This document is an OASIS-Draft and is [largely] in conformance with
relevant OASIS SSTC document standards as described in draft-sstc-doc-guidelines-00.txt.
assertion (aka "security assertion"?)
authn - authentication
authz - authorization
business payload - [Chris F: how is this different or distinguished from "message payload" below?]
message payload - [Chris F: how is this different or distinguished from "business payload" above?]
package -- == assertions [+ entitlements] + payload ? - [Chris F: do we want to use the term "message" here?]
root -- "root of the message" (from mime?)
security package - one or more s2ml documents combined into a single MIME entity.
The high-level goal of the Bindings subcommittee is to specify how..
(1) security assertions are embedded in or combined with other objects (e.g. files of various types), communicated from site to site over various protocols, and subsequently scrutinized, and,
(2) security services defined with SAML as message exchanges
(e.g., the Authz protocol utilized between PDP and PEP in [Use Case 2, Straw2])
are mapped into one or more standard messaging protocols such as SOAP/XP and BEEP.
(1) and (2) MUST be specified in sufficient detail to yield interoperability when independently implemented.
Bindings MUST be specified in enough detail to satisfy the interoperability requirement. The intent here is that such bindings are "recommendations" of the Oasis SSTC; the groups responsible for developing those protocols will be responsible for defining normative bindings with SAML security asssertions. This is facilitated by providing a method for describing and registering bindings.
In case of HTTP, there is a sub-case where the user is utilizing a standard off-the-shelf browser and information about SAML assertions must be conveyed from one site to another through the browser (i.e., there is no direct site-to-site interaction). In this case, we need to ensure that mechanisms for conveying assertions from one site to another be developed that are based on URLs and HTTP headers (e.g., cookies). Both of these entities are strongly size constrained. Representing assertions by some form of "small" fixed-size object is an important consideration here [Section 6.1, S2ML].
[Section 6.2, S2ML] provides some discussion of
a HTTP binding which is not constrained by the use of web browsers.
(b) MIME [Section 6.3 S2ML]
(c) SMTP [Open Issue-2: Relationship to (b) above]
[JeffH: I seriously
wonder if there are any viable use cases for a SMTP binding that aren't
addressed by a definition of MIME packaging for security assertions?][Chris
F: note that BEEP, HTTP and ebXML also leverage or are MIME aware. One
make the same argument for all of these;-)]
When a profile is registered, the following information is supplied: Profile Identification: specify a URI that authoritatively identifies this profile. Message Exchanged during Channel Creation: specify the datatypes that may be exchanged during channel creation. Messages starting one-to-one exchanges: specify the datatypes that may be present when an exchange starts. Messages in positive replies: specify the datatypes that may be present in a positive reply. Messages in negative replies: specify the datatypes that may be present in a negative reply. Messages in one-to-many exchanges: specify the datatypes that may be present in a one-to-many exchange. Message Syntax: specify the syntax of the datatypes exchanged by the profile. Message Semantics: specify the semantics of the datatypes exchanged by the profile. Contact Information: specify the postal and electronic contact information for the author of the profile. 5.2 Feature Registration Template When a feature for the channel management profile is registered, the following information is supplied: Feature Identification: specify a string that identifies this feature. Unless the feature is registered with the IANA, the feature's identification must start with "x-". Feature Semantics: specify the semantics of the feature. Contact Information: specify the postal and electronic contact information for the author of the feature.[JeffH: the below extracted from [SASL] as boilerplate/example text that will need substantial massaging -- but whose underlying concepts are applicable here.]
4. Profiling requirements In order to use this specification, a protocol definition must supply the following information: 1. A service name, to be selected from the IANA registry of "service" elements for the GSSAPI host-based service name form [RFC 2078]. 2. A definition of the command to initiate the authentication protocol exchange. This command must have as a parameter the mechanism name being selected by the client. The command SHOULD have an optional parameter giving an initial response. This optional parameter allows the client to avoid a round trip when using a mechanism which is defined to have the client send data first. When this initial response is sent by the client and the selected mechanism is defined to have the server start with an initial challenge, the command fails. See section 5.1 of this document for further information. 3. A definition of the method by which the authentication protocol exchange is carried out, including how the challenges and responses are encoded, how the server indicates completion or failure of the exchange, how the client aborts an exchange, and how the exchange method interacts with any line length limits in the protocol. 4. Identification of the octet where any negotiated security layer starts to take effect, in both directions. 5. A specification of how the authorization identity passed from the client to the server is to be interpreted. 6. Registration procedures Registration of a SASL mechanism is done by filling in the template in section 6.4 and sending it in to firstname.lastname@example.org. IANA has the right to reject obviously bogus registrations, but will perform no review of clams made in the registration form. There is no naming convention for SASL mechanisms; any name that conforms to the syntax of a SASL mechanism name can be registered. While the registration procedures do not require it, authors of SASL mechanisms are encouraged to seek community review and comment whenever that is feasible. Authors may seek community review by posting a specification of their proposed mechanism as an internet- draft. SASL mechanisms intended for widespread use should be standardized through the normal IETF process, when appropriate. 6.1. Comments on SASL mechanism registrations Comments on registered SASL mechanisms should first be sent to the "owner" of the mechanism. Submitters of comments may, after a reasonable attempt to contact the owner, request IANA to attach their comment to the SASL mechanism registration itself. If IANA approves of this the comment will be made accessible in conjunction with the SASL mechanism registration itself. 6.2. Location of Registered SASL Mechanism List SASL mechanism registrations will be posted in the anonymous FTP directory "ftp://ftp.isi.edu/in-notes/iana/assignments/sasl- mechanisms/" and all registered SASL mechanisms will be listed in the periodically issued "Assigned Numbers" RFC [currently STD 2, RFC 1700]. The SASL mechanism description and other supporting material may also be published as an Informational RFC by sending it to "rfc- email@example.com" (please follow the instructions to RFC authors [RFC 2223]). 6.3. Change Control Once a SASL mechanism registration has been published by IANA, the author may request a change to its definition. The change request follows the same procedure as the registration request. The owner of a SASL mechanism may pass responsibility for the SASL mechanism to another person or agency by informing IANA; this can be done without discussion or review. The IESG may reassign responsibility for a SASL mechanism. The most common case of this will be to enable changes to be made to mechanisms where the author of the registration has died, moved out of contact or is otherwise unable to make changes that are important to the community. SASL mechanism registrations may not be deleted; mechanisms which are no longer believed appropriate for use can be declared OBSOLETE by a change to their "intended use" field; such SASL mechanisms will be clearly marked in the lists published by IANA. The IESG is considered to be the owner of all SASL mechanisms which are on the IETF standards track. 6.4. Registration Template To: firstname.lastname@example.org Subject: Registration of SASL mechanism X SASL mechanism name: Security considerations: Published specification (optional, recommended): Person & email address to contact for further information: Intended usage: (One of COMMON, LIMITED USE or OBSOLETE) Author/Change controller: (Any other information that the author deems interesting may be added below this line.)
[BEEP] The Blocks Extensible Exchange Protocol Core http://www.normos.org/ietf/draft/draft-ietf-beep-framework-11.txt
[S2ML] S2ML: Security Services Markup Language, Version 0.8a, January 8, 2001.
[SASL] Simple Authentication and Security Layer (SASL) http://www.ietf.org/rfc/rfc2222.txt
[Shib] Shiboleth Overview and Requirements
[Straw2] Oasis Security Services Use Cases And Requirements, Straw
Man Draft 2, 9 Feb 2001