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.
The most relevant related work for our scenario has been published by @cite_1 . The authors observe that all currently active customers of an ISP form an anonymity group, in which individual users can hide if addresses assigned to the customers are changed frequently. ISPs are supposed to assign two addresses to each customer: a that is replaced with a randomly assigned address for every outbound flow from the customer's network as well as a that remains constant over time to provide for reachability. The ISP runs a network address translation gateway that rewrites source and destination addresses on the fly. Although the technique is only described in the context of existing IPv4 networks it could be adapted to IPv6 prefixes. While present a single alternative, which resembles our Scheme 2, we focus on surveying and discussing various schemes that are conceivable in IPv6 networks in this paper.
@cite_1
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Today's Internet architecture makes no deliberate attempt to provide identity privacy--IP addresses are, for example, often static and the consistent use of a single IP address can leak private information to a remote party. Existing approaches for rectifying this situation and improving identity privacy fall into one of two broad classes: (1) building a privacy-enhancing overlay layer (like Tor) that can run on top of the existing Internet or (2) research into principled but often fundamentally different new architectures. We suggest a middle-ground: enlisting ISPs to assist in improving the identity privacy of users in a manner compatible with the existing Internet architecture, ISP best practices, and potential legal requirements.