Internet Engineering Task Force (IETF) S. Santesson
Request for Comments: 7773 3xA Security
Category: Standards Track March 2016
ISSN: 2070-1721
Authentication Context Certificate Extension
Abstract
This document defines an extension to X.509 certificates. The
extension defined in this document holds data about how the
certificate subject was authenticated by the Certification Authority
that issued the certificate in which this extension appears.
This document also defines one data structure for inclusion in this
extension. The data structure is designed to hold information when
the subject is authenticated using a Security Assertion Markup
Language (SAML) assertion.
Status of This Memo
This is an Internet Standards Track document.
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 5741.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
http://www.rfc-editor.org/info/rfc7773.
Copyright Notice
Copyright (c) 2016 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Santesson Standards Track [Page 1]
RFC 7773 Authentication Context Extension March 2016
Table of Contents
1. Introduction ....................................................2
1.1. Terminology ................................................3
2. Authentication Context Extension Syntax .........................4
3. SAML Authentication Context Information .........................4
3.1. contextInfo Data Structure .................................5
3.1.1. AuthContextInfo Element .............................5
3.1.2. IdAttributes Element ................................6
4. Security Considerations .........................................8
5. Normative References ............................................8
Appendix A. ASN.1 Modules .........................................10
A.1. ASN.1 1988 Syntax .........................................10
A.2. ASN.1 2008 Syntax .........................................11
Appendix B. SAML Authentication Context Info XML Schema ...........12
B.1. XML Schema ................................................12
Appendix C. SAML Authentication Context Info XML Examples .........14
C.1. Complete Context Information and Mappings .................14
C.2. Only Mapping Information without SAML Attribute Values ....15
C.3. Authentication Context and serialNumber Mapping ...........16
Author's Address ..................................................16
1. Introduction
The primary purpose of this document is to provide a mechanism that
allows an application to obtain information that expresses the
identity of a subject in an X.509 certificate according to [RFC5280].
The identity is stored either in a subject field attribute, as a
subject alternative name, or in a subject directory attribute.
The motivation for this work is to enable mapping of identity data
between an identity system and a certificate where the identity
system and the certificate are using different attributes and data
formats to express the identity of the same entity. In such a
scenario, the certificate subject already has an authenticated
identity composed of a set of attributes, or so-called claims, that
differ from the set of attributes that are commonly used to express
the identity of a certificate subject and that may be governed by a
specific certificate profile limiting that set.
A typical scenario motivating the definition of this extension arises
when the source of user authentication and user identity is derived
from a SAML [SAML] federation attribute profile. In a SAML
federation, the subject presents a SAML assertion in exchange for a
certificate that can be uniquely linked to information provided in
the original SAML assertion, e.g., attributes and/or level of
assurance indicators.
Santesson Standards Track [Page 2]
RFC 7773 Authentication Context Extension March 2016
Such certificates are sometimes issued in order to provide the user
with a means to create an electronic signature that ties the user to
the SAML subject, its attributes, and level of assurance indicators.
If such a certificate needs to conform to a certificate profile such
as [RFC3739], then this certificate may have to use a separate set of
attributes to express the subject identity. The certificate also may
have to employ a format for attribute values that is different from
the set of attributes obtained from the SAML assertion.
The extension defined in the document makes it possible to represent
information about the authentication context employed when
authenticating the subject for the purpose of issuing a certificate.
This may include information such as:
o the Identity Provider that authenticated the subject
o the level of assurance with which the subject was authenticated
o the trust framework where this level of assurance was defined
o a unique reference to the authentication instant
o a mapping between the subject attributes (obtained from the
SAML assertion used to authenticate the subject) and the
subject identity information placed in the issued certificate.
One scenario where this information may be useful arises when a user
logs in to a service using SAML credentials, and the same user (at
some point) is required to sign some information. The service may
need to verify that the signature was created by the same user that
logged on to the service. Today this is only possible using out-of-
band knowledge about the Certification Authority (CA) that issued the
certificate and its practices. However, this approach does not scale
to a large number of service providers, identity providers, and CAs.
The extension defined here provides better scalability since it
requires only the service provider to maintain a list of trusted CAs.
All other information about the relationship between the certificate
subject and the SAML authenticated subject is available in the
certificate.
1.1. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
Santesson Standards Track [Page 3]
RFC 7773 Authentication Context Extension March 2016
2. Authentication Context Extension Syntax
The Authentication Context extension has the following syntax:
AuthenticationContexts ::= SEQUENCE SIZE (1..MAX) OF
AuthenticationContext
AuthenticationContext ::= SEQUENCE {
contextType UTF8String,
contextInfo UTF8String OPTIONAL
}
This extension holds a sequence of AuthenticationContext information.
When present, this extension MUST include at least one
AuthenticationContext.
The type of authentication context defined in AuthenticationContext
is identified by the contextType. The contextType MUST contain a URI
that identifies the context type as well as the data format and
encoding of context information provided in contextInfo.
This extension MAY be marked critical.
Applications that find an authentication context information type
they do not understand MUST ignore it if the extension is non-
critical and MUST reject the certificate if the extension is marked
critical. If an application requires that an authentication context
exist, and either the extension is absent or none of the provided
authentication contexts can be used, the end-user certificate fails
validation.
This document defines one authentication context information type
(Section 3) that is used to provide information about SAML-based
authentication of the subject that was utilized in the certificate
issuance process. Other documents can define other authentication
context information types.
3. SAML Authentication Context Information
The SAML Authentication context information provides a contextType
field that can be used to carry information about SAML-based
authentication of the certified subject as utilized in the
certificate issuance process.
Santesson Standards Track [Page 4]
RFC 7773 Authentication Context Extension March 2016
The data carried in this authentication context information field is
identified by the following XML schema ([Schema1] [Schema2]) name
space:
http://id.elegnamnden.se/auth-cont/1.0/saci
When this URI is specified as contextType, the associated XML data
provided in contextInfo MUST be provided in the form of an XML
document [XML], represented by a string of UTF-8-encoded characters.
The XML document SHOULD exclude any unnecessary line breaks and white
space, such as line indentation, to reduce its size as much as
possible.
3.1. contextInfo Data Structure
The data provided in contextInfo SHALL contain XML that is UTF-8
encoded in accordance with the XML schema provided in Appendix B.
The XML document string in contextInfo MUST NOT include an XML
header. That is, the XML document string contains only the root
element <SAMLAuthContext> with its child elements <AuthContextInfo>
and <IdAttributes>.
The <AuthContextInfo> and <IdAttributes> elements are outlined in the
following subsections.
3.1.1. AuthContextInfo Element
The <AuthContextInfo> element MAY be present. This element contains
the following attributes:
IdentityProvider (required): The SAML EntityID of the Identity
Provider that authenticated the subject.
AuthenticationInstant (required): Date and time when the subject
was authenticated, expressed according to Appendix B.1.
AuthnContextClassRef (required): A URI identifying the
AuthnContextClassRef that is provided in the AuthnStatement of
the Assertion that was used to authenticate the subject. This
URI identifies the context and the level of assurance
associated with this instance of authentication.
AssertionRef (optional): A unique reference to the SAML assertion.
ServiceID (optional): An identifier of the service that verified
the SAML assertion.
Santesson Standards Track [Page 5]
RFC 7773 Authentication Context Extension March 2016
The <AuthContextInfo> element may hold any number of child elements
of type any (processContents="lax"), providing additional information
according to local conventions. Any such elements SHOULD be ignored
if not understood.
3.1.2. IdAttributes Element
The <IdAttributes> element MAY be present. This element holds a
sequence of one or more <AttributeMapping> elements, where each
<AttributeMapping> element contains mapping information about one
certificate subject attribute or name form present in the
certificate.
Each <AttributeMapping> element MUST specify the following
attributes:
Type: A string containing one of the enumerated values "rdn",
"san", or "sda", specifying the type of certificate
attribute or name form for which mapping information is
provided:
"rdn": Mapping information is provided for an attribute in
a Relative Distinguished Name located in the
subject field.
"san": Mapping information is provided for a name in the
Subject Alternative Name extension of the
certificate.
"sda": Mapping information is provided for an attribute in
the Subject Directory Attributes extension.
Ref: A reference to the specific attribute or name field. This
reference is dependent on the value of Type in the following
way:
"rdn": Ref holds a string representation of the object
identifier (OID) of the relative distinguished name
attribute.
"san": Ref holds a string representation of the explicit
tag number of the Subject Alternative Name type
(e.g., "1" = email address (rfc822Name) and "2" =
dNSName). If the SubjectAlternative name is an
otherName, then Ref holds a string representation
of the OID defining the otherName form.
"sda": Ref holds a string representation of the OID of the
subject directory attribute attribute.
Santesson Standards Track [Page 6]
RFC 7773 Authentication Context Extension March 2016
String representations of object identifiers (OID) in the
Ref attribute MUST be represented by a sequence of integers
separated by a period, e.g., "2.5.4.32". This string
contains only numerals (ASCII 0x30 to 0x39) and periods
(ASCII 0x2E), and it MUST NOT contain any other characters.
Each <AttributeMapping> element MUST contain a <saml:Attribute>
element as defined in [SAML]. This SAML attribute element MUST have
a Name attribute (specifying its type), MAY have other attributes,
and MAY have zero or more <saml:AttributeValue> child elements. A
present SAML attribute with absent attribute value limits mapping to
the type of SAML attribute that was used to obtain the value stored
in the referenced certificate subject attribute or name form, without
duplicating the actual attribute value.
If an attribute value is present in the SAML attribute, then the
value stored in the certificate in the referenced attribute or name
form MAY differ in format and encoding from the present SAML
attribute value. For example, a SAML attribute value can specify a
country expressed as "Sweden", while this country value is stored in
the certificate in a countryName attribute using the two letter
country code "SE".
Several <AttributeMapping> elements MAY be present for the same
certificate subject attribute or name form if the certificate
contains multiple instances of this attribute or name form where
their values were obtained from different SAML attributes. However,
in such cases, it is not defined which present subject attribute or
name form maps to which SAML attribute. A certificate-using
application MAY attempt to determine this by comparing attribute
values stored in this extension with attribute or name values present
in the certificate, but this specification does not define any
explicit matching rules that would guarantee an unambiguous result.
The <AttributeMapping> element may hold any number of child elements
of type any (processContents="lax"), providing additional information
according to local conventions. Any such elements MAY be ignored if
not understood.
Note: The <AttributeMapping> element is designed to provide mapping
between SAML attributes and certificate subject attributes and
name forms where there is a distinct and clear relationship
between relevant SAML attributes and corresponding certificate
attributes and name forms. This does not cover all aspects of
complex mapping situations. If more than one SAML attribute
maps to the same certificate attribute or if structured
multivalued attributes are split into a range of other
attributes and name forms, these situations are not covered.
Santesson Standards Track [Page 7]
RFC 7773 Authentication Context Extension March 2016
Such complex mapping situations MAY be covered by extending
this XML schema or by defining a more versatile context
information schema.
4. Security Considerations
This extension allows a CA to outsource the process used to identify
and authenticate a subject to another trust infrastructure in a
dynamic manner that may differ from certificate to certificate.
Since the authentication context is explicitly declared in the
certificate, one certificate may be issued with a lower level of
assurance than another, even though both have the same Issuer.
This means that a relying party needs to be aware of the certificate
policy under which this CA operates in order to understand when the
certificate provides a level of assurance with regard to subject
authentication that is higher than the lowest provided level. A
relying party that is not capable of understanding the information in
the authentication context extension MUST assume that the certificate
is issued using the lowest allowed level of assurance declared by the
policy.
5. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>.
[RFC3739] Santesson, S., Nystrom, M., and T. Polk, "Internet X.509
Public Key Infrastructure: Qualified Certificates
Profile", RFC 3739, DOI 10.17487/RFC3739, March 2004,
<http://www.rfc-editor.org/info/rfc3739>.
[RFC5280] Cooper, D., Santesson, S., Farrell, S., Boeyen, S.,
Housley, R., and W. Polk, "Internet X.509 Public Key
Infrastructure Certificate and Certificate Revocation List
(CRL) Profile", RFC 5280, DOI 10.17487/RFC5280, May 2008,
<http://www.rfc-editor.org/info/rfc5280>.
[RFC5912] Hoffman, P. and J. Schaad, "New ASN.1 Modules for the
Public Key Infrastructure Using X.509 (PKIX)", RFC 5912,
DOI 10.17487/RFC5912, June 2010,
<http://www.rfc-editor.org/info/rfc5912>.
Santesson Standards Track [Page 8]
RFC 7773 Authentication Context Extension March 2016
[SAML] Cantor, S., Kemp, J., Philpott, R., and E. Maler,
"Assertions and Protocols for the OASIS Security Assertion
Markup Language (SAML) V2.0", OASIS Standard, 15 March
2005.
[XML] Bray, T., Paoli, J., Sperberg-McQueen, C., Maler, E., and
F. Yergeau, "Extensible Markup Language (XML) 1.0 (Fifth
Edition)", W3C Recommendation, 26 November 2008,
<https://www.w3.org/TR/2008/REC-xml-20081126/>.
[Schema1] Thompson, H., Beech, D., Maloney, M., and N. Mendelsohn,
"XML Schema Part 1: Structures", W3C Recommendation,
28 October 2004,
<http://www.w3.org/TR/2004/REC-xmlschema-1-20041028/>.
[Schema2] Biron, P. and A. Malhotra, "XML Schema Part 2: Datatypes",
W3C Recommendation, 28 October 2004,
<http://www.w3.org/TR/2004/REC-xmlschema-2-20041028/>.
Santesson Standards Track [Page 9]
RFC 7773 Authentication Context Extension March 2016
Appendix A. ASN.1 Modules
This appendix includes the ASN.1 modules for the authentication
context extension. Appendix B.1 includes an ASN.1 module that
conforms to the 1998 version of ASN.1. Appendix B.2 includes an
ASN.1 module, corresponding to the module present in Appendix B.1,
that conforms to the 2008 version of ASN.1. Although a 2008 ASN.1
module is provided, the module in Appendix B.1 remains the normative
module as per policy adopted by the PKIX working group for
certificate-related specifications.
A.1. ASN.1 1988 Syntax
ACE-88
{iso(1) member-body(2) se(752) e-legnamnden(201)
id-mod(0) id-mod-auth-context-88(1)}
DEFINITIONS EXPLICIT TAGS ::=
BEGIN
-- EXPORTS ALL --
-- Authentication Context Extension
AuthenticationContexts ::= SEQUENCE SIZE (1..MAX) OF
AuthenticationContext
AuthenticationContext ::= SEQUENCE {
contextType UTF8String,
contextInfo UTF8String OPTIONAL
}
e-legnamnden OBJECT IDENTIFIER ::= { iso(1) member-body(2)
se(752) 201 }
id-eleg-ce OBJECT IDENTIFIER ::= { e-legnamnden 5 }
id-ce-authContext OBJECT IDENTIFIER ::= { id-eleg-ce 1 }
END
Santesson Standards Track [Page 10]
RFC 7773 Authentication Context Extension March 2016
A.2. ASN.1 2008 Syntax
ACE-08
{iso(1) member-body(2) se(752) e-legnamnden(201)
id-mod(0) id-mod-auth-context-08(2)}
DEFINITIONS EXPLICIT TAGS ::=
BEGIN
EXPORTS ALL;
IMPORTS
Extensions{}, EXTENSION
FROM PKIX-CommonTypes-2009 -- From [RFC5912]
{iso(1) identified-organization(3) dod(6) internet(1) security(5)
mechanisms(5) pkix(7) id-mod(0) id-mod-pkixCommon-02(57)};
-- Authentication Context Extension
ext-AuthenticationContext EXTENSION ::= { SYNTAX
AuthenticationContexts IDENTIFIED BY
id-ce-authContext }
AuthenticationContexts ::= SEQUENCE SIZE (1..MAX) OF
AuthenticationContext
AuthenticationContext ::= SEQUENCE {
contextType UTF8String,
contextInfo UTF8String OPTIONAL
}
ElegnamndenCertExtensions EXTENSION ::= {
ext-AuthenticationContext, ... }
e-legnamnden OBJECT IDENTIFIER ::= { iso(1) member-body(2)
se(752) 201 }
id-eleg-ce OBJECT IDENTIFIER ::= { e-legnamnden 5 }
id-ce-authContext OBJECT IDENTIFIER ::= { id-eleg-ce 1 }
END
Santesson Standards Track [Page 11]
RFC 7773 Authentication Context Extension March 2016
Appendix B. SAML Authentication Context Info XML Schema
This appendix contains an XML schema ([Schema1] [Schema2]) for the SAML
Authentication context information defined in Section 3.
IMPORTANT NOTE: The XML Schema in Appendix B.1 specifies a URL on rows
9 and 10 to the SAML schemaLocation
(http://docs.oasis-open.org/security/saml/v2.0/
saml-schema-assertion-2.0.xsd), which is too long to
fit into one row and therefore contains a line break.
This line break has to be removed before this schema
can be successfully compiled.
B.1. XML Schema
<?xml version="1.0" encoding="UTF-8"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"
elementFormDefault="qualified"
targetNamespace="http://id.elegnamnden.se/auth-cont/1.0/saci"
xmlns:saci="http://id.elegnamnden.se/auth-cont/1.0/saci"
xmlns:saml="urn:oasis:names:tc:SAML:2.0:assertion">
<xs:import namespace="urn:oasis:names:tc:SAML:2.0:assertion"
schemaLocation="http://docs.oasis-open.org/security/saml/v2.0/
saml-schema-assertion-2.0.xsd"/>
<xs:element name="SAMLAuthContext"
type="saci:SAMLAuthContextType"/>
<xs:complexType name="SAMLAuthContextType">
<xs:sequence>
<xs:element ref="saci:AuthContextInfo" minOccurs="0"/>
<xs:element ref="saci:IdAttributes" minOccurs="0"/>
</xs:sequence>
</xs:complexType>
<xs:element name="AuthContextInfo"
type="saci:AuthContextInfoType"/>
<xs:complexType name="AuthContextInfoType">
<xs:sequence>
<xs:any processContents="lax"
minOccurs="0" maxOccurs="unbounded"/>
</xs:sequence>
<xs:attribute name="IdentityProvider"
type="xs:string" use="required"/>
<xs:attribute name="AuthenticationInstant"
type="xs:dateTime" use="required"/>
<xs:attribute name="AuthnContextClassRef"
type="xs:anyURI" use="required"/>
<xs:attribute name="AssertionRef" type="xs:string"/>
Santesson Standards Track [Page 12]
RFC 7773 Authentication Context Extension March 2016
<xs:attribute name="ServiceID" type="xs:string"/>
</xs:complexType>
<xs:element name="IdAttributes" type="saci:IdAttributesType"/>
<xs:complexType name="IdAttributesType">
<xs:sequence>
<xs:element maxOccurs="unbounded" minOccurs="1"
ref="saci:AttributeMapping"/>
</xs:sequence>
</xs:complexType>
<xs:element name="AttributeMapping"
type="saci:AttributeMappingType"/>
<xs:complexType name="AttributeMappingType">
<xs:sequence>
<xs:element ref="saml:Attribute"/>
<xs:any processContents="lax"
minOccurs="0" maxOccurs="unbounded"/>
</xs:sequence>
<xs:attribute name="Type" use="required">
<xs:simpleType>
<xs:restriction base="xs:string">
<xs:enumeration value="rdn"/>
<xs:enumeration value="san"/>
<xs:enumeration value="sda"/>
</xs:restriction>
</xs:simpleType>
</xs:attribute>
<xs:attribute name="Ref" type="xs:string" use="required"/>
</xs:complexType>
</xs:schema>
Santesson Standards Track [Page 13]
RFC 7773 Authentication Context Extension March 2016
Appendix C. SAML Authentication Context Info XML Examples
This appendix provides examples of SAML Authentication Context
information according to the schema in Appendix B.
C.1. Complete Context Information and Mappings
The following is a complete example with authentication context
information as well as mapping information for several subject field
attributes and a subject alt name.
<saci:SAMLAuthContext
xmlns:saci="http://id.elegnamnden.se/auth-cont/1.0/saci"
xmlns:saml="urn:oasis:names:tc:SAML:2.0:assertion"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<saci:AuthContextInfo
ServiceID="eid2csig"
AssertionRef="_71b981ab017eb42869ae4b62b2a63add"
IdentityProvider="https://idp-test.nordu.net/idp/shibboleth"
AuthenticationInstant="2013-03-05T22:59:57.000+01:00"
AuthnContextClassRef="http://id.elegnamnden.se/loa/1.0/loa3"/>
<saci:IdAttributes>
<saci:AttributeMapping Type="rdn" Ref="2.5.4.6">
<saml:Attribute
FriendlyName="Country"
Name="urn:oid:2.5.4.6">
<saml:AttributeValue xsi:type="xs:string"
>SE</saml:AttributeValue>
</saml:Attribute>
</saci:AttributeMapping>
<saci:AttributeMapping Type="rdn" Ref="2.5.4.5">
<saml:Attribute
FriendlyName="Personal ID Number"
Name="urn:oid:1.2.752.29.4.13">
<saml:AttributeValue xsi:type="xs:string"
>200007292386</saml:AttributeValue>
</saml:Attribute>
</saci:AttributeMapping>
<saci:AttributeMapping Type="rdn" Ref="2.5.4.42">
<saml:Attribute
FriendlyName="Given Name"
Name="urn:oid:2.5.4.42">
<saml:AttributeValue xsi:type="xs:string"
>John</saml:AttributeValue>
</saml:Attribute>
</saci:AttributeMapping>
<saci:AttributeMapping Type="rdn" Ref="2.5.4.4">
<saml:Attribute
Santesson Standards Track [Page 14]
RFC 7773 Authentication Context Extension March 2016
FriendlyName="Surname"
Name="urn:oid:2.5.4.4">
<saml:AttributeValue xsi:type="xs:string"
>Doe</saml:AttributeValue>
</saml:Attribute>
</saci:AttributeMapping>
<saci:AttributeMapping Type="rdn" Ref="2.5.4.3">
<saml:Attribute
FriendlyName="Display Name"
Name="urn:oid:2.16.840.1.113730.3.1.241">
<saml:AttributeValue xsi:type="xs:string"
>John Doe</saml:AttributeValue>
</saml:Attribute>
</saci:AttributeMapping>
<saci:AttributeMapping Type="san" Ref="1">
<saml:Attribute
FriendlyName="E-mail"
Name="urn:oid:0.9.2342.19200300.100.1.3">
<saml:AttributeValue xsi:type="xs:string"
>john.doe@example.com</saml:AttributeValue>
</saml:Attribute>
</saci:AttributeMapping>
</saci:IdAttributes>
</saci:SAMLAuthContext>
C.2. Only Mapping Information without SAML Attribute Values
This example shows an instance of the SAML Authentication Context
information that only provides a mapping table without providing any
authentication context information or SAML attribute values.
<saci:SAMLAuthContext
xmlns:saci="http://id.elegnamnden.se/auth-cont/1.0/saci"
xmlns:saml="urn:oasis:names:tc:SAML:2.0:assertion">
<saci:IdAttributes>
<saci:AttributeMapping Type="rdn" Ref="2.5.4.6">
<saml:Attribute Name="urn:oid:2.5.4.6"/>
</saci:AttributeMapping>
<saci:AttributeMapping Type="rdn" Ref="2.5.4.5">
<saml:Attribute Name="urn:oid:1.2.752.29.4.13"/>
</saci:AttributeMapping>
<saci:AttributeMapping Type="rdn" Ref="2.5.4.42">
<saml:Attribute Name="urn:oid:2.5.4.42"/>
</saci:AttributeMapping>
<saci:AttributeMapping Type="rdn" Ref="2.5.4.4">
<saml:Attribute Name="urn:oid:2.5.4.4"/>
</saci:AttributeMapping>
<saci:AttributeMapping Type="rdn" Ref="2.5.4.3">
Santesson Standards Track [Page 15]
RFC 7773 Authentication Context Extension March 2016
<saml:Attribute Name="urn:oid:2.16.840.1.113730.3.1.241"/>
</saci:AttributeMapping>
<saci:AttributeMapping Type="san" Ref="1">
<saml:Attribute Name="urn:oid:0.9.2342.19200300.100.1.3"/>
</saci:AttributeMapping>
</saci:IdAttributes>
</saci:SAMLAuthContext>
C.3. Authentication Context and serialNumber Mapping
This example shows an instance of the SAML Authentication Context
information; it provides authentication context information and
mapping information that specifies the source of the data stored in
the serialNumber attribute in the subject field.
<saci:SAMLAuthContext
xmlns:saci="http://id.elegnamnden.se/auth-cont/1.0/saci"
xmlns:saml="urn:oasis:names:tc:SAML:2.0:assertion"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<saci:AuthContextInfo
ServiceID="eid2csig"
AssertionRef="_71b981ab017eb42869ae4b62b2a63add"
IdentityProvider="https://idp-test.nordu.net/idp/shibboleth"
AuthenticationInstant="2013-03-05T22:59:57.000+01:00"
AuthnContextClassRef="http://id.elegnamnden.se/loa/1.0/loa3"/>
<saci:IdAttributes>
<saci:AttributeMapping Type="rdn" Ref="2.5.4.5">
<saml:Attribute
FriendlyName="Personal ID Number"
Name="urn:oid:1.2.752.29.4.13">
<saml:AttributeValue xsi:type="xs:string"
>200007292386</saml:AttributeValue>
</saml:Attribute>
</saci:AttributeMapping>
</saci:IdAttributes>
</saci:SAMLAuthContext>
Author's Address
Stefan Santesson
3xA Security AB
Scheelev. 17
223 70 Lund
Sweden
Email: sts@aaa-sec.com
Santesson Standards Track [Page 16]