In this paper, we present a novel paradigm for studying the problem of group key distribution, use it to analyze existing key distribution schemes, and then present a novel scheme for group key distribution which we call "Dynamic Set Key Encryption," or DSKE. DSKE meets the demands of a tactical environment while relying only on standard cryptographic primitives. Our "set key" paradigm allows us to focus on the underlying problem of establishing a confidential communication channel shared by a group of users, without concern for related security factors like authenticity and integrity, and without the need to consider any properties of the group beyond a list of its members. This separation of concerns is vital to our development and analysis of DSKE, and can be applied elsewhere to simplify the analyses of other group key distribution schemes.