Abstract-Procurement refers to a process resulting in delivery of goods or services within a set time period. The process includes aspects of purchasing, specifications to be met, and solicitation notifications as in the case of Request For Proposals (RFPs). Typically, such an RFP is described in a verbal ad hoc fashion, in English, with tables and graphs, resulting in imprecise specifications of requirements. It has been proposed that BPMN diagrams be used to specify requirements to be included in RFP. This paper is a merger of three topics: 1) Procurement development with a focus on operational specification of RFP; 2) Public key infrastructure (PKI) as an RFP subject; and 3) Conceptual modeling that produces a diagram as a supplement to an RFP to clarify requirements more precisely than traditional tools, such as natural language, tables, and ad hoc graphs.