WinRAR Password Recovery

Soldato
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A colleague of mine has sent me two password protected .rar files with some fairly important information in. The person that set the passwords has now left the company and no one can get hold of him :rolleyes:. Dose anyone know of any tools that can be used to recover the password. All the tools I've found on Google ether don't work or take weeks to complete. Any ideas?
 
Caporegime
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How big are the files? It will take a long time no matter what as you will have to brute force them. The bigger the files the longer they take. Anything over say 5MB is not worth thinking of as it will take months of 24/7 activity.

If they are a couple of word documents and you have access to a fast PC which can concentrate on just this then maybe a couple of weeks if the password isnt too long.
 
Caporegime
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Do you know how long the password is?

First thing you should try is a dictionary attack if the password was something easy to guess then it will find it, if that doesn't work you'll have to use brute force which could take weeks if the password is long. You can speed it up considerably though if you utilise the processing power of the whole network.
 
Caporegime
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If he knows the password is definitly 7-8 characters that can help you a lot as the password program doesnt have to try shorter ones. 500MB could be a serious issue though, having said that trying one of my rar files doesnt seem to make a difference what size it is, I'm sure it has in the past. :confused:

Hopefully someone else can set that one right.

Have a look at these. They are quite good but you have to pay.
 
Caporegime
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If you have the workstation on which the file was originally created you can use programs to recover saved password info from that pc saving you a lot of time.
 
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Permabanned
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Provided the person used a decent password (non dictionary, characters, lower & upper case and numbers) then your never gonna brute force it.

WinRAR use AES encryption with 128-bit keys.

P.S) The size of the file being rar'ed makes no difference to the encryption strength, the length and uniqueness of the password does however.
 
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Caporegime
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Chingoo said:
Provided the person used a decent password (non dictionary, characters, lower & upper case and numbers) then your never gonna brute force it.

WinRAR use AES encryption with 128-bit keys.

P.S) The size of the file being rar'ed makes no difference to the encryption strength, the length and uniqueness of the password does however.

Not never but a very long time, based on a computer doing 30 passwords a second (1 core of my X2 4400) it will take 1 1/2 hours to do 3 characters, 62 hours to do 4 and 146 days to do 5 and thats only with 52 characters to choose from (non and caps letters). It depends on how important the information is. You could use a few computers each analying a small section of the possible passwords (such as ones beginning with a, b etc.) and that would take less time, but still a long time.

The file size shouldnt make a difference but I tried brute forcing a 700mb file and it only did one password every minute or so, like it was decompressing it then asking for the password at the end each time. It can't have been but I couldnt see any other reason, it may have just been the file though.
 
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