More information can be found at http: / /www.ciphersbyritter.com / GLOSSARY.HTM#IV, http: / /fn2.freenet.edmonton.ab.ca / ~jsavard / crypto / co0409.htm and in chapter 9.3 of Applied Cryptography by Schneier (ISBN 0-471-11709-9) for a discussion of this topic.
?php $cipher = MCRYPT_TripleDES; $block_size = mcrypt_get_block_size($cipher); $iv = mcrypt_create_iv($block_size, MCRYPT_DEV_RANDOM);?