Efficient Short Group Signatures for Conditional Privacy in Vehicular Ad Hoc Networks via ID Caching and Timed Revocation

Abstract

Vehicular Ad hoc Networks (VANETs) are a subset of the Internet of Things (IoT) that are used in smart traffic applications. Due to their high speed, mobility, and exposure to the environment, the security requirements for VANETs result in the conflicting design goals of protecting member privacy while also ensuring non-repudiation. Group signature schemes can fulfill these requirements, but often at the cost of expensive bilinear pairing operations. Furthermore, the cost of updating the group key information can be costly. Accordingly, this paper has two goals. First, it presents a group signature scheme that has been modified to remove pairing operations by caching computed values, while still preserving the critical requirement of conditional privacy. Second, this paper presents an argument for the abandonment of perfect forward and backward secrecy in VANET schemes in order to prevent the generation of keys that are never used, or used only once, and reduce the twin burdens of excessive key recalculation and key redistribution on the system.

Pairing-Free Signatures With Insider-Attack Resistance for Vehicular Ad-Hoc Networks (VANETs)

“…He15 [32] 124 Azees17 [24] 848 Vijayakumar17 [26] 1044 ZhangC19 [29] 532 Lim19 [30] 508 ZhangJ20 [33] 124 ZhangJ21 [34] 84 Funderburg21 [5] 504 Proposed 144 cost as each other for both signature generation and verification.…”

“…This mobility leads to dynamic group membership that changes at a much greater rate than most MANETs or other IoT applications. At highway speeds, in densely populated areas, group membership can change every 140ms or more [5]. In addition, group membership and wireless connections are open to the public, so members should be untrusted.…”

“…Schemes using elliptic curve pairings include those proposed by Azees et al [24], Vijayakumar et al [25][26][27], Ahamed et al [28], Zhang C. et al [29], Lim et al [30], and Funderburg & Lee [5]. The Azees et al scheme uses pairings for confirming message integrity and anonymous, short-term identity certificates for authenticating the sender.…”

“…In comparison to the scheme proposed in [5], the new scheme uses pseudonyms rather than Short Group Signatures as a base and therefore does not require pairings. Furthermore, the TA does not know the vehicles' private keys in the proposed scheme.…”

“…Furthermore, the TA does not know the vehicles' private keys in the proposed scheme. In the scheme from [5], the TA has full knowledge of all vehicles' private keys and the system is therefore vulnerable to attacks targeting the TA that result in the theft of key material.…”