XML Encryption
A specification that defines how to encrypt the content of an XML element. It's a W3C's recommendation. Following is an excerpt from the same :
The XML Encryption specification must describe how to use XML to represent a digitally encrypted Web resource (including XML itself). {prop1, prop2}. The XML representation of the encrypted resource must be a first class object (i.e., referenceable and consequently describable, signable, etc.) and represented by a distinct element type.
The specification must provide for the encryption of a part or totality of an XML document
Granularity of encryption in an XML document is limited to an element (including start/end tags) or element content (between the start/end tags). {prop2, WS, FTF1}
More infos : http://www.w3.org/TR/2002/REC-xmlenc-core-20021210/#sec-Introduction