X509-bindings-profiles-sep061 Bindings and Profiles for Attribute-based Authz in the Grid Tom Scavo...

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Bindings and Profilesfor Attribute-based Authz

in the Grid

Tom Scavotrscavo@ncsa.uiuc.edu

NCSA

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Overview• Metadata Profile for the OASIS Security

Assertion Markup Language (SAML) V1.x• Metadata Extension for SAML V2.0 and V1.x

Query Requesters• SAML V1.1 Profiles for X.509 Subjects• SAML V2.0 Profiles for X.509 Subjects• X.509 Binding for SAML• X.509 Attribute-based Authorization Profile for

SAML• BONUS! Level of Assurance Attribute!

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Metadata Profile for SAML V1.x• SAML V2.0 includes a Metadata Profile

• The Metadata Profile for the OASIS Security Assertion Markup Language (SAML) V1.x profiles the use of SAML V2.0 metadata with SAML V1.x entities

• Document is in final stages of pipeline

• Shibboleth V1.3 (or later) supports SAML V1.x metadata

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Metadata for Query Requesters• GridShib use cases (e.g.) are rife with notion

of standalone attribute requesters• The Metadata Extension for SAML V2.0 and

V1.x Query Requesters profiles use of SAML metadata with standalone query requesters

• Document is in final stages of pipeline• Shibboleth V1.3 (or later) supports metadata

for SAML V1.x attribute requester• It’s not clear if Shibboleth V2.0 will support

SAML V2.0 attribute requester

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SAML Profiles for X.509 Subjects• Two profile sets have been submitted to the

OASIS Security Services TC:– SAML V1.1 Profiles for X.509 Subjects

http://www.oasis-open.org/committees/document.php?document_id=19996&wg_abbrev=security

– SAML V2.0 Profiles for X.509 Subjectshttp://www.oasis-open.org/committees/document.php?document_id=20000&wg_abbrev=security

• Comments are welcome!http://www.oasis-open.org/committees/tc_home.php?wg_abbrev=security

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SAML V1.1 Profiles• The SAML V1.1 profile set consists of

four layered profiles for X.509 subjects:1. X.509 SAML Subject Profile

2. SAML Assertion Profile for X.509 Subjects

3. SAML Attribute Query Profile for X.509 Subjects

4. SAML Attribute Self-Query Profile for X.509 Subjects

• Document is brand new and not vetted

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X.509 SAML Subject Profile• The X.509 SAML Subject Profile

specifies a <saml:Subject> element:<saml:Subject> <saml:NameIdentifier Format="urn:oasis:names:tc:SAML:1.1:nameid-format:X509SubjectName"> C=US, O=NCSA-TEST, OU=User, CN=trscavo@uiuc.edu </saml:NameIdentifier></saml:Subject>

• The DN SHOULD be RFC2253 format

• The NameQualifier attribute SHOULD be omitted

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X.509 SAML Subject Profile• From the profile:

– “This profile specifies a SAML V1.1 <saml:Subject> element that represents a principal who has been issued an X.509 certificate.”

– “An entity that produces a <saml:Subject> element according to this profile MUST have previously determined that the principal does in fact possess the corresponding private key.”

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SAML Assertion Profile• The SAML Assertion Profile for X.509

Subjects is a very general profile for SAML V1.1 assertions based on the X.509 SAML Subject Profile

• The number of SAML statements per assertion is arbitrary but– Each pair of <saml:Subject> elements

MUST very strongly match (for all practical purposes, they must be identical)

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SAML Assertion Profile• Excerpt from the profile:

– “The SAML Assertion Profile for X.509 Subjects describes how a SAML V1.1 assertion regarding a principal who has been issued an X.509 certificate is produced.”

• Holder-of-key subject confirmation is optional but tied to the X.509 certificate

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SAML Attribute Query Profile• The SAML Attribute Query Profile for

X.509 Subjects specifies how a service provider and an identity provider exchange attributes about a principal who has been issued an X.509 certificate

• This profile relies on the X.509 SAML Subject Profile and the SAML Assertion Profile for X.509 Subjects

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SAML Attribute Query ProfilePrincipal Service

ProviderIdentity

Provider

1. Service Request

2. Attribute Request

3. Attribute Response

4. Service Response

(X.509 authentication)

CheckPolicy

CheckPolicy

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SAML Attribute Query• SAML V1.1 doesn’t provide much

guidance re attribute query

• A standard Shibboleth attribute query is profiled:

• <samlp:Request ...> <samlp:AttributeQuery ...> <saml:Subject>...</saml:Subject> <saml:AttributeDesignator .../> ... </samlp:AttributeQuery></samlp:Request>

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Attribute Query Response• <samlp:Response ...>

<samlp:Status>...</samlp:Status> <saml:Assertion ...> <saml:Conditions NotBefore="2006-07-17T22:21:41Z" NotOnOrAfter="2006-07-17T22:51:41Z"> <saml:AudienceRestrictionCondition> <saml:Audience>...</saml:Audience> </saml:AudienceRestrictionCondition> </saml:Conditions> <saml:AttributeStatement> <saml:Subject>...</saml:Subject> <saml:Attribute ...> <saml:AttributeValue ...> ... </saml:AttributeValue> </saml:Attribute> ... </saml:AttributeStatement> </saml:Assertion></samlp:Response>

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SAML Attribute Self-Query Profile• The SAML Attribute Self-Query Profile

for X.509 Subjects specifies how a principal who has been issued an X.509 certificate self-queries an identity provider for attributes

• This profile extends the SAML Attribute Query Profile for X.509 Subjects

• A driving use case for self-query is caBIG Dorian

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SAML Attribute Self-Query ProfilePrincipal

ServiceProvider

IdentityProvider

1. Attribute Request

2. Attribute Response

3. Service Request

4. Service Response

(X.509 authentication)

CheckPolicy

CheckPolicy

(X.509 authentication)

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Attribute Self-Query Response• <saml:Assertion ...>

<!-- assertion lifetime constrained by X.509 --> <saml:Conditions ...> <!-- no AudienceRestrictionCondition --> </saml:Conditions> <saml:AuthenticationStatement ...> <saml:Subject>...</saml:Subject> </saml:AuthenticationStatement> <saml:AttributeStatement> <saml:Subject>...</saml:Subject> <saml:Attribute ...> <saml:AttributeValue ...> ... </saml:AttributeValue> </saml:Attribute> ... </saml:AttributeStatement> <ds:Signature>...</ds:Signature></saml:Assertion>

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Subject of Self-Query• The <saml:Subject> of a self-query uses holder-of-key:

<saml:Subject> <saml:NameIdentifier Format="urn:oasis:names:tc:SAML:1.1:nameid-format:X509SubjectName"> C=US, O=NCSA-TEST, OU=User, CN=trscavo@uiuc.edu </saml:NameIdentifier> <saml:SubjectConfirmation> <saml:ConfirmationMethod> urn:oasis:names:tc:SAML:1.0:cm:holder-of-key </saml:ConfirmationMethod> <saml:SubjectConfirmationData> <ds:KeyInfo> <ds:X509Data> <!-- principal's X.509 cert --> <ds:X509Certificate> ... </ds:X509Certificate> </ds:X509Data> </ds:KeyInfo> </saml:SubjectConfirmationData> </saml:SubjectConfirmation></saml:Subject>

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SAML V2.0 Profiles• Likewise the SAML V2.0 profile set

consists of four sub-profiles:1. X.509 SAML Subject Profile

2. SAML Assertion Profile for X.509 Subjects

3. SAML Attribute Query Profile for X.509 Subjects

4. SAML Attribute Self-Query Profile for X.509 Subjects

• Significant difference is encryption

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Revision History• SAML V2.0 profiles have a long history:

– Draft-01, 22 Jun 2004– Draft-02, 03 Feb 2005– Draft-07, 23 May 2005– CD-01, 01 Jun 2005– Draft-08, 14 Mar 2006– CD-02, 28 Mar 2006– Draft-09, 26 Jun 2006– Draft-10, 05 Jul 2006– Draft-11, 24 Aug 2006

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X.509 Binding for SAML

<Assertion>…</Assertion>

An ASN.1 SEQUENCE of <saml:Assertion> elements at a well-known, non-critical X.509 v3 certificate extension

This profile is a work in progress (but it won’t be an OASIS profile)

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X.509 Attribute-based Authz• Goal: Use SAML Assertion Profile and

X.509 Binding to profile attribute push• Distinguish between two types of bound

attribute assertions:– Self-issued assertions– Third-party assertions (e.g., Shib-issued)

• https://authdev.it.ohio-state.edu/twiki/bin/view/GridShib/X509BindingSAML

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Bound Assertion Example• <!-- shib-enabled community portal -->

<saml:Assertion ...> <saml:Conditions ...>...</saml:Conditions> <saml:Advice> <!-- attribute assertion obtained from campus Shib AA --> <saml:Assertion ...>...</saml:Assertion> <!-- authn assertion obtained from campus Shib IdP (if available) --> <saml:Assertion ...>...</saml:Assertion> </saml:Advice> <!-- community attributes --> <saml:AttributeStatement ...> <!-- the subject of this proxy --> <saml:Subject>...</saml:Subject> ... </saml:AttributeStatement></saml:Assertion>

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MACE-Dir LoA Attribute• MACE-Dir is profiling use of authnLoa

attribute in conjunction with usPerson • Proposed SAML binding:

<saml:Attribute xmlns:saml="urn:oasis:names:tc:SAML:2.0:assertion“ xmlns:x500="urn:oasis:names:tc:SAML:2.0:profiles:attribute:X500" x500:Encoding="LDAP" NameFormat="urn:oasis:names:tc:SAML:2.0:attrname-format:uri" Name="urn:oid:..." FriendlyName="authnLOA"> <saml:AttributeValue xsi:type="xs:anyURI"> ... </saml:AttributeValue></saml:Attribute>

• Legal attribute values are per federation

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E-Auth LoA Values• For the E-Authentication Program, the

recommended initial set of values is:– http://www.cio.gov/eauthentication/usperson/authnloa#nist-sp-800-63-1

– http://www.cio.gov/eauthentication/usperson/authnloa#nist-sp-800-63-2

– http://www.cio.gov/eauthentication/usperson/authnloa#nist-sp-800-63-3

– http://www.cio.gov/eauthentication/usperson/authnloa#nist-sp-800-63-4

– http://www.cio.gov/eauthentication/usperson/authnloa#test

• InCommon values have not been proposed