Abstract: The eXtensible Markup Language (XML) is widely seen as the successor to HTML. XML facilitates Internet B2B messaging owing to its simplicity and flexibility. The eXtensible Markup Language's strength for e-commerce applications will be realized only when its inherent security weak1Jesses are identified and dislodged. XML was initially introduced as a dataformat for documents. Some applications need to block or allow access to entire XML instances, while others control access at the tag level. The control residing at the tag level is particularly important in the view of wider use of the Xlink and XPointer standards, which enable applications to retrieve portions of documents. This paper discusses how security could be provided by XML documents based on authentication and encryption techniques using Document type Definition (DTDs) and digital signatures.