fun sencrypt/2.
reduc sdecrypt(sencrypt(x,y),y) = x.

private free secret.
free c.

query	attacker:secret.

process	new cle;
	new d;
	out(c,cle);
	out(c,sencrypt(d,cle));
 	in(c,x);
	out(d,e);
	out(c,secret)