Penetration Testing mailing list archives
Re: Determining the encryption used
From: Tim <tim-pentest () sentinelchicken org>
Date: Thu, 11 May 2006 17:46:20 -0400
Is it possible to determine the encryption used by "looking" at the encrypted results or lenght ? I know that with Base64 it's pretty easy because of the "==" at the end.
This can be very difficult. Ciphertext is supposed to look completely random, so a secure algorithm will give away little. Length can be helpful though. If the encryption was done with a block cipher in ECB or CBC modes, then all texts will have lengths which are a multiple of the block size. There are many ciphers which have the same block size now though, and most new ones are using 128 bit (16-byte) blocks. Common ciphers which use 64-bit blocks are DES and Blowfish. If the length across many instances is not a multiple of any large block size, then it may be a block cipher used in OFB/CFB modes, or a stream cipher. That, or something home-grown and likely weak. HTH, tim ------------------------------------------------------------------------------ This List Sponsored by: Cenzic Concerned about Web Application Security? Why not go with the #1 solution - Cenzic, the only one to win the Analyst's Choice Award from eWeek. As attacks through web applications continue to rise, you need to proactively protect your applications from hackers. Cenzic has the most comprehensive solutions to meet your application security penetration testing and vulnerability management needs. You have an option to go with a managed service (Cenzic ClickToSecure) or an enterprise software (Cenzic Hailstorm). Download FREE whitepaper on how a managed service can help you: http://www.cenzic.com/news_events/wpappsec.php And, now for a limited time we can do a FREE audit for you to confirm your results from other product. Contact us at request () cenzic com for details. ------------------------------------------------------------------------------
Current thread:
- Determining the encryption used John Madden (May 11)
- Re: Determining the encryption used Art Cooper (May 12)
- Re: Determining the encryption used Tim (May 12)
- Re: Determining the encryption used Rodrigo Ramos (May 12)
- Re: Determining the encryption used Tim (May 12)
- Re: Determining the encryption used Byron Sonne (May 12)
- Re: Determining the encryption used Peter Kosinar (May 12)
- Re: Determining the encryption used Tonnerre Lombard (May 12)
- Re: Determining the encryption used Tim (May 12)
- Re: Determining the encryption used Phoebe Tunstall (May 12)
- Re: Determining the encryption used Peter Kosinar (May 13)
- Re: Determining the encryption used Tim (May 13)
- Re: Determining the encryption used Tim (May 12)
- RE: Determining the encryption used Sahir Hidayatullah (May 12)