Security associations: building blocks for secure communications

History tells us that Julius Cesar shifted each letter in his messages to his generals by three places in the alphabet. The generals knew to shift back by three letters to read the message. Securing information for transfer between entities requires an agreement on how the information will be protected. Modern science and technology has brought more advanced methods of protecting information, but the basic need for an agreement between entities desiring to communicate securely still exists. In modern terms this agreement is a security association (SA). There are varying definitions of a security association in current standards and this paper attempts to clarify, these definitions. Security protocols requiring security associations as well as emerging protocols that establish and manage security associations are presented. If future global interoperability is to be provided securely one of the first building blocks will be the ability to negotiate and establish security associations. Therefore, issues that must be resolved for future global interoperability are discussed. Our work to create a network security research environment for future global needs is also presented.