rfc9809.original   rfc9809.txt 
LAMPS Working Group H. Brockhaus Internet Engineering Task Force (IETF) H. Brockhaus
Internet-Draft Siemens Request for Comments: 9809 Siemens
Intended status: Standards Track D. Goltzsche Category: Standards Track D. Goltzsche
Expires: 11 October 2025 Siemens Mobility ISSN: 2070-1721 Siemens Mobility
9 April 2025 June 2025
X.509 Extended Key Usage (EKU) for configuration, updates and safety- X.509 Extended Key Usage (EKU) for Configuration, Updates, and Safety
communication Communication
draft-ietf-lamps-automation-keyusages-08
Abstract Abstract
RFC 5280 defines the Extended Key Usage (EKU) extension and several RFC 5280 defines the Extended Key Usage (EKU) extension and specifies
extended key purposes (KeyPurposeIds) for use with that extension in several extended key purpose identifiers (KeyPurposeIds) for use with
X.509 certificates. This document defines KeyPurposeIds for general- that extension in X.509 certificates. This document defines
purpose and trust anchor configuration files, for software and KeyPurposeIds for general-purpose and trust anchor configuration
firmware update packages, and for safety-critical communication to be files, for software and firmware update packages, and for safety-
included in the EKU extension of X.509 v3 public key certificates. critical communication to be included in the EKU extension of X.509
v3 public key certificates.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This is an Internet Standards Track document.
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
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time. It is inappropriate to use Internet-Drafts as reference received public review and has been approved for publication by the
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Internet Standards is available in Section 2 of RFC 7841.
This Internet-Draft will expire on 11 October 2025. Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
https://www.rfc-editor.org/info/rfc9809.
Copyright Notice Copyright Notice
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction
2. Conventions and Definitions . . . . . . . . . . . . . . . . . 4 2. Conventions and Definitions
3. Extended Key Purpose for configuration files, update packages 3. Extended Key Purpose for Configuration Files, Update Packages,
and safety-communication . . . . . . . . . . . . . . . . 4 and Safety Communication
4. Including the Extended Key Purpose in Certificates . . . . . 5 4. Including the Extended Key Purpose in Certificates
5. Implications for a Certification Authority . . . . . . . . . 6 5. Implications for a Certification Authority
6. Security Considerations . . . . . . . . . . . . . . . . . . . 7 6. Security Considerations
7. Privacy Considerations . . . . . . . . . . . . . . . . . . . 7 7. Privacy Considerations
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7 8. IANA Considerations
9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 8 9. References
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 8 9.1. Normative References
10.1. Normative References . . . . . . . . . . . . . . . . . . 8 9.2. Informative References
10.2. Informative References . . . . . . . . . . . . . . . . . 9 Appendix A. ASN.1 Module
Appendix A. ASN.1 Module . . . . . . . . . . . . . . . . . . . . 11 Appendix B. Use Cases
Appendix B. Use Cases . . . . . . . . . . . . . . . . . . . . . 12 Acknowledgments
Appendix C. History of Changes . . . . . . . . . . . . . . . . . 13 Contributors
Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . 15 Authors' Addresses
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 15
1. Introduction 1. Introduction
Key purposes (KeyPurposeIds) added to the certificate's extended key Key purpose identifiers (KeyPurposeIds) added to the certificate's
usage extension as defined in [RFC5280] are meant to express intent EKU extension [RFC5280] are meant to express intent as to the purpose
as to the purpose of the named usage, for humans and for complying of the named usage, for humans and complying libraries. A full list
libraries. A full list of KeyPurposeIds is maintained in the IANA of KeyPurposeIds is maintained in the IANA registry "SMI Security for
registry "SMI Security for PKIX Extended Key Purpose" PKIX Extended Key Purpose" [SMI-PKIX-PURPOSE]. The use of the
[SMI-PKIX-PURPOSE]. The use of the anyExtendedKeyUsage KeyPurposeId, anyExtendedKeyUsage KeyPurposeId, as defined in Section 4.2.1.12 of
as defined in Section 4.2.1.12 of [RFC5280], is generally considered [RFC5280], is generally considered a poor practice.
a poor practice.
This document defines KeyPurposeIds for certificates that are used This document defines KeyPurposeIds for certificates that are used
for the following purposes, among others: for the following purposes, among others:
* Validating signatures of general-purpose software configuration * Validating signatures of general-purpose software configuration
files. files.
* Validating signatures of trust anchor configuration files. * Validating signatures of trust anchor configuration files.
* Validating signatures of software and firmware update packages. * Validating signatures of software and firmware update packages.
skipping to change at page 3, line 21 skipping to change at line 104
type of operations for which a public key contained in the type of operations for which a public key contained in the
certificate can be used in unintended ways, the risk of cross- certificate can be used in unintended ways, the risk of cross-
application attacks is increased. Failure to ensure adequate application attacks is increased. Failure to ensure adequate
segregation of duties means that an application or system that segregation of duties means that an application or system that
generates the public/private keys and applies for a certificate to generates the public/private keys and applies for a certificate to
the operator Certification Authority (CA) could obtain a certificate the operator Certification Authority (CA) could obtain a certificate
that can be misused for tasks that this application or system is not that can be misused for tasks that this application or system is not
entitled to perform. For example, management of trust anchors is a entitled to perform. For example, management of trust anchors is a
particularly critical task. A device could potentially accept a particularly critical task. A device could potentially accept a
trust anchor configuration file signed by a service that uses a trust anchor configuration file signed by a service that uses a
certificate with no Extended Key Usage (EKU) or with the KeyPurposeId certificate with no EKU or with the KeyPurposeIds id-kp-codeSigning
id-kp-codeSigning (Section 4.2.1.12 of [RFC5280]) or id-kp- (Section 4.2.1.12 of [RFC5280]) or id-kp-documentSigning [RFC9336].
documentSigning [RFC9336]. A device should only accept trust anchor A device should only accept trust anchor configuration files if the
configuration files if the file is verified with a certificate that file is verified with a certificate that has been explicitly issued
has been explicitly issued for this purpose. for this purpose.
The KeyPurposeId id-kp-serverAuth (Section 4.2.1.12 of [RFC5280]) can The KeyPurposeId id-kp-serverAuth (Section 4.2.1.12 of [RFC5280]) can
be used to identify that the certificate is for a TLS WWW server, and be used to identify that the certificate is for a TLS WWW server, and
the KeyPurposeId id-kp-clientAuth (Section 4.2.1.12 of [RFC5280]) can the KeyPurposeId id-kp-clientAuth (Section 4.2.1.12 of [RFC5280]) can
be used to identify that the certificate is for a TLS WWW client. be used to identify that the certificate is for a TLS WWW client.
However, there are currently no KeyPurposeIds for usage with X.509 However, there are currently no KeyPurposeIds for usage with X.509
certificates for safety-critical communication. certificates for safety-critical communication.
This document addresses the above problems by defining keyPurposeIds This document addresses the above problems by defining KeyPurposeIds
for the EKU extension of X.509 public key certificates. These for the EKU extension of X.509 public key certificates. These
certificates are either used for signing files (general-purpose certificates are used either for signing files (general-purpose
configuration and trust anchor configuration files, software and configuration files, trust anchor configuration files, and software
firmware update packages) or are used for safety-critical and firmware update packages) or for safety-critical communication.
communication.
Vendor-defined KeyPurposeIds used within a PKI governed by vendors Vendor-defined KeyPurposeIds used within a PKI governed by vendors
typically do not pose interoperability concerns, as non-critical typically do not pose interoperability concerns, as non-critical
extensions can be safely ignored if unrecognized. However, using extensions can be safely ignored if unrecognized. However, using
KeyPurposeIds outside of their intended vendor-controlled environment KeyPurposeIds outside of their intended vendor-controlled environment
or in ExtendedKeyUsage extensions that have been marked critical can or in ExtendedKeyUsage extensions that have been marked critical can
lead to interoperability issues. Therefore, it is advisable not to lead to interoperability issues. Therefore, it is advisable not to
rely on vendor-defined KeyPurposeIds. Instead, this specification rely on vendor-defined KeyPurposeIds. Instead, this specification
defines standard KeyPurposeIds to ensure interoperability across defines standard KeyPurposeIds to ensure interoperability across
various vendors and industries. various vendors and industries.
The definitions of theses KeyPurposeIds are intentionally broad to The definitions of these KeyPurposeIds are intentionally broad to
allow their use in different deployments even though they were allow their use in different deployments even though they were
initially motivated by industrial automation and rail automation, see initially motivated by industrial automation and rail automation (see
Appendix B. The details for each deployment needs to be described in Appendix B). The details for each deployment need to be described in
the relevant technical standards and certificate policies. the relevant technical standards and certificate policies.
2. Conventions and Definitions 2. Conventions and Definitions
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in "OPTIONAL" in this document are to be interpreted as described in
BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here. capitals, as shown here.
This document uses terms defined in [RFC5280]. X.509 certificate This document uses terms defined in [RFC5280]. X.509 certificate
extensions are defined using ASN.1 [X.680] and [X.690]. extensions are defined using ASN.1 [X.680] [X.690].
The term 'safety-critical communication' refers to communication that The term "safety-critical communication" refers to communication that
could, under certain conditions, lead to a state in which human life, could, under certain conditions, lead to a state in which human life,
health, property, or the environment is endangered. For the health, property, or the environment is endangered. For the
definition of 'safety' see [NIST_Glossary] and [ISO.IEC.IEEE_12207]. definition of "safety", see [NIST_Glossary] and [ISO.IEC.IEEE_12207].
3. Extended Key Purpose for configuration files, update packages and 3. Extended Key Purpose for Configuration Files, Update Packages, and
safety-communication Safety Communication
This specification defines the KeyPurposeIds id-kp-configSigning, id- This specification defines the KeyPurposeIds id-kp-configSigning, id-
kp-trustAnchorConfigSigning, id-kp-updatePackageSigning, and id-kp- kp-trustAnchorConfigSigning, id-kp-updatePackageSigning, and id-kp-
safetyCommunication. These KeyPurposeIds are used, respectively, safetyCommunication. These KeyPurposeIds are used, respectively, for
for: signing general-purpose configuration files or trust anchor signing general-purpose configuration files, signing trust anchor
configuration files, signing software or firmware update packages, or configuration files, signing software or firmware update packages,
authenticating communication peers for safety-critical communication. and authenticating communication peers for safety-critical
As described in Section 4.2.1.12 of [RFC5280], "[i]f the [extended communication. As described in Section 4.2.1.12 of [RFC5280], "[i]f
key usage] extension is present, then the certificate MUST only be the [extended key usage] extension is present, then the certificate
used for one of the purposes indicated" and "[i]f multiple [key] MUST only be used for one of the purposes indicated", and "[i]f
purposes are indicated the application need not recognize all multiple [key] purposes are indicated the application need not
purposes indicated, as long as the intended purpose is present". recognize all purposes indicated, as long as the intended purpose is
present".
None of the KeyPurposeIds specified in this document are None of the KeyPurposeIds specified in this document are
intrinsically mutually exclusive. Instead, the acceptable intrinsically mutually exclusive. Instead, the acceptable
combinations of those KeyPurposeIds with others specified in this combinations of those KeyPurposeIds with others specified in this
document and with other KeyPurposeIds specified elsewhere are left to document and with other KeyPurposeIds specified elsewhere are left to
the technical standards of the respective application and the the technical standards of the respective application and the
certificate policy of the respective PKI. For example, a technical certificate policy of the respective PKI. For example, a technical
standard may specify: 'Different keys and certificates must be used standard may specify the following: "Different keys and certificates
for safety communication and for trust anchor updates, and a relying must be used for safety communication and for trust anchor updates,
party must ignore the KeyPurposeId id-kp-trustAnchorConfigSigning if and a relying party must ignore the KeyPurposeId id-kp-
id-kp-safetyCommunication is one of the specified key purposes in a trustAnchorConfigSigning if id-kp-safetyCommunication is one of the
certificate.' The certificate policy for example may specify: 'The specified key purposes in a certificate." For example, the
id-kp-safetyCommunication KeyPuposeId should not be included in an certificate policy may specify the following: "The id-kp-
issued certificate together with the KeyPurposeId id-kp- safetyCommunication KeyPuposeId should not be included in an issued
trustAnchorConfigSigning.' Technical standards and certificate certificate together with the KeyPurposeId id-kp-
trustAnchorConfigSigning." Technical standards and certificate
policies of different applications may specify other rules. Further policies of different applications may specify other rules. Further
considerations on prohibiting combinations of KeyPurposeIds is considerations on prohibiting combinations of KeyPurposeIds is
described in Section 6. described in Section 6.
Systems or applications that verify the signature of a general- Systems or applications that verify the signature of a general-
purpose configuration file or trust anchor configuration file, the purpose configuration file or trust anchor configuration file, the
signature of a software or firmware update package, or the signature of a software or firmware update package, or the
authentication of a communication peer for safety-critical authentication of a communication peer for safety-critical
communication SHOULD require that corresponding KeyPurposeIds be communication SHOULD require that corresponding KeyPurposeIds be
specified by the EKU extension. If the certificate requester knows specified by the EKU extension. If the certificate requester knows
the certificate users are mandated to use these KeyPurposeIds, it the certificate users are mandated to use these KeyPurposeIds, it
MUST enforce their inclusion. Additionally, such a certificate MUST enforce their inclusion. Additionally, such a certificate
requester MUST ensure that the KeyUsage extension be set to requester MUST ensure that the KeyUsage extension be set to
digitalSignature for signature verification, to keyEncipherment for digitalSignature for signature verification, to keyEncipherment for
public key encryption, and keyAgreement for key agreement. public key encryption, and keyAgreement for key agreement.
4. Including the Extended Key Purpose in Certificates 4. Including the Extended Key Purpose in Certificates
[RFC5280] specifies the EKU X.509 certificate extension for use on [RFC5280] specifies the EKU X.509 certificate extension for use on
end entity certificates. The extension indicates one or more end-entity certificates. The extension indicates one or more
purposes for which the certified public key is valid. The EKU purposes for which the certified public key is valid. The EKU
extension can be used in conjunction with the Key Usage (KU) extension can be used in conjunction with the Key Usage (KU)
extension, which indicates the set of basic cryptographic operations extension, which indicates the set of basic cryptographic operations
for which the certified key may be used. The EKU extension syntax is for which the certified key may be used. The EKU extension syntax is
repeated here for convenience: repeated here for convenience:
ExtKeyUsageSyntax ::= SEQUENCE SIZE (1..MAX) OF KeyPurposeId ExtKeyUsageSyntax ::= SEQUENCE SIZE (1..MAX) OF KeyPurposeId
KeyPurposeId ::= OBJECT IDENTIFIER KeyPurposeId ::= OBJECT IDENTIFIER
skipping to change at page 6, line 41 skipping to change at line 268
security(5) mechanisms(5) pkix(7) 3 } security(5) mechanisms(5) pkix(7) 3 }
id-kp-configSigning OBJECT IDENTIFIER ::= { id-kp 41 } id-kp-configSigning OBJECT IDENTIFIER ::= { id-kp 41 }
id-kp-trustAnchorConfigSigning OBJECT IDENTIFIER ::= { id-kp 42 } id-kp-trustAnchorConfigSigning OBJECT IDENTIFIER ::= { id-kp 42 }
id-kp-updatePackageSigning OBJECT IDENTIFIER ::= { id-kp 43 } id-kp-updatePackageSigning OBJECT IDENTIFIER ::= { id-kp 43 }
id-kp-safetyCommunication OBJECT IDENTIFIER ::= { id-kp 44 } id-kp-safetyCommunication OBJECT IDENTIFIER ::= { id-kp 44 }
5. Implications for a Certification Authority 5. Implications for a Certification Authority
The procedures and practices employed by a certification authority The procedures and practices employed by a certification authority
must ensure that the correct values for the EKU extension as well as must ensure that the correct values for the EKU extension and the KU
the KU extension are inserted in each certificate that is issued. extension are inserted in each certificate that is issued. The
The inclusion of the id-kp-configSigning, id-kp- inclusion of the id-kp-configSigning, id-kp-trustAnchorConfigSigning,
trustAnchorConfigSigning, id-kp-updatePackageSigning, and id-kp- id-kp-updatePackageSigning, and id-kp-safetyCommunication
safetyCommunication KeyPurposeIds does not preclude the inclusion of KeyPurposeIds does not preclude the inclusion of other KeyPurposeIds.
other KeyPurposeIds.
6. Security Considerations 6. Security Considerations
The Security Considerations of [RFC5280] are applicable to this The security considerations of [RFC5280] are applicable to this
document. These extended key usage key purposes do not introduce new document. These EKU key purposes do not introduce new security risks
security risks but instead reduce existing security risks by but instead reduce existing security risks by providing the means to
providing the means to identify if a certificate is generated to identify if a certificate is generated to verify the signature of a
verify the signature of a general-purpose or trust anchor general-purpose or trust anchor configuration file, the signature of
configuration file, the signature of a software or firmware update a software or firmware update package, or the authentication of a
package, or the authentication of a communication peer for safety- communication peer for safety-critical communication.
critical communication.
To reduce the risk of specific cross-protocol attacks, the relying To reduce the risk of specific cross-protocol attacks, the relying
party may additionally prohibit use of specific combinations of party may additionally prohibit use of specific combinations of
KeyPurposeIds. The procedure for allowing or disallowing KeyPurposeIds. The procedure for allowing or disallowing
combinations of KeyPurposeIds using excluded KeyPurposeId and combinations of KeyPurposeIds using excluded KeyPurposeId and
permitted KeyPurposeId, as carried out by a relying party, is defined permitted KeyPurposeId, as carried out by a relying party, is defined
in Section 4 of [RFC9336]. The technical standards and certificate in Section 4 of [RFC9336]. The technical standards and certificate
policies of the application should explicitly enumerate requirements policies of the application should explicitly enumerate requirements
for excluded or permitted KeyPurposeIds or their combinations. It is for excluded or permitted KeyPurposeIds or their combinations. It is
out of scope of this document to enumerate those, but an example of out of scope of this document to enumerate those, but an example of
excluded KeyPurposeIds can be the presence of the anyExtendedKeyUsage excluded KeyPurposeIds can be the presence of the anyExtendedKeyUsage
KeyPurposeId. Examples of allowed KeyPurposeIds combinations can be KeyPurposeId. Examples of allowed KeyPurposeIds combinations can be
the presence of id-kp-safetyCommunication together with id-kp- the presence of id-kp-safetyCommunication together with id-kp-
clientAuth or id-kp-serverAuth. clientAuth or id-kp-serverAuth.
7. Privacy Considerations 7. Privacy Considerations
In some protocols, e.g., TLS 1.2 [RFC5246], certificates are In some protocols (e.g., TLS 1.2 [RFC5246]), certificates are
exchanged in the clear. In other protocols, e.g., TLS 1.3 [RFC8446], exchanged in the clear. In other protocols (e.g., TLS 1.3
the certificates are encrypted. The inclusion of the EKU extension [RFC8446]), certificates are encrypted. The inclusion of the EKU
can help an observer determine the purpose of the certificate. In extension can help an observer determine the purpose of the
addition, if the certificate is issued by a public certification certificate. In addition, if the certificate is issued by a public
authority, the inclusion of an EKU extension can help an attacker to certification authority, the inclusion of an EKU extension can help
monitor the Certificate Transparency logs [RFC9162] to identify the an attacker to monitor the Certificate Transparency logs [RFC9162] to
purpose of the certificate which may reveal private information of identify the purpose of the certificate, which may reveal private
the certificate subject. information of the certificate subject.
8. IANA Considerations 8. IANA Considerations
IANA is requested to register the following ASN.1 [X.680] module OID IANA has registered the following ASN.1 [X.680] module OID in the
in the "SMI Security for PKIX Module Identifier" registry "SMI Security for PKIX Module Identifier" registry [SMI-PKIX-MOD].
[SMI-PKIX-MOD]. This OID is defined in Appendix A. This OID is defined in Appendix A.
+=========+=============================+============+
| Decimal | Description | References |
+=========+=============================+============+
| TBD1 | id-mod-config-update-sc-eku | This-RFC |
+---------+-----------------------------+------------+
Table 1
IANA is also requested to register the following OIDs in the "SMI
Security for PKIX Extended Key Purpose" registry [SMI-PKIX-PURPOSE].
These OIDs are defined in Section 4.
+=========+================================+============+ +=========+=============================+===========+
| Decimal | Description | References | | Decimal | Description | Reference |
+=========+================================+============+ +=========+=============================+===========+
| 41 | id-kp-configSigning | This-RFC | | 117 | id-mod-config-update-sc-eku | RFC 9809 |
+---------+--------------------------------+------------+ +---------+-----------------------------+-----------+
| 42 | id-kp-trustAnchorConfigSigning | This-RFC |
+---------+--------------------------------+------------+
| 43 | id-kp-updatePackageSigning | This-RFC |
+---------+--------------------------------+------------+
| 44 | id-kp-safetyCommunication | This-RFC |
+---------+--------------------------------+------------+
Table 2 Table 1
9. Acknowledgments IANA has also registered the following OIDs in the "SMI Security for
PKIX Extended Key Purpose" registry [SMI-PKIX-PURPOSE]. These OIDs
are defined in Section 4.
We would like to thank the authors of [RFC9336] and [RFC9509] for +=========+================================+===========+
their excellent template. | Decimal | Description | Reference |
+=========+================================+===========+
| 41 | id-kp-configSigning | RFC 9809 |
+---------+--------------------------------+-----------+
| 42 | id-kp-trustAnchorConfigSigning | RFC 9809 |
+---------+--------------------------------+-----------+
| 43 | id-kp-updatePackageSigning | RFC 9809 |
+---------+--------------------------------+-----------+
| 44 | id-kp-safetyCommunication | RFC 9809 |
+---------+--------------------------------+-----------+
We also thank all reviewers of this document for their valuable Table 2
feedback.
10. References 9. References
10.1. Normative References 9.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/rfc/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
[RFC5280] Cooper, D., Santesson, S., Farrell, S., Boeyen, S., [RFC5280] Cooper, D., Santesson, S., Farrell, S., Boeyen, S.,
Housley, R., and W. Polk, "Internet X.509 Public Key Housley, R., and W. Polk, "Internet X.509 Public Key
Infrastructure Certificate and Certificate Revocation List Infrastructure Certificate and Certificate Revocation List
(CRL) Profile", RFC 5280, DOI 10.17487/RFC5280, May 2008, (CRL) Profile", RFC 5280, DOI 10.17487/RFC5280, May 2008,
<https://www.rfc-editor.org/rfc/rfc5280>. <https://www.rfc-editor.org/info/rfc5280>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/rfc/rfc8174>. May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[X.680] ITU-T, "Information Technology - Abstract Syntax Notation [X.680] ITU-T, "Information Technology - Abstract Syntax Notation
One (ASN.1): Specification of basic notation", ITU-T One (ASN.1): Specification of basic notation", ITU-T
Recommendation X.680 , February 2021, Recommendation X.680, February 2021,
<https://www.itu.int/rec/T-REC.X.680>. <https://www.itu.int/rec/T-REC-X.680-202102-I/en>.
[X.690] ITU-T, "Information Technology - ASN.1 encoding rules: [X.690] ITU-T, "Information Technology - ASN.1 encoding rules:
Specification of Basic Encoding Rules (BER), Canonical Specification of Basic Encoding Rules (BER), Canonical
Encoding Rules (CER) and Distinguished Encoding Rules Encoding Rules (CER) and Distinguished Encoding Rules
(DER)", ITU-T Recommendation X.690 , February 2021, (DER)", ITU-T Recommendation X.690, February 2021,
<https://www.itu.int/rec/T-REC.X.690>. <https://www.itu.int/rec/T-REC-X.690-202102-I/en>.
10.2. Informative References 9.2. Informative References
[RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security [RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security
(TLS) Protocol Version 1.2", RFC 5246, (TLS) Protocol Version 1.2", RFC 5246,
DOI 10.17487/RFC5246, August 2008, DOI 10.17487/RFC5246, August 2008,
<https://www.rfc-editor.org/rfc/rfc5246>. <https://www.rfc-editor.org/info/rfc5246>.
[RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol [RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol
Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018, Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018,
<https://www.rfc-editor.org/rfc/rfc8446>. <https://www.rfc-editor.org/info/rfc8446>.
[RFC9162] Laurie, B., Messeri, E., and R. Stradling, "Certificate [RFC9162] Laurie, B., Messeri, E., and R. Stradling, "Certificate
Transparency Version 2.0", RFC 9162, DOI 10.17487/RFC9162, Transparency Version 2.0", RFC 9162, DOI 10.17487/RFC9162,
December 2021, <https://www.rfc-editor.org/rfc/rfc9162>. December 2021, <https://www.rfc-editor.org/info/rfc9162>.
[RFC9336] Ito, T., Okubo, T., and S. Turner, "X.509 Certificate [RFC9336] Ito, T., Okubo, T., and S. Turner, "X.509 Certificate
General-Purpose Extended Key Usage (EKU) for Document General-Purpose Extended Key Usage (EKU) for Document
Signing", RFC 9336, DOI 10.17487/RFC9336, December 2022, Signing", RFC 9336, DOI 10.17487/RFC9336, December 2022,
<https://www.rfc-editor.org/rfc/rfc9336>. <https://www.rfc-editor.org/info/rfc9336>.
[RFC9509] Reddy.K, T., Ekman, J., and D. Migault, "X.509 Certificate [RFC9509] Reddy.K, T., Ekman, J., and D. Migault, "X.509 Certificate
Extended Key Usage (EKU) for 5G Network Functions", Extended Key Usage (EKU) for 5G Network Functions",
RFC 9509, DOI 10.17487/RFC9509, March 2024, RFC 9509, DOI 10.17487/RFC9509, March 2024,
<https://www.rfc-editor.org/rfc/rfc9509>. <https://www.rfc-editor.org/info/rfc9509>.
[Directive-2016_797] [Directive-2016_797]
European Parliament, Council of the European Union, European Parliament, Council of the European Union,
"Directive 2016/797 - Interoperability of the rail system "Directive (EU) 2016/797 of the European Parliament and of
within the EU", May 2020, the Council of 11 May 2016 on the interoperability of the
rail system within the European Union", May 2020,
<https://eur-lex.europa.eu/eli/dir/2016/797/2020-05-28>. <https://eur-lex.europa.eu/eli/dir/2016/797/2020-05-28>.
[ERJU] Europe's Rail Joint Undertaking, "Shared Cybersecurity [ERJU] Europe's Rail Joint Undertaking, "Shared Cybersecurity
Services Specification - SP-SEC-ServSpec - V1.0", February Services Specification - SP-SEC-ServSpec - V1.0", February
2025, <https://rail-research.europa.eu/wp- 2025, <https://rail-research.europa.eu/wp-
content/uploads/2025/03/ERJU-SP-Cybersecurity- content/uploads/2025/03/ERJU-SP-Cybersecurity-
Specifications-V1.0.zip>. Specifications-V1.0.zip>.
[ERJU-web] Europe's Rail Joint Undertaking, "Europe’s Rail Joint [ERJU-web] Europe's Rail Joint Undertaking, "Europe's Rail Joint
Undertaking - System Pillar", Undertaking - System Pillar",
<https://rail-research.europa.eu/system_pillar/>. <https://rail-research.europa.eu/system_pillar/>.
[EU-CRA] European Commission, "Proposal for a REGULATION OF THE [EU-CRA] European Commission, "Proposal for a REGULATION OF THE
EUROPEAN PARLIAMENT AND OF THE COUCIL on horizontal EUROPEAN PARLIAMENT AND OF THE COUNCIL on horizontal
cybersecurity requirements for products with digital cybersecurity requirements for products with digital
elements and amending Regulation (EU) 2019/1020", elements and amending Regulation (EU) 2019/1020",
September 2022, <https://digital- September 2022, <https://digital-
strategy.ec.europa.eu/en/library/cyber-resilience-act>. strategy.ec.europa.eu/en/library/cyber-resilience-act>.
[EU-STRATEGY] [EU-STRATEGY]
European Commission, "The EU's Cybersecurity Strategy for European Commission, "The EU's Cybersecurity Strategy for
the Digital Decade", December 2020, <https://digital- the Digital Decade", December 2020, <https://digital-
strategy.ec.europa.eu/en/library/eus-cybersecurity- strategy.ec.europa.eu/en/library/eus-cybersecurity-
strategy-digital-decade-0>. strategy-digital-decade-0>.
[NIST_Glossary] [NIST_Glossary]
NIST CSRC, "Directive (EU) 2022/2555 of the European NIST CSRC, "safety",
Parliament and of the Council", n.d.,
<https://csrc.nist.gov/glossary/term/safety>. <https://csrc.nist.gov/glossary/term/safety>.
[ISO.IEC.IEEE_12207] [ISO.IEC.IEEE_12207]
ISO/IEC/IEEE, "Systems and software engineering – Software ISO/IEC/IEEE, "Systems and software engineering - Software
life cycle processes", December 2024, life cycle processes", ISO/IEC/IEEE 12207:2017, November
<https://www.iso.org/standard/63712.html>. 2017, <https://www.iso.org/standard/63712.html>.
[NIS2] European Commission, "Directive (EU) 2022/2555 of the [NIS2] European Commission, "Directive (EU) 2022/2555 of the
European Parliament and of the Council", December 2024, European Parliament and of the Council", December 2024,
<https://digital-strategy.ec.europa.eu/en/policies/ <https://digital-strategy.ec.europa.eu/en/policies/
nis2-directive>. nis2-directive>.
[IEC.62443-4-2] [IEC.62443-4-2]
IEC, "Security for industrial automation and control IEC, "Security for industrial automation and control
systems - Part 4-2: Technical security requirements for systems - Part 4-2: Technical security requirements for
IACS components", IEC 62443-4-2:2019 , February 2019, IACS components", IEC 62443-4-2:2019, February 2019,
<https://webstore.iec.ch/publication/34421>. <https://webstore.iec.ch/publication/34421>.
[IEC.62443-3-3] [IEC.62443-3-3]
IEC, "Industrial communication networks - Network and IEC, "Industrial communication networks - Network and
system security - Part 3-3: System security requirements system security - Part 3-3: System security requirements
and security levels", IEC 62443-3-3:2013 , August 2013, and security levels", IEC 62443-3-3:2013, August 2013,
<https://webstore.iec.ch/publication/7033>. <https://webstore.iec.ch/publication/7033>.
[CE-marking] [CE-marking]
European Commission, "CE marking", n.d., <https://single- European Commission, "CE marking", <https://single-market-
market-economy.ec.europa.eu/single-market/ce-marking_en>. economy.ec.europa.eu/single-market/ce-marking_en>.
[SMI-PKIX-PURPOSE] [SMI-PKIX-PURPOSE]
IANA, "SMI Security for PKIX Extended Key Purpose", IANA, "SMI Security for PKIX Extended Key Purpose",
<https://www.iana.org/assignments/smi-numbers/smi- <https://www.iana.org/assignments/smi-numbers>.
numbers.xhtml#smi-numbers-1.3.6.1.5.5.7.3>.
[SMI-PKIX-MOD] [SMI-PKIX-MOD]
IANA, "SMI Security for PKIX Module Identifier", IANA, "SMI Security for PKIX Module Identifier",
<https://www.iana.org/assignments/smi-numbers/smi- <https://www.iana.org/assignments/smi-numbers>.
numbers.xhtml#smi-numbers-1.3.6.1.5.5.7.0>.
Appendix A. ASN.1 Module Appendix A. ASN.1 Module
The following module adheres to ASN.1 specifications [X.680] and The following module adheres to ASN.1 specifications [X.680] and
[X.690]. [X.690].
<CODE BEGINS> <CODE BEGINS>
Automation-EKU Automation-EKU
{ iso(1) identified-organization(3) dod(6) internet(1) { iso(1) identified-organization(3) dod(6) internet(1)
security(5) mechanisms(5) pkix(7) id-mod(0) security(5) mechanisms(5) pkix(7) id-mod(0)
id-mod-config-update-sc-eku (TBD1) } id-mod-config-update-sc-eku (117) }
DEFINITIONS IMPLICIT TAGS ::= DEFINITIONS IMPLICIT TAGS ::=
BEGIN BEGIN
-- OID Arc -- OID Arc
id-kp OBJECT IDENTIFIER ::= id-kp OBJECT IDENTIFIER ::=
{ iso(1) identified-organization(3) dod(6) internet(1) { iso(1) identified-organization(3) dod(6) internet(1)
security(5) mechanisms(5) pkix(7) kp(3) } security(5) mechanisms(5) pkix(7) kp(3) }
skipping to change at page 12, line 38 skipping to change at line 503
END END
<CODE ENDS> <CODE ENDS>
Appendix B. Use Cases Appendix B. Use Cases
These use cases are only for informational purposes. These use cases are only for informational purposes.
Automation hardware and software products strive to become more safe Automation hardware and software products strive to become more safe
and secure by fulfilling mandatory, generic system requirements and secure by fulfilling mandatory, generic system requirements
related to cyber security, e.g., driven by federal offices like the related to cybersecurity, e.g., driven by federal offices like the
European Union Cyber Resilience Act [EU-CRA] governed by the European European Union Cyber Resilience Act [EU-CRA] governed by the European
Commission and the High Representative of the Union for Foreign Commission and the High Representative of the Union for Foreign
Affairs and Security Policy. Automation products connected to the Affairs and Security Policy. Automation products connected to the
Internet would bear the so-called CE marking [CE-marking] to indicate Internet would bear the so-called "CE marking" [CE-marking] to
they comply. Such regulation was announced in the 2020 EU indicate they comply. Such regulation was announced in the 2020 EU
Cybersecurity Strategy [EU-STRATEGY], and complements other Cybersecurity Strategy [EU-STRATEGY] and complements other
legislation in this area, like the NIS2 Framework, Directive on legislation in this area, like the NIS2 Framework, Directive on
measures for a high common level of cybersecurity across the Union measures for a high common level of cybersecurity across the Union
[NIS2]. [NIS2].
2020 EU Cybersecurity Strategy [EU-STRATEGY] suggests to implement The 2020 EU Cybersecurity Strategy [EU-STRATEGY] suggests
and extend international standards such as the Security for implementing and extending international standards such as "Security
industrial automation and control systems - Part 4-2: Technical for industrial automation and control systems - Part 4-2: Technical
security requirements for IACS components [IEC.62443-4-2] (IACS security requirements for IACS components" [IEC.62443-4-2] (IACS
refers to industrial automation and control system) and the refers to Industrial Automation and Control System) and "Industrial
Industrial communication networks - Network and system security - communication networks - Network and system security - Part 3-3:
Part 3-3: System security requirements and security levels System security requirements and security levels" [IEC.62443-3-3].
[IEC.62443-3-3]. Automation hardware and software products of Automation hardware and software products of diverse vendors that are
diverse vendors that are connected on automation networks and the connected on automation networks and the Internet can be used to
Internet can be used to build common automation solutions. build common automation solutions. Standardized attributes would
Standardized attributes would allow transparency of security allow transparency of security properties and interoperability for
properties and interoperability for vendors in context of software vendors in the context of software and firmware updates, general-
and firmware updates, general-purpose configuration, trust anchor purpose configuration, trust anchor configuration, and safety
configuration, and safety communication. communication.
A concrete example for automation is a Rail Automation system. The
Europe's Rail web page [ERJU-web] states: "The System Pillar [ERJU]
brings rail sector representatives under a single coordination body.
To achieve this, the System Pillar will deliver a unified operational
concept and a functional, safe and secure system architecture, with
due consideration of cyber-security aspects, focused on the European
railway network to which Directive 2016/797 [Directive-2016_797]
applies (i.e. the heavy rail network) as well as associated
specifications and/or standards."
Appendix C. History of Changes
[RFC Editor: Please remove this appendix in the release version of
the document.]
Changes from 07 -> 08:
* Updated Appendix B
Changes from 06 -> 07:
* Moved Section 1.1 to the Appendix
* Addressed DISCUSS items from Mohamed Boucadair and Paul Wouters
* Addressed AD review comments from Paul Wouters and Orie Steele
* Fixed some minor issues
* Updated reference of EU Rail specification to V1.0
Changes from 05 -> 06:
* Addressed AD review comments from Mike Bishop, Gorry Fairhurst,
Andy Newton, Mohamed Boucadair, Erik Kline, and Eric Vyncke
Changes from 04 -> 05:
* Addressed SECDIR review comments from Carl Wallace
Changes from 03 -> 04:
* Addressed Deb's AD review comments (see "AD Comments on draft-
ietf-lamps-automation-keyusages")
* Added early allocated OIDs
Changes from 02 -> 03:
* Rename id-kp-trustanchorSigning to id-kp-trustAnchorConfigSigning
* Rename id-kp-updateSigning to id-kp-updatePackageSigning
* Fixed some nits
Changes from 01 -> 02:
* Updates Sections 3 and 6 addressing last call comments (see "WG
Last Call for draft-ietf-lamps-automation-keyusages-01")
Changes from 01 -> 02:
* Implemented the changes requested during WGLC
Changes from 00 -> 01:
* Fixed some minor nids and wording issues
draft-ietf-lamps-automation-keyusages version 00:
* Updated document and filename after WG adoption
Changes from 00 -> 01:
* Updated last paragraph of Section 1 addressing WG adoption
comments by Rich and Russ
* Updated name and OID of ASN.1 module A concrete example for automation is a rail automation system. The
Europe's Rail web page [ERJU-web] states:
draft-brockhaus-lamps-automation-keyusages version 00: | The System Pillar brings rail sector representatives under a
| single coordination body. To achieve this, the System Pillar will
| deliver a unified operational concept and a functional, safe and
| secure system architecture, with due consideration of cyber-
| security aspects, focused on the European railway network to which
| Directive 2016/797 applies (i.e. the heavy rail network) as well
| as associated specifications and/or standards.
* Broadened the scope to general automation use case and use ERJU as See [Directive-2016_797]. For details about the System Pillar, see
an example. [ERJU].
* Fixed some nits reported. Acknowledgments
draft-brockhaus-lamps-eu-rail-keyusages version 00: We would like to thank the authors of [RFC9336] and [RFC9509] for
their excellent template.
* Initial version of the document following best practices from RFC We also thank all reviewers of this document for their valuable
9336 and RFC 9509 feedback.
Contributors Contributors
Szofia Fazekas-Zisch Szofia Fazekas-Zisch
Siemens AG Siemens AG
Breslauer Str. 5 Breslauer Str. 5
90766 Fuerth 90766 Fuerth
Germany Germany
Email: szofia.fazekas-zisch@siemens.com Email: szofia.fazekas-zisch@siemens.com
URI: https://www.siemens.com URI: https://www.siemens.com
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