3GPP Release 15, the first 5G standard, includes protection of user identity privacy against IMSI catchers. These protection mechanisms are based on public key encryption. Despite this protection, IMSI catching is still possible in LTE networks which opens the possibility of a downgrade attack on user identity privacy, where a fake LTE base station obtains the identity of a 5G user equipment. We propose (i) to use an existing pseudonym-based solution to protect user identity privacy of 5G user equipment against IMSI catchers in LTE and (ii) to include a mechanism for updating LTE pseudonyms in the public key encryption based 5G identity privacy procedure. The latter helps to recover from a loss of synchronization of LTE pseudonyms. Using this mechanism, pseudonyms in the user equipment and home network are automatically synchronized when the user equipment connects to 5G. Our mechanisms utilize existing LTE and 3GPP Release 15 messages and require modifications only in the user equipment and home network in order to provide identity privacy. Additionally, lawful interception requires minor patching in the serving network.
In , @cite_7 , one-time pseudonyms are created by probabilistic encryption of the user's identity using a key that is known only by the HN. The HN sends a set of pseudonyms to the UE when the UE and the HN have a secure communication channel.
@cite_7
2103647628 2027274379 91828656 1427965619
A technique based on public key cryptography is presented that allows an electronic mail system to hide who a participant communicates with as well as the content of the communication - in spite of an unsecured underlying telecommunication system. The technique does not require a universally trusted authority. One correspondent can remain anonymous to a second, while allowing the second to respond via an untraceable return address. The technique can also be used to form rosters of untraceable digital pseudonyms from selected applications. Applicants retain the exclusive ability to form digital signatures corresponding to their pseudonyms. Elections in which any interested party can verify that the ballots have been properly counted are possible if anonymously mailed ballots are signed with pseudonyms from a roster of registered voters. Another use allows an individual to correspond with a record-keeping organization under a unique pseudonym, which appears in a roster of acceptable clients. The issuing of pseudonyms is an established approach for protecting the privacy of users while limiting access and preventing sybil attacks. To prevent pseudonym deanonymization through continuous observation and correlation, frequent and unlinkable pseudonym changes must be enabled. Existing approaches for realizing sybil-resistant pseudonymization and pseudonym change (PPC) are either inherently dependent on trusted third parties (TTPs) or involve significant computation overhead at end-user devices. In this paper, we investigate a novel, TTP-independent approach towards sybil-resistant PPC. Our proposal is based on the use of cryptocurrency block chains as general-purpose, append-only bulletin boards. We present a general approach as well as BitNym, a specific design based on the unmodified Bitcoin network. We discuss and propose TTP-independent mechanisms for realizing sybil-free initial access control, pseudonym validation and pseudonym mixing. Evaluation results demonstrate the practical feasibility of our approach and show that anonymity sets encompassing nearly the complete user population are easily achievable. Many security mechanisms are based on specific assumptions of identity and are vulnerable to attacks when these assumptions are violated. For example, impersonation is the well-known consequence when authenticating credentials are stolen by a third party. Another attack on identity occurs when credentials for one identity are purposely shared by multiple individuals, for example to avoid paying twice for a service. Such shared accounts are common in practice: friends exchange iTunes passwords to share purchased music; BugMeNot.com is a community that shares website registration passwords; and network address translation [29] devices allow multiple users to pay for a single IP address which is then shared among them. In this paper, we survey the impact of the Sybil attack [26], an attack against identity in which an individual entity masquerades as multiple simultaneous identities. The Sybil attack is a fundamental problem in many systems, and it has so far resisted a universally applicable solution. Many distributed applications and everyday services assume each participating entity controls exactly one identity. When this assumption is unverifiable or unmet, the sevice is subject to attack and the results of the application are questionable if not incorrect. A concrete example of this would be an online voting system where one person can vote using many online identities. Notably, this problem is currently only solved if a central authority, such as the administrator of a certificate authority, can guarantee that each person has a single identity represented by one key; in practice, this is very difficult to ensure on a large scale and would require costly manual attention. Anonymous authoring includes writing reviews, comments and blogs, using pseudonyms with the general assumption that using these pseudonyms will protect the real identity of authors and allows them to freely express their views. It has been shown, however, that writing style may be used to trace authors across multiple Websites. This is a serious threat to privacy and may even result in revealing the authors's identities. In obfuscating authors' writing style, an authored document is modified to hide the writing characteristics of the author. In this paper we first show that existing obfuscation systems are insecure and propose a general approach for constructing obfuscation algorithms, and then instantiate the framework to give an algorithm that semi-automatically modifies an author's document. We provide a secure obfuscation scheme that is able to hide an author's document securely among other authors' documents in a corpus. As part of our obfuscation algorithm we present a new algorithm for identifying an author's unique words that would be of independent interest. We present a security model and use it to analyze our scheme and also the previous schemes. We implement our scheme and give its performances through experiments. We show that our algorithm can be used to obfuscate documents securely and effectively.