ACTION-235: SubjectPublicKeyInfo proposal

Reworked proposal follows. The element name is appropriate, but admittedly
might be a little confusing because of overlap with "KeyInfo".

-----

<complexType name="SubjectPublicKeyInfoType">
	<simpleContent>
		<extension base="base64Binary">
			<attribute name="Id" type="ID" use="optional"/>
		</extension>
	</simpleContent>
</complexType>

<element name="SubjectPublicKeyInfo" type="ds11:SubjectPublicKeyInfoType"/>

----

4.4.3 The SubjectPublicKeyInfo Element

Identifier
    Type="http://www.w3.org/2008/01/xmldsig# SubjectPublicKeyInfo"
    (this can be used within a RetrievalMethod or Reference element to
identify the referent's type)

The public key algorithm and value are DER-encoded in accordance with the
value that would be used in the Subject Public Key Info field of an X.509
certificate, per section 4.1.2.7 of [RFC5280]. The DER-encoded value is then
base64-encoded.

For example, RSA and DSA keys are encoded as described by section 2.3.1 and
2.3.2 of
[RFC3279].

Schema Definition:
(see above)

-- Scott