From: adrian.floarea (adrian.floarea@uti.ro)
Date: Mon Aug 20 2007 - 07:21:47 EDT
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 Şerban Vodă 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
Liability limited by a scheme approved under Professional Standards Legislation in respect of matters arising within those States and Territories of Australia where such legislation exists.
The information in this email and any attachments is confidential. If you are not the named addressee you must not read, print, copy, distribute, or use in any way this transmission or any information it contains. If you have received this message in error, please notify the sender by return email, destroy all copies and delete it from your system.
Any views expressed in this message are those of the individual sender and not necessarily endorsed by BDO Kendalls. You may not rely on this message as advice unless subsequently confirmed by fax or letter signed by a Partner or Director of BDO Kendalls. It is your responsibility to scan this communication and any files attached for computer viruses and other defects. BDO Kendalls does not accept liability for any loss or damage however caused which may result from this communication or any files attached. A full version of the BDO Kendalls disclaimer, and our Privacy statement, can be found on the BDO Kendalls website at http://www.bdo.com.au or by emailing administrator@bdo.com.au.
BDO Kendalls is a national association of separate partnerships and entities.
-----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 Şerban Vodă 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 Şerban Vodă 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
>
> ------------------------------------------------------------------------
> This list is sponsored by: Cenzic
>
> Need to secure your web apps NOW?
> Cenzic finds more, "real" vulnerabilities fast.
> Click to try it, buy it or download a solution FREE today!
>
> http://www.cenzic.com/downloads
> ------------------------------------------------------------------------
>
>
> ------------------------------------------------------------------------
> This list is sponsored by: Cenzic
>
> Need to secure your web apps NOW?
> Cenzic finds more, "real" vulnerabilities fast.
> Click to try it, buy it or download a solution FREE today!
>
> http://www.cenzic.com/downloads
> ------------------------------------------------------------------------
>
>
------------------------------------------------------------------------
This list is sponsored by: Cenzic
Need to secure your web apps NOW?
Cenzic finds more, "real" vulnerabilities fast.
Click to try it, buy it or download a solution FREE today!
http://www.cenzic.com/downloads
------------------------------------------------------------------------
------------------------------------------------------------------------
This list is sponsored by: Cenzic
Need to secure your web apps NOW?
Cenzic finds more, "real" vulnerabilities fast.
Click to try it, buy it or download a solution FREE today!
http://www.cenzic.com/downloads
------------------------------------------------------------------------
This archive was generated by hypermail 2.1.7 : Sat Apr 12 2008 - 10:58:02 EDT