free c_secret:bitstring [private].
free c:channel.
event Toto(bitstring).
event Bob(bitstring).
free a:bitstring.
free b:bitstring.

query x:bitstring, y:bitstring, x':bitstring, y':bitstring; attacker(c_secret) ==> (event(Toto(x)) && event(Toto(y)) && x <> y) || (event(Bob(x')) && event(Bob(y')) && x' <> y').

process
  in(c,x:bitstring);
  event Toto(x);
  event Toto(a);
  event Bob(x);
  event Bob(b);
  out(c,c_secret)

(* EXPECTPV
RESULT attacker(c_secret[]) ==> (event(Toto(x_1)) && event(Toto(y)) && x_1 ≠ y) || (event(Bob(x')) && event(Bob(y')) && x' ≠ y') is true.
0.004s (user 0.004s + system 0.000s), max rss 7312K
END *)
