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

private free secret,c.
free e.

query	attacker : secret.

process new cle2;
	(!in(c,x); out(e,sdecrypt(x,cle2)))
	|
	( 
	new cle;
	out(c,sencrypt(cle,cle2));
	out(c,sencrypt(sencrypt(secret,cle),cle2))
	)
