note 52373 added to function.mcrypt-enc-get-key-size

The key size returned by this function is for keys consisting of 8-bit characters. For example, 256-bit algorithms require 32-character keys. However, if you are using alphanumeric keys [A-Za-z0-9] beware that strength is reduced, because you are only using a set of 64 characters, which could be represented in 6 bits. You get: 6 x 32 = 192-bit encryption. Avoid using string representations hashes - md5() or sha1() - because hex encoding uses a set of only 16 characters [0-9a-f], which is equivalent to 4 bits, and thus halve the strength of your encryption: 4 x 32 = 128-bit. A 64 character hex representation of an SHA-256 hash will not improve matters, because only the first 32 characters can be used. You need an 8-bit representation of SHA-256, or of two MD5s, to get full 256-bit strength. The problem is somewhat reduced in OFB, CFB or CBC mode by the use of IVs, but only if you do not package your IV with the encrypted data. ---- Manual Page -- http://www.php.net/manual/en/function.mcrypt-enc-get-key-size.php Edit -- http://master.php.net/manage/user-notes.php?action=edit+52373 Delete: added to the manual -- http://master.php.net/manage/user-notes.php?action=delete+52373&report=yes&reason=added+to+the+manual Delete: bad code -- http://master.php.net/manage/user-notes.php?action=delete+52373&report=yes&reason=bad+code Delete: spam -- http://master.php.net/manage/user-notes.php?action=delete+52373&report=yes&reason=spam Delete: useless -- http://master.php.net/manage/user-notes.php?action=delete+52373&report=yes&reason=useless Delete: other reasons -- http://master.php.net/manage/user-notes.php?action=delete+52373&report=yes Reject -- http://master.php.net/manage/user-notes.php?action=reject+52373&report=yes Search -- http://master.php.net/manage/user-notes.php