scyther/gui/Protocols/andrew-lowe-ban.spdl
2012-04-26 16:40:01 +02:00

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# Lowe modified BAN concrete Andrew Secure RPC
#
# Modelled after the description in the SPORE library
# http://www.lsv.ens-cachan.fr/spore/andrewLowe.html
#
# Note:
# The shared key between I and R is modelled as k(I,R) currently
# there is no way to express that this key is equal to k(R,I)
# So it is possile that certain attacks that use this property are not found
#
# Note:
# Recv 4 by the Initatior has been placed after the synchronisation claim
# as it allows trivial synchronisation attacks otherwise (the message is
# completely fresh and can therefore always be replaced by an arbitrary value
# created by the intruder) which are not considered in SPORE
#
# Note:
# According to SPORE there are no known attacks on this protocol
#
usertype SessionKey;
const Fresh: Function;
const Compromised: Function;
protocol andrew-LoweBan(I,R)
{
role I
{
fresh ni: Nonce;
var nr: Nonce;
var kir: SessionKey;
send_1(I,R, I,ni );
recv_2(R,I, {ni,kir,R}k(I,R) );
send_3(I,R, {ni}kir );
claim_I1(I,Nisynch);
claim_I2(I,Secret, kir);
claim_I3(I,Empty, (Fresh,kir));
recv_4(R,I, nr );
}
role R
{
var ni: Nonce;
fresh nr: Nonce;
fresh kir: SessionKey;
recv_1(I,R, I,ni );
send_2(R,I, {ni,kir,R}k(I,R) );
recv_3(I,R, {ni}kir );
send_4(R,I, nr );
claim_R1(R,Nisynch);
claim_R2(R,Secret, kir);
claim_R3(R,Empty, (Fresh,kir));
}
}