scyther/protocols/misc/boyd-nsl-fix.spdl

/*
 * Boyd fix for NS(L)
 *
 * From the paper "Towards Extensional Goals in Authentication
 * Protocols"
 *
 * Broken. Best shown by attack id 4.
 */

const pk: Function;
secret sk: Function;
inversekeys (pk,sk);
const hash: Function;
secret unhash: Function;
inversekeys (hash,unhash);

protocol boydNS(I,R)
{
	role I
	{
		fresh ni: Nonce;
		var nr: Nonce;

		send_1(I,R, {ni}pk(R),I );
		read_2(R,I, {nr}pk(I),hash(ni,R) );
		send_3(I,R, hash(nr, I,R) );
		claim_i1(I,Secret,ni);
		claim_i2(I,Secret,nr);
		claim_i3(I,Niagree);
		claim_i4(I,Nisynch);
	}	
	
	role R
	{
		var ni: Nonce;
		fresh nr: Nonce;

		read_1(I,R, {ni}pk(R),I );
		send_2(R,I, {nr}pk(I),hash(ni,R) );
		read_3(I,R, hash(nr, I,R) );
		claim_r1(R,Secret,ni);
		claim_r2(R,Secret,nr);
		claim_r3(R,Niagree);
		claim_r4(R,Nisynch);
	}
}