Many content distribution applications are characterized by frequent, incremental updates. Efficiency is not the only requirement in that security is also crucial for a large spectrum of applications. The goal of this work is to develop an approach for efficient and scalable dissemination of XML documents while assuring confidentiality, integrity and complete-ness without requiring the third-party publishers to be trusted. The key element of our approach to reduce the bandwidth requirements is to use delta messaging. Our approach takes every possible measure to minimize indirect information leakage by making the rest of the structure of XML documents to which clients do not have access oblivious. The experimental results show that our scheme is superior to conventional techniques of securing XML documents when the percentage of updates with respect to original documents is low.