Concurrently Deniable Group Key Agreement and Its Application to Privacy-Preserving VANETs

Algorithm 2

Our deniable group key agreement protocol.

Let denote the private/public key pair for the participant and is the number of the participants of this

session.

Round 1: Participant performs the following steps:

(1) Choose and compute , .

(2) Broadcast message .

Round 2: Upon the receipt of all messages , parses , and . Next, executes the

following operations:

(1) Compute , , , .

(2) Generate a two-member ring signature on the message : .

(3) Broadcast message .

Session Key Generation: Upon the receipt of all messages , each carries out the following steps:

(1) Compute orderly , . Check . If it is true,

continue; Otherwise, abort.

(2) Check hold or not for and . If it fails to any participant, abort; Otherwise,

continue.

(3) Generate the session key .