#1
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question about winrar passwords
hi , I have learned alot in this forum and I still learnning >> so thank you evryone .... and please execuse my bad english
I forgot a password in a protected rar file... I know there are some software to recover that but they take long time and my question >>> is it possible to find out a password for a rar or zip document using ollydbg if yes are there any tutorials in the net about that .. thanks Last edited by abccc; 04-07-2005 at 22:20. |
#2
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Hi
This is one of the question that is asked too much.But I should say that attacking to a rar or any other compressing ways theoricaly has no way except Bruteforce or dictionary attack(If it developed well such as rar and zip). Because algorithm is too simple,You add a signature in for example start of file and then encrypt all the file.When you want to decrypt it,after decoding some blocks of file if the signature was wrong that means you enter the password wrong and in this way there is no need for saving password in file and attacking to it is similar to attacking an encryption algorithm(It is a way that can be used,I didn't know rar or zip algorithms but they should be similar). sincerely yours
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I should look out my posts,or JMI gets mad on me! |
#3
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If the password is given by you. Create a possible dictionary and use bruteforce to crack will be helpful.
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#4
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Hero, fsheron thank you very much for quick response..
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#5
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But if your rar version is >= 3.0 , you may get very-very long time to bruteforce because of use a new algorithm in v3.0+
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#6
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Because Winrar in that version uses powerfull AES algorithm for its password.
But there is no other way except bruteforce or dictionary attacks. sincerely yours
__________________
I should look out my posts,or JMI gets mad on me! |
#7
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Just to complement this answer, this is also same for WinZip.
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#8
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Hi visu
That's right that I heard that WinZip uses AES too,But I don't know why its best bruteforce password finder can work with too high speed for it. It can test almost 2 million passwords per second! Any idea why these two is that deferent?(winrar check almost 700 pps) sincerely yours
__________________
I should look out my posts,or JMI gets mad on me! |
#9
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2Hero:
The main performance fall not in AES encrypting itself but in generating encryption key. The last one takes long time when using WinRAR. You can speed up WinRAR breaking by brute-forcing decryption key, not password. But it'll make no sense due to a very big number of possible keys |
#10
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hi amitophia
I'm not a professional in encryption algorithms,but I know that AES is an symmetric algothirm,that means the encryption and decryption keys are the same. What do you mean by: Quote:
(I always think that they should get the AES 128bits key by making a simple padding from your password.) sincerely yours
__________________
I should look out my posts,or JMI gets mad on me! |
#11
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2Hero:
You mean that password is deferent by the AES encryption/decryption keys? No-no. When I said "ecnryption/decryption key" I just meant different roles of the key in apporpriate processes. Sorry for misleading you by making a simple padding from your password Actually this "padding" is calcualtion of hash from the password. And it shouldn't be simple to be invulnerable to brute-force attacks. The faster (simpler) hash is calculated, the faster brute-force can be done. Last edited by amitophia; 04-20-2005 at 04:46. |
#12
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it is impossible to recovery files from a winrar v3 password protected file. unless you have a very powerful machine.
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