Notation

We use the following notation to describe protocols in this paper.

$A,\; B$ are the principals

$N$_A is a nonce generated by $A$

$K$_A denotes $A$'s public key

$K$_A^-1 denotes $A$'s private key

$K$_AB denotes the secret (symmetric) key which is shared between $A$ and $B$

$\{M\}$K_B is the encryption of message $M$ with $B$'s public key