Internet Engineering Task Force (IETF) K. LI, Ed.

Internet Engineering Task Force (IETF) K. LI, Ed.
Request for Comments: 7642 Alibaba Group
Category: Informational P. Hunt
ISSN: 2070-1721 Oracle
B. Khasnabish
ZTE (TX) Inc.
A. Nadalin
Microsoft
Z. Zeltsan
Individual
September 2015

System for Cross-domain Identity Management:
Definitions, Overview, Concepts, and Requirements

Abstract

This document provides definitions and an overview of the System for
Cross-domain Identity Management (SCIM). It lays out the system's
concepts, models, and flows, and it includes user scenarios, use
cases, and requirements.

Status of This Memo

This document is not an Internet Standards Track specification; it is
published for informational purposes.

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). Not all documents
approved by the IESG are a candidate for any level of Internet
Standard; see 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/rfc7642.

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Copyright Notice

Copyright (c) 2015 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.

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Table of Contents

1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 4
2. SCIM User Scenarios . . . . . . . . . . . . . . . . . . . . . 5
2.1. Background and Context . . . . . . . . . . . . . . . . . 5
2.2. Model Concepts . . . . . . . . . . . . . . . . . . . . . 5
2.2.1. Triggers . . . . . . . . . . . . . . . . . . . . . . 5
2.2.2. Actors . . . . . . . . . . . . . . . . . . . . . . . 6
2.2.3. Modes and Flows . . . . . . . . . . . . . . . . . . . 7
2.2.4. Bulk and Batch Operational Semantics . . . . . . . . 8
2.3. Flows from Cloud Service Provider to Cloud Service
Provider (CSP->CSP) . . . . . . . . . . . . . . . . . . . 8
2.3.1. CSP->CSP: Create Identity (Push) . . . . . . . . . . 8
2.3.2. CSP->CSP: Update Identity (Push) . . . . . . . . . . 9
2.3.3. CSP->CSP: Delete Identity (Push) . . . . . . . . . . 9
2.3.4. CSP->CSP: SSO Trigger (Push) . . . . . . . . . . . . 9
2.3.5. CSP->CSP: SSO Trigger (Pull) . . . . . . . . . . . . 10
2.3.6. CSP->CSP: Password Reset (Push) . . . . . . . . . . . 10
2.4. Flows from Enterprise Cloud Subscriber to Cloud Service
Provider (ECS->CSP) . . . . . . . . . . . . . . . . . 10
2.4.1. ECS->CSP: Create Identity (Push) . . . . . . . . . . 10
2.4.2. ECS->CSP: Update Identity (Push) . . . . . . . . . . 11
2.4.3. ECS->CSP: Delete Identity (Push) . . . . . . . . . . 11
2.4.4. ECS->CSP: SSO Trigger (Pull) . . . . . . . . . . . . 11
3. SCIM Use Cases . . . . . . . . . . . . . . . . . . . . . . . 11
3.1. Migration of the Identities . . . . . . . . . . . . . . . 11
3.2. Single Sign-On (SSO) Service . . . . . . . . . . . . . . 12
3.3. Provisioning of the User Accounts for a Community of
Interest (COI) . . . . . . . . . . . . . . . . . . . . . 14
3.4. Transfer of Attributes to a Relying Party's Website . . . 15
3.5. Change Notification . . . . . . . . . . . . . . . . . . . 16
4. Security Considerations . . . . . . . . . . . . . . . . . . . 17
5. References . . . . . . . . . . . . . . . . . . . . . . . . . 18
5.1. Normative References . . . . . . . . . . . . . . . . . . 18
5.2. Informative References . . . . . . . . . . . . . . . . . 18
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 18
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 19

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1. Introduction

This document provides the SCIM definitions, overview, concepts,
flows, scenarios, and use cases. It also provides a list of the
requirements derived from the use cases.

The document's objective is to help with understanding of the design
and applicability of the SCIM schema [RFC7643] and SCIM protocol
[RFC7644].

Unlike the practice of some protocols like Application Bridging for
Federated Access Beyond web (ABFAB) and SAML2 WebSSO, SCIM provides
provisioning and de-provisioning of resources in a separate context
from authentication (aka just-in-time provisioning).

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 [RFC2119] when they
appear in ALL CAPS. These words may also appear in this document in
lowercase as plain English words, absent their normative meanings.

Here is a list of acronyms and abbreviations used in this document:

o COI: Community of Interest

o CRM: Customer Relationship Management

o CRUD: Create, Read, Update, Delete

o CSP: Cloud Service Provider

o CSU: Cloud Service User

o ECS: Enterprise Cloud Subscriber

o IaaS: Infrastructure as a Service

o JIT: Just In Time

o PaaS: Platform as a Service

o SaaS: Software as a Service

o SAML: Security Assertion Markup Language

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o SCIM: System for Cross-domain Identity Management

o SSO: Single Sign-On

2. SCIM User Scenarios

2.1. Background and Context

The System for Cross-domain Identity Management (SCIM) specification
is designed to manage user identity in cloud-based applications and
services in a standardized way to enable interoperability, security,
and scalability. The specification suite seeks to build upon
experience with existing schemas and deployments, placing specific
emphasis on simplicity of development and integration, while applying
existing authentication, authorization, and privacy models. The
intent of the SCIM specification is to reduce the cost and complexity
of user management operations by providing a common user schema and
extension model, as well as binding documents to provide patterns for
exchanging this schema using standard protocols. In essence, make it
fast, cheap, and easy to move users in to, out of, and around the
cloud.

The SCIM scenarios are overviews of user stories designed to help
clarify the intended scope of the SCIM effort.

2.2. Model Concepts

2.2.1. Triggers

Quite simply, triggers are actions or activities that start SCIM
flows. Triggers may not be relevant at the protocol level or the
schema level; they really serve to help identify the type or activity
that resulted in a SCIM protocol exchange. Triggers make use of the
traditional provisioning CRUD (Create, Read, Update, Delete)
operations but add additional use-case contexts like SSO (Single-Sign
On) as it is designed to capture a class of use case that makes sense
to the actor requesting it rather than to describe a protocol
operation.

o Create SCIM Identity Resource - Service On-boarding Trigger: A
"create SCIM identity resource" trigger is a service on-boarding
activity in which a business action such as a new hire or new
service subscription is initiated by one of the SCIM Actors. In
the protocol itself, service on-boarding may well be implemented
via the same resource PUT method as a service change. This is
particular to the implementation, and not to the use cases that
drive that implementation.

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o Update SCIM Identity Resource - Service Change Trigger: An "update
SCIM identity resource" trigger is a service change activity as a
result of an identity moving or changing its service level. An
"update SCIM identity" trigger might be the result of a change in
a service subscription level or a change to key identity data used
to denote a service subscription level. Password changes are
specifically called out from other more general identity attribute
changes as they are considered to have specific use-case
differences.

o Delete SCIM Identity Resource - Service Termination Trigger: A
"delete SCIM identity resource" trigger represents a specific and
deliberate action to remove an identity from a given SCIM service
point. At this stage, it is unclear if the SCIM protocol needs to
identify a separate protocol exchange for service suspension
actions. This may be relevant as target services usually
differentiate between these results and thus may require separate
resource representations.

o Single Sign-On (SSO) Trigger - Service Access Request: A "Single
Sign-On" trigger is a special class of activity in which a Create
or Update trigger is initiated during an SSO operational flow.
The implication here is that, as the result of a service access
request by the end user (SSO), defined SCIM protocol exchanges can
be used to initiate SCIM resource CRUD operations somewhere in the
service cloud.

2.2.2. Actors

Actors are the operating parties that take part in both sides of a
SCIM protocol exchange and help identify the source of a given
Trigger. So far, we have identified the following SCIM Actors:

o Cloud Service Provider (CSP): A CSP is the entity operating a
given cloud service. In a SaaS scenario, this is simply the
application provider. In an IaaS or PaaS scenario, the CSP may be
the underlying IaaS/PaaS infrastructure provider or the owner of
the application running on that platform. In all cases, the CSP
is the thing that holds the identity information being operated
upon. Put another way, the CSP really is the service that the end
user interacts with.

o Enterprise Cloud Subscriber (ECS): An ECS represents a middle tier
of aggregation for related identity records. In one of our sample
enterprise SaaS scenarios, the ECS is "Example.com" that
subscribes to a cloud-based CRM service "SaaS-CRM Inc." (the CSP)
for all of its sales staff. The actual Cloud Service Users (CSUs)
are the FooBar Inc. sales staff. The ECS Actor is identified to

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help capture use cases in which a single entity is given
administrative responsibility for other identity accounts. SCIM
may not address the configuration and setup of an ECS within the
CSP, but it does address use cases in which SCIM identity
resources are grouped together and administered as part of some
broader agreement or operational exchange.

o Cloud Service User (CSU): A CSU represents the real cloud service
end user -- i.e., the person logging into and using the cloud
service. As described above, and ECS will typically own or manage
multiple CSU identities, whereas the CSU represents the FooBar
Inc. employee using the cloud service to manage their CRM process.

+---------------------+
| Cloud Service |
| Provider (CSP) |
+---------------------+
|
+--------------------------------+
| |
v v
+----------------+ +----------------+
|Enterprise Cloud| |Enterprise Cloud|
|Subscriber (ECS)| |Subscriber (ECS)|
+----------------+ +----------------+
| |
+----------------+ +----------------+
| | | |
v v v v
+-------------+ +-------------+ +-------------+ +-------------+
|Cloud Service| |Cloud Service| |Cloud Service| |Cloud Service|
| User (CSU) | | User (CSU) | | User (CSU) | | User (CSU) |
+-------------+ +-------------+ +-------------+ +-------------+

Figure 1: SCIM Actors

2.2.3. Modes and Flows

Modes identify the functional intent of a data flow initiated in a
SCIM scenario. The modes identified so far are 'Push' and 'Pull'
referring to pushing data to and pulling data from an authoritative
identity data store.

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In the SCIM scenarios, modes are often used in the context of a flow
between two Actors. For example, one might refer to a Cloud-to-Cloud
Pull exchange. Here one Cloud Service Provider (CSP) is pulling
identity information from another CSP. Commonly referenced flows
are:

o Cloud Service Provider to Cloud Service Provider (CSP->CSP)

o Enterprise Cloud Subscriber to Cloud Service Provider (ECS->CSP)

Modes and flows simply help us understand what is taking place; they
are likely to be technically meaningless at the protocol level, but
they help the reader follow the SCIM scenarios and apply them to
real-world use cases.

2.2.4. Bulk and Batch Operational Semantics

It is assumed that each of the trigger actions outlined in this
document may be part of the larger bulk or batch operation.
Individual SCIM actions should be able to be collected together to
create single protocol exchanges.

The initial focus of SCIM scenarios is on identifying base flows and
single operations. The specific complexity of full bulk and batch
operations is left to a later version of the scenarios or to the main
specification.

2.3. Flows from Cloud Service Provider to Cloud Service Provider
(CSP->CSP)

These scenarios represent flows between two Cloud Service Providers
(CSPs). It is assumed that each CSP maintains an Identity Data Store
for its Cloud Service Users (CSUs). These scenarios address various
joiner, mover, leaver, and JIT triggers, resulting in push and pull
data exchanges between the CSPs.

2.3.1. CSP->CSP: Create Identity (Push)

In this scenario, two CSPs (CSP-1 and CSP-2) have a shared service
agreement in place that requires the exchange of Cloud Service User
(CSU) accounts. CSP-1 receives a Create Identity trigger action from
its Enterprise Cloud Subscriber (ECS-1). CSP-1 creates a local user
account for the new CSU. CSP-1 then pushes the new CSU joiner push
request downstream to CSU-2 and gets confirmation that the account
was successfully created. After receiving the confirmation from CSP-
2, CSP-1 sends an acknowledgment to the requesting ECS.

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2.3.2. CSP->CSP: Update Identity (Push)

In this scenario, two CSPs (CSP-1 and CSP-2) have a shared service
agreement in place that requires the exchange of Cloud Service User
(CSU) accounts. The Enterprise Cloud Subscriber (ECS-1) has already
created an account with CSP-1 and supplied a critical attribute
"department" that is used by CSP-1 to drive service options. CSP-1
then receives an Update Identity trigger action from its Enterprise
Cloud Subscriber (ECS). CSP-1 updates its local directory account
with the new department value. CSP-1 then initiates a separate SCIM
protocol exchange to push the mover change request downstream to CSP-
2. After receiving the confirmation from CSP-2, CSP-1 sends an
acknowledgment to ECS-1.

2.3.3. CSP->CSP: Delete Identity (Push)

In this scenario, two CSPs (CSP-1 and CSP-2) have a shared service
agreement in place that requires the exchange of Cloud Service User
(CSU) accounts. CSP-1 receives a Delete Identity trigger action from
its Enterprise Cloud Subscriber (ECS-1). CSP-1 suspends the local
directory account for the specified CSU account. CSP-1 then pushes a
termination request for the specified CSU account downstream to CSP-2
and gets confirmation that the account was successfully removed.
After receiving the confirmation from CSP-2, CSP-1 finalizes the
deletion operation and sends an acknowledgment to the requesting ECS.

This use case highlights how different CSPs may implement different
operational semantics behind the same SCIM operation. Note CSP-1
suspends the account representation for its service, whereas CPS-2
implements a true delete operation.

2.3.4. CSP->CSP: SSO Trigger (Push)

In this scenario, two CSPs (CSP-1 and CSP-2) have a shared service
agreement in place that requires the exchange of Cloud Service User
(CSU) accounts. However, rather than pre-provisioning accounts from
CSP-1 to CSP-2, CSP-1 waits for a service access request from the end
Cloud Service User (CSU-1) before issuing account creation details to
CSP-2. When the CSU completes a SSO transaction from CSP-1 to CSP-2,
CSP-2 then creates an account for the CSU based on information pushed
to it from CSP-1.

At the protocol level, this class of scenarios may result in the use
of common protocol exchange patterns between CSP-1 and CSP-2.

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2.3.5. CSP->CSP: SSO Trigger (Pull)

In this scenario, two CSPs (CSP-1 and CSP-2) have a shared service
agreement in place that requires the exchange of Cloud Service User
(CSU) accounts. However, rather than pre-provisioning accounts from
CSP-1 to CSP-2, CSP-2 waits for a service access request from the
Cloud Service User (CSU-1) before initiating a Pull request to gather
information about the CSU sufficient to create a local account.

At the protocol level, this class of scenarios may result in the use
of common protocol exchange patterns between CSP-2 and CSP-1.

2.3.6. CSP->CSP: Password Reset (Push)

In this scenario, two CSPs (CSP-1 and CSP-2) have a shared service
agreement in place that requires the exchange of Cloud Service User
(CSU) accounts. CSP-1 wants to change the password for a specific
Cloud Service User (CSU-1). CSP-1 sends a request to CSP-2 to reset
the password value for CSU-1.

At the protocol level, this scenario may result in the same protocol
exchange as any other attribute change request.

2.4. Flows from Enterprise Cloud Subscriber to Cloud Service Provider
(ECS->CSP)

These scenarios represent flows between an Enterprise Cloud
Subscriber (ECS) and a Cloud Service Providers (CSP). It is assumed
that the ECS and the CSP each maintain an information access service
for the relevant Cloud Service Users (CSUs). These scenarios address
various joiner, mover, leaver, and JIT triggers, resulting in push
and pull data exchanges between the ECS and the CSP.

Many of these scenarios are very similar to those defined in
Section 2.3. They are identified separately here so that we may
explore any differences that might emerge.

2.4.1. ECS->CSP: Create Identity (Push)

In this scenario, an Enterprise Cloud Subscriber (ECS-1) maintains a
service with a Cloud Service Provider (CSP-1) that requires the
sharing of various Cloud Service User (CSU) accounts. A new user
joins ECS-1 and so ECS-1 pushes an account creation request to CSP-1,
supplying all required attribute values for the base SCIM schema and
additional values for the extended SCIM schema as required.

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2.4.2. ECS->CSP: Update Identity (Push)

In this scenario, an Enterprise Cloud Subscriber (ECS-1) maintains a
service with Cloud Service Provider (CSP-1) that drives service
definition from a key account schema attribute called Department.
ECS-1 wishes to move a given CSU from Department A to Department B
and so it pushes an attribute update request to the CSP.

2.4.3. ECS->CSP: Delete Identity (Push)

In this scenario, an Enterprise Cloud Subscriber (ECS-1) maintains a
service with a Cloud Service Provider (CSP-1). Upon termination of
one of its employee's employment agreement, ECS-1 sends a suspend
account request to CSP-1. One week later, the ECS wishes to complete
the process by fully removing the Cloud Service User (CSU) account,
so it sends a terminate account request to CSP-1.

2.4.4. ECS->CSP: SSO Trigger (Pull)

In this scenario, an Enterprise Cloud Subscriber (ECS-1) maintains a
service with a Cloud Service Provider (CSP-1). No accounts are
created or exchanged in advance. However, rather than pre-
provisioning accounts from ECS-1 to CSP-1, CSP-1 waits for a service
access request from the Cloud Service User (CSU-1) under the control
domain of ECS-1, before issuing an account Pull request to ECS-1.

3. SCIM Use Cases

This section lists the SCIM use cases.

3.1. Migration of the Identities

Description:

A company SomeEnterprise runs an application ManageThem that relies
on the identity information about its employees (e.g., identifiers,
attributes). The identity information is stored at the cloud
provided by SomeCSP. SomeEnterprise has decided to move identity
information to the cloud of a different provider -- AnotherCSP. In
addition, SomeEnterprise has purchased a second application
ManageThemMore, which also relies on the identity information.
SomeEnterprise is able to move identity information to AnotherCSP
without changing the format of identity information. The application
ManageThemMore is able to use the identity information.

Pre-conditions:

o SomeCSP is a cloud service provider for SomeEnterprise.

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o SomeCSP has a known attribute name and value for the Enterprise
used for managing and transferring data.

o AnotherCSP is a new cloud service provider for SomeEnterprise.

o All involved cloud service providers and applications support the
same standard specifying the format for and actions on the user
(e.g., employee) identity information.

Post-conditions:

o SomeEnterprise has moved its employees' identity information from
SomeCSP to AnotherCSP without making any changes to representation
of identity information.

o Application ManageThemMore is able to use the identity
information.

Requirements:

o SomeEnterprise, the applications ManageThem and ManageThemMore,
and the providers SomeCSP and AnotherCSP support a common standard
for identity information, which specifies the following:

* Format (or schema) for representing user identity information

* Interfaces and protocol for managing user identity information

o Cloud providers shall be able to meet regulatory requirements when
migrating identity information between jurisdictional regions
(e.g., countries and states may have differing regulations on
privacy).

o Cloud providers shall be able to log all actions related to
SomeEnterprise employees' identities.

o The logs should be secure and available for auditing.

3.2. Single Sign-On (SSO) Service

Description:

Bob has an account in an application hosted by a cloud service
provider SomeCSP. SomeCSP has federated its user identities with a
cloud service provider AnotherCSP. Bob requests a service from an
application running on AnotherCSP. The application running on
AnotherCSP, relying on Bob's authentication by SomeCSP and using
identity information provided by SomeCSP, serves Bob's request.

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Pre-conditions:

o Bob's identity information is stored on SomeCSP.

o SomeCSP and AnotherCSP have established trust and federated their
user identities.

o SomeCSP is able to authenticate Bob.

o SomeCSP is able to securely provide the authentication results to
AnotherCSP.

o SomeCSP is able to securely provide Bob's identity information
(e.g., attributes) to AnotherCSP.

o AnotherCSP is able to verify information provided by SomeCSP.

o SomeCSP is able to process the identity information received from
AnotherCSP.

Post-conditions:

Bob has received the requested service from an application running on
AnotherCSP without having to authenticate to that application
explicitly.

Requirements:

o Bob must have an account with SomeCSP.

o SomeCSP and AnotherCSP must establish trust and federate their
user identities.

o SomeCSP must be able to authenticate Bob.

o SomeCSP must be able to securely provide the authentication
results to AnotherCSP.

o SomeCSP must be able to securely provide Bob's identity
information (e.g., attributes) to AnotherCSP.

o AnotherCSP must be able to verify the identity information
provided by SomeCSP.

o SomeCSP must be able to process the identity information received
from AnotherCSP.

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o SomeCSP and AnotherCSP must log information generated by Bob's
actions according to their policies and the trust agreement
between them.

3.3. Provisioning of the User Accounts for a Community of Interest
(COI)

Description:

Organization YourHR provides Human Resources (HR) services to a
Community of Interest (COI) YourCOI. The HR services are offered as
Software as a Service (SaaS) on public and private clouds. YourCOI's
offices are located all over the world. Their Information Technology
(IT) systems may be composed of combinations of the applications
running on private and public clouds along with traditional IT
systems. The local YourCOI offices are responsible for collecting
personal information (i.e., user identities and attributes). YourHR
services provide means for provisioning and distributing the employee
identity information across all YourCOI offices. YourHR also enables
individual users (e.g., employees) to manage personal information
that they are responsible for (e.g., update of an address or a
telephone number).

Pre-conditions:

o YourCOI has a complex infrastructure composed of a large number of
local offices that rely on diverse IT systems.

o YourCOI has contracted YourHR to provide the HR services.

o Each local office has a right to establish a personal account for
an employee.

Post-conditions:

o All personal accounts are globally available to any authorized
user or application across the YourCOI system through the services
provided by YourHR.

o The employees have the ability to manage the part of personal
information that is their responsibility.

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Requirements:

o YourHR must ensure that the local offices generate information
that is provisioned securely and consider privacy requirements in
a timely fashion across systems that may span technical (e.g.,
protocols and applications), administrative (e.g., corporate),
regulatory (e.g., location), and jurisdictional domains.

o Management of personal information must be protected against
unauthorized access and eavesdropping, and it should be
distributed only to authorized parties and services.

o Regulatory requirements shall be met when migrating identity
information between jurisdictional regions (e.g., countries and
states may have differing regulations on privacy).

o All operations with identity data must be securely logged.

o The logs should be available for auditing.

3.4. Transfer of Attributes to a Relying Party's Website

Description:

An end user has an account in a directory service A with one or more
attributes. That user then visits the website of relying party B,
and the website requires attributes of the user. The user selects
some attributes and authorizes the transfer of data via authorization
protocols (e.g., OAuth, SAML), so selected attributes of the user are
transferred from the user's account in directory service A to the
website of replying party B at the time of the user's first visit to
that site.

Pre-conditions:

o User has an account in directory service A.

o User has one or more attributes.

o User visits website of relying party B.

Post-conditions:

Selected attributes of the user are transferred from the user's
account in directory service A to the website of relying party B at
the time of the user's first visit to that site.

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Requirements:

o Relying party B must be able to authenticate the end user.

o Relying party B must be able to securely provide the
authentication results to directory service A.

o Directory service A must be able to securely provide end user's
identity information (e.g., attributes) to relying party B.

o Regulatory requirements shall be met when migrating identity
information between jurisdictional regions (e.g., countries and
states may have differing regulations on privacy).

o Relying parties have to be aware of changes to their cached copy,
as these would potentially cause a state change in other relying
parties.

o A maximum period should be set for the relying party to cache the
information.

3.5. Change Notification

Description:

An end user has an account in a directory service A with one or more
attributes. That user then visits the web site of relying party B.
The website of relying party B queries directory service A for
attributes associated with that user, and related resources.

The attributes of the user change later in directory service A. For
example, the attributes might change if the user changes their name,
has their account disabled, or terminates their relationship with
directory service A. Furthermore, other resources and their
attributes might also change. The directory service A then wishes to
notify the website of relying party B of these changes, as relying
party B might (or might not) have a cache of those attributes, and if
relying party B were aware of these changes to their cached copy, it
would potentially cause a state change in relying party B.

The volume of changes, however, might be substantial, and only some
of the changes may be of interest to relying party B, so directory
service A does not wish to "push" all the changes to B. Instead,
directory service A wishes to notify B that there are changes
potentially of interest, such that B can at an appropriate time
subsequently contact directory service A and retrieve just the subset
of changes of interest to B.

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Note that the user must authorize directory service A to transfer
data to the website, and the user must authorize directory service A
to notify the website.

Pre-conditions:

o User has an account in directory service A.

o User has one or more attributes.

o User visits the website of relying party B.

o The resource being updated is at the website.

Post-conditions:

Directory service A is able to notify relying party B that there are
changes potentially of interest.

Requirements:

o Relying party B must be able to authenticate the end user.

o Relying party B must be able to securely provide the
authentication results to directory service A.

o Directory service A must be able to securely provide end user's
changed identity information (e.g., attributes) to relying party
B.

o Relying party B must be able at an appropriate time to
subsequently contact directory service A and retrieve just the
subset of changes of interest to relying party B.

4. Security Considerations

Authentication and authorization must be guaranteed for the SCIM
operations to ensure that only authenticated entities can perform the
SCIM requests and the requested SCIM operations are authorized.

SCIM resources (e.g., Users and Groups) can contain sensitive
information. Thus, data confidentiality MUST be guaranteed at the
transport layer.

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There can be privacy issues that go beyond transport security, e.g.,
moving personally identifying information (PII) offshore between
CSPs. Regulatory requirements shall be met when migrating identity
information between jurisdictional regions (e.g., countries and
states may have differing regulations on privacy).

Additionally, privacy-sensitive data elements may be omitted or
obscured in SCIM transactions or stored records to protect these data
elements for a user. For instance, a role-based identifier might be
used in place of an individual's name.

Detailed security considerations are specified in Section 7 of the
SCIM protocol [RFC7644] and Section 9 of the SCIM schema [RFC7643].

5. References

5.1. 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>.

5.2. Informative References

[RFC7643] Hunt, P., Ed., Grizzle, K., Wahlstroem, E., and
C. Mortimore, "System for Cross-domain Identity
Management: Core Schema", RFC 7643, DOI 10.17487/RFC7643,
September 2015, <http://www.rfc-editor.org/info/rfc7643>.

[RFC7644] Hunt, P., Ed., Grizzle, K., Ansari, M., Wahlstroem, E.,
and C. Mortimore, "System for Cross-domain Identity
Management: Protocol", RFC 7644, DOI 10.17487/RFC7644,
September 2015, <http://www.rfc-editor.org/info/rfc7644>.

Acknowledgments

The authors would like to thank Ray Counterman, Richard Fiekowsky,
Bert Greevenbosch, Barry Leiba, Kelly Grizzle, Magnus Nystrom,
Stephen Farrell, Kathleen Moriarty, Benoit Claise, Dapeng Liu, and
Jun Li for their reviews and comments.

Also, thanks to Darran Rolls and Patrick Harding; Section 2 ("SCIM
User Scenarios") is taken from them.

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Authors' Addresses

Kepeng LI (editor)
Alibaba Group
969 Wenyixi Road, Yuhang District
Hangzhou, Zhejiang 311121
China

Email: [email protected]

Phil Hunt
Oracle

Email: [email protected]

Bhumip Khasnabish
ZTE (TX) Inc.
55 Madison Ave, Suite 302
Morristown, New Jersey 07960
United States

Phone: +001-781-752-8003
Email: [email protected], [email protected]
URI: http://tinyurl.com/bhumip/

Anthony Nadalin
Microsoft

Email: [email protected]

Zachary Zeltsan
Individual

Email: [email protected]

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