note 70947 added to function.mcrypt-create-iv

>First, the IV should be random and variable. The whole >point of it is to ensure that the >same plaintext does not >encrypt to the same ciphertext every time. You most >certainly do >lose security if the IV is constant or public. Wrong, Wrong WRONG! The initialization vector is ALLOWED to be PUBLIC! It is generally sent along with the ciphertext, UNENCRYPTED. >The ciphertext should be E(IV | plaintext, key) Wrong again! The initialization vector is NOT prepended to the plaintext before encryption. The IV is used to seed the feedback system! (which is why you don't need one in ECB mode - there is no feedback) >Second, the IV should not be part of the decryption >parameters at all. You should be able to >decrypt the cipher >text, throw away the initial vector at the front w/o even >reading it, and >have your plaintext: Nope. You need to seed the feedback mechanism during decryption to the SAME state as it was seeded during encryption. This means using the SAME IV! ---- Server IP: 66.207.199.35 Probable Submitter: 64.180.161.38 ---- Manual Page -- http://www.php.net/manual/en/function.mcrypt-create-iv.php Edit -- https://master.php.net/note/edit/70947 Del: integrated -- https://master.php.net/note/delete/70947/integrated Del: useless -- https://master.php.net/note/delete/70947/useless Del: bad code -- https://master.php.net/note/delete/70947/bad+code Del: spam -- https://master.php.net/note/delete/70947/spam Del: non-english -- https://master.php.net/note/delete/70947/non-english Del: in docs -- https://master.php.net/note/delete/70947/in+docs Del: other reasons-- https://master.php.net/note/delete/70947 Reject -- https://master.php.net/note/reject/70947 Search -- https://master.php.net/manage/user-notes.php