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

[Shwetha <[e-mail]>]

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