XSLT is a very popular and flexible language for transforming XML documents which provides a powerful implementation of a tree-oriented transformation language for transmuting instances of XML using a single vocabulary into a desired output. In this paper, we propose a processing model that enables the XSLT processor to encrypt and decrypt XML documents. Our model supports a more general encryption scope than previous models. The implementation and experimental results demonstrate the practicality of the proposed model. Keyword: XML, Security, DSL, XSLT.