use Crypt::Rijndael;

 # keysize() is 32, but 24 and 16 are also possible
 # blocksize() is 16

 $cipher = Crypt::Rijndael->new( "a" x 32, Crypt::Rijndael::MODE_CBC() ); # <-- key and CBC-MODE

 $cipher->set_iv($iv);  # <-- here's your I-Vector
 $crypted = $cipher->encrypt($plaintext);
        # - OR -
 $plaintext = $cipher->decrypt($crypted);