scyther/spdl/SPORE/needham-schroeder-sk.spdl
2005-05-23 12:35:58 +00:00

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# Needham Schroeder Symmetric Key
#
# Modelled after the description in the SPORE library
# http://www.lsv.ens-cachan.fr/spore/nssk.html
#
#
# Note:
# This protocol uses a ticket so scyther will only be able to verify
# the protocol using the ARACHNE engine (-a) and type 2 matching (-m2)
#
secret k: Function;
# Model dec that is invertible by inc
const dec,inc: Function;
inversekeys(dec,inc);
usertype SessionKey;
usertype Ticket;
protocol needhamschroedersk(I,R,S)
{
role I
{
const Ni: Nonce;
var Nr: Nonce;
var Kir: SessionKey;
var T: Ticket;
send_1(I,S,(I,R,Ni));
read_2(S,I, {Ni,R,Kir,T}k(I,S));
send_3(I,R,T);
read_4(R,I,{Nr}Kir);
send_5(I,R,{{Nr}dec}Kir);
claim_I2(I,Secret,Kir);
claim_I3(I,Nisynch);
}
role R
{
const Nr: Nonce;
var Kir: SessionKey;
read_3(I,R,{Kir,I}k(R,S));
send_4(R,I,{Nr}Kir);
read_5(I,R,{{Nr}dec}Kir);
claim_R1(R,Secret,Kir);
claim_R3(R,Nisynch);
}
role S
{
var Ni: Nonce;
const Kir: SessionKey;
read_1(I,S,(I,R,Ni));
send_2(S,I,{Ni,R,Kir,{Kir,I}k(R,S)}k(I,S));
}
}
const Alice,Bob,Simon,Eve: Agent;
untrusted Eve;
const ne: Nonce;
compromised k(Eve,Simon);
# General scenario, 2 parallel runs of the protocol
run needhamschroedersk.I(Agent,Agent,Simon);
run needhamschroedersk.R(Agent,Agent,Simon);
run needhamschroedersk.S(Agent,Agent,Simon);
run needhamschroedersk.I(Agent,Agent,Simon);
run needhamschroedersk.R(Agent,Agent,Simon);
run needhamschroedersk.S(Agent,Agent,Simon);