We present a general methodology for integrating arbitrary security requirements in the development of business processes in a both elegant and rigorous way. We show how trust relationships between different parties and their respective security goals can be reflected in a specification, which results in a realistic modeling of business processes in the presence of malicious adversaries. Special attention is given to the incorporation of cryptography in the development process with the main goal of achieving specifications that are sufficiently simple to be suited for formal verification, yet allow for a provably secure cryptographic implementation.