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Table 1 Notations in this study

From: Secure protocols for data propagation and group communication in vehicular networks

Notations Descriptions
E(Msgs, K) The messages (Msgs) are encrypted by the key, K
R i or RSU i The identity of a fixed station on the roadside
TPmap A travel route, tp, in the Google MAP
PK/SK An asymmetric key pair, issued by the trusted third party
K i, j A secret key between v i and v j
k/k P A key pair, private/public keys in the Elliptic Curve Cryptography
VGK A virtual group key among the vehicles in a V2I virtual group
GGK A global group key among the vehicles in a V2V global group
GKset, GKsetP A ECDH-based key pair, generated by the trusted third party at a time, Tstamp, for a set of RSUs, {R j }, on the route (tp) to service the vehicles, {v i }, when they travel during the required trip period, ΔT. (i.e. set = hash(tp||ΔT||{R j }||{vi}||Tstamp))
Cert vi The certificate with a valid public key of v i , issued by the trusted third party
GPS vi The GPS position (x, y) of v i
v i or V i The identity of vehicle i
Event k An event type of traffic-related information
TH A head vehicle in a one-hop physical group, moving with a steady velocity (or approximately steady velocity)
NList x The latest identities of neighboring vehicles of Vehicle x
gk x A group key, shared between all members and their head, x, in a physical group
Sign(Msg, SK) The digital signature of Msg, signed by the private key, SK
MAC(Msg, K) The MAC code of Msg, encrypted with the secret key, K
v limit The maximum speed limit on the roadway
R T The standard transmission range of a vehicle
Δdpj s→R The projection distance from Sender(S) to Receiver (R) over the vector from the preceding sender of Sender
Δt p The delay time for the propagation of traffic-related information, defined in Equation (1)
Δt A The delay time for the role announcement of a TH, defined in Equation (2)
ΔT The trip period required by groups of friends, when they travel together
Warn# A warn message for the propagation of the traffic-related information
Req# A request message for that a vehicle applies for a virtual group
Resp# The response message corresponding to the Req#
Req@ A request message for that one TH tells its members to start the group key agreement process
Notify# A notification message from a RSU to the vehicles contains the information, "the RSU set is ready for your trip"
"||" The meaning of "join"