Throughout both XML Digital Signatures, covered in Part III, and XML Encryption, covered in Part V, we have noted provisions for referring to algorithms using URIs as well-known names. These include both cryptographic algorithms, which actually do the bit scrambling and unscrambling of cryptography, and algorithms operating at the XML or text level. For most types of algorithms, one or a few algorithms are mandatory to implement their use maximizes the possibility of interoperability. Other algorithms are optional. The URI naming convention is so general that proprietary or nonstandard user-specified algorithms are easily accommodated though their use decreases the chances for interoperability.
Chapter 17 provides an overview of the types of algorithms found in XML Security; Chapter 18 offers specifications for each cryptographic algorithms used, and Chapter 19 does the same for non-cryptographic algorithms.