note 56941 added to function.sha1

It should be noted that sha1("") does not return an empty string. This means that if you are running a system that does not require users to have a password, the following code will not work as expected: <?php if ($StoredPassword == sha1($NewPassword)) // Password good ?> If $StoredPassword and $NewPassword are both blank, then the password should be treated as good, but because sha1("") != "" it will be treated as bad. To get the correct behaviour you need to use: <?php if (($StoredPassword == "" && $NewPassword == "") || ($StoredPassword == sha1($NewPassword))) // Password good ?> (Note: I use a custom IsBlank() function instead of comparison against the empty string, so NULL values are also matched.) For reference, here are a couple of special values put through sha1(). Note that sha1("") == sha1(NULL) == sha1(false), and also that sha1(0) != sha1(false) "" -> da39a3ee5e6b4b0d3255bfef95601890afd80709 NULL -> da39a3ee5e6b4b0d3255bfef95601890afd80709 0 -> b6589fc6ab0dc82cf12099d1c2d40ab994e8410c 1 -> 356a192b7913b04c54574d18c28d46e6395428ab false -> da39a3ee5e6b4b0d3255bfef95601890afd80709 true -> 356a192b7913b04c54574d18c28d46e6395428ab ---- Manual Page -- http://www.php.net/manual/en/function.sha1.php Edit -- http://master.php.net/manage/user-notes.php?action=edit+56941 Delete: added to the manual -- http://master.php.net/manage/user-notes.php?action=delete+56941&report=yes&reason=added+to+the+manual Delete: bad code -- http://master.php.net/manage/user-notes.php?action=delete+56941&report=yes&reason=bad+code Delete: spam -- http://master.php.net/manage/user-notes.php?action=delete+56941&report=yes&reason=spam Delete: useless -- http://master.php.net/manage/user-notes.php?action=delete+56941&report=yes&reason=useless Delete: non-english -- http://master.php.net/manage/user-notes.php?action=delete+56941&report=yes&reason=non-english Delete: already in docs -- http://master.php.net/manage/user-notes.php?action=delete+56941&report=yes&reason=already+in+docs Delete: other reasons -- http://master.php.net/manage/user-notes.php?action=delete+56941&report=yes Reject -- http://master.php.net/manage/user-notes.php?action=reject+56941&report=yes Search -- http://master.php.net/manage/user-notes.php