scyther/protocols/misc/ns-symmetric-amended.spdl
2012-06-12 23:12:14 +02:00

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/*
* Needham-Schroeder symmetric
* Amended version (from Sjouke's interpret.)
*/
/* symmetric */
usertype SessionKey;
secret k: Function;
/* agents */
/* untrusted e */
untrusted e;
const kee: SessionKey;
compromised k(e,e);
compromised k(e,a);
compromised k(e,b);
compromised k(a,e);
compromised k(b,e);
/* {}x used for public (invertible) function modeling */
usertype PseudoFunction;
const succ: PseudoFunction;
usertype Ticket;
protocol nssymmetricamended(A,S,B)
{
role A
{
fresh na: Nonce;
var T1: Ticket;
var T2: Ticket;
var kab: SessionKey;
var nb: Nonce;
send_1(A,B, A );
recv_2(B,A, T1 );
send_3(A,S, A,B,na,T1 );
recv_4(S,A, { na,B,kab,T2 }k(A,S) );
send_5(A,B, T2 );
recv_6(B,A, { nb }kab );
send_7(A,B, { {nb}succ }kab );
claim_8(A, Secret, kab);
claim_8a(A, Niagree);
claim_8b(A, Nisynch);
}
role S
{
fresh kab: SessionKey;
var na: Nonce;
var nb: Nonce;
recv_3(A,S, A,B,na, { A,nb }k(B,S) );
send_4(S,A, { na,B,kab, { kab,A }k(B,S) }k(A,S) );
}
role B
{
var kab: SessionKey;
fresh nb: Nonce;
recv_1(A,B, A );
send_2(B,A, { A,nb }k(B,S) );
recv_5(A,B, { kab,A }k(B,S) );
send_6(B,A, { nb }kab );
recv_7(A,B, { {nb}succ }kab );
claim_9(B, Secret, kab);
claim_9a(B, Niagree);
claim_9b(B, Nisynch);
}
}