note 17410 added to function.md5
| From: | nadavs at hotpop dot com | Date: | Fri, 07 Dec 2001 11:49:04 +0000 |
| Subject: | note 17410 added to function.md5 | ||
| Groups: | php.notes | ||
| Request: | Send a blank email to php-notes+get-21855@lists.php.net to get a copy of this message | ||
Login delays have nothing to do with it.
We're talking about calculating the password from the password-hash
say, from /etc/shadow.
If a hacker gets into your system to read the hashes, he'll crack
the passwords sooner or later. Against a hash-based-attack, your
password must have alot more than 16 bit entropy (as commonly-strong passwords have) - it must have
more than 64 bits of entropy!
Read the RFC about cryptographically-strong random numbers for info
about how much entropy is in password, but the rule of thumb is:
a letter in english (out of text with spaces and all) contains 1 bit
of entropy. So, you'd need a sentence 64 letters long to be hard to
crack.
A typable letter (say, a random upper or lower case or digit)
is about 6 bits of entropy, but damn hard to memorize.
--
http://www.php.net/manual/en/function.md5.php
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