note 52555 added to function.uniqid

From: Date: Thu, 05 May 2005 15:18:08 +0000
Subject: note 52555 added to function.uniqid
Groups: php.notes 
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"It seems intuitively likely that at least 2 people somewhere in the world over the past 12 years have already got back exactly the same hash because of what they fed in to be digested." Really? 12 years = 86400 * 365 *12 seconds = 3,7 * 10^8 seconds 2^128 = 3,4 * 10^38, thus approximately 10^38 samples are needed to find a collison (1.7* 10^38, more exactly) Consequently, this means: --> MD5 calculations per second during last 12 years = 10^30 (worldwide) Approx. number of PCs worldwide: 820 million (2004), this is <= 10^9 --> MD5 calculations per PC per second >= 10^21 An optimized MD5 implementation takes around 400-450 clock cycles on Pentium-class hardware. --> During the past 12 years, the average PC had a clock frequency of 10^23 Hertz. That is about a quadrillion times faster than the PC which I bought last week :) ---- Manual Page -- http://www.php.net/manual/en/function.uniqid.php Edit -- http://master.php.net/manage/user-notes.php?action=edit+52555 Delete: added to the manual -- http://master.php.net/manage/user-notes.php?action=delete+52555&report=yes&reason=added+to+the+manual Delete: bad code -- http://master.php.net/manage/user-notes.php?action=delete+52555&report=yes&reason=bad+code Delete: spam -- http://master.php.net/manage/user-notes.php?action=delete+52555&report=yes&reason=spam Delete: useless -- http://master.php.net/manage/user-notes.php?action=delete+52555&report=yes&reason=useless Delete: other reasons -- http://master.php.net/manage/user-notes.php?action=delete+52555&report=yes Reject -- http://master.php.net/manage/user-notes.php?action=reject+52555&report=yes Search -- http://master.php.net/manage/user-notes.php

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