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Re: padding in ESP

At 12:28 PM +0530 11/15/02, Lokesh wrote:
>Hi all
>One questions each on ESP and AH protocols:
>
>1] why do we need to adjust ESP packet size by padding to be aligned 
>to 4 byte boundary in case of
>null encryption? can we bypass padding for null encryption?
>
>2] AH RFC says ICV can be of variable size, and is normally taken as 
>12 bytes, in case if someone
>wants > 12 bytes of ICV how he/she can intimate other party of new 
>size of the ICV?
>
>Thanks
>Lokesh

The ICV follows the end of the data that is nominally encrypted 
(i.e., the NEXT field in ESP). We want the ICV aligned on a 4-byte 
boundary for ease of access, hence the requirement for the padding to 
be used even in the case of NULL encryption.

Steve