diff --git a/src/ns3 b/src/ns3
new file mode 100644
index 0000000..943fc7f
--- /dev/null
+++ b/src/ns3
@@ -0,0 +1,76 @@
+const pk: Function;
+secret sk: Function;
+inversekeys (pk,sk);
+
+protocol ns3(I,R)
+{
+	role I
+	{
+		const ni: Nonce;
+		var nr: Nonce;
+
+		send_1(I,R, {I,ni}pk(R) );
+		read_2(R,I, {ni,nr}pk(I) );
+		send_3(I,R, {nr}pk(R) );
+		claim_4(I,Secret,ni,nr);
+		claim_6(I,Nisynch);
+	}	
+	
+	role R
+	{
+		var ni: Nonce;
+		const nr: Nonce;
+
+		read_1(I,R, {I,ni}pk(R) );
+		send_2(R,I, {ni,nr}pk(I) );
+		read_3(I,R, {nr}pk(R) );
+		claim_5(R,Secret,ni,nr);
+		claim_7(R,Nisynch);
+	}
+}
+
+// We leave out: M (from M_0) and Decryption, because that causes
+// problems with the inverse key.
+protocol I_MALICE (I_F, I_T, I_V, I_R, I_E)
+{
+	role I_F {
+	        var t;
+		read_if1 (F,F, t);
+	}
+	role I_T {
+	        var t;
+		read_it1 (T,T, t);
+		send_it2 (T,T, t);
+		send_it3 (T,T, t);
+	}
+	role I_V {
+	        var t1;
+		var t2;
+		read_iv1 (V,V, t1);
+		read_iv2 (V,V, t2);
+		send_iv3 (V,V, (t1,t2));
+	}
+	role I_R {
+	        var t1;
+		var t2;
+		read_ir1 (I_R,I_R, (t1,t2));
+		read_ir2 (I_R,I_R, t1);
+		send_ir3 (I_R,I_R, t2);
+	}
+	role I_E {
+	        var t1;
+		var t2;
+		read_ie1 (I_E,I_E, t1);
+		read_ie2 (I_E,I_E, t2);
+		send_ie3 (I_E,I_E, {t1}t2);
+	}
+}
+
+const Alice,Bob,Eve: Agent;
+
+untrusted Eve;
+const nc: Nonce;
+compromised sk(Eve);
+
+run ns3.I(Alice,Eve);
+run ns3.R(Alice,Bob);