Explore application-layer guarantees for data authenticity, integrity, and privacy in this comprehensive conference talk from DevSecCon. Delve into the challenges faced by modern applications operating in multi-tenant cloud and edge environments, and untrusted networks. Examine the exponential growth in vulnerability surfaces caused by complex data flows across network boundaries, data centers, queues, caches, gateways, and brokers. Learn how to build secure-by-design and private-by-default applications by incorporating end-to-end guarantees into distributed systems. Gain insights from Mrinal Wadhwa, CTO at Ockam, on open-source tools for developing safe and secure applications. Originally presented at StepZen headquarters in Santa Clara, California, this 1-hour 20-minute talk offers valuable knowledge for developers and security professionals seeking to enhance application security in modern computing environments.