Preview
Open Original
Workload Identity in Multi System Environments J. Salowey
Internet-Draft CyberArk
Intended status: Informational Y. Rosomakho
Expires: 4 April 2026 Zscaler
H. Tschofenig
H-BRS
1 October 2025
Workload Identity in a Multi System Environment (WIMSE) Architecture
draft-ietf-wimse-arch-06
Abstract
The increasing prevalence of cloud computing and micro service
architectures has led to the rise of complex software functions being
built and deployed as workloads, where a workload is defined as a
running instance of software executing for a specific purpose. This
document discusses an architecture for designing and standardizing
protocols and payloads for c...Workload Identity in Multi System Environments J. Salowey
Internet-Draft CyberArk
Intended status: Informational Y. Rosomakho
Expires: 4 April 2026 Zscaler
H. Tschofenig
H-BRS
1 October 2025
Workload Identity in a Multi System Environment (WIMSE) Architecture
draft-ietf-wimse-arch-06
Abstract
The increasing prevalence of cloud computing and micro service
architectures has led to the rise of complex software functions being
built and deployed as workloads, where a workload is defined as a
running instance of software executing for a specific purpose. This
document discusses an architecture for designing and standardizing
protocols and payloads for conveying workload identity and security
context information.
Discussion Venues
This note is to be removed before publishing as an RFC.
Discussion of this document takes place on the Workload Identity in
Multi System Environments Working Group mailing list
(wimse@ietf.org), which is archived at
https://mailarchive.ietf.org/arch/browse/wimse/.
Source for this draft and an issue tracker can be found at
https://github.com/jsalowey/wimse-arch.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
Salowey, et al. Expires 4 April 2026 [Page 1]
Internet-Draft WIMSE Architecture October 2025
This Internet-Draft will expire on 4 April 2026.
Copyright Notice
Copyright (c) 2025 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 (https://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 Revised BSD License text as
described in Section 4.e of the Trust Legal Provisions and are
provided without warranty as described in the Revised BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Conventions and Definitions . . . . . . . . . . . . . . . . . 3
3. Architecture . . . . . . . . . . . . . . . . . . . . . . . . 5
3.1. Workload Identity Concepts . . . . . . . . . . . . . . . 5
3.1.1. Trust Domain . . . . . . . . . . . . . . . . . . . . 5
3.1.2. Workload Identifier . . . . . . . . . . . . . . . . . 6
3.1.3. Workload Identity Credentials . . . . . . . . . . . . 6
3.2. Workload Identity System Scenarios . . . . . . . . . . . 7
3.2.1. Basic Workload Identity Scenario . . . . . . . . . . 7
3.2.2. Context and workload Identity . . . . . . . . . . . . 10
3.2.3. Cross-Domain Communication . . . . . . . . . . . . . 12
3.3. Workload Identity Use Cases . . . . . . . . . . . . . . . 15
3.3.1. Bootstrapping Workload Identifiers and Credentials . 15
3.3.2. Service Authentication . . . . . . . . . . . . . . . 17
3.3.3. Service Authorization . . . . . . . . . . . . . . . . 18
3.3.4. Audit Trails . . . . . . . . . . . . . . . . . . . . 19
3.3.5. Security Context Establishment and Propagation . . . 20
3.3.6. Service Authorization . . . . . . . . . . . . . . . . 20
3.3.7. Delegation and Impersonation . . . . . . . . . . . . 21
3.3.8. Asynchronous and Batch Requests . . . . . . . . . . . 21
3.3.9. Cross-boundary Workload Identity . . . . . . . . . . 21
3.3.10. AI and ML-Based Intermediaries . . . . . . . . . . . 23
4. Security Considerations . . . . . . . . . . . . . . . . . . . 24
4.1. Traffic Interception . . . . . . . . . . . . . . . . . . 24
4.2. Information Disclosure . . . . . . . . . . . . . . . . . 24
4.3. Credential Theft . . . . . . . . . . . . . . . . . . . . 24
4.4. Workload Compromise . . . . . . . . . . . . . . . . . . . 25
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 25
6. References . . . . . . . . . . . . . . . . . . . . . . . . . 25
6.1. Normative References . . . . . . . . . . . . . . . . . . 25
Salowey, et al. Expires 4 April 2026 [Page 2]
Internet-Draft WIMSE Architecture October 2025
6.2. Informative References . . . . . . . . . . . . . . . . . 26
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 26
Changes since draft -05 . . . . . . . . . . . . . . . . . . . . . 27
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 27
1. Introduction
The increasing prevalence of cloud computing and micro service
architectures has led to the rise of complex software functions being
built and deployed as systems composed of workloads, where a workload
is defined as a running instance of software executing for a specific
purpose.
Workloads need to be provisioned with an identity when they are
started. Often, additional information needs to be provided, such as
trust anchors and security context details. Workloads make use of
identity information and additional context information to perform
authentication and authorization. Workload identity credentials are
used to authenticate communications between workloads.
This architecture considers two ways to express identity information:
X.509 certificates often used in the TLS layer and JSON Web Tokens
(JWTs) used at the application layer. The applicability of given
token format depends on application and security context and will be
explored in later sections.
Once the workload is started and has obtained identity information,
it can start performing its functions. Once the workload is invoked
it may require interaction with other workloads. An example of such
interaction is shown in [I-D.ietf-oauth-transaction-tokens] where an
externally-facing endpoint is invoked using conventional
authorization mechanism, such as an OAuth 2.0 access token. The
interaction with other workload may require the security context
associated with the authorization to be passed along the call chain.
In the rest of the document we describe terminology and use cases,
discuss details of the architecture, and discuss threats.
2. Conventions and Definitions
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in
BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
This document uses the following terms:
Salowey, et al. Expires 4 April 2026 [Page 3]
Internet-Draft WIMSE Architecture October 2025
* Workload
A workload is a running instance of software executing for a specific
purpose. Workload typically interacts with other parts of a larger
system. A workload may exist for a very short duration of time
(fraction of a second) and run for a specific purpose such as to
provide a response to an API request. Other kinds of workloads may
execute for a very long duration, such as months or years. Examples
include database services and machine learning training jobs.
* Security Context
A security context provides information needed for a workload to
perform its function. This information is often used for
authorization, accounting and auditing purposes and often contains
information about the request being made. Some examples include user
information, software and hardware information or information about
what processing has already happened for the request. Different
pieces of context information may originate from different sources.
* Identity Proxy
Identity proxy is an intermediary that can inspect, replace or
augment workload identity and security context information. Identity
proxy can be a capability of a transparent network service, such as a
security gateway, or it can be implemented in a service performing
explicit connection processing, such as an ingress gateway or a
Content Delivery Network (CDN) service. Identity proxy MAY introduce
additional context based on source identifier, communication
properties and administrative policy. This context MAY be
communicated as a transaction token
[I-D.ietf-oauth-transaction-tokens].
* Remote Attestation
The term "attestation", as defined in [RFC9683], refers to the
process of generating and evaluating remote attestation Evidence.
[RFC9334] describes Evidence and the different communication
patterns.
* Workload Identity Credential
Salowey, et al. Expires 4 April 2026 [Page 4]
Internet-Draft WIMSE Architecture October 2025
A credential that contains a workload identifier used for service to
service authentication. The credential is bound to a cryptographic
key and requires that the presenter provide proof of possession of
the secret key material. Examples of this credential include
Workload Identity Certificates and the Workload Identity Token
defined in [I-D.ietf-wimse-s2s-protocol]. Deployments may also
deploy bearer tokens as workload identity credentials to interoperate
with legacy systems that do not support credentials bound to keys.
* Trust Domain
A trust domain is a logical grouping of systems that share a common
set of security controls and policies. As described in
[I-D.ietf-wimse-s2s-protocol], trust domains should be identified by
a fully qualified domain name associated with the organization
defining the trust domain.
3. Architecture
3.1. Workload Identity Concepts
Workload identity construct consists of three basic building blocks:
trust domain, workload identifier and identity credentials. These
components are sufficient for establishing authentication,
authorization and accounting processes. More complex workload
identity constructs can be created from these basic building blocks.
3.1.1. Trust Domain
A trust domain is a logical grouping of systems that share a common
set of security controls and policies. Workload certificates and
tokens are issued under the authority of a trust domain. Trust
domains SHOULD be identified by a fully qualified domain name
associated with the organization defining the trust domain. The FQDN
format of a trust domain helps to ensure global uniqueness of the
trust domain identifier. A trust domain maps to one or more trust
anchors for validating X.509 certificates and a mechanism to securely
obtain a JWK Set [RFC7517] for validating WIMSE WIT tokens. This
mapping MUST be obtained through a secure mechanism that ensures the
authenticity and integrity of the mapping is fresh and not
compromised. This secure mechanism is out of scope for this
document.
A single organization may define multiple trust domains for different
purposes such as different departments or environments. Each trust
domain must have a unique domain identifier. Workload identifiers
are scoped within a trust domain. If two identifiers differ only by
trust domain they still refer to two different entities.
Salowey, et al. Expires 4 April 2026 [Page 5]
Internet-Draft WIMSE Architecture October 2025
3.1.2. Workload Identifier
The WIMSE architecture defines a workload identifier as a URI
[RFC3986]. This URI is used in the subject fields in the
certificates and tokens defined later in this document. The URI MUST
meet the criteria for the URI type of Subject Alternative Name
defined in Section 4.2.1.6 of [RFC5280].
The name MUST NOT be a relative URI, and it MUST follow the URI
syntax and encoding rules specified in [RFC3986]. The name MUST
include both a scheme and a scheme-specific-part.
In addition the URI MUST include an authority that identifies the
trust domain within which the identifier is scoped. The trust domain
SHOULD be a fully qualified domain name belonging to the organization
defining the trust domain to help provide uniqueness for the trust
domain identifier. The scheme and scheme specific part are not
defined by this specification. An example of an identifier format
that conforms to this definition is SPIFFE ID
(https://github.com/spiffe/spiffe/blob/main/standards/SPIFFE-ID.md).
While IP addresses are allowed as host names in the URI encoding
rules, they MUST NOT be used to represent trust domains except in the
case where they are needed for compatibility with legacy naming
schemes.
A workload identifier only has a meaning within the scope of a
specific issuer. Two identities of the same value signed by
different issuers may or may not refer to the same workload. In
order to avoid collisions identity URIs SHOULD specify, in the URI's
"authority" field, the trust domain associated with an issuer that is
selected from a global name space such as host domains. However, the
validator of an identity credential MUST make sure that they are
using the correct issuer credential to verify the identity credential
and that the issuer is trusted to issue tokens for the defined trust
domain.
3.1.3. Workload Identity Credentials
An agent provisions the identity credentials to the workload. These
credentials are represented in form of JWT tokens and/or X.509
certificates.
Salowey, et al. Expires 4 April 2026 [Page 6]
Internet-Draft WIMSE Architecture October 2025
JWT bearer tokens are presented to another party as a proof of
identity. They are signed to prevent forgery, however since these
credentials are often not bound to other information it is possible
that they could be stolen and reused elsewhere. To mitigate these
risks and make the token more generally useful the WIMSE architecture
defines a workload identity credential that binds a JWT to a
cryptographic key.
Both workload identity certificate and workload identity token (WIT)
credentials consist of two parts:
* a certificate or WIT is a signed data structure that contains a
public key and identity information
* a corresponding private key
The workload identity certificate or WIT is presented during
authentication, however the private key is kept secret and only used
in cryptographic computation to prove that the presenter has access
to the private key corresponding to the public key.
3.2. Workload Identity System Scenarios
3.2.1. Basic Workload Identity Scenario
Salowey, et al. Expires 4 April 2026 [Page 7]
Internet-Draft WIMSE Architecture October 2025
+--------------------------------Trust Boundary---------------+
| |
.---+-. |
| .---+-. +--------------+ |
| | | | | (3) |
| | | +---> Workload 1 +-------------------+ |
| | G | | | | | |
| | a | | +-------^------+ | |
| | t | | | | |
+------------+ | | e | | | (1) | |
| | (2) | | w | (3) | | | |
| App Client +----->| | a +-----+ +-------+-------+ | |
| | | | y | | | +-------+------+ |
+------------+ | | +-----+ | CA/Credential | (1) | | |
| | S | (4) | | Service +----------> Workload 3 | |
| | e | | | | | | |
| | r | | +-------+-------+ +-------+------+ |
| | v | | | | |
| | i | | | (1) | |
| | c | | | | |
| | e | | +-------v------+ | |
| | | | | | (4) | |
| | | +---> Workload 2 +-------------------+ |
'-+ | | | |
'-+---' +--------------+ |
| |
| |
| |
+-------------------------------------------------------------+
Figure 1: Basic example workload application system.
The above diagram presents a basic workload application system. The
large box represents a trust domain within which the workload
application is hosted. Within this example there are three
workloads, a gateway service, that accepts external clients and a CA/
credential service that issues workload identity credentials for the
trust domain. External to the workload application system there is
an application client that calls APIs on workloads.
Here is a brief summary of each component
* Trust Domain
The large box represents a trust domain of the application that is
composed of several workloads. A trust domain may have a more
complex internal structure with more workloads, multiple gateways,
internal infrastructure, and other services.
Salowey, et al. Expires 4 April 2026 [Page 8]
Internet-Draft WIMSE Architecture October 2025
* Workload
Three workloads are shown. Each workload is an instance of running
software executing for a specific purpose. Workloads obtain their
identity credentials from a Credentials Service (1) and use them to
authenticate to other workloads and systems in the process of sending
and receiving requests to and from external systems or other internal
workloads.
* Gateway Service
A gateway service typically acts as an intermediary between the
internal application trust domain and external systems. It typically
consists of multiple resilient instances. The gateway is responsible
for ensuring appropriate isolation between external and internal
domains. It also routes incoming requests to the correct workload.
The gateway MAY also implement identity proxy functionality including
authentication, token exchange, and token transformation.
* CA/Credential Service
In this diagram the token/Credential service is a service responsible
for issuing workload identities to workloads in the same trust
domain. The credentials are often X.509 based or JWT based.
High level flows within the diagram
* (1) Workload Identity Credential Distribution
Workloads typically retrieve their workload identity credentials
early in their lifecycle from a credentials service associated with
their trust domain. The protocol interaction for obtaining
credentials varies with deployment and is not detailed here.
* (2) Application client Requests
Clients send API requests to the application. In the example above,
the gateway routes the request to the correct workload. In addition,
the gateway may assist in authenticating the incoming request and
provide information resulting from the authentication to the target
workload. The authentication exchange is not covered in detail in
this example. The client request is typically made over HTTPS, but
other protocols may be used in some systems. The gateway usually
terminates the TLS session so it has visibility into the request in
order to route it correctly.
* (3) API request to workload 1
Salowey, et al. Expires 4 April 2026 [Page 9]
Internet-Draft WIMSE Architecture October 2025
The gateway is configured to forward requests to the correct
workload. The gateway often modifies the request to include specific
authentication information about the application client and to remove
any information that should not be forwarded internally. The gateway
authenticates the workload before forwarding the request. This
authentication usually uses TLS. The target workload may
authenticate the gateway using TLS or some other means. As part of
servicing the request the workload must make a request to another
workload in the system. In this scenario the workload is making a
request to workload 3 over HTTPS. Workload 1 may be able to
authenticate the identity of workload 3 through the TLS protocol to
ensure it is making a request of the right party. Workload 3 will
authenticate workload 1 using its workload identity credentials. If
the Workload Identity Credentials are workload identity certificates
then this can happen through TLS client authentication (mutual TLS).
Alternatively, the workloads can use a JWT based authentication
mechanism to authenticate on another. Workload three can use the
authenticated identity of workload 1 to determine which APIs workload
1 is authorized 2 and to associated the authenticated identity with
logs and other audit information.
* (4) API request to workload 2
Similarly to the previous flow, the gateway may determine that for
another API call, the application client's request needs to be
handled by workload 2. The case behaves the same as the previous
flow except that the gateway may need to authenticate workload 2
before forwarding traffic to it. Workload 3 will then authorize and
audit the request based on the authenticated identity of workload 2.
Workload 2 and workload 1 may be authorized to use different APIs on
workload 3. If workload 1 or 2 makes an API request that it is not
authorized for, then workload 3 will reject the request.
3.2.2. Context and workload Identity
Salowey, et al. Expires 4 April 2026 [Page 10]
Internet-Draft WIMSE Architecture October 2025
+------------------------Trust Boundary---------+
| |
.---+-. +----------------+ |
| .---+-. | | |
| | +------------------>| Context | |
| | | (3) | | |
| | |<------------------+ Service | |
| | | (c) | | |
| | G | +----------------+ |
| | a | |
(1) | | t | |
+-------+ | | e | +------------+ +-------------+ |
| App | (2) | | w | (4) | | (5) | | |
| Client+---->| | a +----->| workload 1 +----->| workload 2 | |
+-------+ (a) | | y | (c) | | (c) | | |
| | | +------------+ +-------------+ |
| | S | |
| | e | |
| | r | |
| | v | |
| | i | |
| | c | |
| | e | |
'-+ | |
'-+---' |
| |
| |
| |
+-----------------------------------------------+
Figure 2: Context example workload application system.
In many cases the application system uses other security context
information about the request during authorization and auditing. The
following is a basic scenario that illustrates the propagation of
security context in the workload system. Some of the components and
interactions have been removed from the previous scenario for
simplicity.
* Context Service This scenario adds a context service component
which is responsible for creating security context based on
authentication and other calculations. Context can be represented
in many ways; it can be a plaintext data structure, a signed data
structure such as a JWT or a pointer used to lookup the context as
a data structure stored somewhere else. In one common example,
creating the context may involve a token exchange converting an
OAuth 2.0 access token into a different token format, such as a
transaction token, that is understood by internal services.
Salowey, et al. Expires 4 April 2026 [Page 11]
Internet-Draft WIMSE Architecture October 2025
* (1) Initial Authentication In the initial authentication the
gateway service obtains credentials it can use with the gateway
service. This authentication may involve several steps and may be
performed by an external entity such as an identity provider. The
authentication process will result in a credential that the
gateway service can evaluate. For example, the credential could
be an OAuth Access token. If the client already has an access
token that it can use to authenticate to the gateway, such as an
X.509 certificate, then it may skip this step.
* (2) Application Client Request The application client makes a
request to the gateway over HTTPS. The client may be
authenticated to the gateway through TLS client authentication
(mutual TLS) or through a credential such as an access token
obtained in step 1.
* (3) Establishing the request context The gateway service requests
a security context token (c) from a token service. This process
may entail sending an access token (a) along with other
information to a token exchange endpoint to obtain the context
token, which contains information about the entity accessing the
system. This context is typically only relevant to the internal
system and is not returned to the client. The gateway may use
alternative mechanisms to get the internal security context
information (c).
* (4) Forwarding Request to Workload The gateway forwards the
request along with the context information (c) to the appropriate
workload. A bearer token, such as an access token (a), is not
usually forwarded as it is only meant for external access. The
workload uses information in the context token in applying
authorization policy to the application client's request. If the
workload does not receive a context token, then it will deny
requests that rely on information from the token.
* (5) Making Additional Workload Originated Requests The workload
may need to make requests of other workloads. When making these
requests, the workload includes the context information so
Workload 2 can authorize and audit the request. Workload 2 may
have a policy requiring Workload 1 to authenticate its service
identity and provide valid context information (c) to access
certain APIs.
3.2.3. Cross-Domain Communication
Salowey, et al. Expires 4 April 2026 [Page 12]
Internet-Draft WIMSE Architecture October 2025
+---------------------------Trust Boundary------+
| |
.---+-. |
| .---+-. |
| | | |
| | G | |
| | a | |
| | t | |
+-------+ | | e | +------------+ +-------------+ |
| App | (1) | | w | (2) | | (4) | | |
| Client+---->| | a +----->| workload 1 +----->| workload 2 | |
+-------+ (a) | | y | (c) | | (c) | | |
| | | +-+----------+ +^----^----+--+ |
| | S | | | | | |
| | e | (3)| (5)(c)|(t) | | |
| | r | | | | | |
| | v | | +-+--------v+ | | |
| | i | | | Token | | | |
| | c | | | | | (7)|(a) |
| | e | | | Service | | | |
'-+ | | +-----------+ | | |
'-+---' | | | |
| | | | |
| | (6)(t)|(a) | |
| | | | |
+------------+-----------------------+----+-----+
| | |
| +-+-------V-+ |
| | External | |
| | Token | |
| | Service | |
| +-----------+ |
| |
+---------v------+ +---------------v-+
| Infrastructure | | External |
| | | |
| Service | | Service |
+----------------+ +-----------------+
Figure 3: External request workload application system.
In many applications workloads must make requests of infrastructure
or external services that operate as a different trust domain. Steps
5-7 of Figure 3 involve a generic cross domain pattern as described
in [I-D.draft-ietf-oauth-identity-chaining]. This document refers to
a token service which performs a similar functions with respect to
token issuance as the authorization service in
[I-D.draft-ietf-oauth-identity-chaining]. The scenario shows some
Salowey, et al. Expires 4 April 2026 [Page 13]
Internet-Draft WIMSE Architecture October 2025
new components described below. Components and interactions from
previous scenarios are still relevant to this example, but are
omitted for simplicity.
* Token Service - the token service is responsible for exchanging
information that is internal to the system such as service
identity and/or security context information for a token that can
be presented to an external token service in another trust domain
to gain access to infrastructure or an external service.
* External Token Service - the external token service is part of
another trust domain. Workloads in the originating trust domain
contact this service to get an access token to authenticate to
external services.
* Infrastructure Service - this service is often part of the
application, but it is managed by an infrastructure provider and
may require different information to access it.
* External Service - this service is distinct from the application
and hosted in a separate trust domain. This trust domain often
has different access requirements that workloads in the internal
trust domain.
Some example interactions in this scenario:
* (1) The application client is making requests with authentication
information as in the other scenarios
* (2) The gateway forwards the request to the appropriate workload
with the security context information
* (3) The workload needs to access an infrastructure service and,
because it is managed by the same organization, it authenticates
to the service directly using its workload credentials.
* (4) Workload 1 contacts Workload 2 to perform an operation. This
request is accompanied by a security context as in the other
scenarios.
* (5) Workload 2 determines it needs to communicate with an external
service. In order to gain access to this service it must first
obtain a token/credential (t) that it can use externally. It
authenticates to the token service using its workload identity
credential (c) and provides security context information. The
token service determines what type of externally usable token to
issue to the workload for use with the external token service.
Salowey, et al. Expires 4 April 2026 [Page 14]
Internet-Draft WIMSE Architecture October 2025
* (6) Workload 2 uses this new token/credential (t) to request an
access token (a) for the external service from the token service.
* (7) Workload 2 uses the access token (a) to access the external
service in the other trust domain.
There can be variations on cross domain workflows. For example, in
step 3 the workload was able to use its Workload Identity Credentials
to directly access an infrastructure service. It also may be
possible for an workload to request an access token for an external
service using its Workload Identity Credentials directly with an
external token service.
3.3. Workload Identity Use Cases
3.3.1. Bootstrapping Workload Identifiers and Credentials
A workload needs to obtain its identifier and associated credentials
early in its lifecycle. It also needs to learn what trust domain it
belongs to. The identifier, trust domain and credentials forms the
basis from which further credentials, attributes, identifiers and
security context are derived.
Identifier and credential bootstrapping often utilizes attribute
information provisioned through mechanisms specific to hosting
platforms and orchestration services. This initial bootstrapping
information is used to issue specific credentials for a workload.
This process may use attestation to ensure the workload receives the
correct identity credentials. An example of a bootstrapping process
follows.
Figure 4 provides an example of software layering at a host running
workloads. During startup, workloads bootstrap their identifiers and
credentials with the help of an agent. The agent may be associated
with one or more workloads to help ensure that workloads are
provisioned with the correct identifiers and credentials. The agent
provides attestation evidence and other relevant information to a
server. The server validates this information and provides the agent
with identifiers and credentials for the workloads it is associated
with. The server can use a variety of internal and external means to
validate the request against policy. After obtaining credentials
from the server, the agent passes them to the workload.
Salowey, et al. Expires 4 April 2026 [Page 15]
Internet-Draft WIMSE Architecture October 2025
+-----------------+
| Server |
| |
| +-------------+ |
| | Attestation | |
| +-------------+ |
+---------+-------+
^ | . .
| | Identity | | Workload
| | Credentials | | to
| | | | Workload
| | | | Communication
+-------+-+------------------------------+-+-----------+
| | | v V |
| | v +----------------+ |
| +----+----------+ +-+--------------+ | |
| | Agent | | Workloads | | |
| | <+--------------+> | | |
| | ^ | Identity | ^ +-+ |
| +------------+--+ Credentials +--+-------------+ |
| | | |
| | | Identity |
| Attestation | | Credentials |
| v v |
+------------------------------------------------------+
| Host Operating System and Hardware |
+------------------------------------------------------+
Figure 4: Host Software Layering in a Workload Identity Architecture.
How the workload obtains its identity credentials and interacts with
the agent is subject to different implementations. Some common
mechanisms for obtaining this initial identity include:
* File System - in this mechanism the identity credential is
provisioned to the workload via the filesystem.
* Local API - the identity credential is provided through an API,
such as a local domain socket (for example SPIFFE or QEMU guest
agent) or network API (for example Cloud Provider Metadata
Server).
* Environment Variables - identity credential may also be injected
into workloads using operating system environment variables.
Salowey, et al. Expires 4 April 2026 [Page 16]
Internet-Draft WIMSE Architecture October 2025
3.3.2. Service Authentication
One of the most basic use cases for workload identity is
authentication of one workload to another, such as in the case where
one service is making a request to another service as part of a
larger, more complex application. Following authentication, the
identity of the peer can be used to enforce fine-grained
authorization policies as described in Section 3.3.3 and generate
audit trails as described in Section 3.3.4.
Authentication mechanisms are used to establish the identity of the
peer workload before secure communication can proceed.
Workloads often obtain their credentials without relying on pre-
provisioned long-lived secrets. Instead, short-lived credentials are
established through mechanisms provided by the infrastructure that
allow a workload to prove it is running in a given environment.
Common delivery patterns are described in Section 3 of
[I-D.ietf-wimse-workload-identity-practices].
Once credentials are issued, they are conveyed to peers using common
security protocols. Typical mechanisms include:
* Mutual TLS authentication using X.509 certificate for both client
and server as described in Section 4 of
[I-D.ietf-wimse-s2s-protocol].
* Application level authentication using cryptographic credentials
passed within HTTP message as described in Section 3 of
[I-D.ietf-wimse-s2s-protocol].
These authentication mechanisms establish a cryptographically
verifiable identity for the communicating party, which can then be
used for further policy enforcement.
Figure 5 illustrates the communication between different workloads.
Two aspects are important to highlight: First, there is a need to
consider the interaction with workloads that are external to the
trust domain (sometimes called cross-domain). Second, the
interaction does not only occur between workloads that directly
interact with each other but instead may also take place across
intermediate workloads (in an end-to-end style).
Salowey, et al. Expires 4 April 2026 [Page 17]
Internet-Draft WIMSE Architecture October 2025
+-----------------+
| Workload |
| (external) |
| ^ |
+-------+---------+
|
|
+-------+-------------------------Trust Boundary---------------+
| | |
| | |
| +----+------+ Hop-by- +-----------+ Hop-by- +-----------+ |
| | v | Hop | | Hop | | |
| | Workload | Security | Workload | Security | Workload | |
| | <+----------+> <+----------+> | |
| | | | | | | |
| | | | | | | |
| | O<-----+----------+-----------+----------+---->O | |
| +-----------+ E2E +-----------+ E2E +-----------+ |
| |
| |
+--------------------------------------------------------------+
Figure 5: Workload-to-Workload Communication.
3.3.3. Service Authorization
Once authentication has successfully established the identity of a
peer workload, authorization mechanisms determine whether the
authenticated identity is permitted to perform the requested action
on the target workload.
Authorization specified by WIMSE is context-aware. It relies on
attributes carried in the security context, which may originate from
upstream systems such as gateways or identity proxies. This context
may be derived from end-user attributes, trust domain policies, or
deployment-specific metadata (e.g., environment, service role,
workload instance).
Authorization decisions typically include:
* Validating the integrity and provenance of the security context.
* Ensuring the authenticated identity has the correct role and
attributes to access the requested API or resource.
* Applying fine-grained policy rules, which may include path,
method, action type, and contextual constraints (e.g., geographic
location, time of day).
Salowey, et al. Expires 4 April 2026 [Page 18]
Internet-Draft WIMSE Architecture October 2025
Authorization checks may also incorporate delegation and
impersonation semantics, as described in Section 3.3.7, where
upstream workloads are authorized to act on behalf of end-users or
other services, within the scope of their issued credentials and
policy.
A key architectural consideration is where authorization is
evaluated. For most workload-to-workload interactions (e.g., REST
APIs, gRPC, or pub/sub flows), authorization is performed by the
callee, ensuring that the target workload enforces its own access
policies. But in some scenarios, such as database access or
operations on complex back-end systems, authorization decisions may
be too fine-grained or application-specific to be enforced by the
subject of the operation. In these cases, authorization MAY be
performed by the caller, provided that the caller has sufficient
context and policy information to make a correct decision.
3.3.4. Audit Trails
Auditability is a critical requirement in systems that rely on
workload identities and security context. Each authenticated request
MUST leave a verifiable and inspectable trace regardless of
authentication and authorization decision.
Audit trails are typically generated at multiple points:
* Gateway Services: Log incoming client requests and their
authenticated identities, including access tokens or client
certificates used.
* Workloads: Log authenticated peer identities, security context
attributes, requested resources, and authorization outcomes.
* Identity and Token Services: Log issuance and validation events
for workload identity credentials and context tokens.
Audit records may include:
* Timestamp of the request
* Source workload identifier
* Target workload identifier
* Authentication method used
* Decision outcome (authorized/denied)
Salowey, et al. Expires 4 April 2026 [Page 19]
Internet-Draft WIMSE Architecture October 2025
* Security context claims
* Delegation/impersonation metadata (if present)
To avoid inadvertent disclosure of sensitive information, workloads
and services generating audit logs MUST NOT log secrets such as
bearer tokens, private keys, or passwords. If logging of credential-
related data is necessary for diagnostic or policy purposes, these
values MUST be redacted, hashed, or otherwise sanitised to prevent
misuse.
WIMSE systems SHOULD ensure audit logs are tamper-evident and
securely stored. Logs may be forwarded to centralized security
information and event management (SIEM) systems to enable compliance,
threat detection, and incident response.
3.3.5. Security Context Establishment and Propagation
In a typical system of workloads additional information is needed in
order for the workload to perform its function. For example, it is
common for a workload to require information about a user or other
entity that originated the request. Other types of information may
include information about the hardware or software that the workload
is running or information about what processing and validation has
already been done to the request. This type of information is part
of the security context that the workload uses during authorization,
accounting and auditing. This context is propagated and possibly
augmented from workload to workload using tokens. The context may be
associated with a specific source or target workload by binding it to
a specific workload identifier. This may indicate that the context
originated from a specific workload, or that only a specific workload
may make use of the context. A workload may also use a workload
identity credential to bind a context to one or more transaction so
the receiver can verify which workload initiated the transaction and
the context that was intended for the transaction.
3.3.6. Service Authorization
After authentication of the peer, a workload can perform
authorization by verifying that the authenticated identity has the
appropriate permissions to access the requested resources and perform
required actions. This process involves evaluating the security
context described previously. The workload validates the security
context, and checks the validity of permissions against its security
policies to ensure that only authorized actions are allowed.
Salowey, et al. Expires 4 April 2026 [Page 20]
Internet-Draft WIMSE Architecture October 2025
3.3.7. Delegation and Impersonation
When source workloads send authenticated requests to destination
workloads, those destination workloads may rely on upstream
dependencies to fulfill such requests. Such access patterns are
increasingly common in a microservices architecture. While X.509
certificates can be used for point-to-point authentication, such
services relying on upstream microservices for answers, may use
delegation and/or impersonation semantics as described in RFC 8693
OAuth 2.0 Access Token Exchange.
WIMSE credentials constrain the subjects and actors identified in
delegation and impersonation tokens to be bound by a trust domain,
and to follow their issuing authorities' trust configurations.
Upstream workloads should consider the security context of delegation
and/or impersonation tokens within and across trust domains, when
arriving at authorization decisions.
3.3.8. Asynchronous and Batch Requests
Source workloads may send authenticated asynchronous and batch
requests to destination workloads. A destination workload may need
to fulfill such requests with requests to authorized upstream
protected resources and workloads, after the source workload
credentials have expired. Credentials identifying the original
source workload as subject may need to be obtained from the
credential issuing authority with appropriately-downscoped context
needed access to upstream workloads. These credentials should
identify the workload as the actor in the actor chain, but may also
identify other principals that the action is taken on behalf. To
mitigate risks associated with long-duration credentials, these
credentials should be bound to the Workload Identity Credential such
as a workload identity certificate or Workload Identity Token (WIT)
of the acting service performing asynchronous computation on the
source workload's behalf.
3.3.9. Cross-boundary Workload Identity
As workloads often need to communicate across trust boundaries, extra
care needs to be taken when it comes to identity communication to
ensure scalability and privacy. (TODO: align with OAuth cross domain
identity and authorization)
Salowey, et al. Expires 4 April 2026 [Page 21]
Internet-Draft WIMSE Architecture October 2025
3.3.9.1. Egress Identity Generalization
A workload communicating with a service or another workload located
outside the trust boundary may need to provide modified identity
information. The detailed identity of an internal workload
originating the communication is relevant inside the trust boundary
but could be excessive for the outside world and expose potentially
sensitive internal topology information.
For example, in a microservices architecture, an internal service may
use workload-specific identities that include fine-grained details
such as instance names or deployment-specific attributes. When
interacting with external systems, exposing such details may
inadvertently provide attackers with insights into the internal
deployment structure, scaling strategies, security policies,
technologies in use, or failover mechanisms, potentially giving them
a tactical advantage. In such cases, an identity proxy at the trust
boundary can generalize the Workload Identity by replacing the
specific microservice instance name with the name of the overall
service. This allows external parties to recognize the service while
abstracting internal deployment details.
A security gateway implementing Identity Proxy functionality at the
edge of a trust boundary can validate identity information of the
workload, perform context-specific authorization of the transaction,
and replace workload-specific identity with a generalized one for a
given trust domain. This approach ensures that external
communications adhere to security and privacy requirements while
maintaining interoperability across trust boundaries.
3.3.9.2. Inbound Gateway Identity Validation
Inbound security gateway is a common design pattern for service
protection. This functionality is often found in CDN services, API
gateways, load balancers, Web Application Firewalls (WAFs) and other
security solutions. Workload identity verification of inbound
requests should be performed as a part of these security services.
After validation of workload identity, the gateway may either leave
it unmodified or replace it with its own identity to be validated by
the dest