scyther/spdl/bke-broken.spdl

/* 
	Bilateral Key Exchange with Public Key protocol (BKEPK)
	Broken version with man in the middle attack.
*/

usertype Key;

const PK,h: Function;
secret SK,hinv: Function;

inversekeys (PK,SK);
inversekeys (h,hinv);

protocol bkepk(I,R)
{
	role I
	{
		const ni: Nonce;
		var nr: Nonce;
		var kir: Key;

		send_1 (I,R, { ni,I }PK(R) );
		read_2 (R,I, { h(ni),nr,kir }PK(I) );
		send_3 (I,R, { h(nr),kir }PK(R) );
		claim_4 (I, Secret, kir );
	}

	role R
	{
		var ni: Nonce;
		const nr: Nonce;
		const kir: Key;

		read_1 (I,R, { ni,I }PK(R) );
		send_2 (R,I, { h(ni),nr,kir }PK(I) );
		read_3 (I,R, { h(nr),kir }PK(R) );
		claim_5 (R, Secret, kir );
	}
}

const a,b,e: Agent;

untrusted e;
compromised SK(e);
const ne: Nonce;

run bkepk.I(a,Agent);
run bkepk.R(Agent,b);