We present a symbolic analysis of the ephemerizer's protocol by Radia Perlman, using the CL-Atse tool from the AVISPA's tool-suite. This protocol allows transmitting a data that will "disappear" (i.e. cannot be retrieved) after a certain time. We show that this protocol is secured for this property plus the secrecy of the data, but is trivially non secured for it's integrity. Therefore, we present two extensions of this protocol, one natural and probably already done in practice, the other one much less obvious. We shows that while the first extension guaranty the basic integrity property under certain conditions, the second one is much stronger and even allows faster computations.