Educause Security Discussion mailing list archives
Re: Passwords & Passphrases
From: Paul Keser <pkeser () STANFORD EDU>
Date: Mon, 26 Nov 2007 14:52:43 -0800
Harold- I think Alex is saying the cracking program is more likely to guess aaaaaaa...., I believe John the Ripper includes all a's, all b's, etc in its dictionary attack. Dictionary attacks usually take a very few minutes on a typical workstation while if it has to fall back to brute force it will take days or weeks, this is assuming the already have a coup of your san file or your shadow file and they are cracking it locally vs password guessing across the network. The SANS hacking class has an excellent password cracking and password guessing lab. -PaulK Paul Keser Assoc. Information Security Officer Stanford University 650.724.9051 GPG Fingerprint: DBA3 E20F CE91 28AA DA1C 4A77 3BD9 C82D 2699 24FB Harold Winshel wrote:
Are you saying a password cracking program is more likely to guess the letter "a" repeated 15 times or that an individual user trying to break in to a machine will more likely try that? Harold At 05:37 PM 11/19/2007, Alex wrote:Harold: I think there is confusion betweeen pure mathematical probability and probability based on historical attacks/human created passwords. An attacker is more likely to try repetitive or dictionary-based/hybrid attacks over a network (or against a hash) than random passwords. Additionally, people are more likely to use certain characters than others when creating passwords (e.g. wheel of fortune). Therefore, user created passwords are not random. So, given that we know attackers typically use 'easy' passwords, the character 'a' repeated 15 times is more likely to be cracked than a 15 character passphrase. Likely, so is a 15 character passphrase when compared to a truly randomly generated password of 15 characters from the same character set. Hence, we have password complexity rules as those in Microsoft Server 2003 and linux. -Alex -----Original Message----- From: Harold Winshel [mailto:winshel () CAMDEN RUTGERS EDU] Sent: Monday, November 19, 2007 5:16 PM To: SECURITY () LISTSERV EDUCAUSE EDU Subject: Re: [SECURITY] Passwords & Passphrases I may have missed some of the earlier emails but I thought that a 15 character passphrase is as secure as a 15 character random password. For that matter, I thought the user could use the letter "a" fifteen times and it could be as secure as a random 15-character password or a 15-character password such as '"I don't like the Red Sox" (I think that's more than 15, though). Harold At 04:44 PM 11/19/2007, Roger Safian wrote:At 02:01 PM 11/19/2007, Martin Manjak put fingers to keyboard andwrote:move beyond 8 characters with mixed case and special characters. I would like to see us require a 15 character pass phrase which, in my view, is more secure (even without complexity), and both easier to type and remember.Personally I'd love to see a password minimum length of 15 characters. My fear is that a password database get's compromised, and the weak passwords are cracked and bad things take place. I think that 15 characters is a long enough string to make brute force cracking time consuming enough to allow us to change the passwords in a reasonable time-frame. I think the reality is that 15 characters will be too much for the community. We'll see. -- Roger A. Safian r-safian () northwestern edu (email) public key available on many keyservers.(847) 491-4058 (voice) (847) 467-6500 (Fax) "You're never too old to have a greatchildhood!" Harold Winshel Computing and Instructional Technologies Faculty of Arts & Sciences Rutgers University, Camden Campus 311 N. 5th Street, Room B10 Armitage Hall Camden NJ 08102 (856) 225-6669 (O)Harold Winshel Computing and Instructional Technologies Faculty of Arts & Sciences Rutgers University, Camden Campus 311 N. 5th Street, Room B10 Armitage Hall Camden NJ 08102 (856) 225-6669 (O)
Current thread:
- Re: Passwords & Passphrases, (continued)
- Re: Passwords & Passphrases John Ladwig (Nov 20)
- Re: Passwords & Passphrases Ozzie Paez (Nov 20)
- Re: Passwords & Passphrases David Harley (Nov 20)
- Re: Passwords & Passphrases Zach Jansen (Nov 20)
- Re: Passwords & Passphrases Gary Flynn (Nov 20)
- Re: Passwords & Passphrases Matthew Gracie (Nov 20)
- Re: Fwd: Passwords & Passphrases Andrea Beesing (Nov 20)
- Re: Passwords & Passphrases Eric Case (Nov 21)
- Re: Passwords & Passphrases Andrea Beesing (Nov 25)
- Re: Passwords & Passphrases Kees Leune (Nov 26)
- Re: Passwords & Passphrases Paul Keser (Nov 26)