# CCITT X.509 (1)
#
# Modelled after the description in the SPORE library
# http://www.lsv.ens-cachan.fr/spore/ccittx509_1.html
#
# Note:
# The attack in SPORE is not found as this is not an attack against
# synchronisation, but an attack against the freshness of Xa and Ya
# which can currently not be modelled in scyther
#

const pk: Function;
secret sk: Function;
inversekeys(pk,sk);
usertype Timestamp;

protocol ccitt509-1(I,R)
{
    role I
    {
        const Ta: Timestamp;
        const Na,Xa,Ya: Nonce;
        send_1(I,R, I,{Ta, Na, R, Xa,{Ya}pk(R)}sk(I));
        # claim_2(I,Nisynch);
        # This claim is useless as there are no preceding read events
    }    
    
    role R
    {
        var Ta: Timestamp;
        var Na,Xa,Ya: Nonce;

        read_1(I,R, I,{Ta, Na, R, Xa,{Ya}pk(R)}sk(I));
        claim_3(R,Nisynch);
        # There should also be Fresh Xa and Fresh Ya claims here
    }
}

const Alice,Bob,Eve: Agent;

untrusted Eve;
const ne: Nonce;
const te: Timestamp;
compromised sk(Eve);

# General scenario, 2 parallel runs of the protocol

run ccitt509-1.I(Agent,Agent);
run ccitt509-1.R(Agent,Agent);
run ccitt509-1.I(Agent,Agent);
run ccitt509-1.R(Agent,Agent);