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Old 2016-06-25, 07:18   #1
craneduitre
 
Jun 2016

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Unhappy Help to install and factor large number

Good morning all. Hope this post finds you well.

I'm new here and have an IT background but in aviation now. I do also have a lady friend who got all her pictures encrypted by a virus.
Cryptography is the next level for me but had few memories from uni. I decided to help and followed a tutorial to try to extract the encryption key, and so far it went well as I think I got it :

Code:
File: u'./IMG_3267.JPG.vvv'
     AES: u'9B2A14529F5CEF649FD0330D15B4E59A9F60484DB5D044E44F757521850BC8E1DCDF3CB770FEE0DD2B6A7742B99300ED02103027B742BC862110A1765A8B4FC6'
     BTC: u'372AE820BBF2C3475E18F165F46772087EFFC7D378A3A4D10789AE7633EC09C74578993A2A7104EBA577D229F935AF77C647F18E113647C25EF19CC7E4EE3C4C'
AES converted to decimal:

Code:
8126617599207443348986490006049212956268718489283948438673983714596683304044955742664060883447819181330966710002780429642374333138816650318920123595575238
Now i'm trying to factor this number and factordb.com can only do a partial factorisation.
I tried to install desperately msieve on my iMac (dont have my other PCs with me) and this is where I'm stuck. I did follow this guide (http://gilchrist.ca/jeff/factoring/n...ers_guide.html) but still too complex for me (Not even sure how to compile.)

I would really appreciate if someone could take me through the installation on osx like a beginner or help me factorise this ugly number. I'm even happy to provide a compensation for the trouble if needed.

Thanks :)
Seb.
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Old 2016-06-25, 08:18   #2
LaurV
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It takes few hours to factor the remaining C123 on a good CPU. I will factor it for you. Then you can pay me by installing P95 and run some DC tests or LL tests in the future, for yourself, up to your convenience. Who knows, you may be even lucky and find a prime and make some money...

Edit: as someone here said, a good part of this idiocy called "teslacrypt" or however is called, is the fact that it ran many many people to came here and find about us, and what we are doing. A part of these people stay(ed) and help(ed) with our efforts. This is good for our projects.

Last fiddled with by LaurV on 2016-06-25 at 08:44
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Old 2016-06-25, 08:23   #3
craneduitre
 
Jun 2016

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I have no clue what a P95 and DC LL tests are but thanks for the help !
If it work let me know how I can help back :)
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Old 2016-06-25, 17:09   #4
wombatman
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http://www.mersenneforum.org/showthread.php?t=20779

Start with this post. It will walk you through how to try and factor the number (assuming LaurV doesn't finish it soon). Then we can talk about running Prime95
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Old 2016-06-25, 17:22   #5
bgbeuning
 
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Default Advanced Encryption Standard

So AES (Advanced Encryption Standard) does not use prime numbers so
I am not sure how factoring helps find the AES key.

One does not extract an AES key. If you don't know it, you need a brute force
exhaustive search to find it. If they used AES-256 (and why wouldn't they)
it is way beyond practical to find the key.
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Old 2016-06-25, 17:53   #6
wombatman
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Because it's Teslacrypt and doesn't actually use a high standard. See the other threads about Teslacrypt in this subforum. A lot of times the "AES" number has many small factors that YAFU finds in a matter of seconds or minutes.
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Old 2016-06-25, 19:17   #7
bgbeuning
 
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Wikipedia has some information

Quote:
TeslaCrypt was a ransomware trojan. It is now defunct, and its master key released by the developers. A free decryption tool is available on the web.
http://download.eset.com/special/ESE...tDecryptor.exe
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Old 2016-06-26, 02:58   #8
LaurV
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As said, the remaining C123 (sorry for the delay, there was a night here, we are now at the morning coffee):
Code:
P61 = 2640055505350166842011831270884389537881022481540999907428329
P63 = 307350395247922573157070469565587371380533590999759725034121709
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Old 2016-06-26, 15:11   #9
craneduitre
 
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Ah man you are a star thank you !
I still need to see how I can decrypt my photos from that but its in FF status now on factordb so its a good start.
Let me know how to help back
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Old 2016-06-26, 15:28   #10
LaurV
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Keep us informed how it went.
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Old 2016-06-26, 16:34   #11
craneduitre
 
Jun 2016

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Ok i'm a bit confused as when I run the python script it says that the primes may not be valid.
So just for interest I restarted the whole process again, starting with that:

Code:
Unknown key: 18191BFF12E7367A33B0B4EF5639406B40A9E5756C33EF0DE06C186E34C796A7FB356FD87A68D48541C344BE40B42C7956ACC65B6CD14C3E2F0F4A3F0F7481D5 
  in file: ./IMG_3267.JPG.vvv
2016-06-26 17:27:38,026:INF: +++Unknown key(s) encountered: 1 
     AES: u'18191BFF12E7367A33B0B4EF5639406B40A9E5756C33EF0DE06C186E34C796A7FB356FD87A68D48541C344BE40B42C7956ACC65B6CD14C3E2F0F4A3F0F7481D5'
     BTC: u'2970452D95A6DBD450658E2D1ADDB8440138F1A6D7023757693F81B7240B5C0C172A33CB7C59F697538FCDDAF83EA530F2CE34C9E2D8BD4C9879E1B4E59A2011'
    File: u'./IMG_3267.JPG.vvv'
then AES to decimal:

Code:
1262119040059327873765770617224497883380713324649219646187831247738474383543984062853003275360039038674909697947419974209349712095030672264065310992400853
I dont understand why I have a different number to factorise now, as this one is on CF in factordb.com :(
I'll try to factor this one and hope its going to work better.

edit: I think I read it wrong and ask you to factor the wrong number !

Last fiddled with by craneduitre on 2016-06-26 at 16:37
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