]> CyberArk

joe@salowey.net

Zscaler

yaroslavros@gmail.com

Applications and Real-Time Workload Identity in Multi System Environments workload identity The WIMSE architecture defines authentication and authorization for software workloads in a variety of runtime environments, from the most basic ones to complex multi-service, multi-cloud, multi-tenant deployments. This document profiles a workload authentication based on X.509 workload identity certificates using mutual TLS (mTLS). About This Document The latest revision of this draft can be found at . Status information for this document may be found at . Discussion of this document takes place on the Workload Identity in Multi System Environments Working Group mailing list (), which is archived at . Subscribe at . Source for this draft and an issue tracker can be found at .

Introduction This document defines authentication and authorization in the context of interaction between two workloads. This is the core component of the WIMSE architecture . This document focuses on using X.509 workload identity certificates to authenticate the communication between workloads using TLS. The use of TLS for authentication is widely deployed, however it may not be applicable to all environments. For example, some deployments may lack the PKI infrastructure necessary to manage certificates or inter-service communication consists of multiple separate TLS hops. For these cases, other options based on Workload Identity Tokens (WIT) may be more appropriate since they are not based on X.509 certificates and are communicated at the application layer rather than the transport layer.

Deployment Architecture and Message Flow Refer to Sec. 1.2 of for the deployment architecture which is common to all three protection options, including the one described here.

Workload Identity Certificates Workload identity certificates are X.509 certificates that carry workload identifiers as described in section 4.1 of

Conventions and Definitions All terminology in this document follows . 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 when, and only when, they appear in all capitals, as shown here.

Using Mutual TLS for Workload-to-Workload Authentication As noted in the introduction, for many deployments, transport-level protection of application traffic using TLS is ideal.

The Workload Identity Certificate Workload identity certificates are X.509 certificates that carry workload identifiers as described in section 4.1 of

Workload Identity Certificate Validation Workload Identity Certificates may be used to authenticate both the server and client side of the connections. When validating a Workload Identity Certificate, the relying party MUST use the trust anchors configured for the trust domain in the workload identity to validate the peer's certificate. Other PKIX path validation rules apply. Workloads acting as TLS clients and servers MUST validate that the trust domain portion of the Workload Identity Certificate matches the expected trust domain for the other side of the connection. Servers wishing to use the Workload Identity Certificate for authorizing the client MUST require client certificate authentication in the TLS handshake. Other methods of post handshake authentication are not specified by this document. Workload Identity Certificates used by TLS servers SHOULD have the id-kp-serverAuth extended key usage field set and Workload Identity Certificates used by TLS clients SHOULD have the id-kp-clientAuth extended key usage field set. A certificate that is used for both client and server connections may have both fields set. This specification does not make any other requirements beyond on the contents of Workload Identity Certificates or on the certification authorities that issue workload certificates.

Server Name Validation If the WIMSE client uses a hostname to connect to the server and the server certificate contain a DNS SAN the client MUST perform standard host name validation () unless it is configured with the additional information necessary to perform alternate validation of the peer's workload identity. If the client did not perform standard host name validation then the WIMSE client SHOULD further use the workload identifier to validate the server. The host portion of the workload identifier is NOT treated as a host name as specified in section 6.4 of but rather as a trust domain. The server identity is encoded in the path portion of the workload identifier in a deployment specific way. Validating the workload identity could be a simple match on the trust domain and path portions of the identifier or validation may be based on the specific details on how the identifier is constructed. The path portion of the WIMSE identifier MUST always be considered in the scope of the trust domain. In most cases it is preferable to validate the entire workload identifier, see section 1.3 of for additional implementation advice.

Client Authorization Using the Workload Identity The server application retrieves the workload identifier from the client certificate subjectAltName, which in turn is obtained from the TLS layer. The identifier is used in authorization, accounting and auditing. For example, the full workload identifier may be matched against ACLs to authorize actions requested by the peer and the identifier may be included in log messages to associate actions to the client workload for audit purposes. A deployment may specify other authorization policies based on the specific details of how the workload identifier is constructed. The path portion of the workload identifier MUST always be considered in the scope of the trust domain. See section 1.3 of on additional security implications of workload identifiers.

IANA Considerations This document does not include any IANA considerations.

Security Considerations ToDo: perhaps some discussion of certificate lifetimes and their implications, various server name validation choices, implications of middle boxes, etc.

References Normative References In many standards track documents several words are used to signify the requirements in the specification. These words are often capitalized. This document defines these words as they should be interpreted in IETF documents. This document specifies an Internet Best Current Practices for the Internet Community, and requests discussion and suggestions for improvements. RFC 2119 specifies common key words that may be used in protocol specifications. This document aims to reduce the ambiguity by clarifying that only UPPERCASE usage of the key words have the defined special meanings. This memo profiles the X.509 v3 certificate and X.509 v2 certificate revocation list (CRL) for use in the Internet. An overview of this approach and model is provided as an introduction. The X.509 v3 certificate format is described in detail, with additional information regarding the format and semantics of Internet name forms. Standard certificate extensions are described and two Internet-specific extensions are defined. A set of required certificate extensions is specified. The X.509 v2 CRL format is described in detail along with standard and Internet-specific extensions. An algorithm for X.509 certification path validation is described. An ASN.1 module and examples are provided in the appendices. [STANDARDS-TRACK] Many application technologies enable secure communication between two entities by means of Transport Layer Security (TLS) with Internet Public Key Infrastructure using X.509 (PKIX) certificates. This document specifies procedures for representing and verifying the identity of application services in such interactions. This document obsoletes RFC 6125. Informative References CyberArk Zscaler University of Applied Sciences Bonn-Rhein-Sieg 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.

Document History RFC Editor: please remove before publication.

draft-ietf-wimse-mutual-tls-00

• Initial version, extracted from the draft-ietf-wimse-s2s-protocol-07 S2s draft with minimal edits.
• added security consideration for Server Name Validation

Acknowledgments We thank Yaron Sheffer, Arndt Schwenkschuster, Brian Campbell, and Daniel Feldman for their contributions to earlier versions of this document.