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OPS netconf This document presents a YANG module called "ietf-keystore" that enables centralized configuration of both symmetric and asymmetric keys. The secret value for both key types may be encrypted or hidden. Asymmetric keys may be associated with certificates. Notifications are sent when certificates are about to expire.

Status of This Memo This is an Internet Standards Track document. This document is a product of the Internet Engineering Task Force (IETF). It represents the consensus of the IETF community. It has received public review and has been approved for publication by the Internet Engineering Steering Group (IESG). Further information on Internet Standards is available in Section 2 of RFC 7841. Information about the current status of this document, any errata, and how to provide feedback on it may be obtained at .

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Table of Contents

• .  Introduction
  • .  Relation to Other RFCs
  • .  Specification Language
  • .  Terminology
  • .  Adherence to the NMDA
  • .  Conventions
• .  The "ietf-keystore" Module
  • .  Data Model Overview
  • .  Example Usage
  • .  YANG Module
• .  Support for Built-In Keys
• .  Encrypting Keys in Configuration
• .  Security Considerations
  • .  Security of Data at Rest and in Motion
  • .  Unconstrained Private Key Usage
  • .  Security Considerations for the "ietf-keystore" YANG Module
• .  IANA Considerations
  • .  The IETF XML Registry
  • .  The YANG Module Names Registry
• .  References
  • .  Normative References
  • .  Informative References
• Acknowledgements
• Author's Address

Introduction This document presents a YANG 1.1 module called "ietf-keystore" that enables centralized configuration of both symmetric and asymmetric keys. The secret value for both key types may be encrypted or hidden (see ). Asymmetric keys may be associated with certificates. Notifications are sent when certificates are about to expire. The "ietf-keystore" module defines many "grouping" statements intended for use by other modules that may import it. For instance, there are groupings that define enabling a key to be configured either inline (within the defining data model) or as a reference to a key in the central keystore. Special consideration has been given for servers that have cryptographic hardware, such as a trusted platform module (TPM). These servers are unique in that the cryptographic hardware hides the secret key values. Additionally, such hardware is commonly initialized when manufactured to protect a "built-in" asymmetric key for which its public half is conveyed in an identity certificate (e.g., an Initial Device Identifier (IDevID) certificate). See how built-in keys are supported in . This document is intended to reflect existing practices that many server implementations support at the time of writing. To simplify implementation, advanced key formats may be selectively implemented. Implementations may utilize operating-system level keystore utilities (e.g., "Keychain Access" on MacOS) and/or cryptographic hardware (e.g., TPMs).

Relation to Other RFCs This document presents a YANG module that is part of a collection of RFCs that work together to ultimately support the configuration of both the clients and servers of the Network Configuration Protocol (NETCONF) and RESTCONF . The dependency relationship between the primary YANG groupings defined in the various RFCs is presented in the diagram below. In some cases, a document may define secondary groupings that introduce dependencies not illustrated in the diagram. The labels in the diagram are shorthand names for the defining RFCs. The citation references for the shorthand names are provided below the diagram. Please note that the arrows in the diagram point from referencer to referenced. For example, the "crypto-types" RFC does not have any dependencies, whilst the "keystore" RFC depends on the "crypto-types" RFC. crypto-types ^ ^ / \ / \ truststore keystore ^ ^ ^ ^ | +---------+ | | | | | | | +------------+ | tcp-client-server | / | | ^ ^ ssh-client-server | | | | ^ tls-client-server | | | ^ ^ http-client-server | | | | | ^ | | | +-----+ +---------+ | | | | | | | | +-----------|--------|--------------+ | | | | | | | | +-----------+ | | | | | | | | | | | | | | | | | netconf-client-server restconf-client-server Labels in Diagram to RFC Mapping

Label in Diagram	Originating RFC
crypto-types
truststore
keystore	RFC 9642
tcp-client-server
ssh-client-server
tls-client-server
http-client-server
netconf-client-server
restconf-client-server

Specification Language 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.

Terminology The terms "client" and "server" are defined in and are not redefined here. The term "keystore" is defined in this document as a mechanism that intends to safeguard secrets. The nomenclatures "<running>" and "<operational>" are defined in . The sentence fragments "augmented" and "augmented in" are used herein as the past tense verbified form of the "augment" statement defined in . The term "key" may be used to mean one of three things in this document: 1) the YANG-defined "asymmetric-key" or "symmetric-key" node defined in this document, 2) the raw key data possessed by the aforementioned key nodes, or 3) the "key" of a YANG "list" statement. This document qualifies types '2' and '3' using "raw key value" and "YANG list key" where needed. In all other cases, an unqualified "key" refers to a YANG-defined "asymmetric-key" or "symmetric-key" node.

Adherence to the NMDA This document is compliant with Network Management Datastore Architecture (NMDA) . For instance, keys and associated certificates installed during manufacturing (e.g., for an IDevID certificate) are expected to appear in <operational> (see ).

Conventions Various examples in this document use "BASE64VALUE=" as a placeholder value for binary data that has been base64 encoded (per ). This placeholder value is used because real base64-encoded structures are often many lines long and hence distracting to the example being presented. Various examples in this document use the XML encoding. Other encodings, such as JSON , could alternatively be used. Various examples in this document contain long lines that may be folded, as described in . This document uses the adjective "central" to the word "keystore" to refer to the top-level instance of the "keystore-grouping", when the "central-keystore-supported" feature is enabled. Please be aware that consuming YANG modules MAY instantiate the "keystore-grouping" in other locations. All such other instances are not the "central" instance.

The "ietf-keystore" Module This section defines a YANG 1.1 module called "ietf-keystore". A high-level overview of the module is provided in . Examples illustrating the module's use are provided in . The YANG module itself is defined in .

Data Model Overview This section provides an overview of the "ietf-keystore" module in terms of its features, typedefs, groupings, and protocol-accessible nodes.

Features The following diagram lists all the "feature" statements defined in the "ietf-keystore" module: Features: +-- central-keystore-supported +-- inline-definitions-supported +-- asymmetric-keys +-- symmetric-keys The diagram above uses syntax that is similar to but not defined in .

Typedefs The following diagram lists the "typedef" statements defined in the "ietf-keystore" module: Typedefs: leafref +-- central-symmetric-key-ref +-- central-asymmetric-key-ref The diagram above uses syntax that is similar to but not defined in . Comments:

• All the typedefs defined in the "ietf-keystore" module extend the base "leafref" type defined in .
• The leafrefs refer to symmetric and asymmetric keys in the central keystore when this module is implemented.
• These typedefs are provided as an aid to consuming modules that import the "ietf-keystore" module.

Groupings The "ietf-keystore" module defines the following "grouping" statements:

• encrypted-by-grouping
• central-asymmetric-key-certificate-ref-grouping
• inline-or-keystore-symmetric-key-grouping
• inline-or-keystore-asymmetric-key-grouping
• inline-or-keystore-asymmetric-key-with-certs-grouping
• inline-or-keystore-end-entity-cert-with-key-grouping
• keystore-grouping

Each of these groupings are presented in the following subsections.

The "encrypted-by-grouping" Grouping The following tree diagram illustrates the "encrypted-by-grouping" grouping: grouping encrypted-by-grouping: +-- (encrypted-by) +--:(central-symmetric-key-ref) | {central-keystore-supported,symmetric-keys}? | +-- symmetric-key-ref? ks:central-symmetric-key-ref +--:(central-asymmetric-key-ref) {central-keystore-supported,asymmetric-keys}? +-- asymmetric-key-ref? ks:central-asymmetric-key-ref Comments:

• This grouping defines a "choice" statement with options to reference either a symmetric or an asymmetric key configured in the keystore.
• This grouping is usable only when the keystore module is implemented. Servers defining custom keystore locations MUST augment in alternate "encrypted-by" references to the alternate locations.

The "central-asymmetric-key-certificate-ref-grouping" Grouping The following tree diagram illustrates the "central-asymmetric-key-certificate-ref-grouping" grouping: grouping central-asymmetric-key-certificate-ref-grouping: +-- asymmetric-key? ks:central-asymmetric-key-ref | {central-keystore-supported,asymmetric-keys}? +-- certificate? leafref Comments:

• This grouping defines a reference to a certificate in two parts: the first being the name of the asymmetric key the certificate is associated with, and the second being the name of the certificate itself.
• This grouping is usable only when the keystore module is implemented. Servers defining custom keystore locations can define an alternate grouping for references to the alternate locations.

The "inline-or-keystore-symmetric-key-grouping" Grouping The following tree diagram illustrates the "inline-or-keystore-symmetric-key-grouping" grouping: grouping inline-or-keystore-symmetric-key-grouping: +-- (inline-or-keystore) +--:(inline) {inline-definitions-supported}? | +-- inline-definition | +---u ct:symmetric-key-grouping +--:(central-keystore) {central-keystore-supported,symmetric-keys}? +-- central-keystore-reference? ks:central-symmetric-key-ref Comments:

• The "inline-or-keystore-symmetric-key-grouping" grouping is provided solely as convenience to consuming modules that wish to offer an option for a symmetric key that is defined either inline or as a reference to a symmetric key in the keystore.
• A "choice" statement is used to expose the various options. Each option is enabled by a "feature" statement. Additional "case" statements MAY be augmented in if, e.g., there is a need to reference a symmetric key in an alternate location.
• For the "inline-definition" option, the definition uses the "symmetric-key-grouping" grouping discussed in .
• For the "central-keystore" option, the "central-keystore-reference" is an instance of the "symmetric-key-ref" discussed in .

The "inline-or-keystore-asymmetric-key-grouping" Grouping The following tree diagram illustrates the "inline-or-keystore-asymmetric-key-grouping" grouping: grouping inline-or-keystore-asymmetric-key-grouping: +-- (inline-or-keystore) +--:(inline) {inline-definitions-supported}? | +-- inline-definition | +---u ct:asymmetric-key-pair-grouping +--:(central-keystore) {central-keystore-supported,asymmetric-keys}? +-- central-keystore-reference? ks:central-asymmetric-key-ref Comments:

• The "inline-or-keystore-asymmetric-key-grouping" grouping is provided solely as convenience to consuming modules that wish to offer an option for an asymmetric key that is defined either inline or as a reference to an asymmetric key in the keystore.
• A "choice" statement is used to expose the various options. Each option is enabled by a "feature" statement. Additional "case" statements MAY be augmented in if, e.g., there is a need to reference an asymmetric key in an alternate location.
• For the "inline-definition" option, the definition uses the "asymmetric-key-pair-grouping" grouping discussed in .
• For the "central-keystore" option, the "central-keystore-reference" is an instance of the "asymmetric-key-ref" typedef discussed in .

The "inline-or-keystore-asymmetric-key-with-certs-grouping" Grouping The following tree diagram illustrates the "inline-or-keystore-asymmetric-key-with-certs-grouping" grouping: grouping inline-or-keystore-asymmetric-key-with-certs-grouping: +-- (inline-or-keystore) +--:(inline) {inline-definitions-supported}? | +-- inline-definition | +---u ct:asymmetric-key-pair-with-certs-grouping +--:(central-keystore) {central-keystore-supported,asymmetric-keys}? +-- central-keystore-reference? ks:central-asymmetric-key-ref Comments:

• The "inline-or-keystore-asymmetric-key-with-certs-grouping" grouping is provided solely as convenience to consuming modules that wish to offer an option for an asymmetric key that is defined either inline or as a reference to an asymmetric key in the keystore.
• A "choice" statement is used to expose the various options. Each option is enabled by a "feature" statement. Additional "case" statements MAY be augmented in if, e.g., there is a need to reference an asymmetric key in an alternate location.
• For the "inline-definition" option, the definition uses the "asymmetric-key-pair-with-certs-grouping" grouping discussed in .
• For the "central-keystore" option, the "central-keystore-reference" is an instance of the "asymmetric-key-ref" typedef discussed in .

The "inline-or-keystore-end-entity-cert-with-key-grouping" Grouping The following tree diagram illustrates the "inline-or-keystore-end-entity-cert-with-key-grouping" grouping: grouping inline-or-keystore-end-entity-cert-with-key-grouping: +-- (inline-or-keystore) +--:(inline) {inline-definitions-supported}? | +-- inline-definition | +---u ct:asymmetric-key-pair-with-cert-grouping +--:(central-keystore) {central-keystore-supported,asymmetric-keys}? +-- central-keystore-reference +---u central-asymmetric-key-certificate-ref-grouping Comments:

• The "inline-or-keystore-end-entity-cert-with-key-grouping" grouping is provided solely as convenience to consuming modules that wish to offer an option for a symmetric key that is defined either inline or as a reference to a symmetric key in the keystore.
• A "choice" statement is used to expose the various options. Each option is enabled by a "feature" statement. Additional "case" statements MAY be augmented in if, e.g., there is a need to reference a symmetric key in an alternate location.
• For the "inline-definition" option, the definition uses the "asymmetric-key-pair-with-certs-grouping" grouping discussed in .
• For the "central-keystore" option, the "central-keystore-reference" uses the "central-asymmetric-key-certificate-ref-grouping" grouping discussed in .

The "keystore-grouping" Grouping The following tree diagram illustrates the "keystore-grouping" grouping: grouping keystore-grouping: +-- asymmetric-keys {asymmetric-keys}? | +-- asymmetric-key* [name] | +-- name string | +---u ct:asymmetric-key-pair-with-certs-grouping +-- symmetric-keys {symmetric-keys}? +-- symmetric-key* [name] +-- name string +---u ct:symmetric-key-grouping Comments:

• The "keystore-grouping" grouping defines a keystore instance as being composed of symmetric and asymmetric keys. The structure for the symmetric and asymmetric keys is essentially the same: a "list" inside a "container".
• For asymmetric keys, each "asymmetric-key" uses the "asymmetric-key-pair-with-certs-grouping" grouping discussed in .
• For symmetric keys, each "symmetric-key" uses the "symmetric-key-grouping" grouping discussed in .

Protocol-Accessible Nodes The following tree diagram lists all the protocol-accessible nodes defined in the "ietf-keystore" module without expanding the "grouping" statements: module: ietf-keystore +--rw keystore {central-keystore-supported}? +---u keystore-grouping The following tree diagram lists all the protocol-accessible nodes defined in the "ietf-keystore" module, with all "grouping" statements expanded, enabling the keystore's full structure to be seen. =============== NOTE: '\' line wrapping per RFC 8792 ================ module: ietf-keystore +--rw keystore {central-keystore-supported}? +--rw asymmetric-keys {asymmetric-keys}? | +--rw asymmetric-key* [name] | +--rw name string | +--rw public-key-format? identityref | +--rw public-key? binary | +--rw private-key-format? identityref | +--rw (private-key-type) | | +--:(cleartext-private-key) {cleartext-private-keys}? | | | +--rw cleartext-private-key? binary | | +--:(hidden-private-key) {hidden-private-keys}? | | | +--rw hidden-private-key? empty | | +--:(encrypted-private-key) {encrypted-private-keys}? | | +--rw encrypted-private-key | | +--rw encrypted-by | | | +--rw (encrypted-by) | | | +--:(central-symmetric-key-ref) | | | | {central-keystore-supported,symme\ tric-keys}? | | | | +--rw symmetric-key-ref? | | | | ks:central-symmetric-key-ref | | | +--:(central-asymmetric-key-ref) | | | {central-keystore-supported,asymm\ etric-keys}? | | | +--rw asymmetric-key-ref? | | | ks:central-asymmetric-key-ref | | +--rw encrypted-value-format identityref | | +--rw encrypted-value binary | +--rw certificates | | +--rw certificate* [name] | | +--rw name string | | +--rw cert-data end-entity-cert-cms | | +---n certificate-expiration | | {certificate-expiration-notification}? | | +-- expiration-date yang:date-and-time | +---x generate-csr {csr-generation}? | +---w input | | +---w csr-format identityref | | +---w csr-info csr-info | +--ro output | +--ro (csr-type) | +--:(p10-csr) | +--ro p10-csr? p10-csr +--rw symmetric-keys {symmetric-keys}? +--rw symmetric-key* [name] +--rw name string +--rw key-format? identityref +--rw (key-type) +--:(cleartext-symmetric-key) | +--rw cleartext-symmetric-key? binary | {cleartext-symmetric-keys}? +--:(hidden-symmetric-key) {hidden-symmetric-keys}? | +--rw hidden-symmetric-key? empty +--:(encrypted-symmetric-key) {encrypted-symmetric-keys}? +--rw encrypted-symmetric-key +--rw encrypted-by | +--rw (encrypted-by) | +--:(central-symmetric-key-ref) | | {central-keystore-supported,symme\ tric-keys}? | | +--rw symmetric-key-ref? | | ks:central-symmetric-key-ref | +--:(central-asymmetric-key-ref) | {central-keystore-supported,asymm\ etric-keys}? | +--rw asymmetric-key-ref? | ks:central-asymmetric-key-ref +--rw encrypted-value-format identityref +--rw encrypted-value binary Comments:

• Protocol-accessible nodes are those nodes that are accessible when the module is "implemented", as described in .
• The protocol-accessible nodes for the "ietf-keystore" module are instances of the "keystore-grouping" grouping discussed in .
• The top-level node "keystore" is additionally constrained by the feature "central-keystore-supported".
• The "keystore-grouping" grouping is discussed in .
• The reason for why "keystore-grouping" exists separate from the protocol-accessible nodes definition is to enable instances of the keystore to be instantiated in other locations, as may be needed or desired by some modules.

Example Usage The examples in this section are encoded using XML, such as might be the case when using the NETCONF protocol. Other encodings MAY be used, such as JSON when using the RESTCONF protocol.

A Keystore Instance The following example illustrates keys in <running>. Please see for an example illustrating built-in values in <operational>. =============== NOTE: '\' line wrapping per RFC 8792 ================ <keystore xmlns="urn:ietf:params:xml:ns:yang:ietf-keystore" xmlns:ct="urn:ietf:params:xml:ns:yang:ietf-crypto-types"> <symmetric-keys> <symmetric-key> <name>cleartext-symmetric-key</name> <key-format>ct:octet-string-key-format</key-format> <cleartext-symmetric-key>BASE64VALUE=</cleartext-symmetric-\ key> </symmetric-key> <symmetric-key> <name>hidden-symmetric-key</name> <hidden-symmetric-key/> </symmetric-key> <symmetric-key> <name>encrypted-symmetric-key</name> <key-format>ct:one-symmetric-key-format</key-format> <encrypted-symmetric-key> <encrypted-by> <asymmetric-key-ref>hidden-asymmetric-key</asymmetric-k\ ey-ref> </encrypted-by> <encrypted-value-format>ct:cms-enveloped-data-format</enc\ rypted-value-format> <encrypted-value>BASE64VALUE=</encrypted-value> </encrypted-symmetric-key> </symmetric-key> </symmetric-keys> <asymmetric-keys> <asymmetric-key> <name>ssh-rsa-key</name> <private-key-format>ct:rsa-private-key-format</private-key-\ format> <cleartext-private-key>BASE64VALUE=</cleartext-private-key> </asymmetric-key> <asymmetric-key> <name>ssh-rsa-key-with-cert</name> <private-key-format>ct:rsa-private-key-format</private-key-\ format> <cleartext-private-key>BASE64VALUE=</cleartext-private-key> <certificates> <certificate> <name>ex-rsa-cert2</name> <cert-data>BASE64VALUE=</cert-data> </certificate> </certificates> </asymmetric-key> <asymmetric-key> <name>raw-private-key</name> <private-key-format>ct:rsa-private-key-format</private-key-\ format> <cleartext-private-key>BASE64VALUE=</cleartext-private-key> </asymmetric-key> <asymmetric-key> <name>rsa-asymmetric-key</name> <private-key-format>ct:rsa-private-key-format</private-key-\ format> <cleartext-private-key>BASE64VALUE=</cleartext-private-key> <certificates> <certificate> <name>ex-rsa-cert</name> <cert-data>BASE64VALUE=</cert-data> </certificate> </certificates> </asymmetric-key> <asymmetric-key> <name>ec-asymmetric-key</name> <private-key-format>ct:ec-private-key-format</private-key-f\ ormat> <cleartext-private-key>BASE64VALUE=</cleartext-private-key> <certificates> <certificate> <name>ex-ec-cert</name> <cert-data>BASE64VALUE=</cert-data> </certificate> </certificates> </asymmetric-key> <asymmetric-key> <name>hidden-asymmetric-key</name> <public-key-format>ct:subject-public-key-info-format</publi\ c-key-format> <public-key>BASE64VALUE=</public-key> <hidden-private-key/> <certificates> <certificate> <name>builtin-idevid-cert</name> <cert-data>BASE64VALUE=</cert-data> </certificate> <certificate> <name>my-ldevid-cert</name> <cert-data>BASE64VALUE=</cert-data> </certificate> </certificates> </asymmetric-key> <asymmetric-key> <name>encrypted-asymmetric-key</name> <private-key-format>ct:one-asymmetric-key-format</private-k\ ey-format> <encrypted-private-key> <encrypted-by> <symmetric-key-ref>encrypted-symmetric-key</symmetric-k\ ey-ref> </encrypted-by> <encrypted-value-format>ct:cms-encrypted-data-format</enc\ rypted-value-format> <encrypted-value>BASE64VALUE=</encrypted-value> </encrypted-private-key> </asymmetric-key> </asymmetric-keys> </keystore>

A Certificate Expiration Notification The following example illustrates a "certificate-expiration" notification for a certificate associated with an asymmetric key configured in the keystore. =============== NOTE: '\' line wrapping per RFC 8792 ================ <notification xmlns="urn:ietf:params:xml:ns:netconf:notification:1.0"> <eventTime>2018-05-25T00:01:00Z</eventTime> <keystore xmlns="urn:ietf:params:xml:ns:yang:ietf-keystore"> <asymmetric-keys> <asymmetric-key> <name>hidden-asymmetric-key</name> <certificates> <certificate> <name>my-ldevid-cert</name> <certificate-expiration> <expiration-date>2018-08-05T14:18:53-05:00</expiration\ -date> </certificate-expiration> </certificate> </certificates> </asymmetric-key> </asymmetric-keys> </keystore> </notification>

The "Inline or Keystore" Groupings This section illustrates the various "inline-or-keystore" groupings defined in the "ietf-keystore" module, specifically the "inline-or-keystore-symmetric-key-grouping" (), "inline-or-keystore-asymmetric-key-grouping" (), "inline-or-keystore-asymmetric-key-with-certs-grouping" (), and "inline-or-keystore-end-entity-cert-with-key-grouping" () groupings. These examples assume the existence of an example module called "ex-keystore-usage" that has the namespace "https://example.com/ns/example-keystore-usage". The ex-keystore-usage module is first presented using tree diagrams , followed by an instance example illustrating all the "inline-or-keystore" groupings in use, followed by the YANG module itself.

Tree Diagrams for the "ex-keystore-usage" Module The following tree diagram illustrates "ex-keystore-usage" without expanding the "grouping" statements: =============== NOTE: '\' line wrapping per RFC 8792 ================ module: ex-keystore-usage +--rw keystore-usage +--rw symmetric-key* [name] | +--rw name string | +---u ks:inline-or-keystore-symmetric-key-grouping +--rw asymmetric-key* [name] | +--rw name string | +---u ks:inline-or-keystore-asymmetric-key-grouping +--rw asymmetric-key-with-certs* [name] | +--rw name | | string | +---u ks:inline-or-keystore-asymmetric-key-with-certs-groupi\ ng +--rw end-entity-cert-with-key* [name] +--rw name | string +---u ks:inline-or-keystore-end-entity-cert-with-key-grouping The following tree diagram illustrates the "ex-keystore-usage" module with all "grouping" statements expanded, enabling the usage's full structure to be seen: =============== NOTE: '\' line wrapping per RFC 8792 ================ module: ex-keystore-usage +--rw keystore-usage +--rw symmetric-key* [name] | +--rw name string | +--rw (inline-or-keystore) | +--:(inline) {inline-definitions-supported}? | | +--rw inline-definition | | +--rw key-format? identityref | | +--rw (key-type) | | +--:(cleartext-symmetric-key) | | | +--rw cleartext-symmetric-key? binary | | | {cleartext-symmetric-keys}? | | +--:(hidden-symmetric-key) | | | {hidden-symmetric-keys}? | | | +--rw hidden-symmetric-key? empty | | +--:(encrypted-symmetric-key) | | {encrypted-symmetric-keys}? | | +--rw encrypted-symmetric-key | | +--rw encrypted-by | | +--rw encrypted-value-format identityref | | +--rw encrypted-value binary | +--:(central-keystore) | {central-keystore-supported,symmetric-keys}? | +--rw central-keystore-reference? | ks:central-symmetric-key-ref +--rw asymmetric-key* [name] | +--rw name string | +--rw (inline-or-keystore) | +--:(inline) {inline-definitions-supported}? | | +--rw inline-definition | | +--rw public-key-format? identityref | | +--rw public-key? binary | | +--rw private-key-format? identityref | | +--rw (private-key-type) | | +--:(cleartext-private-key) | | | {cleartext-private-keys}? | | | +--rw cleartext-private-key? binary | | +--:(hidden-private-key) {hidden-private-keys}? | | | +--rw hidden-private-key? empty | | +--:(encrypted-private-key) | | {encrypted-private-keys}? | | +--rw encrypted-private-key | | +--rw encrypted-by | | +--rw encrypted-value-format identityref | | +--rw encrypted-value binary | +--:(central-keystore) | {central-keystore-supported,asymmetric-keys}? | +--rw central-keystore-reference? | ks:central-asymmetric-key-ref +--rw asymmetric-key-with-certs* [name] | +--rw name string | +--rw (inline-or-keystore) | +--:(inline) {inline-definitions-supported}? | | +--rw inline-definition | | +--rw public-key-format? identityref | | +--rw public-key? binary | | +--rw private-key-format? identityref | | +--rw (private-key-type) | | | +--:(cleartext-private-key) | | | | {cleartext-private-keys}? | | | | +--rw cleartext-private-key? binary | | | +--:(hidden-private-key) {hidden-private-keys}? | | | | +--rw hidden-private-key? empty | | | +--:(encrypted-private-key) | | | {encrypted-private-keys}? | | | +--rw encrypted-private-key | | | +--rw encrypted-by | | | +--rw encrypted-value-format identityref | | | +--rw encrypted-value binary | | +--rw certificates | | | +--rw certificate* [name] | | | +--rw name string | | | +--rw cert-data | | | | end-entity-cert-cms | | | +---n certificate-expiration | | | {certificate-expiration-notification}? | | | +-- expiration-date yang:date-and-time | | +---x generate-csr {csr-generation}? | | +---w input | | | +---w csr-format identityref | | | +---w csr-info csr-info | | +--ro output | | +--ro (csr-type) | | +--:(p10-csr) | | +--ro p10-csr? p10-csr | +--:(central-keystore) | {central-keystore-supported,asymmetric-keys}? | +--rw central-keystore-reference? | ks:central-asymmetric-key-ref +--rw end-entity-cert-with-key* [name] +--rw name string +--rw (inline-or-keystore) +--:(inline) {inline-definitions-supported}? | +--rw inline-definition | +--rw public-key-format? identityref | +--rw public-key? binary | +--rw private-key-format? identityref | +--rw (private-key-type) | | +--:(cleartext-private-key) | | | {cleartext-private-keys}? | | | +--rw cleartext-private-key? binary | | +--:(hidden-private-key) {hidden-private-keys}? | | | +--rw hidden-private-key? empty | | +--:(encrypted-private-key) | | {encrypted-private-keys}? | | +--rw encrypted-private-key | | +--rw encrypted-by | | +--rw encrypted-value-format identityref | | +--rw encrypted-value binary | +--rw cert-data? | | end-entity-cert-cms | +---n certificate-expiration | | {certificate-expiration-notification}? | | +-- expiration-date yang:date-and-time | +---x generate-csr {csr-generation}? | +---w input | | +---w csr-format identityref | | +---w csr-info csr-info | +--ro output | +--ro (csr-type) | +--:(p10-csr) | +--ro p10-csr? p10-csr +--:(central-keystore) {central-keystore-supported,asymmetric-keys}? +--rw central-keystore-reference +--rw asymmetric-key? | ks:central-asymmetric-key-ref | {central-keystore-supported,asymmetric-keys\ }? +--rw certificate? leafref

Example Usage for the "ex-keystore-usage" Module The following example provides two equivalent instances of each grouping, the first being a reference to a keystore and the second being inlined. The instance having a reference to a keystore is consistent with the keystore defined in . The two instances are equivalent, as the inlined instance example contains the same values defined by the keystore instance referenced by its sibling example. =============== NOTE: '\' line wrapping per RFC 8792 ================ <keystore-usage xmlns="https://example.com/ns/example-keystore-usage" xmlns:ct="urn:ietf:params:xml:ns:yang:ietf-crypto-types"> <!-- The following two equivalent examples illustrate the --> <!-- "inline-or-keystore-symmetric-key-grouping" grouping: --> <symmetric-key> <name>example 1a</name> <central-keystore-reference>cleartext-symmetric-key</central-key\ store-reference> </symmetric-key> <symmetric-key> <name>example 1b</name> <inline-definition> <key-format>ct:octet-string-key-format</key-format> <cleartext-symmetric-key>BASE64VALUE=</cleartext-symmetric-key> </inline-definition> </symmetric-key> <!-- The following two equivalent examples illustrate the --> <!-- "inline-or-keystore-asymmetric-key-grouping" grouping: --> <asymmetric-key> <name>example 2a</name> <central-keystore-reference>rsa-asymmetric-key</central-keystore\ -reference> </asymmetric-key> <asymmetric-key> <name>example 2b</name> <inline-definition> <public-key-format>ct:subject-public-key-info-format</public-k\ ey-format> <public-key>BASE64VALUE=</public-key> <private-key-format>ct:rsa-private-key-format</private-key-for\ mat> <cleartext-private-key>BASE64VALUE=</cleartext-private-key> </inline-definition> </asymmetric-key> <!-- The following two equivalent examples illustrate the --> <!-- "inline-or-keystore-asymmetric-key-with-certs-grouping" --> <!-- grouping: --> <asymmetric-key-with-certs> <name>example 3a</name> <central-keystore-reference>rsa-asymmetric-key</central-keystore\ -reference> </asymmetric-key-with-certs> <asymmetric-key-with-certs> <name>example 3b</name> <inline-definition> <public-key-format>ct:subject-public-key-info-format</public-k\ ey-format> <public-key>BASE64VALUE=</public-key> <private-key-format>ct:rsa-private-key-format</private-key-for\ mat> <cleartext-private-key>BASE64VALUE=</cleartext-private-key> <certificates> <certificate> <name>a locally defined cert</name> <cert-data>BASE64VALUE=</cert-data> </certificate> </certificates> </inline-definition> </asymmetric-key-with-certs> <!-- The following two equivalent examples illustrate the --> <!-- "inline-or-keystore-end-entity-cert-with-key-grouping" --> <!-- grouping: --> <end-entity-cert-with-key> <name>example 4a</name> <central-keystore-reference> <asymmetric-key>rsa-asymmetric-key</asymmetric-key> <certificate>ex-rsa-cert</certificate> </central-keystore-reference> </end-entity-cert-with-key> <end-entity-cert-with-key> <name>example 4b</name> <inline-definition> <public-key-format>ct:subject-public-key-info-format</public-k\ ey-format> <public-key>BASE64VALUE=</public-key> <private-key-format>ct:rsa-private-key-format</private-key-for\ mat> <cleartext-private-key>BASE64VALUE=</cleartext-private-key> <cert-data>BASE64VALUE=</cert-data> </inline-definition> </end-entity-cert-with-key> </keystore-usage>

The "ex-keystore-usage" YANG Module Following is the "ex-keystore-usage" module's YANG definition: module ex-keystore-usage { yang-version 1.1; namespace "https://example.com/ns/example-keystore-usage"; prefix ex-keystore-usage; import ietf-keystore { prefix ks; reference "RFC 9642: A YANG Data Model for a Keystore"; } organization "Example Corporation"; contact "Author: YANG Designer <mailto:yang.designer@example.com>"; description "This example module illustrates notable groupings defined in the 'ietf-keystore' module."; revision 2024-10-10 { description "Initial version"; reference "RFC 9642: A YANG Data Model for a Keystore"; } container keystore-usage { description "An illustration of the various keystore groupings."; list symmetric-key { key "name"; leaf name { type string; description "An arbitrary name for this key."; } uses ks:inline-or-keystore-symmetric-key-grouping; description "An symmetric key that may be configured locally or be a reference to a symmetric key in the keystore."; } list asymmetric-key { key "name"; leaf name { type string; description "An arbitrary name for this key."; } uses ks:inline-or-keystore-asymmetric-key-grouping; description "An asymmetric key, with no certs, that may be configured locally or be a reference to an asymmetric key in the keystore. The intent is to reference just the asymmetric key, not any certificates that may also be associated with the asymmetric key."; } list asymmetric-key-with-certs { key "name"; leaf name { type string; description "An arbitrary name for this key."; } uses ks:inline-or-keystore-asymmetric-key-with-certs-grouping; description "An asymmetric key and its associated certs that may be configured locally or be a reference to an asymmetric key (and its associated certs) in the keystore."; } list end-entity-cert-with-key { key "name"; leaf name { type string; description "An arbitrary name for this key."; } uses ks:inline-or-keystore-end-entity-cert-with-key-grouping; description "An end-entity certificate and its associated asymmetric key that may be configured locally or be a reference to another certificate (and its associated asymmetric key) in the keystore."; } } }

YANG Module This YANG module has normative references to and . module ietf-keystore { yang-version 1.1; namespace "urn:ietf:params:xml:ns:yang:ietf-keystore"; prefix ks; import ietf-netconf-acm { prefix nacm; reference "RFC 8341: Network Configuration Access Control Model"; } import ietf-crypto-types { prefix ct; reference "RFC 9640: YANG Data Types and Groupings for Cryptography"; } organization "IETF NETCONF (Network Configuration) Working Group"; contact "WG Web: https://datatracker.ietf.org/wg/netconf WG List: NETCONF WG list <mailto:netconf@ietf.org> Author: Kent Watsen <mailto:kent+ietf@watsen.net>"; description "This module defines a 'keystore' to centralize management of security credentials. 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 (RFC 2119) (RFC 8174) when, and only when, they appear in all capitals, as shown here. Copyright (c) 2024 IETF Trust and the persons identified as authors of the code. All rights reserved. Redistribution and use in source and binary forms, with or without modification, is permitted pursuant to, and subject to the license terms contained in, the Revised BSD License set forth in Section 4.c of the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/license-info). This version of this YANG module is part of RFC 9642 (https://www.rfc-editor.org/info/rfc9642); see the RFC itself for full legal notices."; revision 2024-10-10 { description "Initial version"; reference "RFC 9642: A YANG Data Model for a Keystore"; } /****************/ /* Features */ /****************/ feature central-keystore-supported { description "The 'central-keystore-supported' feature indicates that the server supports the central keystore (i.e., fully implements the 'ietf-keystore' module)."; } feature inline-definitions-supported { description "The 'inline-definitions-supported' feature indicates that the server supports locally defined keys."; } feature asymmetric-keys { description "The 'asymmetric-keys' feature indicates that the server implements the /keystore/asymmetric-keys subtree."; } feature symmetric-keys { description "The 'symmetric-keys' feature indicates that the server implements the /keystore/symmetric-keys subtree."; } /****************/ /* Typedefs */ /****************/ typedef central-symmetric-key-ref { type leafref { path "/ks:keystore/ks:symmetric-keys/ks:symmetric-key" + "/ks:name"; } description "This typedef enables modules to easily define a reference to a symmetric key stored in the central keystore."; } typedef central-asymmetric-key-ref { type leafref { path "/ks:keystore/ks:asymmetric-keys/ks:asymmetric-key" + "/ks:name"; } description "This typedef enables modules to easily define a reference to an asymmetric key stored in the central keystore."; } /*****************/ /* Groupings */ /*****************/ grouping encrypted-by-grouping { description "A grouping that defines a 'choice' statement that can be augmented into the 'encrypted-by' node, present in the 'symmetric-key-grouping' and 'asymmetric-key-pair-grouping' groupings defined in RFC 9640, enabling references to keys in the central keystore."; choice encrypted-by { nacm:default-deny-write; mandatory true; description "A choice amongst other symmetric or asymmetric keys."; case central-symmetric-key-ref { if-feature "central-keystore-supported"; if-feature "symmetric-keys"; leaf symmetric-key-ref { type ks:central-symmetric-key-ref; description "Identifies the symmetric key used to encrypt the associated key."; } } case central-asymmetric-key-ref { if-feature "central-keystore-supported"; if-feature "asymmetric-keys"; leaf asymmetric-key-ref { type ks:central-asymmetric-key-ref; description "Identifies the asymmetric key whose public key encrypted the associated key."; } } } } // *-ref groupings grouping central-asymmetric-key-certificate-ref-grouping { description "A grouping for the reference to a certificate associated with an asymmetric key stored in the central keystore."; leaf asymmetric-key { nacm:default-deny-write; if-feature "central-keystore-supported"; if-feature "asymmetric-keys"; type ks:central-asymmetric-key-ref; must '../certificate'; description "A reference to an asymmetric key in the keystore."; } leaf certificate { nacm:default-deny-write; type leafref { path "/ks:keystore/ks:asymmetric-keys/ks:asymmetric-key" + "[ks:name = current()/../asymmetric-key]/" + "ks:certificates/ks:certificate/ks:name"; } must '../asymmetric-key'; description "A reference to a specific certificate of the asymmetric key in the keystore."; } } // inline-or-keystore-* groupings grouping inline-or-keystore-symmetric-key-grouping { description "A grouping for the configuration of a symmetric key. The symmetric key may be defined inline or as a reference to a symmetric key stored in the central keystore. Servers that wish to define alternate keystore locations SHOULD augment in custom 'case' statements enabling references to those alternate keystore locations."; choice inline-or-keystore { nacm:default-deny-write; mandatory true; description "A choice between an inlined definition and a definition that exists in the keystore."; case inline { if-feature "inline-definitions-supported"; container inline-definition { description "A container to hold the local key definition."; uses ct:symmetric-key-grouping; } } case central-keystore { if-feature "central-keystore-supported"; if-feature "symmetric-keys"; leaf central-keystore-reference { type ks:central-symmetric-key-ref; description "A reference to a symmetric key that exists in the central keystore."; } } } } grouping inline-or-keystore-asymmetric-key-grouping { description "A grouping for the configuration of an asymmetric key. The asymmetric key may be defined inline or as a reference to an asymmetric key stored in the central keystore. Servers that wish to define alternate keystore locations SHOULD augment in custom 'case' statements enabling references to those alternate keystore locations."; choice inline-or-keystore { nacm:default-deny-write; mandatory true; description "A choice between an inlined definition and a definition that exists in the keystore."; case inline { if-feature "inline-definitions-supported"; container inline-definition { description "A container to hold the local key definition."; uses ct:asymmetric-key-pair-grouping; } } case central-keystore { if-feature "central-keystore-supported"; if-feature "asymmetric-keys"; leaf central-keystore-reference { type ks:central-asymmetric-key-ref; description "A reference to an asymmetric key that exists in the central keystore. The intent is to reference just the asymmetric key without any regard for any certificates that may be associated with it."; } } } } grouping inline-or-keystore-asymmetric-key-with-certs-grouping { description "A grouping for the configuration of an asymmetric key and its associated certificates. The asymmetric key and its associated certificates may be defined inline or as a reference to an asymmetric key (and its associated certificates) in the central keystore. Servers that wish to define alternate keystore locations SHOULD augment in custom 'case' statements enabling references to those alternate keystore locations."; choice inline-or-keystore { nacm:default-deny-write; mandatory true; description "A choice between an inlined definition and a definition that exists in the keystore."; case inline { if-feature "inline-definitions-supported"; container inline-definition { description "A container to hold the local key definition."; uses ct:asymmetric-key-pair-with-certs-grouping; } } case central-keystore { if-feature "central-keystore-supported"; if-feature "asymmetric-keys"; leaf central-keystore-reference { type ks:central-asymmetric-key-ref; description "A reference to an asymmetric key (and all of its associated certificates) in the keystore, when this module is implemented."; } } } } grouping inline-or-keystore-end-entity-cert-with-key-grouping { description "A grouping for the configuration of an asymmetric key and its associated end-entity certificate. The asymmetric key and its associated end-entity certificate may be defined inline or as a reference to an asymmetric key (and its associated end-entity certificate) in the central keystore. Servers that wish to define alternate keystore locations SHOULD augment in custom 'case' statements enabling references to those alternate keystore locations."; choice inline-or-keystore { nacm:default-deny-write; mandatory true; description "A choice between an inlined definition and a definition that exists in the keystore."; case inline { if-feature "inline-definitions-supported"; container inline-definition { description "A container to hold the local key definition."; uses ct:asymmetric-key-pair-with-cert-grouping; } } case central-keystore { if-feature "central-keystore-supported"; if-feature "asymmetric-keys"; container central-keystore-reference { uses central-asymmetric-key-certificate-ref-grouping; description "A reference to a specific certificate associated with an asymmetric key stored in the central keystore."; } } } } // the keystore grouping grouping keystore-grouping { description "A grouping definition enables use in other contexts. If ever done, implementations MUST augment new 'case' statements into the various inline-or-keystore 'choice' statements to supply leafrefs to the model-specific location(s)."; container asymmetric-keys { nacm:default-deny-write; if-feature "asymmetric-keys"; description "A list of asymmetric keys."; list asymmetric-key { key "name"; description "An asymmetric key."; leaf name { type string; description "An arbitrary name for the asymmetric key."; } uses ct:asymmetric-key-pair-with-certs-grouping; } } container symmetric-keys { nacm:default-deny-write; if-feature "symmetric-keys"; description "A list of symmetric keys."; list symmetric-key { key "name"; description "A symmetric key."; leaf name { type string; description "An arbitrary name for the symmetric key."; } uses ct:symmetric-key-grouping; } } } /*********************************/ /* Protocol accessible nodes */ /*********************************/ container keystore { if-feature "central-keystore-supported"; description "A central keystore containing a list of symmetric keys and a list of asymmetric keys."; nacm:default-deny-write; uses keystore-grouping { augment "symmetric-keys/symmetric-key/key-type/encrypted-" + "symmetric-key/encrypted-symmetric-key/encrypted-by" { description "Augments in a choice statement enabling the encrypting key to be any other symmetric or asymmetric key in the central keystore."; uses encrypted-by-grouping; } augment "asymmetric-keys/asymmetric-key/private-key-type/" + "encrypted-private-key/encrypted-private-key/" + "encrypted-by" { description "Augments in a choice statement enabling the encrypting key to be any other symmetric or asymmetric key in the central keystore."; uses encrypted-by-grouping; } } } }

Support for Built-In Keys In some implementations, a server may support keys built into the server. Built-in keys MAY be set during the manufacturing process or be dynamically generated the first time the server is booted or a particular service (e.g., Secure Shell (SSH)) is enabled. Built-in keys are "hidden" keys expected to be set by a vendor-specific process. Any ability for operators to set and/or modify built-in keys is outside the scope of this document. The primary characteristic of the built-in keys is that they are provided by the server, as opposed to being configured. As such, they are present in <operational> () and <system> , if implemented. The example below illustrates what the keystore in <operational> might look like for a server in its factory default state. Note that the built-in keys have the "or:origin" annotation value "or:system". =============== NOTE: '\' line wrapping per RFC 8792 ================ <keystore xmlns="urn:ietf:params:xml:ns:yang:ietf-keystore" xmlns:ct="urn:ietf:params:xml:ns:yang:ietf-crypto-types" xmlns:or="urn:ietf:params:xml:ns:yang:ietf-origin" or:origin="or:intended"> <asymmetric-keys> <asymmetric-key or:origin="or:system"> <name>Manufacturer-Generated Hidden Key</name> <public-key-format>ct:subject-public-key-info-format</public-k\ ey-format> <public-key>BASE64VALUE=</public-key> <hidden-private-key/> <certificates> <certificate> <name>Manufacturer-Generated IDevID Cert</name> <cert-data>BASE64VALUE=</cert-data> </certificate> </certificates> </asymmetric-key> </asymmetric-keys> </keystore> The following example illustrates how a single built-in key definition from the previous example has been propagated to <running>: =============== NOTE: '\' line wrapping per RFC 8792 ================ <keystore xmlns="urn:ietf:params:xml:ns:yang:ietf-keystore" xmlns:ct="urn:ietf:params:xml:ns:yang:ietf-crypto-types"> <asymmetric-keys> <asymmetric-key> <name>Manufacturer-Generated Hidden Key</name> <public-key-format>ct:subject-public-key-info-format</public-k\ ey-format> <public-key>BASE64VALUE=</public-key> <hidden-private-key/> <certificates> <certificate> <name>Manufacturer-Generated IDevID Cert</name> <cert-data>BASE64VALUE=</cert-data> </certificate> <certificate> <name>Deployment-Specific LDevID Cert</name> <cert-data>BASE64VALUE=</cert-data> </certificate> </certificates> </asymmetric-key> </asymmetric-keys> </keystore> After the above configuration is applied, <operational> should appear as follows: =============== NOTE: '\' line wrapping per RFC 8792 ================ <keystore xmlns="urn:ietf:params:xml:ns:yang:ietf-keystore" xmlns:ct="urn:ietf:params:xml:ns:yang:ietf-crypto-types" xmlns:or="urn:ietf:params:xml:ns:yang:ietf-origin" or:origin="or:intended"> <asymmetric-keys> <asymmetric-key or:origin="or:system"> <name>Manufacturer-Generated Hidden Key</name> <public-key-format>ct:subject-public-key-info-format</public-k\ ey-format> <public-key>BASE64VALUE=</public-key> <hidden-private-key/> <certificates> <certificate> <name>Manufacturer-Generated IDevID Cert</name> <cert-data>BASE64VALUE=</cert-data> </certificate> <certificate or:origin="or:intended"> <name>Deployment-Specific LDevID Cert</name> <cert-data>BASE64VALUE=</cert-data> </certificate> </certificates> </asymmetric-key> </asymmetric-keys> </keystore>

Encrypting Keys in Configuration This section describes an approach that enables both the symmetric and asymmetric keys on a server to be encrypted, such that backup/restore procedures can be used without concern for raw key data being compromised when in transit. The approach presented in this section is not normative. This section answers how a configuration containing secrets that are encrypted by a built-in key () can be backed up from one server and restored on a different server when each server has unique primary keys. The API defined by the "ietf-keystore" YANG module presented in this document is sufficient to support the workflow described in this section.

Key Encryption Key The ability to encrypt configured keys is predicated on the existence of a key encryption key (KEK). There may be any number of KEKs in a server. A KEK, by its namesake, is a key that is used to encrypt other keys. A KEK MAY be either a symmetric key or an asymmetric key. If a KEK is a symmetric key, then the server MUST provide an API for administrators to encrypt other keys without needing to know the symmetric key's value. If the KEK is an asymmetric key, then the server SHOULD provide an API enabling the encryption of other keys or, alternatively, assume the administrators can do so themselves using the asymmetric key's public half. A server MUST possess access to the KEK, or an API using the KEK, so that it can decrypt the other keys in the configuration at runtime.

Configuring Encrypted Keys Each time a new key is configured, it SHOULD be encrypted by a KEK. In the "ietf-crypto-types" module , the format for encrypted values is described by identity statements derived from the "symmetrically-encrypted-value-format" and "asymmetrically-encrypted-value-format" identity statements. Implementations of servers implementing the "ietf-keystore" module SHOULD provide an API that simultaneously generates a key and encrypts the generated key using a KEK. Thus, the cleartext value of the newly generated key may never be known to the administrators generating the keys. Such an API is defined in the "ietf-ssh-common" and "ietf-tls-common" YANG modules defined in and , respectively. In case the server implementation does not provide such an API, then the generating and encrypting steps MAY be performed outside the server, e.g., by an administrator with special access control rights (such as an organization's crypto officer). In either case, the encrypted key can be configured into the keystore using either the "encrypted-symmetric-key" (for symmetric keys) or the "encrypted-private-key" (for asymmetric keys) nodes. These two nodes contain both the encrypted raw key value as well as a reference to the KEK that encrypted the key.

Migrating Configuration to Another Server When a KEK is used to encrypt other keys, migrating the configuration to another server is only possible if the second server has the same KEK. How the second server comes to have the same KEK is discussed in this section. In some deployments, mechanisms outside the scope of this document may be used to migrate a KEK from one server to another. That said, beware that the ability to do so typically entails having access to the first server; however, in some scenarios, the first server may no longer be operational. In other deployments, an organization's crypto officer, possessing a KEK's cleartext value, configures the same KEK on the second server, presumably as a hidden key or a key protected by access control, so that the cleartext value is not disclosed to regular administrators. However, this approach creates high coupling to and dependency on the crypto officers that does not scale in production environments. In order to decouple the crypto officers from the regular administrators, a special KEK, called the "primary key" (PK), may be used. A PK is commonly a globally unique built-in (see ) asymmetric key. The private raw key value, due to its long lifetime, is hidden (i.e., "hidden-private-key"; see ). The raw public key value is often contained in an identity certificate (e.g., IDevID). How to configure a PK during the manufacturing process is outside the scope of this document. Assuming the server has a PK, the PK can be used to encrypt a "shared KEK", which is then used to encrypt the keys configured by regular administrators. With this extra level of indirection, it is possible for a crypto officer to encrypt the same KEK for a multiplicity of servers offline using the public key contained in their identity certificates. The crypto officer can then safely hand off the encrypted KEKs to regular administrators responsible for server installations, including migrations. In order to migrate the configuration from a first server, an administrator would need to make just a single modification to the configuration before loading it onto a second server, which is to replace the encrypted KEK keystore entry from the first server with the encrypted KEK for the second server. Upon doing this, the configuration (containing many encrypted keys) can be loaded into the second server while enabling the second server to decrypt all the encrypted keys in the configuration. The following diagram illustrates this idea: +-------------+ +-------------+ | shared KEK | | shared KEK | |(unencrypted)|-------------------------------> | (encrypted) | +-------------+ encrypts offline using +-------------+ ^ each server's PK | | | | | | possesses \o | +-------------- |\ | / \ shares with | crypto +--------------------+ officer | | | +----------------------+ | +----------------------+ | server-1 | | | server-2 | | configuration | | | configuration | | | | | | | | | | | | +----------------+ | | | +----------------+ | | | PK-1 | | | | | PK-2 | | | | (hidden) | | | | | (hidden) | | | +----------------+ | | | +----------------+ | | ^ | | | ^ | | | | | | | | | | | | | | | | | encrypted | | | | encrypted | | | by | | | | by | | | | | | | | | | | | | | | | +----------------+ | | | +----------------+ | | | shared KEK | | | | | shared KEK | | | | (encrypted) | | v | | (encrypted) | | | +----------------+ | | +----------------+ | | ^ | regular | ^ | | | | admin | | | | | | | | | | | encrypted | \o | | encrypted | | | by | |\ | | by | | | | / \ | | | | | | | | | | +----------------+ |----------------->| +----------------+ | | | all other keys | | migrate | | all other keys | | | | (encrypted) | | configuration | | (encrypted) | | | +----------------+ | | +----------------+ | | | | | +----------------------+ +----------------------+

Security Considerations

Security of Data at Rest and in Motion The YANG module defined in this document defines a mechanism called a "keystore" that intends to protect its contents from unauthorized disclosure and modification. In order to satisfy the expectations of a keystore, it is RECOMMENDED that server implementations ensure that the keystore contents are encrypted when persisted to non-volatile memory and that the keystore contents that have been decrypted in volatile memory are zeroized when not in use. The keystore contents may be encrypted by either encrypting the contents individually (e.g., using the "encrypted" value formats) or using persistence-layer-level encryption. If storing cleartext values (which is NOT RECOMMENDED per ), then persistence-layer-level encryption SHOULD be used to protect the data at rest. If the keystore contents are not encrypted when persisted, then server implementations MUST ensure the persisted storage is inaccessible.

Unconstrained Private Key Usage This module enables the configuration of private keys without constraints on their usage, e.g., what operations the key is allowed to be used for (such as signature, decryption, or both). This module also does not constrain the usage of the associated public keys other than in the context of a configured certificate (e.g., an identity certificate), in which case the key usage is constrained by the certificate.

Security Considerations for the "ietf-keystore" YANG Module This section is modeled after the template defined in . The ietf-keystore YANG module defines a data model that is designed to be accessed via YANG-based management protocols, such as NETCONF and RESTCONF . These protocols have mandatory-to-implement secure transport layers (e.g., SSH , TLS , and QUIC ) and mandatory-to-implement mutual authentication. The Network Configuration Access Control Model (NACM) provides the means to restrict access for particular users to a preconfigured subset of all available protocol operations and content. Please be aware that this YANG module uses groupings from other YANG modules that define nodes that may be considered sensitive or vulnerable in network environments. Please review the Security Considerations for dependent YANG modules for information as to which nodes may be considered sensitive or vulnerable in network environments. Some of the readable data nodes in this YANG module may be considered sensitive or vulnerable in some network environments. It is thus important to control read access (e.g., via get, get-config, or notification) to these data nodes. These are the subtrees and data nodes and their sensitivity/vulnerability:

The "cleartext-symmetric-key" node:

This node, imported from the "symmetric-key-grouping" grouping defined in , is additionally sensitive to read operations such that, in normal use cases, it should never be returned to a client. For this reason, the NACM extension "default-deny-all" was applied to it in .

The "cleartext-private-key" node:

This node, defined in the "asymmetric-key-pair-grouping" grouping in , is additionally sensitive to read operations such that, in normal use cases, it should never be returned to a client. For this reason, the NACM extension "default-deny-all" is applied to it in .

All the writable data nodes defined by this YANG module, both in the "grouping" statements as well as the protocol-accessible "keystore" instance, may be considered sensitive or vulnerable in some network environments. For instance, any modification to a key or reference to a key may dramatically alter the implemented security policy. For this reason, the NACM extension "default-deny-write" has been set for all data nodes defined in this module. This YANG module does not define any "rpc" or "action" statements, and thus the security considerations for such is not provided here. Built-in key types SHOULD be hidden and/or encrypted (not cleartext). If this is not possible, access control mechanisms like NACM SHOULD be used to limit access to the key's secret data to only the most trusted authorized clients (e.g., belonging to an organization's crypto officer).

IANA Considerations

The IETF XML Registry IANA has registered the following URI in the "ns" registry of the "IETF XML Registry" .

URI:

urn:ietf:params:xml:ns:yang:ietf-keystore

Registrant Contact:

The IESG

XML:

N/A; the requested URI is an XML namespace.

The YANG Module Names Registry IANA has registered the following YANG module in the "YANG Module Names" registry defined in .

Name:

ietf-keystore

Maintained by IANA:

N

Namespace:

urn:ietf:params:xml:ns:yang:ietf-keystore

Prefix:

ks

Reference:

RFC 9642

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. The Secure Shell Protocol (SSH) is a protocol for secure remote login and other secure network services over an insecure network. This document describes the SSH authentication protocol framework and public key, password, and host-based client authentication methods. Additional authentication methods are described in separate documents. The SSH authentication protocol runs on top of the SSH transport layer protocol and provides a single authenticated tunnel for the SSH connection protocol. [STANDARDS-TRACK] YANG is a data modeling language used to model configuration and state data manipulated by the Network Configuration Protocol (NETCONF), NETCONF remote procedure calls, and NETCONF notifications. [STANDARDS-TRACK] The Network Configuration Protocol (NETCONF) defined in this document provides mechanisms to install, manipulate, and delete the configuration of network devices. It uses an Extensible Markup Language (XML)-based data encoding for the configuration data as well as the protocol messages. The NETCONF protocol operations are realized as remote procedure calls (RPCs). This document obsoletes RFC 4741. [STANDARDS-TRACK] YANG is a data modeling language used to model configuration data, state data, Remote Procedure Calls, and notifications for network management protocols. This document describes the syntax and semantics of version 1.1 of the YANG language. YANG version 1.1 is a maintenance release of the YANG language, addressing ambiguities and defects in the original specification. There are a small number of backward incompatibilities from YANG version 1. This document also specifies the YANG mappings to the Network Configuration Protocol (NETCONF). This document describes an HTTP-based protocol that provides a programmatic interface for accessing data defined in YANG, using the datastore concepts defined in the Network Configuration Protocol (NETCONF). 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. The standardization of network configuration interfaces for use with the Network Configuration Protocol (NETCONF) or the RESTCONF protocol requires a structured and secure operating environment that promotes human usability and multi-vendor interoperability. There is a need for standard mechanisms to restrict NETCONF or RESTCONF protocol access for particular users to a preconfigured subset of all available NETCONF or RESTCONF protocol operations and content. This document defines such an access control model. This document obsoletes RFC 6536. This document specifies version 1.3 of the Transport Layer Security (TLS) protocol. TLS allows client/server applications to communicate over the Internet in a way that is designed to prevent eavesdropping, tampering, and message forgery. This document updates RFCs 5705 and 6066, and obsoletes RFCs 5077, 5246, and 6961. This document also specifies new requirements for TLS 1.2 implementations. This document defines the core of the QUIC transport protocol. QUIC provides applications with flow-controlled streams for structured communication, low-latency connection establishment, and network path migration. QUIC includes security measures that ensure confidentiality, integrity, and availability in a range of deployment circumstances. Accompanying documents describe the integration of TLS for key negotiation, loss detection, and an exemplary congestion control algorithm. Watsen Networks Informative References Watsen Networks This document presents two YANG modules: the first defines a minimal grouping for configuring an HTTP client, and the second defines a minimal grouping for configuring an HTTP server. It is intended that these groupings will be used to help define the configuration for simple HTTP-based protocols (not for complete web servers or browsers). Support is provided for HTTP/1.1, HTTP/2, and HTTP/3. Work in Progress Watsen Networks This document presents two YANG modules, one module to configure a NETCONF client and the other module to configure a NETCONF server. Both modules support both the SSH and TLS transport protocols, and support both standard NETCONF and NETCONF Call Home connections. Editorial Note (To be removed by RFC Editor) This draft contains placeholder values that need to be replaced with finalized values at the time of publication. This note summarizes all of the substitutions that are needed. No other RFC Editor instructions are specified elsewhere in this document. Artwork in this document contains shorthand references to drafts in progress. Please apply the following replacements (note: not all may be present): * AAAA --> the assigned RFC value for draft-ietf-netconf-crypto- types * BBBB --> the assigned RFC value for draft-ietf-netconf-trust- anchors * CCCC --> the assigned RFC value for draft-ietf-netconf-keystore * DDDD --> the assigned RFC value for draft-ietf-netconf-tcp-client- server * EEEE --> the assigned RFC value for draft-ietf-netconf-ssh-client- server * FFFF --> the assigned RFC value for draft-ietf-netconf-tls-client- server * GGGG --> the assigned RFC value for draft-ietf-netconf-http- client-server * HHHH --> the assigned RFC value for this draft Artwork in this document contains placeholder values for the date of publication of this draft. Please apply the following replacement: * 2024-08-14 --> the publication date of this draft The "Relation to other RFCs" section Section 1.1 contains the text "one or more YANG modules" and, later, "modules". This text is sourced from a file in a context where it is unknown how many modules a draft defines. The text is not wrong as is, but it may be improved by stating more directly how many modules are defined. The "Relation to other RFCs" section Section 1.1 contains a self- reference to this draft, along with a corresponding reference in the Appendix. Please replace the self-reference in this section with "This RFC" (or similar) and remove the self-reference in the "Normative/Informative References" section, whichever it is in. Tree-diagrams in this draft may use the '\' line-folding mode defined in RFC 8792. However, nicer-to-the-eye is when the '\\' line-folding mode is used. The AD suggested suggested putting a request here for the RFC Editor to help convert "ugly" '\' folded examples to use the '\\' folding mode. "Help convert" may be interpreted as, identify what looks ugly and ask the authors to make the adjustment. The following Appendix section is to be removed prior to publication: * Appendix A. Change Log Work in Progress Huawei Huawei Work in Progress Watsen Networks This document presents two YANG modules, one module to configure a RESTCONF client and the other module to configure a RESTCONF server. Both modules support the TLS transport protocol with both standard RESTCONF and RESTCONF Call Home connections. Editorial Note (To be removed by RFC Editor) This draft contains placeholder values that need to be replaced with finalized values at the time of publication. This note summarizes all of the substitutions that are needed. No other RFC Editor instructions are specified elsewhere in this document. Artwork in this document contains shorthand references to drafts in progress. Please apply the following replacements (note: not all may be present): * AAAA --> the assigned RFC value for draft-ietf-netconf-crypto- types * BBBB --> the assigned RFC value for draft-ietf-netconf-trust- anchors * CCCC --> the assigned RFC value for draft-ietf-netconf-keystore * DDDD --> the assigned RFC value for draft-ietf-netconf-tcp-client- server * EEEE --> the assigned RFC value for draft-ietf-netconf-ssh-client- server * FFFF --> the assigned RFC value for draft-ietf-netconf-tls-client- server * GGGG --> the assigned RFC value for draft-ietf-netconf-http- client-server * HHHH --> the assigned RFC value for draft-ietf-netconf-netconf- client-server * IIII --> the assigned RFC value for this draft Artwork in this document contains placeholder values for the date of publication of this draft. Please apply the following replacement: * 2024-08-14 --> the publication date of this draft The "Relation to other RFCs" section Section 1.1 contains the text "one or more YANG modules" and, later, "modules". This text is sourced from a file in a context where it is unknown how many modules a draft defines. The text is not wrong as is, but it may be improved by stating more directly how many modules are defined. The "Relation to other RFCs" section Section 1.1 contains a self- reference to this draft, along with a corresponding reference in the Appendix. Please replace the self-reference in this section with "This RFC" (or similar) and remove the self-reference in the "Normative/Informative References" section, whichever it is in. Tree-diagrams in this draft may use the '\' line-folding mode defined in RFC 8792. However, nicer-to-the-eye is when the '\\' line-folding mode is used. The AD suggested suggested putting a request here for the RFC Editor to help convert "ugly" '\' folded examples to use the '\\' folding mode. "Help convert" may be interpreted as, identify what looks ugly and ask the authors to make the adjustment. The following Appendix section is to be removed prior to publication: * Appendix A. Change Log Work in Progress This document describes an IANA maintained registry for IETF standards which use Extensible Markup Language (XML) related items such as Namespaces, Document Type Declarations (DTDs), Schemas, and Resource Description Framework (RDF) Schemas. JavaScript Object Notation (JSON) is a lightweight, text-based, language-independent data interchange format. It was derived from the ECMAScript Programming Language Standard. JSON defines a small set of formatting rules for the portable representation of structured data. This document removes inconsistencies with other specifications of JSON, repairs specification errors, and offers experience-based interoperability guidance. This document captures the current syntax used in YANG module tree diagrams. The purpose of this document is to provide a single location for this definition. This syntax may be updated from time to time based on the evolution of the YANG language. Datastores are a fundamental concept binding the data models written in the YANG data modeling language to network management protocols such as the Network Configuration Protocol (NETCONF) and RESTCONF. This document defines an architectural framework for datastores based on the experience gained with the initial simpler model, addressing requirements that were not well supported in the initial model. This document updates RFC 7950. This memo provides guidelines for authors and reviewers of specifications containing YANG modules. Recommendations and procedures are defined, which are intended to increase interoperability and usability of Network Configuration Protocol (NETCONF) and RESTCONF protocol implementations that utilize YANG modules. This document obsoletes RFC 6087. This document defines two strategies for handling long lines in width-bounded text content. One strategy, called the "single backslash" strategy, is based on the historical use of a single backslash ('\') character to indicate where line-folding has occurred, with the continuation occurring with the first character that is not a space character (' ') on the next line. The second strategy, called the "double backslash" strategy, extends the first strategy by adding a second backslash character to identify where the continuation begins and is thereby able to handle cases not supported by the first strategy. Both strategies use a self-describing header enabling automated reconstitution of the original content. Watsen Networks Watsen Networks Hochschule Esslingen - University of Applied Sciences Watsen Networks Watsen Networks IEEE W3C Recommendation REC-xml-20081126

Acknowledgements The authors would like to thank the following for lively discussions on list and in the halls (ordered by first name): , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , and .

Author's Address Watsen Networks

kent+ietf@watsen.net