KeyInfo Element Syntax

In this chapter, the following namespace prefixes are used for the sake of brevity:

 xmlns:ds='http://www.w3.org/2000/09/xmldsig#' xmlns:enc='http://www.w3.org/2001/04/xmlenc#' xmlns:dsm='http://www.w3.org/2001/04/xmldsig-more#' 

The syntax for KeyInfo, as defined in XMLDSIG, follows:

 <!-- XMLDSIG KeyInfo DTD --> <!ELEMENT KeyInfo (#PCDATA|KeyName|KeyValue|RetrievalMethod|                    X509Data|PGPData|SPKIData|MgmtData                    %KeyInfo.ANY;)* > <!ATTLIST KeyInfo           Id  ID   #IMPLIED > 

In schema notation, it has the following form:

 <!-- KeyInfo schema --> <element name="KeyInfo" type="ds:KeyInfoType"/> <complexType name="KeyInfoType" mixed="true">     <choice maxOccurs="unbounded">         <element ref="ds:KeyName"/>         <element ref="ds:KeyValue"/>         <element ref="ds:RetrievalMethod"/>         <element ref="ds:X509Data"/>         <element ref="ds:PGPData"/>         <element ref="ds:SPKIData"/>         <element ref="ds:MgmtData"/>         <any processContents="lax" namespace="##other"/>         <!-- (1,1) elements from (0,unbounded) namespaces -->     </choice>     <attribute name="Id" type="ID" use="optional"/> </complexType> 

XML Encryption extends this definition to include the EncryptedKey and AgreementMethod optional children of KeyInfo. Although defined in connection with encryption, these elements can also be used for a signature if the sender and recipient support them.

As expanded by XML Encryption, the KeyInfo DTD would be something like the following:

 <!-- Extended KeyInfo DTD --> <!ELEMENT KeyInfo (#PCDATA|KeyName|KeyValue|RetrievalMethod|                    X509Data|PGPData|SPKIData|MgmtData|                    EncryptedKey|AgreementMethod|                    %KeyInfo.ANY;)* > <!ATTLIST KeyInfo           Id  ID   #IMPLIED > 

In schema notation, the extended KeyInfo looks like this:

 <!-- Extended KeyInfo schema --> <element name="KeyInfo" type="ds:KeyInfoType"/> <complexType name="KeyInfoType" mixed="true">     <choice maxOccurs="unbounded">         <element ref="ds:KeyName"/>         <element ref="ds:KeyValue"/>         <element ref="ds:RetrievalMethod"/>         <element ref="ds:X509Data"/>         <element ref="ds:PGPData"/>         <element ref="ds:SPKIData"/>         <element ref="ds:MgmtData"/>         <element ref="enc:AgreementMethod"/>         <element ref="enc:EncryptedKey"/>         <any processContents="lax" namespace="##other"/>         <!-- (1,1) elements from (0,unbounded) namespaces -->     </choice>     <attribute name="Id" type="ID" use="optional"/> </complexType>