Security Basics mailing list archives
Re: MD5-Hash of a SHA-1-Hash unsecure?
From: Alexander Klimov <alserkli () inbox ru>
Date: Mon, 8 Dec 2008 12:45:49 +0200 (IST)
On Fri, 5 Dec 2008, Andre Pawlowski wrote:
I've written a program which can store files encrypted ( http://h4des.org/index.php?inhalt=kastalia ). The user enters a password when he wants to encrypt a file. The programm makes a SHA-1-Hash of this password and transfers it from the browser to the server. When the encryption starts, the program makes a MD5-Hash of this SHA-1-Hash for the IV of the blowfish algorithm. Here is my question: Is it less secure when I make a MD5-Hash of a SHA-1-Hash?
Depending on encryption mode, IV must be either random or unique and thus from the cryptography point of view, using the same IV is wrong, on the other hand the problem is rather theoretical for the target audience of a system that has the option to store the files encrypted on the server so the user can be sure his files are securely safed. [...] Even though the files are stored encrypted on the server they must be transfered to the user unencrypted. One who cares about security would rather use GnuPG (or 7-Zip) to encrypt files locally. -- Regards, ASK
Current thread:
- MD5-Hash of a SHA-1-Hash unsecure? Andre Pawlowski (Dec 05)
- RE: MD5-Hash of a SHA-1-Hash unsecure? David Gillett (Dec 08)
- Re: MD5-Hash of a SHA-1-Hash unsecure? Andre Pawlowski (Dec 08)
- Re: MD5-Hash of a SHA-1-Hash unsecure? Alexander Klimov (Dec 08)
- <Possible follow-ups>
- Re: MD5-Hash of a SHA-1-Hash unsecure? jason . gerfen (Dec 05)
- Re: MD5-Hash of a SHA-1-Hash unsecure? Tom Ritter (Dec 08)
- Re: Re: MD5-Hash of a SHA-1-Hash unsecure? asdfs (Dec 09)
- RE: MD5-Hash of a SHA-1-Hash unsecure? David Gillett (Dec 08)