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Date: Mon Mar 27 06:57:58 2006 From: Valdis.Kletnieks at vt.edu (Valdis.Kletnieks@...edu) Subject: guidelines for good password policy and maintenance / user centric identity with single passwords (or a small number at most over time) On Sun, 26 Mar 2006 20:12:04 +0200, Anders B Jansson said: > 128 bit entropy in a password requires a long randomized passphrase. Do you really need a full 128 bits of entropy? Certainly 64 bits or so isn't sufficient - but re-evaluate what you *really* need from the password - 80, 96, or 112 bits may suffice... > Avoiding accented chars (which is good unless you want to be locked out) > You'll end up with just under 6 1/2 bits per char. And that's assuming you pick a totally random series from the 96 or so printable characters. On the other hand, common english text manages a whole whopping 2 1/2 bits per character. > And a password/passphrase meeting all requirements above and being at least > 20 chars long isn't very usable. On the other hand, "My unckle Fred's purple iguane has a wart on its eyelid." is 57 characters long and gets you at least fairly close to 128 bits of entropy. More if you randomly insert a special character or three. (As an aside, note that wr17ing 1t in '1337 sty1e doesn't add much entropy - only about 1 bit of entropy (since all you need to do is record "was it an o or a 0", or "1 or l" or '3 or e' and so on. Random injection of special characters, such as 'igu#ana' adds more entropy.... -------------- next part -------------- A non-text attachment was scrubbed... Name: not available Type: application/pgp-signature Size: 228 bytes Desc: not available Url : http://lists.grok.org.uk/pipermail/full-disclosure/attachments/20060327/6144b24c/attachment.bin
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