This data connector was historically used to produce both the "eduPersonTargetedID" SAML Attribute, which contains a SAML <NameID> element in its values, and to generate SAML 2.0 "persistent" NameID values. The attribute use case is itself generally deprecated because SAML 1 itself is a legacy standard and because the use of the attribute in SAML 2 is both redundant, and overly complex. The NameID use case has been replaced by an equivalent NameID "generator" (see the NameIDGenerationConfiguration topic).
The connector remains supported to facilitate future compliance with emerging profiles for SAML subject identification the Shibboleth community hopes will replace the older options.
The ComputedId data connector generates an attribute from the SHA-1 hash of the requesting entity's ID, an attribute value, and a salt that must be kept secret to prevent off-line generation of the hashes to recover the underlying attribute value.
The attribute value is therefore opaque and unique per user, per relying party, for use as a SAML "persistent" NameID.
Schema Name and Location
This xsi:type is defined by the urn:mace:shibboleth:2.0:resolver schema 3.3, located at http://shibboleth.net/schema/idp/shibboleth-attribute-resolver.xsd.
Prior to V3.3 supplied plugins were defined by a schema type (xsi:type) in the urn:mace:shibboleth:2.0:resolver:dc namespace, the schema for which is located at http://shibboleth.net/schema/idp/shibboleth-attribute-resolver-dc.xsd. This is still supported, but every element or type in the urn:mace:shibboleth:2.0:resolver:dc namespace has an equivalently named (but not necessarily identical) version in the urn:mace:shibboleth:2.0:resolver namespace. The use of the urn:mace:shibboleth:2.0:resolver namespace also allows a relaxation of the ordering requirements of child elements to reduce strictness.
Attributes
Any of the common attributes can be specified. In addition the following attributes are supported:
| Name | Type | Default | Description |
|---|---|---|---|
generatedAttributeID | string | ID of the connector | The id of the IdPAttribute that is generated |
sourceAttributeID | string, required | The id of the IdPAttribute used as input to the computed ID. | |
salt | string. required | A salt, of at least 16 bytes, used in the computed ID | |
| string | BASE64 | Controls the eventual text encoding of the value, this should be set to "BASE32" for new deployments (see the warning box about case sensitivity under PersistentNameIDGenerationConfiguration) |
Configuring salt prior to V3.3
Prior to release 3.3 the parser mishandled the provided salt and stripped trailing and leading spaces from it, see case IDP-982. This rendered the values incompatible with those used in V2.
Until 3.3 is release, a workaround is to indirect through a property: for instance
Attribute-resolver.xml:
<DataConnector id="computed" xsi:type="ComputedId"
sourceAttributeID="theSourceRemainsTheSame"
generatedAttributeID="jenny"
salt="%{idp.ComputedIDDataConnector.salt}"/>
idp.properties
idp.ComputedIDDataConnector.salt= String with Spaces before and after
Child Elements
Any of the common child elements can be specified.
Examples
<DataConnector id="ComputedIDConnector" xsi:type="ComputedId"
sourceAttributeID="Foo"
generatedAttributeID="ComputedID"
salt="abcdefghijklmnopqrstuvwxyz"
encoding="BASE32">
<Dependency ref="AttributeSourceForFoo"/>
</DataConnector>