Independent The Secured Digital Lifecycle Protocol (SDLP) defines a physics-layer security model in which digital objects secure themselves throughout their entire lifecycle. Existing security measures—such as cryptographic signatures, watermarking, provenance metadata, and attestation—are integrated and enforced within a unified physics layer positioned between the Transport and Application layers. This document describes the SDLP security architecture, including the environment safety check, the composite PASS/FAIL trust verdict, and the mandatory BitDrop behavior applied when any trust condition fails. The SDLP security architecture ensures that digital objects operate only within verified, tamper-resistant environments and provides a complete, end-to-end defense against unauthorized access, copying, modification, and redistribution.