One document matched: draft-ietf-kitten-gssapi-naming-exts-15.xml
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<rfc category="std" docName="draft-ietf-kitten-gssapi-naming-exts-15"
ipr="pre5378Trust200902">
<front>
<title abbrev="GSS-API Naming Extensions">GSS-API Naming
Extensions</title>
<author fullname="Nicolas Williams" initials="N." surname="Williams">
<organization>Cryptonector, LLC</organization>
<address>
<email>nico@cryptonector.com</email>
</address>
</author>
<author fullname="Leif Johansson" initials="L." surname="Johansson">
<organization abbrev="SUNET">Swedish University Network</organization>
<address>
<postal>
<street>Thulegatan 11</street>
<city>Stockholm</city>
<country>Sweden</country>
</postal>
<email>leifj@sunet.se</email>
<uri>http://www.sunet.se</uri>
</address>
</author>
<author fullname="Sam Hartman" initials="S. " surname="Hartman">
<organization>Painless Security</organization>
<address>
<postal>
<street></street>
<city></city>
<region></region>
<code></code>
<country></country>
</postal>
<phone></phone>
<facsimile></facsimile>
<email>hartmans-ietf@mit.edu</email>
<uri></uri>
</address>
</author>
<author fullname="Simon Josefsson" initials="S. " surname="Josefsson">
<organization>SJD AB</organization>
<address>
<postal>
<street>Hagagatan 24</street>
<city>Stockholm</city>
<code>113 47</code>
<country>SE</country>
</postal>
<email>simon@josefsson.org</email>
<uri>http://josefsson.org/</uri>
</address>
</author>
<date day="31" month="May" year="2012" />
<area>Security</area>
<workgroup>KITTEN WORKING GROUP</workgroup>
<keyword>Internet-Draft</keyword>
<abstract>
<t>The Generic Security Services API (GSS-API) provides a simple naming
architecture that supports name-based authorization. This document
introduces new APIs that extend the GSS-API naming model to support name
attribute transfer between GSS-API peers.</t>
</abstract>
</front>
<middle>
<section title="Conventions used in this document">
<t>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 <xref
target="RFC2119"></xref> .</t>
</section>
<section title="Introduction">
<t>As described in <xref target="RFC4768"></xref> the GSS-API's naming
architecture suffers from certain limitations. This document defines
concrete GSS-API extensions.</t>
<t>A number of extensions to the GSS-API <xref target="RFC2743"></xref>
and its C Bindings <xref target="RFC2744"></xref> are described herein.
The goal is to make information modeled as "name attributes" available
to applications. Such information MAY for instance be used by
applications to make authorization-decisions. For example, Kerberos V
authorization data elements, both in their raw forms, as well as mapped
to more useful value types, can be made available to GSS-API
applications through these interfaces.</t>
<t>The model is that GSS names have attributes. The attributes of a name
may be authenticated (e.g., an X509 attribute certificate or signed SAML
attribute assertion), or may have been set on a GSS name for the purpose
of locally "asserting" the attribute during credential acquisition or
security context exchange. Name attributes' values are network
representations thereof (e.g., the actual value octets of the contents
of an X.509 certificate extension, for example) and are intended to be
useful for constructing portable access control facilities. Applications
may often require language- or platform-specific data types, rather than
network representations of name attributes, so a function is provided to
obtain objects of such types associated with names and name
attributes.</t>
<t>Future updates of this specification may involve adding an attribute
namespace for attributes that only have application-specific semantics.
Note that mechanisms will still need to know how to transport such
attributes. The IETF may also wish to add functions by which to inquire
whether a mechanism(s) understands a given attribute name or namespace,
and to list which attributes or attribute namespaces a mechanism
understands. Finally, the IETF may want to consider adding a function by
which to determine the name of the issuer of a name attribute.</t>
</section>
<section title="Name Attribute Authenticity">
<t>An attribute is 'authenticated' if and only if there is a secure association
between the attribute (and its values) and the trusted source of the
peer credential. Examples of authenticated attributes are (any part of)
the signed portion of an X.509 certificate or AD-KDCIssued
authorization-data elements in Kerberos V Tickets provided of course
that the authenticity of the respective security associations (e.g.,
signatures) have been verified.</t>
<t>Note that the fact that an attribute is authenticated does not imply
anything about the semantics of the attribute nor that the trusted
credential source was authorized to assert the attribute. Such
interpretations SHOULD be the result of applying local policy to the
attribute.</t>
<t>An un-authenticated attribute is called <spanx style="emph">asserted</spanx>
in what follows. This is not to be confused with other uses of the word
asserted or assertion such as "SAML attribute assertion", the attributes of
which may be authenticated in the sense of this document for instance if
the SAML attribute assertion was signed by a key trusted by the
peer.</t>
</section>
<section title="Name Attributes/Values as ACL Subjects">
<t>To facilitate the development of portable applications that make use
of name attributes to construct and evaluate portable ACLs the GSS-API
makes name attribute values available in canonical network encodings
thereof.</t>
</section>
<section title="Naming Contexts">
<t>Several factors influence the context in which a name attribute is
interpreted. One is the trust context.</t>
<t>As discussed previously, applications apply local policy to determine
whether a particular peer credential issuer is trusted to make a given
statement. Different GSS-API mechanisms and deployments have different
trust models surrounding attributes they provide about a name.</t>
<t>For example, Kerberos deployments in the enterprise typically trust a
KDC to make any statement about principals in a realm. This includes
attributes such as group membership.</t>
<t>In contrast, in a federated SAML environment, the identity provider
typically exists in a different organization than the acceptor. In this
case, the set of group memberships or entitlements that the IDP is
permitted to make needs to be filtered by the policy of the acceptor and
federation.</t>
<t>So even an attribute containing the same information such as e-mail
address would need to be treated differently by the application in the
context of an enterprise deployment from the context of a
federation.</t>
<t>Another aspect related to trust is the role of the credential issuer
in providing the attribute. Consider Kerberos PKINIT <xref
target='RFC4556'/>. In this
protocol, a public key and associated certificate are used to
authenticate to a Kerberos KDC. Consider how attributes related to a
pkinit certificate should be made available in GSS-API authentications
based on the Kerberos ticket. In some deployments the certificate may be
fully trusted; in including the certificate information in the ticket,
the KDC permits the acceptor to trust the information in the certificate
just as if the KDC itself had made these statements. In other
deployments, the KDC may have authorized a hash of the certificate
without evaluating the content of the certificate or generally trusting
the issuing certification authority. In this case, if the certificate were
included in the issued ticket, the KDC would only be making the
statement that the certificate was used in the authentication. This
statement would be authenticated, but would not imply that the KDC
stated particular attributes of the certificate described the
initiator.</t>
<t>Another aspect of context is encoding of the attribute information.
An attribute containing an ASCII <xref target='ANSI.X3-4.1986'/> or UTF-8 <xref target='RFC3629'/> version of an e-mail address
could not be interpreted the same as a ASN.1 Distinguished Encoding
Rules e-mail address in a certificate.</t>
<t>All of these contextual aspects of a name attribute affect whether
two attributes can be treated the same by an application and thus
whether they should be considered the same name attribute. In the
GSS-API naming extensions, attributes that have different contexts MUST
have different names so they can be distinguished by applications. As an
unfortunate consequence of this requirement, multiple attribute names
will exist for the same basic information. That is, there is no single
attribute name for the e-mail address of an initiator. Other aspects of
how mechanisms describe information about subjects would already make
this true. For example, some mechanisms use OIDs to name attributes;
others use URIs.</t>
<t>Local implementations or platforms are likely to have sufficient
policy and information to know when contexts can be treated as the same.
For example the GSS-API implementation may know that a particular
certification authority can be trusted in the context of a pkinit
authentication. The local implementation may have sufficient policy to
know that a particular credential issuer is trusted to make a given
statement. In order to take advantage of this local knowledge within the
GSS-API implementation, naming extensions support the concept of local
attributes in addition to standard attributes. For example, an
implementation might provide a local attribute for e-mail address. The
implementation would specify the encoding and representation of this
attribute; mechanism-specific standards attributes would be re-encoded
if necessary to meet this representation. Only e-mail addresses in
contexts that meet the requirements of local policy would be mapped into
this local attribute.</t>
<t>Such local attributes inherently expose a tradeoff between
interoperability and usability. Using a local attribute in an
application requires knowledge of the local implementation. However
using a standardized attribute in an application requires more knowledge
of policy and more validation logic in the application. Sharing this
logic in the local platform provides more consistency across
applications as well as reducing implementation costs. Both options are
needed.</t>
</section>
<section title="Representation of Attribute Names">
<t>Different underlying mechanisms (e.g., SAML or X.509 certificates)
provide different representations for the names of their attribute. In
X.509 certificates, most objects are named by object identifiers (OIDs).
The type of object (certificate extension, name constraint,
keyPurposeID, etc) along with the OID is sufficient to identify the
attribute. By contrast, according to Section 8.2 and 2.7.3.1 of <xref
target="OASIS.saml-core-2.0-os"></xref>, the name of an attribute has
two parts. The first is a URI describing the format of the name. The
second part, whose form depends on the format URI, is the actual name.
In other cases an attribute might represent a certificate that plays
some particular role in a GSS-API mechanism; such attributes might have
a simple mechanism-defined name.</t>
<t>Attribute names MUST support multiple components. If there are more
than one component in an attribute name, the more significant components
define the semantics of the less significant components.</t>
<t>Attribute names are represented as OCTET STRING elements in the API
described below. These attribute names have syntax and semantics that
are understood by the application and by the lower-layer implementations
(some of which are described below).</t>
<t>If an attribute name contains a space (ASCII 0x20), the first space
separates the most significant or primary component of the name from the
remainder. We may refer to the primary component of the attribute
name as the attribute name's "prefix". If there is no space, the
primary component is the entire name, otherwise it defines the
interpretation of the remainder of the name.s</t>
<t>If the primary component contains an ASCII : (0x3a), then the primary
component is a URI. Otherwise, the attribute is a local attribute and
the primary component has meaning to the implementation of GSS-API or to
the specific configuration of the application. Local attribute
names with an at-sign ('@') in them are reserved for future allocation by
the IETF.</t>
<t>Since attribute names are split at the first space into prefix
and suffix, there is a potential for ambiguity if a mechanism
blindly passes through a name attribute whose name it does not
understand. In order to prevent such ambiguities the mechanism
MUST always prefix raw name attributes with a prefix that reflects
the context of the attribute.</t>
<t>Local attribute names under the control of an administrator or a
sufficiently trusted part of the platform need not have a prefix to
describe context.</t>
</section>
<section title="API">
<section title="SET OF OCTET STRING">
<t>The construct SET OF OCTET STRING occurs once in <xref
target="RFC2743">RFC 2743</xref> where it is used to represent a set
of status strings in the GSS_Display_status call. The Global Grid
Forum has defined SET OF OCTET STRING as a buffer-set type in <xref
target="GFD.024">GFD.024</xref> which also provides one API for memory
management of these structures. The normative reference to <xref
target="GFD.024">GFD.024</xref> is for the buffer set functions
defined in section 2.5 and the associated buffer set C types defined
in section 6 (namely gss_buffer_set_desc, gss_buffer_set_t,
gss_create_empty_buffer_set, gss_add_buffer_set_member,
gss_release_buffer_set). Nothing else from GFD.024 is required to
implement this document. In particular, that document specify changes
in behaviour existing GSS-API functions in section 3: implementing
those changes are not required to implement this document. Any
implementation of SET OF OCTET STRING for use by this specification
MUST preserve order.</t>
</section>
<section title="Const types">
<t>The C bindings for the new APIs uses some types from <xref
target="RFC5587"></xref> to avoid issues with the use of "const". The
normative reference to <xref target="RFC5587"></xref> is for the C
types specified in Figure 1 of 3.4.6, nothing else from that document
is required to implement this document.</t>
</section>
<section title="GSS_Display_name_ext()">
<t>Inputs: <vspace blankLines="1" /> <list style="symbols">
<t>name INTERNAL NAME,</t>
<t>display_as_name_type OBJECT IDENTIFIER</t>
</list></t>
<t>Outputs: <vspace blankLines="1" /> <list style="symbols">
<t>major_status INTEGER,</t>
<t>minor_status INTEGER,</t>
<t>display_name OCTET STRING -- caller must release with
GSS_Release_buffer()</t>
</list></t>
<t>Return major_status codes: <list style="symbols">
<t>GSS_S_COMPLETE indicates no error.</t>
<t>GSS_S_UNAVAILABLE indicates that the given name could not be
displayed using the syntax of the given name type.</t>
<t>GSS_S_FAILURE indicates a general error.</t>
</list></t>
<t>This function displays a given name using the given name syntax, if
possible. This operation may require mapping Mechanism Names (MNs) to
generic name syntaxes or generic name syntaxes to mechanism-specific
name syntaxes; such mappings may not always be feasible and MAY be
inexact or lossy, therefore this function may fail.</t>
<section title="C-Bindings">
<t>The display_name buffer is de-allocated by the caller with
gss_release_buffer.</t>
<figure>
<artwork><![CDATA[
OM_uint32 gss_display_name_ext(
OM_uint32 *minor_status,
gss_const_name_t name,
gss_const_OID display_as_name_type,
gss_buffer_t display_name
);
]]></artwork>
</figure>
</section>
</section>
<section title="GSS_Inquire_name()">
<t>Inputs: <vspace blankLines="1" /> <list style="symbols">
<t>name INTERNAL NAME</t>
</list></t>
<t>Outputs: <vspace blankLines="1" /> <list style="symbols">
<t>major_status INTEGER,</t>
<t>minor_status INTEGER,</t>
<t>name_is_MN BOOLEAN,</t>
<t>mn_mech OBJECT IDENTIFIER,</t>
<t>attrs SET OF OCTET STRING -- the caller is responsible for
de-allocating memory using GSS_Release_buffer_set</t>
</list></t>
<t>Return major_status codes: <list style="symbols">
<t>GSS_S_COMPLETE indicates no error.</t>
<t>GSS_S_FAILURE indicates a general error.</t>
</list></t>
<t>This function outputs the set of attributes of a name. It also
indicates if a given name is an Mechanism Name (MN) or not and, if it
is, what mechanism it's an MN of.</t>
<section title="C-Bindings">
<figure>
<artwork><![CDATA[
OM_uint32 gss_inquire_name(
OM_uint32 *minor_status,
gss_const_name_t name,
int *name_is_MN,
gss_OID *MN_mech,
gss_buffer_set_t *attrs
);
]]></artwork>
</figure>
<t>The gss_buffer_set_t is used here as the C representation of SET
OF OCTET STRING. This type is used to represent a set of attributes
and is a NULL-terminated array of gss_buffer_t. The gss_buffer_set_t
type and associated API is defined in <xref
target="GFD.024">GFD.024</xref>. The "attrs" buffer set is
de-allocated by the caller using gss_release_buffer_set().</t>
</section>
</section>
<section title="GSS_Get_name_attribute()">
<t>Inputs: <vspace blankLines="1" /> <list style="symbols">
<t>name INTERNAL NAME,</t>
<t>attr OCTET STRING</t>
</list></t>
<t>Outputs: <vspace blankLines="1" /> <list style="symbols">
<t>major_status INTEGER,</t>
<t>minor_status INTEGER,</t>
<t>authenticated BOOLEAN, -- TRUE if and only if authenticated by the trusted
peer credential source.</t>
<t>complete BOOLEAN -- TRUE if and only if this represents a complete set of
values for the name.</t>
<t>values SET OF OCTET STRING -- the caller is responsible for
de-allocating memory using GSS_Release_buffer_set.</t>
<t>display_values SET OF OCTET STRING -- the caller is responsible
for de-allocating memory using GSS_Release_buffer_set</t>
</list></t>
<t>Return major_status codes: <list style="symbols">
<t>GSS_S_COMPLETE indicates no error.</t>
<t>GSS_S_UNAVAILABLE indicates that the given attribute OID is not
known or set.</t>
<t>GSS_S_FAILURE indicates a general error.</t>
</list></t>
<t>This function outputs the value(s) associated with a given GSS name
object for a given name attribute.</t>
<t>The complete flag denotes that (if TRUE) the set of values
represents a complete set of values for this name. The peer being an
authoritative source of information for this attribute is a sufficient
condition for the complete flag to be set by the peer.</t>
<t>In the federated case when several peers may hold some of the
attributes about a name this flag may be highly dangerous and SHOULD
NOT be used.</t>
<t>NOTE: This function relies on the GSS-API notion of "SET OF"
allowing for order preservation; this has been discussed on the KITTEN
WG mailing list and the consensus seems to be that, indeed, that was
always the intention. It should be noted however that the order
presented does not always reflect an underlying order of the mechanism
specific source of the attribute values.</t>
<section title="C-Bindings">
<t>The C-bindings of GSS_Get_name_attribute() requires one function
call per-attribute value, for multi-valued name attributes. This is
done by using a single gss_buffer_t for each value and an
input/output integer parameter to distinguish initial and subsequent
calls and to indicate when all values have been obtained.</t>
<t>The 'more' input/output parameter should point to an integer
variable whose value, on first call to gss_get_name_attribute() MUST
be -1, and whose value upon function call return will be non-zero to
indicate that additional values remain, or zero to indicate that no
values remain. The caller should not modify this parameter after the
initial call. The status of the complete and authenticated flags
MUST NOT change between multiple calls to iterate over values for an
attribute.</t>
<t>The output buffers "value" and "display_value" are de-allocated
by the caller using gss_release_buffer().</t>
<figure>
<artwork><![CDATA[
OM_uint32 gss_get_name_attribute(
OM_uint32 *minor_status,
gss_const_name_t name,
gss_const_buffer_t attr,
int *authenticated,
int *complete,
gss_buffer_t value,
gss_buffer_t display_value,
int *more
);
]]></artwork>
</figure>
</section>
</section>
<section title="GSS_Set_name_attribute()">
<t>Inputs: <vspace blankLines="1" /> <list style="symbols">
<t>name INTERNAL NAME,</t>
<t>complete BOOLEAN, -- TRUE if and only if this represents a complete set of
values for the name.</t>
<t>attr OCTET STRING,</t>
<t>values SET OF OCTET STRING</t>
</list></t>
<t>Outputs: <vspace blankLines="1" /> <list style="symbols">
<t>major_status INTEGER,</t>
<t>minor_status INTEGER</t>
</list></t>
<t>Return major_status codes: <list style="symbols">
<t>GSS_S_COMPLETE indicates no error.</t>
<t>GSS_S_UNAVAILABLE indicates that the given attribute NAME is
not known or could not be set.</t>
<t>GSS_S_FAILURE indicates a general error.</t>
</list>When the given NAME object is an MN this function MUST fail
(with GSS_S_FAILURE) if the mechanism for which the name is an MN does
not recognize the attribute name or the namespace it belongs to. This
is because name attributes generally have some semantics that
mechanisms must understand.</t>
<t>On the other hand, when the given name is not an MN this function
MAY succeed even if none of the available mechanisms understand the
given attribute, in which subsequent credential acquisition attempts
(via GSS_Acquire_cred() or GSS_Add_cred()) with the resulting name
MUST fail for mechanisms that do not understand any one or more name
attributes set with this function. Applications may wish to use a
non-MN, then acquire a credential with that name as the desired name.
The acquired credentials will have elements only for the mechanisms
that can carry the name attributes set on the name.</t>
<t>Note that this means that all name attributes are locally critical:
the mechanism(s) must understand them. The reason for this is that
name attributes must necessarily have some meaning that the mechanism
must understand, even in the case of application-specific attributes
(in which case the mechanism must know to transport the attribute to
any peer). However, there is no provision to ensure that peers
understand any given name attribute. Individual name attributes may be
critical with respect to peers, and the specification of the attribute
will have to indicate which of the mechanism's protocol or the
application is expected to enforce criticality.</t>
<t>The complete flag denotes that (if TRUE) the set of values
represents a complete set of values for this name. The peer being an
authoritative source of information for this attribute is a sufficient
condition for the complete flag to be set by the peer.</t>
<t>In the federated case when several peers may hold some of the
attributes about a name this flag may be highly dangerous and SHOULD
NOT be used.</t>
<t>NOTE: This function relies on the GSS-API notion of "SET OF"
allowing for order preservation; this has been discussed on the KITTEN
WG mailing list and the consensus seems to be that, indeed, that was
always the intention. It should be noted that underlying mechanisms
may not respect the given order.</t>
<section title="C-Bindings">
<t>The C-bindings of GSS_Set_name_attribute() requires one function
call per-attribute value, for multi-valued name attributes -- each
call adds one value. To replace an attribute's every value delete
the attribute's values first with GSS_Delete_name_attribute().</t>
<figure>
<artwork><![CDATA[
OM_uint32 gss_set_name_attribute(
OM_uint32 *minor_status,
gss_const_name_t name,
int complete,
gss_const_buffer_t attr,
gss_const_buffer_t value
);
]]></artwork>
</figure>
</section>
</section>
<section title="GSS_Delete_name_attribute()">
<t>Inputs: <vspace blankLines="1" /> <list style="symbols">
<t>name INTERNAL NAME,</t>
<t>attr OCTET STRING,</t>
</list></t>
<t>Outputs: <vspace blankLines="1" /> <list style="symbols">
<t>major_status INTEGER,</t>
<t>minor_status INTEGER</t>
</list></t>
<t>Return major_status codes: <list style="symbols">
<t>GSS_S_COMPLETE indicates no error.</t>
<t>GSS_S_UNAVAILABLE indicates that the given attribute NAME is
not known.</t>
<t>GSS_S_UNAUTHORIZED indicates that a forbidden delete operation
was attempted, such as deleting a negative attribute.</t>
<t>GSS_S_FAILURE indicates a general error.</t>
</list></t>
<t>Deletion of negative authenticated attributes from NAME objects
MUST NOT be allowed and must result in a GSS_S_UNAUTHORIZED.</t>
<section title="C-Bindings">
<figure>
<artwork><![CDATA[
OM_uint32 gss_delete_name_attribute(
OM_uint32 *minor_status,
gss_const_name_t name,
gss_const_buffer_t attr
);
]]></artwork>
</figure>
</section>
</section>
<section title="GSS_Export_name_composite()">
<t>Inputs: <vspace blankLines="1" /> <list style="symbols">
<t>name INTERNAL NAME</t>
</list></t>
<t>Outputs: <vspace blankLines="1" /> <list style="symbols">
<t>major_status INTEGER,</t>
<t>minor_status INTEGER,</t>
<t>exp_composite_name OCTET STRING -- the caller is responsible
for de-allocating memory using GSS_Release_buffer</t>
</list></t>
<t>Return major_status codes: <list style="symbols">
<t>GSS_S_COMPLETE indicates no error.</t>
<t>GSS_S_FAILURE indicates a general error.</t>
</list></t>
<t>This function outputs a token which can be imported with
GSS_Import_name(), using GSS_C_NT_COMPOSITE_EXPORT as the name type
and which preserves any name attribute information (including the
authenticated/complete flags) associated with the input name (which
GSS_Export_name() may well not). The token format is not specified
here as this facility is intended for inter-process communication
only; however, all such tokens MUST start with a two-octet token ID,
hex 04 02, in network byte order.</t>
<t>The OID for GSS_C_NT_COMPOSITE_EXPORT is <TBD>.</t>
<section title="C-Bindings">
<t>The "exp_composite_name" buffer is de-allocated by the caller
with gss_release_buffer.</t>
<figure>
<artwork><![CDATA[
OM_uint32 gss_export_name_composite(
OM_uint32 *minor_status,
gss_const_name_t name,
gss_buffer_t exp_composite_name
);
]]></artwork>
</figure>
</section>
</section>
</section>
<section title="IANA Considerations">
<t>This specification has no actions for IANA.</t>
<t>This document creates a namespace of GSS-API name attributes.
Attributes are named by URIs, so no single authority is technically
needed for allocation. However future deployment experience may indicate
the need for an IANA registry for URIs used to reference names specified
by IETF standards. It is expected that this will be a registry of URNs
but this document provides no further guidance on this registry.</t>
</section>
<section title="Security Considerations">
<t>This document extends the GSS-API naming model to include support for
name attributes. The intention is that name attributes are to be used as
a basis for (among other things) authorization decisions or
personalization for applications relying on GSS-API security
contexts.</t>
<t>The security of the application may be critically dependent on the
security of the attributes. This document classifies attributes as
asserted or authenticated. Asserted (non-authenticated) attributes MUST
NOT be used if the attribute has security implications for the
application (e.g., authorization decisions) since asserted attributes may
easily be controlled by the peer directly.</t>
<t>It is important to understand the meaning of 'authenticated' in this
setting. Authenticated does not imply that any semantic of the attribute
is claimed to be true. The only implication is that a trusted third
party has asserted the attribute as opposed to the attribute being
asserted by the peer itself. Any additional semantics are always the
result of applying policy. For instance in a given deployment the mail
attribute of the subject may be authenticated and sourced from an email
system where 'authoritive' values are kept. In another situation users
may be allowed to modify their mail addresses freely. In both cases the
'mail' attribute may be authenticated by virtue of being included in
signed SAML attribute assertions or by other means authenticated by the
underlying mechanism.</t>
<t>When the underlying security mechanism does not provide a permanent
unique identity (e.g., anonymous kerberos), GSS-API naming extensions
may be used to provide a permanent unique identity attribute. This may
be a globally unique identifier, a value unique within the namespace of
the attribute issuer, or a "directed" identifier that is unique per peer
acceptor identity. SAML, to use one example technology, offers a number
of built-in constructs for this purpose, such as a <NameID> with a
Format of "urn:oasis:names:tc:SAML:2.0:nameid-format:persistent". SAML
deployments also typically make use of domain-specific attribute types
that can serve as identifiers.</t>
</section>
</middle>
<back>
<references title="Normative References">
&rfc2119;
&rfc2743;
&rfc2744;
&rfc5587;
<reference anchor="GFD.024">
<front>
<title>GSS-API Extensions</title>
<author fullname="Samuel Meder">
<organization>Argonne National Laboratory</organization>
</author>
<author fullname="Von Welch">
<organization>National Center for Supercomputing
Applications</organization>
<address>
<postal>
<street></street>
<city></city>
<region></region>
<code></code>
<country></country>
</postal>
<phone></phone>
<facsimile></facsimile>
<email></email>
<uri></uri>
</address>
</author>
<author fullname="Steven Tuecke">
<organization>Argonne National Laboratory</organization>
<address>
<postal>
<street></street>
<city></city>
<region></region>
<code></code>
<country></country>
</postal>
<phone></phone>
<facsimile></facsimile>
<email></email>
<uri></uri>
</address>
</author>
<author fullname="Doug Engert">
<organization>Argonne National Laboratory</organization>
<address>
<postal>
<street></street>
<city></city>
<region></region>
<code></code>
<country></country>
</postal>
<phone></phone>
<facsimile></facsimile>
<email></email>
<uri></uri>
</address>
</author>
<date month="June" year="2004" />
</front>
<seriesInfo name="GFD" value="GFD.024" />
<format target="http://www.ggf.org/documents/GFD.24.pdf" type="PDF" />
</reference>
</references>
<references title="Informative References">
&rfc4768;
&rfc4556;
&saml-core;
&saml-bindings;
&ascii;
&rfc3629;
</references>
</back>
</rfc>
| PAFTECH AB 2003-2026 | 2026-04-23 21:42:19 |