To provide a communication environment with higher security with respect to a communication apparatus and method, and a program.

The communication apparatuses 10, 20 use a fixed setting common-key key stored respectively in them and a variable variation common key T whose value is identical to each of the communication apparatuses 10, 20 in an optional timing, determine at least either of the port or the protocol used for communication and carry out the communication by using the port or the protocol. Further, the communication apparatuses 10, 20 use at least either of the setting common-key key or the variation common key T to carry out encryption processing of communication data. The technology disclosed herein is applicable to, e.g. www servers and www clients or the like.