Pica Pica is a project aimed to create and support the distributed decentralized secure instant messaging system. Pica Pica network consists of nodes and clients. Nodes are hosted by volunteers on their computers. Nodes connect to each other and exchange info about other nodes and online clients, transfer encrypted data between clients. All the data transferred between clients is protected by end-to-end encryption using TLS 1.2 protocol. User accounts are based on self-signed X.509 certificates. Users are identified by unique SHA224 hash of such certificates.Pica Pica ID is a Base64 representation of this SHA224 hash and looks like this: m+2TC+ZYDx0crQZK1p97cuAIp1rH5i1SLe6EtA==. It has to be this cryptic because there is no central authority that can ensure uniqueness of human-readable identifiers.