  Communications play a vital role in the response to disasters and crises.
However, existing communications infrastructure is often impaired, destroyed or
overwhelmed during such events. This leads to the use of substitute
communications solutions including analog two-way radio or unsecured internet
access. Often provided by unknown third parties, these solutions may have less
sophisticated security characteristics than is desirable. While substitute
communications are often invaluable, care is required to minimize the risk to
NGOs and individuals stemming from the use of communications channels with
reduced or unknown security properties. This is particularly true if private
information is involved, including the location and disposition of individuals
and first responders. In this work we enumerate the principal risks and
challenges that may arise, and provide practical guidelines for mitigating them
during crises. We take plausible threats from contemporary disaster and crisis
events into account and discuss the security and privacy features of
state-of-the-art communications mechanisms.
