  In the context of security protocol parallel composition, where messages
belonging to different protocols can intersect each other, we introduce a new
paradigm: term-based composition (i.e. the composition of message components
also known as terms). First, we create a protocol specification model by
extending the original strand spaces. Then, we provide a term composition
algorithm based on which new terms can be constructed. To ensure that security
properties are maintained, we introduce the concept of term connections to
express the existing connections between terms and encryption contexts. We
illustrate the proposed composition process by using two existing protocols.
