IPv6 introduces the
SeND to help mitigate identity theft, however, is the non-PKI public/private key pair used during the process persistent to some degree, or generated on every connection with the router?
RFC3972 hints at a possible persistent key combination:
One optimization is particularly important. If the subnet prefix of
the address changes but the address owner's public key does not, the
old modifier value MAY be reused. If it is reused, the algorithm
SHOULD be started from step 4. This optimization avoids repeating
the expensive search for an acceptable modifier value but may, in
some situations, make it easier for an observer to link two addresses to each other.
This isn't very concrete however, stating only a case where it might happen.