  This paper describes a decentralized low-cost system designed to reinforce
personal security in big events in case of emergency. The proposal consists of
using smart contracts supported by blockchain in the management of events. An
alternative communication channel that does not require any cloud service is
also provided with the aim of improving the coordination of emergency services.
Peers may use this emergency support tool to interact with each other through a
chat when additional support is required. Since information security is
mandatory in this scenario, Identity-Based Signcryption schemes are here used
in order to guarantee communication confidentiality, authenticity and
integrity. Depending on the communication mode (peer-to-peer or broadcast),
different signcryption methods are used. A first implementation of the proposal
has produced promising results.
