A memory card device comprises an input unit such as button, etc. Information flow to the individual is authorized if the source of the information is a member of the individual’s social network who is connected to the individual along a path that does not traverse through anyone on a gray list of the individual. The other devices may check that the one-way function applied to this input results in the shared output value, and if so, close the communication link. Gate assemblies of arbitrary height and width can be formed using the bracket system. When not in use it is folded to conceal the hook, eliminating the potential to inflict damage to a garment when packed together for travel.