note 97055 deleted from function.str-shuffle by danbrown
| From: | danbrown@php.net | Date: | Tue, 30 Mar 2010 14:28:53 +0000 |
| Subject: | note 97055 deleted from function.str-shuffle by danbrown | ||
| References: | 1 | Groups: | php.notes |
| Request: | Send a blank email to php-notes+get-167530@lists.php.net to get a copy of this message | ||
Note Submitter: Anonymous
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a note to all the passwordgenerators below:
if you use str_shuffle it's impossible to have any letter twice thus reducing the possible
keyspace:
maximum keyspace (with replacements):
n^k
keyspace without replacements:
n! / (n-k)!
if you only use letters (a-zA-Z: 52 characters) as password, a truly random password of length 12
has a keyspace of
52^12 = 3.9*10^20 = 2^68.4 (68.4Bit)
a shuffle-password with letters (a-zA-Z) of length 12:
52! / (52-12)! = 9.9*10^19 = 2^66.2 (66.2Bit)
so basically reducing the keyspace by 2 Bit which means a brute-force attack would take only take
one fourth of the time compared to a truly random password.