Common use of Historical analysis Clause in Contracts

Historical analysis. In current (2G-4G) networks the main actors are the (mobile) network operators, subscribers (i.e. users) with some User Equipment (UE) and interconnection providers (see Figure 7). At this level a formal domain model can be found in 3GPP TS 23.101 [3GPP 2015] which is reproduced below. Home Network Domain Cu Uu Iu [Zu] [Yu] Serving Network Domain Transit Network Domain USIM Domain Mobile Equipment Domain Access Network Domain Core Network Domain User Equipment Domain Infrastructure Domain The domains of TS 23.101 are therein defined as “highest level of physical grouping" and the partitioning of the network into domains is thus, as such, not trust driven. However, one can already note here that the fact that home, serving and transit domains are separated even though they technically contain similar functionality (and may reside in more or less the same geographical area), implies that the domain boundaries are not purely physical but also related to business boundaries. This is a consequence of physical and business boundaries determining who has control over assets which is a major factor in trust issues. Moreover, the presence of some of the domains is directly related to trust. First of all, the separation of the User Equipment domain into the USIM and Mobile Equipment domains is definitely driven by the assignment of critical functionality to the USIM (or more precisely the UICC). Since the USIM resides in a physical location where it can be subject to e.g. tampering it has become necessary to separate it from the rest of the Mobile Equipment (ME), simply because it would have been too costly to make the whole UE tamper resistant. Secondly, we can consider the access network domain. Originally, the separation of the access domain from the core network domain was motivated by the fact that it involves special type of equipment (radio base stations, etc) which have specific technical functionality that cannot be found anywhere else. In addition, the access domain is by necessity geographically distributed since it is the only way to provide coverage and mobility. However, at the time when 2G was defined, these properties did not seem to warrant any special treatment of the access domain from trust point of view. At the time, the threat of tampering with base stations or gaining access to the backhaul transport network was simply not considered realistic. In 2G networks, communication between the UE (in the user equipment domain) and the base station (in the access domain) was encrypted, and the base station decrypted the data before sending the data on into the core network. In 3G networks, this changed so that the base station just forwarded the encrypted data to the Radio Network Controller (RNC) residing in the core network and therefore the trustworthiness requirements on the access domain were reduced. An additional security feature added in 3G though was that the integrity of signalling data was added and through authentication being made mutual (rather than just the network authenticating the UE). Then, in 4G, it was necessary to move the termination point (user data decryption point) back to the access domain in order to allow the base station to perform header compression and other functions which required access to plaintext data. This was actually one of the key drivers for many of the additional security features that were added such as sophisticated key derivation algorithms, requirements on a “secure environment” inside the base stations and standardization of IP security on the backhaul transport.