rarely self-made virtual machines, etc. Yeah I disagree, it is allways the same and eventually gets excessively boring, saving one or two exceptions of course. The right crackmes are far more interesting, imo - but ofc this is a personal taste. As a side, note there are other sites for good crackmes, advertising aside I have posted on my blog a few ones I reversed lately - crackmes.de/us also offer a great deal of fun moments. Edited January 8, 2015 by xSRTsect Link to comment Share on other sites More sharing options...
Departure Posted January 30, 2015 Share Posted January 30, 2015 Man I miss the Underground forum with chooki, office jesus and the rest that where very active in the keygen me challenge section. I learn't a lot from all you guys. Now I have forgotten a lot due to not having people like your selfs running keygen me challenges. I would love to get back into it again if I had mentors like the underground forum members..... Thanks for the tutorial chooki I will definitely have a read of that. 1 Link to comment Share on other sites More sharing options...
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