rfc:timing_attack

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rfc:timing_attack [2013/12/22 17:02] – created realitykingrfc:timing_attack [2013/12/23 16:45] – realityking
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 ====== Request for Comments: Timing attack safe string comparison function ====== ====== Request for Comments: Timing attack safe string comparison function ======
-  * Version: 0.1+  * Version: 0.2
   * Date: 2013-12-22   * Date: 2013-12-22
   * Author: Rouven Weßling, me@rouvenwessling   * Author: Rouven Weßling, me@rouvenwessling
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 ===== Proposal ===== ===== Proposal =====
  
-Implement a new function called str_equals.+Implement a new function called hash_compare.
  
-Signature bool str_equals(string knownString, string userString)+Signature bool hash_compare(string knownString, string userString)
  
-The time this function takes is based only on two variables: +The time this function takes is based only on the length of the user supplied string.
-* length of userString +
-* whether the length of knownString is zero +
- +
-The latter is a slight information leak but so uncommon it shouldn't be of much concern. However this needs to be documented.+
  
 Users have to be mindful, as it is important that the user supplied string (or a hash of that string) is used as the the second parameter not the first. Users have to be mindful, as it is important that the user supplied string (or a hash of that string) is used as the the second parameter not the first.
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 ===== Open Issues ===== ===== Open Issues =====
  
-* Decide on a name for the function.+  * Decide on a name for the function.
  
 ===== Patches and Tests ===== ===== Patches and Tests =====
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   * [[https://github.com/symfony/security-core/blob/master/Util/StringUtils.php#L36|Symfony2 constant-time string comparison]]   * [[https://github.com/symfony/security-core/blob/master/Util/StringUtils.php#L36|Symfony2 constant-time string comparison]]
   * [[https://github.com/joomla/joomla-cms/blob/master/libraries/joomla/crypt/crypt.php#L262|Joomla constant-time string comparison]]   * [[https://github.com/joomla/joomla-cms/blob/master/libraries/joomla/crypt/crypt.php#L262|Joomla constant-time string comparison]]
 +  * [[https://github.com/zendframework/zf2/blob/master/library/Zend/Crypt/Utils.php#L17|Zend Framework 2 constant-time string comparison]]
 +
 +===== Changelog =====
 +  * 0.1 Initial publication
 +  * 0.2 Renamed to hash_compare, added link to Zend Framework 2, removed information leak when knownString is empty (Thank you Tjerk)
rfc/timing_attack.txt · Last modified: 2017/09/22 13:28 by 127.0.0.1

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