This paper is focused on privacy issues related to the prefix part of IPv6 addresses. Long-lived prefixes may introduce additional tracking opportunities for communication partners and third parties. We outline a number of prefix alteration schemes that may be deployed to maintain the unlinkability of users' activities. While none of the schemes will solve all privacy problems on the Internet on their own, we argue that the development of practical prefix alteration techniques constitutes a worthwile avenue to pursue: They would allow Internet Service Providers to increase the attainable privacy level well above the status quo in today's IPv4 networks.
Privacy is one of the most desirable properties in modern communication systems like the Internet. There are many techniques proposed to protect message contents, but it is difficult to protect message addresses because they should be clear to message router. In this paper we propose a mechanism of one-time receiver address in IPv6 for providing unlinkability against eavesdroppers. In our system, a pair of sender and receiver independently generate an identical sequence of addresses by using a secret key exchanged in advance. The sender changes the destination address every time when it initiates a transaction, and only the corresponding receiver can follow the change of the address. We have implemented the proposed mechanism on Linux systems. The prototype system hides relation between transactions with small overhead.