I think my words begin a small war here:) . Again:
1. You are right, the password has nothing to do with the encrypted file (the
output). So, in order to decrypt the file the easy way (again if the password
is weak and you know the proprietary format of the encrypted file) is an brute
force attack.
2. I assume that encrypted file was encrypted with an commercial encryption
program who usually use a password in order to generate the expanded key which
is used by AES for encryption.
Again, what I say is related with brute force attack. Very improbable to crack
the encrypted file, but it is a chance.
Regards,
Adrian Floarea, CISA
Business Development Manager
SC CERTSIGN srl
Central Business Park
133, Calea Åerban VodÄ St., Building C1, 2nd floor
040205 Bucharest 4, Romania
-----Original Message-----
From: Craig Wright [mailto:Craig.Wright@bdo.com.au]
Sent: Monday, August 20, 2007 1:16 AM
To: adrian.floarea; R Buena
Cc: Kush Wadhwa; pen-test@securityfocus.com; forensics@securityfocus.com
Subject: RE: AES-256 encryption
Hello,
A weak password has nothing to do with this. I did not see any mention that the
key was captured, just the file to be decrypted. If the key file is captured
this is a separate issue and nothing to do with AES.
There is NO password stored with the encrypted file. A password is used to
protect the key, but a key is always to be considered compromised if it is
intercepted. The password takes no place in the encryption scheme. I would
suggest that you have a read on the encryption protocol specifications.
Regards,
Craig
Craig Wright
Manager of Information Systems
Direct : +61 2 9286 5497
Craig.Wright@bdo.com.au
+61 417 683 914
BDO Kendalls (NSW)
Level 19, 2 Market Street Sydney NSW 2000
GPO BOX 2551 Sydney NSW 2001
Fax +61 2 9993 9497
www.bdo.com.au
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-----Original Message-----
From: listbounce@securityfocus.com [mailto:listbounce@securityfocus.com] On
Behalf Of adrian.floarea
Sent: Friday, 17 August 2007 1:49 AM
To: 'R Buena'
Cc: 'Kush Wadhwa'; pen-test@securityfocus.com; forensics@securityfocus.com
Subject: RE: AES-256 encryption
As I say to Kush in a private email, it is almost impossible to crack a file
which is encrypted in a proper way with AES.
But, if the password used for encryption is a week password (like 1234 or abcd
etc) with a specialized tool you can break the encryption.
Even, if the password is weak some tools cannot decrypt the files, because do
not understand the format of the document (for example, if the document is a
PKCS#7 structure), so in this case you must use an appropriate tool.
This was the sense of my words.
Hope to help you.
Regards,
Adrian Floarea, CISA
Business Development Manager
SC CERTSIGN srl
Central Business Park
133, Calea Åerban VodÄ St., Building C1, 2nd floor
040205 Bucharest 4, Romania
-----Original Message-----
From: R Buena [mailto:dreamsbig@gmail.com]
Sent: Thursday, August 16, 2007 6:09 PM
To: adrian.floarea
Cc: Kush Wadhwa; pen-test@securityfocus.com; forensics@securityfocus.com
Subject: Re: AES-256 encryption
Just curious, what if the program was KeyPass or PasswordSafe?
and you don't know the passphrase?
On 8/14/07, adrian.floarea <adrian.floarea@uti.ro> wrote:
Hi Kush,
Please tell me if you know the program which was used for encrypt the file
and also the used password. If not, I am afraid that will be impossible for
you to decrypt the file.
There are some good programs for decrypt files (for example Passware) but
with limited functionalities. For example if was used for encryption a good
password (more than 6-7 characters, numbers or special characters) it is
almost impossible to recover the file.
Regards,
Adrian Floarea, CISA
Business Development Manager
SC CERTSIGN srlr
Central Business Park
133, Calea Åerban VodÄ St., Building C1, 2nd floor
040205 Bucharest 4, Romania
-----Original Message-----
From: listbounce@securityfocus.com [mailto:listbounce@securityfocus.com] On
Behalf Of Kush Wadhwa
Sent: Tuesday, August 14, 2007 1:36 PM
To: pen-test@securityfocus.com; forensics@securityfocus.com
Subject: AES-256 encryption
Hello All,
Is there any way to decrypt a file which is AES-256 encrypted? I used
many of the tools but I was not able to decrypt it. Please help me if
any one knows how to decrypt it
Regards,
Kush Wadhwa
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