Developing secure distributed systems is difficult, and even harder when advanced cryptography must be used to achieve security goals. We present Viaduct, a compiler that transforms high-level programs into secure, efficient distributed realizations. Instead of implementing a system of communicating processes, the Viaduct programmer implements a centralized, sequential program which is automatically compiled into a secure distributed version that uses cryptography. Viaduct programs specify security policies declaratively using information-flow labels, and need not mention cryptographic primitives. Unlike prior compilers for cryptographic libraries, Viaduct is general and extensible: it can efficiently and automatically combine local computation with multiple advanced cryptographic primitives such as commitments, zero-knowledge proofs, secure multiparty computation, and fully homomorphic encryption. We develop a modular security proof for Viaduct that abstracts away from the details of cryptographic mechanisms. Our proof relies on a novel unification of simulation-based security, information-flow control, choreographic programming, and sequentialization techniques for concurrent programs. To our knowledge, this is the first security proof that simultaneously addresses subtleties essential for robust, performant applications, such as multiple cryptographic mechanisms, malicious corruption, and asynchronous communication. Our approach offers a clear path toward leveraging Universal Composability to obtain end-to-end security with fully instantiated cryptographic mechanisms.