Abstract: Aspects of the disclosure provide for methods, systems, and apparatus, including computer-readable storage media for verifying the sources of incoming messages and requests for communication to a computing device. A system can receive a verification request to verify the source of a communication between a source computing device and a recipient computing device. The system can determine, from data defining a mapping between one or more first source identifiers and a user, whether the mapping includes a first source identifier and a second source identifier of the communication request. The mapping can be generated using a digital certificate associated with the user. The one or more first source identifiers can be mapped to the user after the digital certificate is created. The system can send a response to the verification request to the recipient computing device, the response identifying the source of the communication as the user.

Abstract: A method, server, device and computer readable medium for facilitating communication between users permitted to access a messaging server is provided. The messaging server comprises a user database, a processor and memory. The user database is configured to store user information for the users and at least one name directory. The name directory includes a list of users permitted to communicate with each other. The memory has stored thereon instructions which, when executed by the processor, cause the messaging server to transmit the name directory to the users listed therein at predefined times.

Abstract: A method, server, device and computer readable medium for facilitating communication between users permitted to access a messaging server is provided. The messaging server comprises a user database, a processor and memory. The user database is configured to store user information for the users and at least one name directory. The name directory includes a list of users permitted to communicate with each other. The memory has stored thereon instructions which, when executed by the processor, cause the messaging server to transmit the name directory to the users listed therein at predefined times.

Abstract: A method, server, device and computer readable medium for establishing a bi-directional communication session between a first device and a server is provided. During the method, a first transport layer connection between the first device and the server is established. The first device is then authenticated with the server over the first transport layer connection. In the event that authenticating the first device is successful, the server and the first device establish a persistent, bi-directional communication session over the first transport layer connection.