Re: length of IV in ESP_NULL cipher

[Stephen Kent <kent@bbn.com>]

At 15:38 -0800 1/8/04, Tarun Ahuja wrote:
>Hi all
>
>What should be the length of the IV in case of NULL cipher when using ESP
>protocol?
>
>As per RFC 2410
>"Because of the stateless nature of the NULL encryption algorithm, it is not
>necessary to transmit an IV or similar cryptographic
>synchronization data on a per packet (or even a per SA) basis".
>
>Which essentially means the length of the IV should be 0 but FreeSWAN uses a
>length of 4bytes IV (equal to blocksize) for NULL cipher.
>
>-Tarun

If FreeSWAN used an IV length of 4, someone needs to have a talk with 
them. Of course the length should be 0. Anything else is just wasted 
overhead.

Steve