Encrypt then decrypt yields extra dots at end

I thought this code: $enc=mcrypt_ecb(MCRYPT_RIJNDAEL_256,"salt123","encrypt_me",MCRYPT_ENCRYPT); $dec=mcrypt_ecb(MCRYPT_RIJNDAEL_256,"salt123",$enc,MCRYPT_DECRYPT); echo $dec; would yield "encrypt_me". The actual result is "encrypt_me......................" (bunch of extra dots). Why, and how do I fix it? Does it have something to do w/ the warning I get: Warning: mcrypt_ecb() [function.mcrypt-ecb]: Attempt to use an empty IV, which is NOT recommend I assumed that was a security warning, not a functionality warnings? -- We're just a Bunch Of Regular Guys, a collective group that's trying to understand and assimilate technology. We feel that resistance to new ideas and technology is unwise and ultimately futile.