Re: [ippm] Discussion on draft-brockners-ippm-ioam-data-integrity method 3 variant in @ietf110

[Shwetha <[e-mail]>]

My bad, it should be possible to reverse the process for validation and
retrieve the previous signature in the reverse order. We will update the
draft to have Method 3 with both symmetric/asymmetric variants.

Thanks,
Shwetha

On Tue, Mar 9, 2021 at 7:07 AM Shwetha <[e-mail]> wrote:

> During the session 1 of ippm at IETF 110, it was suggested to consider
> introducing a variant of method 3 in  draft-brockners-ippm-ioam-data-integrity with
> asymmetric keys.
>
>
> When we were designing the methods to protect integrity of the entire IOAM
> data collected at each node, the node chains it's own node data with the
> signature from the previous node and overwrites the signature:
> Trace signature = sign([Trace Signature || its node_data_list[x] hash])
>
> In the symmetric key case this operation can be validated by reversing the
> operation by the validator who has the shared secret from each node.
> However this will not work if nodes use their private keys to sign and
> validator has the public key to validate as it can only validate but not
> derive a specific node's signature to reverse the operation.
>
> So I think the space optimized  method to overwrite the signature at each
> node cannot be modified to use asymmetric keys easily. Will be happy to
> discuss ideas to create a space optimized asymmetric key based solution.
>
> Thanks
> Shwetha
>
>