Paper 2022/1081

Pairing-free secure-channel establishment in mobile networks with fine-grained lawful interception

Xavier Bultel, INSA Centre-Val de Loire
Cristina Onete, Université de Limoges

Modern-day mobile communications allow users to connect from any place, at any time. However, this ubiquitous access comes at the expense of their privacy. Currently, the operators providing mobile service to users learn call-and SMS-metadata, and even the contents of those exchanges. A main reason behind this is the Lawful-Interception (LI) requirement, by which serving networks must provide this (meta-)data to authorities, given a warrant. At ESORICS 2021, Arfaoui et al. pioneered a primitive called Lawful-Interception Key-Exchange, which achieves the best of both worlds: (provably) privacy-enhanced communications, and finegrained fine-grained, limited access to user data. Their work had two important shortcomings. First, their protocol required pairings which, while sufficiently efficient, might not always be available in the mobile setting. More importantly, that scheme was only applicable in a domestic setting, where the concerned users (Alice and Bob) were subject to the same LI authorities. The case of roaming was left as an open question. In this paper we answer that open question. We extend the framework of Arfaoui et al. to allow Alice and Bob (now subject to potentially two sets of authorities) to establish a secure channel that guarantees the strong properties afforded by the LIKE schemes of ESORICS 2021. Our construction is pairing-free, faster than that of Arfaoui et al., and its security relies on standard assumptions.

Available format(s)
Cryptographic protocols
Publication info
Published elsewhere. The 21st edition of the Computer Security track at the 37th ACM Symposium on Applied Computing (SEC@SAC22)
Lawful interception roaming mobile networks 5G
Contact author(s)
xavier bultel @ insa-cvl fr
cristina onete @ gmail com
2022-08-21: approved
2022-08-19: received
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Creative Commons Attribution


      author = {Xavier Bultel and Cristina Onete},
      title = {Pairing-free secure-channel establishment in mobile networks with fine-grained lawful interception},
      howpublished = {Cryptology ePrint Archive, Paper 2022/1081},
      year = {2022},
      doi = {10.1145/3477314.3507202},
      note = {\url{}},
      url = {}
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