Re: header and data digest issue

[Jonathan Stone <jonathan@dsg.stanford.edu>]

[...]


>The whole point of separate CRCs on header and data was to allow
>an iSCSI middlebox to modify the header without having to touch
>the data CRC.  As I said, a CRC will not prevent this middlebox problem
>- for example, if iSCSI had a CRC that covered both headers and data,
>one would almost certainly see middleboxes that stripped that CRC
>on input and regenerated it on output, producing a vulnerability to
>the problem of concern.  Something like IPsec ESP cryptographic
>integrity that a middlebox cannot regenerate is necessary to solve
>this problem.  This is a long version of a fairly simple principle
>- those who don't trust middleboxes shouldn't allow their use.

[...]

>For the middlebox problem, ESP cryptographic integrity is the right
>solution,

Technically, ESP isn't necessary.  AH between the iSCSI endpoints is
adequate if the only requirement is to detect and defeat middle boxes.