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I am trying to connect to a VPN using Cisco VPN Client in-build on Mac Snow Leopard. The problem is that I have only the encrypted password. I tried some web sites to decrypt the password, but it does not work. Any idea?

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If you're asking how to decrypt 512-AES, SHA-1 Hashing w/ ESP you are very mistaken on how VPNs (Or encryption) work. –  zv_ Oct 1 '10 at 15:28
    
He could very well be talking about the "encrypted" password located in the pcf file, which, by all accounts, is extremely trivial to crack. –  GregD Nov 1 '10 at 13:31
    
Yes GregD. But it is not trivial for me. –  rtacconi Nov 2 '10 at 8:49
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3 Answers 3

If you could decrypt it without a supercomputer and a few thousand years of computing cycles, that would be a serious security flaw, wouldn't it?

You might have to work on having the password changed on the host or going for the documentation of the sysadmins that set it up.

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This definitely is possible.

There is a known vulnerability with the group password encryption implementation.

http://www.cisco.com/warp/public/707/cisco-sn-20040415-grppass.shtml

Here is C source code that demonstrates the vulnerability: http://www.unix-ag.uni-kl.de/~massar/soft/cisco-decrypt.c

I've successfully used this code to decrypt an encrypted group password for use with the built-in OS X 10.6 VPN client.

If some of the online tools or the source code above do not work for you then perhaps Cisco have a different implementation in the VPN implementation you're using.

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If you're talking about the pcf file and it's "encrypted" password, this is indeed an easy thing to do:

http://coreygilmore.com/projects/decrypt-cisco-vpn-password/

Will get you what you need. I only do this to highlight the fact that you should NOT be using pcf files for VPN access.

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Hi, yes I tried that one without any luck. I get an 'wrong password responce' –  rtacconi Nov 2 '10 at 8:44
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