| Internet-Draft | A YANG Data Model for a Keystore | August 2020 |
| Watsen | Expires 21 February 2021 | [Page] |
This document defines 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. Asymmetric keys may be associated with certificates. Notifications are sent when certificates are about to expire.¶
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AAAA --> the assigned RFC value for draft-ietf-netconf-crypto-types¶
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2020-08-20 --> the publication date of this draft¶
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This document defines a YANG 1.1 [RFC7950] 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 [I-D.ietf-netconf-crypto-types]. 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 either configured locally (within the defining data model) or be a reference to a key in the Keystore.¶
Special consideration has been given for systems that have cryptographic hardware, such as a Trusted Platform Module (TPM). These systems are unique in that the cryptographic hardware hides the secret key values. Additionally, such hardware is commonly initiailized when manufactured to protect a "built-in" asymmetric key for which the public half is conveyed in an identity certificate (e.g., an IDevID [Std-802.1AR-2009] certificate). Please see Section 3 to see how built-in keys are supported.¶
This document intends to support existing practices; it does not intend to define new behvior for systems to implement. To simplify implementation, advanced key formats may be selectively implemented.¶
Implementations may utilize zero or more operating system level keystore utilities and/or hardware security modules (HSMs).¶
This document presents one or more YANG modules [RFC7950] that are part of a collection of RFCs that work together to define configuration modules for clients and servers of both the NETCONF [RFC6241] and RESTCONF [RFC8040] protocols.¶
The modules have been defined in a modular fashion to enable their use by other efforts, some of which are known to be in progress at the time of this writing, with many more expected to be defined in time.¶
The normative dependency relationship between the various RFCs in the collection is presented in the below diagram. The labels in the diagram represent the primary purpose provided by each RFC. Hyperlinks to each RFC are provided below the diagram.¶
crypto-types
^ ^
/ \
/ \
truststore keystore
^ ^ ^ ^
| +---------+ | |
| | | |
| +------------+ |
tcp-client-server | / | |
^ ^ ssh-client-server | |
| | ^ tls-client-server
| | | ^ ^ http-client-server
| | | | | ^
| | | +-----+ +---------+ |
| | | | | |
| +-----------|--------|--------------+ | |
| | | | | |
+-----------+ | | | | |
| | | | | |
| | | | | |
netconf-client-server restconf-client-server
¶
| Label in Diagram | Originating RFC |
|---|---|
| crypto-types | [I-D.ietf-netconf-crypto-types] |
| truststore | [I-D.ietf-netconf-trust-anchors] |
| keystore | [I-D.ietf-netconf-keystore] |
| tcp-client-server | [I-D.ietf-netconf-tcp-client-server] |
| ssh-client-server | [I-D.ietf-netconf-ssh-client-server] |
| tls-client-server | [I-D.ietf-netconf-tls-client-server] |
| http-client-server | [I-D.ietf-netconf-http-client-server] |
| netconf-client-server | [I-D.ietf-netconf-netconf-client-server] |
| restconf-client-server | [I-D.ietf-netconf-restconf-client-server] |
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here.¶
The terms "client" and "server" are defined in [RFC6241] and are not redefined here.¶
The term "keystore" is defined in this draft as a mechanism that intends safeguard secrets placed into it for protection.¶
The nomenclature "<running>" and "<operational>" are defined in [RFC8342].¶
The sentence fragments "augmented" and "augmented in" are used herein as the past tense verbified form of the "augment" statement defined in Section 7.17 of [RFC7950].¶
This document is compliant with Network Management Datastore Architecture (NMDA) [RFC8342]. For instance, keys and associated certificates installed during manufacturing (e.g., for an IDevID certificate) are expected to appear in <operational> (see Section 3).¶
This section defines a YANG 1.1 [RFC7950] module called "ietf-keystore". A high-level overview of the module is provided in Section 2.1. Examples illustatrating the module's use are provided in Examples (Section 2.2). The YANG module itself is defined in Section 2.3.¶
This section provides an overview of the "ietf-keystore" module in terms of its features, typedefs, groupings, and protocol-accessible nodes.¶
The following diagram lists all the "feature" statements defined in the "ietf-keystore" module:¶
Features: +-- keystore-supported +-- local-definitions-supported¶
The following diagram lists the "typedef" statements defined in the "ietf-keystore" module:¶
Typedefs:
leafref
+-- symmetric-key-ref
+-- asymmetric-key-ref
¶
Comments:¶
The following diagram lists all the "grouping" statements defined in the "ietf-keystore" module:¶
Groupings: +-- encrypted-by-choice-grouping +-- asymmetric-key-certificate-ref-grouping +-- local-or-keystore-symmetric-key-grouping +-- local-or-keystore-asymmetric-key-grouping +-- local-or-keystore-asymmetric-key-with-certs-grouping +-- local-or-keystore-end-entity-cert-with-key-grouping +-- keystore-grouping¶
Each of these groupings are presented in the following subsections.¶
The following tree diagram [RFC8340] illustrates the "encrypted-by-choice-grouping" grouping:¶
grouping encrypted-by-choice-grouping
+-- (encrypted-by-choice)
+--:(symmetric-key-ref)
| +-- symmetric-key-ref? ks:symmetric-key-ref
+--:(asymmetric-key-ref)
+-- asymmetric-key-ref? ks:asymmetric-key-ref
¶
Comments:¶
The following tree diagram [RFC8340] illustrates the "asymmetric-key-certificate-ref-grouping" grouping:¶
grouping asymmetric-key-certificate-ref-grouping
+-- asymmetric-key? ks:asymmetric-key-ref
+-- certificate? leafref
¶
Comments:¶
The following tree diagram [RFC8340] illustrates the "local-or-keystore-symmetric-key-grouping" grouping:¶
grouping local-or-keystore-symmetric-key-grouping
+-- (local-or-keystore)
+--:(local) {local-definitions-supported}?
| +-- local-definition
| +---u ct:symmetric-key-grouping
+--:(keystore) {keystore-supported}?
+-- keystore-reference? ks:symmetric-key-ref
¶
Comments:¶
The following tree diagram [RFC8340] illustrates the "local-or-keystore-asymmetric-key-grouping" grouping:¶
grouping local-or-keystore-asymmetric-key-grouping
+-- (local-or-keystore)
+--:(local) {local-definitions-supported}?
| +-- local-definition
| +---u ct:asymmetric-key-pair-grouping
+--:(keystore) {keystore-supported}?
+-- keystore-reference? ks:asymmetric-key-ref
¶
Comments:¶
The following tree diagram [RFC8340] illustrates the "local-or-keystore-asymmetric-key-with-certs-grouping" grouping:¶
grouping local-or-keystore-asymmetric-key-with-certs-grouping
+-- (local-or-keystore)
+--:(local) {local-definitions-supported}?
| +-- local-definition
| +---u ct:asymmetric-key-pair-with-certs-grouping
+--:(keystore) {keystore-supported}?
+-- keystore-reference? ks:asymmetric-key-ref
¶
Comments:¶
The following tree diagram [RFC8340] illustrates the "local-or-keystore-end-entity-cert-with-key-grouping" grouping:¶
grouping local-or-keystore-end-entity-cert-with-key-grouping
+-- (local-or-keystore)
+--:(local) {local-definitions-supported}?
| +-- local-definition
| +---u ct:asymmetric-key-pair-with-cert-grouping
+--:(keystore) {keystore-supported}?
+-- keystore-reference
+---u asymmetric-key-certificate-ref-grouping
¶
Comments:¶
The following tree diagram [RFC8340] illustrates the "keystore-grouping" grouping:¶
grouping keystore-grouping
+-- asymmetric-keys
| +-- asymmetric-key* [name]
| +-- name? string
| +---u ct:asymmetric-key-pair-with-certs-grouping
+-- symmetric-keys
+-- symmetric-key* [name]
+-- name? string
+---u ct:symmetric-key-grouping
¶
Comments:¶
The following tree diagram [RFC8340] lists all the protocol-accessible nodes defined in the "ietf-keystore" module, without expanding the "grouping" statements:¶
module: ietf-keystore
+--rw keystore
+---u keystore-grouping
grouping encrypted-by-choice-grouping
+-- (encrypted-by-choice)
+--:(symmetric-key-ref)
| +-- symmetric-key-ref? ks:symmetric-key-ref
+--:(asymmetric-key-ref)
+-- asymmetric-key-ref? ks:asymmetric-key-ref
grouping asymmetric-key-certificate-ref-grouping
+-- asymmetric-key? ks:asymmetric-key-ref
+-- certificate? leafref
grouping local-or-keystore-symmetric-key-grouping
+-- (local-or-keystore)
+--:(local) {local-definitions-supported}?
| +-- local-definition
| +---u ct:symmetric-key-grouping
+--:(keystore) {keystore-supported}?
+-- keystore-reference? ks:symmetric-key-ref
grouping local-or-keystore-asymmetric-key-grouping
+-- (local-or-keystore)
+--:(local) {local-definitions-supported}?
| +-- local-definition
| +---u ct:asymmetric-key-pair-grouping
+--:(keystore) {keystore-supported}?
+-- keystore-reference? ks:asymmetric-key-ref
grouping local-or-keystore-asymmetric-key-with-certs-grouping
+-- (local-or-keystore)
+--:(local) {local-definitions-supported}?
| +-- local-definition
| +---u ct:asymmetric-key-pair-with-certs-grouping
+--:(keystore) {keystore-supported}?
+-- keystore-reference? ks:asymmetric-key-ref
grouping local-or-keystore-end-entity-cert-with-key-grouping
+-- (local-or-keystore)
+--:(local) {local-definitions-supported}?
| +-- local-definition
| +---u ct:asymmetric-key-pair-with-cert-grouping
+--:(keystore) {keystore-supported}?
+-- keystore-reference
+---u asymmetric-key-certificate-ref-grouping
grouping keystore-grouping
+-- asymmetric-keys
| +-- asymmetric-key* [name]
| +-- name? string
| +---u ct:asymmetric-key-pair-with-certs-grouping
+-- symmetric-keys
+-- symmetric-key* [name]
+-- name? string
+---u ct:symmetric-key-grouping
¶
The following tree diagram [RFC8340] 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:¶
module: ietf-keystore
+--rw keystore
+--rw 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)
| | | +--rw cleartext-private-key? binary
| | +--:(hidden-private-key)
| | | +--rw hidden-private-key? empty
| | +--:(encrypted-private-key) {private-key-encryption}?
| | +--rw encrypted-private-key
| | +--rw encrypted-by
| | | +--rw (encrypted-by-choice)
| | | +--:(symmetric-key-ref)
| | | | +--rw symmetric-key-ref?
| | | | ks:symmetric-key-ref
| | | +--:(asymmetric-key-ref)
| | | +--rw asymmetric-key-ref?
| | | ks:asymmetric-key-ref
| | +--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-certificate-signing-request
| {certificate-signing-request-generation}?
| +---w input
| | +---w csr-info ct:csr-info
| +--ro output
| +--ro certificate-signing-request ct:csr
+--rw symmetric-keys
+--rw symmetric-key* [name]
+--rw name string
+--rw key-format? identityref
+--rw (key-type)
+--:(cleartext-key)
| +--rw cleartext-key? binary
+--:(hidden-key)
| +--rw hidden-key? empty
+--:(encrypted-key) {symmetric-key-encryption}?
+--rw encrypted-key
+--rw encrypted-by
| +--rw (encrypted-by-choice)
| +--:(symmetric-key-ref)
| | +--rw symmetric-key-ref?
| | ks:symmetric-key-ref
| +--:(asymmetric-key-ref)
| +--rw asymmetric-key-ref?
| ks:asymmetric-key-ref
+--rw encrypted-value binary
grouping encrypted-by-choice-grouping
+-- (encrypted-by-choice)
+--:(symmetric-key-ref)
| +-- symmetric-key-ref? ks:symmetric-key-ref
+--:(asymmetric-key-ref)
+-- asymmetric-key-ref? ks:asymmetric-key-ref
grouping asymmetric-key-certificate-ref-grouping
+-- asymmetric-key? ks:asymmetric-key-ref
+-- certificate? leafref
grouping local-or-keystore-symmetric-key-grouping
+-- (local-or-keystore)
+--:(local) {local-definitions-supported}?
| +-- local-definition
| +-- key-format? identityref
| +-- (key-type)
| +--:(cleartext-key)
| | +-- cleartext-key? binary
| +--:(hidden-key)
| | +-- hidden-key? empty
| +--:(encrypted-key) {symmetric-key-encryption}?
| +-- encrypted-key
| +-- encrypted-by
| +-- encrypted-value binary
+--:(keystore) {keystore-supported}?
+-- keystore-reference? ks:symmetric-key-ref
grouping local-or-keystore-asymmetric-key-grouping
+-- (local-or-keystore)
+--:(local) {local-definitions-supported}?
| +-- local-definition
| +-- public-key-format identityref
| +-- public-key binary
| +-- private-key-format? identityref
| +-- (private-key-type)
| +--:(cleartext-private-key)
| | +-- cleartext-private-key? binary
| +--:(hidden-private-key)
| | +-- hidden-private-key? empty
| +--:(encrypted-private-key) {private-key-encryption}?
| +-- encrypted-private-key
| +-- encrypted-by
| +-- encrypted-value binary
+--:(keystore) {keystore-supported}?
+-- keystore-reference? ks:asymmetric-key-ref
grouping local-or-keystore-asymmetric-key-with-certs-grouping
+-- (local-or-keystore)
+--:(local) {local-definitions-supported}?
| +-- local-definition
| +-- public-key-format identityref
| +-- public-key binary
| +-- private-key-format? identityref
| +-- (private-key-type)
| | +--:(cleartext-private-key)
| | | +-- cleartext-private-key? binary
| | +--:(hidden-private-key)
| | | +-- hidden-private-key? empty
| | +--:(encrypted-private-key) {private-key-encryption}?
| | +-- encrypted-private-key
| | +-- encrypted-by
| | +-- encrypted-value binary
| +-- certificates
| | +-- certificate* [name]
| | +-- name? string
| | +-- cert-data end-entity-cert-cms
| | +---n certificate-expiration
| | {certificate-expiration-notification}?
| | +-- expiration-date yang:date-and-time
| +---x generate-certificate-signing-request
| {certificate-signing-request-generation}?
| +---w input
| | +---w csr-info ct:csr-info
| +--ro output
| +--ro certificate-signing-request ct:csr
+--:(keystore) {keystore-supported}?
+-- keystore-reference? ks:asymmetric-key-ref
grouping local-or-keystore-end-entity-cert-with-key-grouping
+-- (local-or-keystore)
+--:(local) {local-definitions-supported}?
| +-- local-definition
| +-- public-key-format identityref
| +-- public-key binary
| +-- private-key-format? identityref
| +-- (private-key-type)
| | +--:(cleartext-private-key)
| | | +-- cleartext-private-key? binary
| | +--:(hidden-private-key)
| | | +-- hidden-private-key? empty
| | +--:(encrypted-private-key) {private-key-encryption}?
| | +-- encrypted-private-key
| | +-- encrypted-by
| | +-- encrypted-value binary
| +-- cert-data?
| | end-entity-cert-cms
| +---n certificate-expiration
| | {certificate-expiration-notification}?
| | +-- expiration-date yang:date-and-time
| +---x generate-certificate-signing-request
| {certificate-signing-request-generation}?
| +---w input
| | +---w csr-info ct:csr-info
| +--ro output
| +--ro certificate-signing-request ct:csr
+--:(keystore) {keystore-supported}?
+-- keystore-reference
+-- asymmetric-key? ks:asymmetric-key-ref
+-- certificate? leafref
grouping keystore-grouping
+-- asymmetric-keys
| +-- asymmetric-key* [name]
| +-- name? string
| +-- public-key-format identityref
| +-- public-key binary
| +-- private-key-format? identityref
| +-- (private-key-type)
| | +--:(cleartext-private-key)
| | | +-- cleartext-private-key? binary
| | +--:(hidden-private-key)
| | | +-- hidden-private-key? empty
| | +--:(encrypted-private-key) {private-key-encryption}?
| | +-- encrypted-private-key
| | +-- encrypted-by
| | +-- encrypted-value binary
| +-- certificates
| | +-- certificate* [name]
| | +-- name? string
| | +-- cert-data end-entity-cert-cms
| | +---n certificate-expiration
| | {certificate-expiration-notification}?
| | +-- expiration-date yang:date-and-time
| +---x generate-certificate-signing-request
| {certificate-signing-request-generation}?
| +---w input
| | +---w csr-info ct:csr-info
| +--ro output
| +--ro certificate-signing-request ct:csr
+-- symmetric-keys
+-- symmetric-key* [name]
+-- name? string
+-- key-format? identityref
+-- (key-type)
+--:(cleartext-key)
| +-- cleartext-key? binary
+--:(hidden-key)
| +-- hidden-key? empty
+--:(encrypted-key) {symmetric-key-encryption}?
+-- encrypted-key
+-- encrypted-by
+-- encrypted-value binary
¶
Comments:¶
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.¶
The following example illustrates keys in <running>. Please see Section 3 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-key>base64encodedvalue==</cleartext-key>
</symmetric-key>
<symmetric-key>
<name>hidden-symmetric-key</name>
<hidden-key/>
</symmetric-key>
<symmetric-key>
<name>encrypted-symmetric-key</name>
<key-format>
ct:encrypted-one-symmetric-key-format
</key-format>
<encrypted-key>
<encrypted-by>
<asymmetric-key-ref>hidden-asymmetric-key</asymmetric-k\
ey-ref>
</encrypted-by>
<encrypted-value>base64encodedvalue==</encrypted-value>
</encrypted-key>
</symmetric-key>
</symmetric-keys>
<asymmetric-keys>
<asymmetric-key>
<name>ssh-rsa-key</name>
<public-key-format>
ct:ssh-public-key-format
</public-key-format>
<public-key>base64encodedvalue==</public-key>
<private-key-format>
ct:rsa-private-key-format
</private-key-format>
<cleartext-private-key>base64encodedvalue==</cleartext-priv\
ate-key>
</asymmetric-key>
<asymmetric-key>
<name>ssh-rsa-key-with-cert</name>
<public-key-format>
ct:subject-public-key-info-format
</public-key-format>
<public-key>base64encodedvalue==</public-key>
<private-key-format>
ct:rsa-private-key-format
</private-key-format>
<cleartext-private-key>base64encodedvalue==</cleartext-priv\
ate-key>
<certificates>
<certificate>
<name>ex-rsa-cert2</name>
<cert-data>base64encodedvalue==</cert-data>
</certificate>
</certificates>
</asymmetric-key>
<asymmetric-key>
<name>raw-private-key</name>
<public-key-format>
ct:subject-public-key-info-format
</public-key-format>
<public-key>base64encodedvalue==</public-key>
<private-key-format>
ct:rsa-private-key-format
</private-key-format>
<cleartext-private-key>base64encodedvalue==</cleartext-priv\
ate-key>
</asymmetric-key>
<asymmetric-key>
<name>rsa-asymmetric-key</name>
<public-key-format>
ct:subject-public-key-info-format
</public-key-format>
<public-key>base64encodedvalue==</public-key>
<private-key-format>
ct:rsa-private-key-format
</private-key-format>
<cleartext-private-key>base64encodedvalue==</cleartext-priv\
ate-key>
<certificates>
<certificate>
<name>ex-rsa-cert</name>
<cert-data>base64encodedvalue==</cert-data>
</certificate>
</certificates>
</asymmetric-key>
<asymmetric-key>
<name>ec-asymmetric-key</name>
<public-key-format>
ct:subject-public-key-info-format
</public-key-format>
<public-key>base64encodedvalue==</public-key>
<private-key-format>
ct:ec-private-key-format
</private-key-format>
<cleartext-private-key>base64encodedvalue==</cleartext-priv\
ate-key>
<certificates>
<certificate>
<name>ex-ec-cert</name>
<cert-data>base64encodedvalue==</cert-data>
</certificate>
</certificates>
</asymmetric-key>
<asymmetric-key>
<name>hidden-asymmetric-key</name>
<public-key-format>
ct:subject-public-key-info-format
</public-key-format>
<public-key>base64encodedvalue==</public-key>
<hidden-private-key/>
<certificates>
<certificate>
<name>builtin-idevid-cert</name>
<cert-data>base64encodedvalue==</cert-data>
</certificate>
<certificate>
<name>my-ldevid-cert</name>
<cert-data>base64encodedvalue==</cert-data>
</certificate>
</certificates>
</asymmetric-key>
<asymmetric-key>
<name>encrypted-asymmetric-key</name>
<public-key-format>
ct:subject-public-key-info-format
</public-key-format>
<public-key>base64encodedvalue==</public-key>
<private-key-format>
ct:encrypted-one-asymmetric-key-format
</private-key-format>
<encrypted-private-key>
<encrypted-by>
<symmetric-key-ref>encrypted-symmetric-key</symmetric-k\
ey-ref>
</encrypted-by>
<encrypted-value>base64encodedvalue==</encrypted-value>
</encrypted-private-key>
</asymmetric-key>
</asymmetric-keys>
</keystore>
¶
The following example illustrates a "certificate-expiration" notification for a certificate associated with a 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>
¶
This section illustrates the various "local-or-keystore" groupings defined in the "ietf-keystore" module, specifically the "local-or-keystore-symmetric-key-grouping" (Section 2.1.3.3), "local-or-keystore-asymmetric-key-grouping" (Section 2.1.3.4), "local-or-keystore-asymmetric-key-with-certs-grouping" (Section 2.1.3.5), and "local-or-keystore-end-entity-cert-with-key-grouping" (Section 2.1.3.6) groupings.¶
These examples assume the existence of an example module called "ex-keystore-usage" having the namespace "http://example.com/ns/example-keystore-usage".¶
The ex-keystore-usage module is first presented using tree diagrams [RFC8340], followed by an instance example illustrating all the "local-or-keystore" groupings in use, followed by the YANG module itself.¶
The following tree diagram illustrates "ex-keystore-usage" without expanding the "grouping" statements:¶
module: ex-keystore-usage
+--rw keystore-usage
+--rw symmetric-key* [name]
| +--rw name string
| +---u ks:local-or-keystore-symmetric-key-grouping
+--rw asymmetric-key* [name]
| +--rw name string
| +---u ks:local-or-keystore-asymmetric-key-grouping
+--rw asymmetric-key-with-certs* [name]
| +--rw name
| | string
| +---u ks:local-or-keystore-asymmetric-key-with-certs-grouping
+--rw end-entity-cert-with-key* [name]
+--rw name
| string
+---u ks:local-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 keystore's full structure to be seen:¶
module: ex-keystore-usage
+--rw keystore-usage
+--rw symmetric-key* [name]
| +--rw name string
| +--rw (local-or-keystore)
| +--:(local) {local-definitions-supported}?
| | +--rw local-definition
| | +--rw key-format? identityref
| | +--rw (key-type)
| | +--:(cleartext-key)
| | | +--rw cleartext-key? binary
| | +--:(hidden-key)
| | | +--rw hidden-key? empty
| | +--:(encrypted-key) {symmetric-key-encryption}?
| | +--rw encrypted-key
| | +--rw encrypted-by
| | +--rw encrypted-value binary
| +--:(keystore) {keystore-supported}?
| +--rw keystore-reference? ks:symmetric-key-ref
+--rw asymmetric-key* [name]
| +--rw name string
| +--rw (local-or-keystore)
| +--:(local) {local-definitions-supported}?
| | +--rw local-definition
| | +--rw public-key-format identityref
| | +--rw public-key binary
| | +--rw private-key-format? identityref
| | +--rw (private-key-type)
| | +--:(cleartext-private-key)
| | | +--rw cleartext-private-key? binary
| | +--:(hidden-private-key)
| | | +--rw hidden-private-key? empty
| | +--:(encrypted-private-key)
| | {private-key-encryption}?
| | +--rw encrypted-private-key
| | +--rw encrypted-by
| | +--rw encrypted-value binary
| +--:(keystore) {keystore-supported}?
| +--rw keystore-reference? ks:asymmetric-key-ref
+--rw asymmetric-key-with-certs* [name]
| +--rw name string
| +--rw (local-or-keystore)
| +--:(local) {local-definitions-supported}?
| | +--rw local-definition
| | +--rw public-key-format
| | | identityref
| | +--rw public-key binary
| | +--rw private-key-format?
| | | identityref
| | +--rw (private-key-type)
| | | +--:(cleartext-private-key)
| | | | +--rw cleartext-private-key? binary
| | | +--:(hidden-private-key)
| | | | +--rw hidden-private-key? empty
| | | +--:(encrypted-private-key)
| | | {private-key-encryption}?
| | | +--rw encrypted-private-key
| | | +--rw encrypted-by
| | | +--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-certificate-signing-request
| | {certificate-signing-request-generation}?
| | +---w input
| | | +---w csr-info ct:csr-info
| | +--ro output
| | +--ro certificate-signing-request ct:csr
| +--:(keystore) {keystore-supported}?
| +--rw keystore-reference? ks:asymmetric-key-ref
+--rw end-entity-cert-with-key* [name]
+--rw name string
+--rw (local-or-keystore)
+--:(local) {local-definitions-supported}?
| +--rw local-definition
| +--rw public-key-format
| | identityref
| +--rw public-key binary
| +--rw private-key-format?
| | identityref
| +--rw (private-key-type)
| | +--:(cleartext-private-key)
| | | +--rw cleartext-private-key? binary
| | +--:(hidden-private-key)
| | | +--rw hidden-private-key? empty
| | +--:(encrypted-private-key)
| | {private-key-encryption}?
| | +--rw encrypted-private-key
| | +--rw encrypted-by
| | +--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-certificate-signing-request
| {certificate-signing-request-generation}?
| +---w input
| | +---w csr-info ct:csr-info
| +--ro output
| +--ro certificate-signing-request ct:csr
+--:(keystore) {keystore-supported}?
+--rw keystore-reference
+--rw asymmetric-key? ks:asymmetric-key-ref
+--rw certificate? leafref
¶
The following example provides two equivalent instances of each grouping, the first being a reference to a keystore and the second being locally-defined. The instance having a reference to a keystore is consistent with the keystore defined in Section 2.2.1. The two instances are equivalent, as the locally-defined 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="http://example.com/ns/example-keystore-usage"
xmlns:ct="urn:ietf:params:xml:ns:yang:ietf-crypto-types">
<!-- The following two equivalent examples illustrate the -->
<!-- "local-or-keystore-symmetric-key-grouping" grouping: -->
<symmetric-key>
<name>example 1a</name>
<keystore-reference>cleartext-symmetric-key</keystore-reference>
</symmetric-key>
<symmetric-key>
<name>example 1b</name>
<local-definition>
<key-format>ct:octet-string-key-format</key-format>
<cleartext-key>base64encodedvalue==</cleartext-key>
</local-definition>
</symmetric-key>
<!-- The following two equivalent examples illustrate the -->
<!-- "local-or-keystore-asymmetric-key-grouping" grouping: -->
<asymmetric-key>
<name>example 2a</name>
<keystore-reference>rsa-asymmetric-key</keystore-reference>
</asymmetric-key>
<asymmetric-key>
<name>example 2b</name>
<local-definition>
<public-key-format>
ct:subject-public-key-info-format
</public-key-format>
<public-key>base64encodedvalue==</public-key>
<private-key-format>
ct:rsa-private-key-format
</private-key-format>
<cleartext-private-key>base64encodedvalue==</cleartext-private\
-key>
</local-definition>
</asymmetric-key>
<!-- the following two equivalent examples illustrate -->
<!-- "local-or-keystore-asymmetric-key-with-certs-grouping": -->
<asymmetric-key-with-certs>
<name>example 3a</name>
<keystore-reference>rsa-asymmetric-key</keystore-reference>
</asymmetric-key-with-certs>
<asymmetric-key-with-certs>
<name>example 3b</name>
<local-definition>
<public-key-format>
ct:subject-public-key-info-format
</public-key-format>
<public-key>base64encodedvalue==</public-key>
<private-key-format>
ct:rsa-private-key-format
</private-key-format>
<cleartext-private-key>base64encodedvalue==</cleartext-private\
-key>
<certificates>
<certificate>
<name>a locally-defined cert</name>
<cert-data>base64encodedvalue==</cert-data>
</certificate>
</certificates>
</local-definition>
</asymmetric-key-with-certs>
<!-- The following two equivalent examples illustrate -->
<!-- "local-or-keystore-end-entity-cert-with-key-grouping": -->
<end-entity-cert-with-key>
<name>example 4a</name>
<keystore-reference>
<asymmetric-key>rsa-asymmetric-key</asymmetric-key>
<certificate>ex-rsa-cert</certificate>
</keystore-reference>
</end-entity-cert-with-key>
<end-entity-cert-with-key>
<name>example 4b</name>
<local-definition>
<public-key-format>
ct:subject-public-key-info-format
</public-key-format>
<public-key>base64encodedvalue==</public-key>
<private-key-format>
ct:rsa-private-key-format
</private-key-format>
<cleartext-private-key>base64encodedvalue==</cleartext-private\
-key>
<cert-data>base64encodedvalue==</cert-data>
</local-definition>
</end-entity-cert-with-key>
</keystore-usage>
¶
Following is the "ex-keystore-usage" module's YANG definition:¶
module ex-keystore-usage {
yang-version 1.1;
namespace "http://example.com/ns/example-keystore-usage";
prefix "eku";
import ietf-keystore {
prefix ks;
reference
"RFC CCCC: A YANG Data Model for a Keystore";
}
organization
"Example Corporation";
contact
"Author: YANG Designer <mailto:yang.designer@example.com>";
description
"This module illustrates notable groupings defined in
the 'ietf-keystore' module.";
revision "2020-08-20" {
description
"Initial version";
reference
"RFC CCCC: 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:local-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:local-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:local-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:local-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.";
}
}
}
¶
This YANG module has normative references to [RFC8341] and [I-D.ietf-netconf-crypto-types].¶
<CODE BEGINS> file "ietf-keystore@2020-08-20.yang"¶
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 AAAA: YANG Data Types and Groupings for Cryptography";
}
organization
"IETF NETCONF (Network Configuration) Working Group";
contact
"WG Web: <http://datatracker.ietf.org/wg/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.
Copyright (c) 2020 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 Simplified
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 CCCC
(https://www.rfc-editor.org/info/rfcCCCC); see the RFC
itself for full legal notices.
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.";
revision 2020-08-20 {
description
"Initial version";
reference
"RFC CCCC: A YANG Data Model for a Keystore";
}
/****************/
/* Features */
/****************/
feature keystore-supported {
description
"The 'keystore-supported' feature indicates that the server
supports the Keystore.";
}
feature local-definitions-supported {
description
"The 'local-definitions-supported' feature indicates that the
server supports locally-defined keys.";
}
/****************/
/* Typedefs */
/****************/
typedef 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 Keystore.";
}
typedef 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 Keystore.";
}
/*****************/
/* Groupings */
/*****************/
grouping encrypted-by-choice-grouping {
description
"A grouping that defines a choice that can be augmented
into the 'encrypted-by' node presented by the
'symmetric-key-grouping' and 'asymmetric-key-pair-grouping'
groupings defined in RFC AAAA.";
choice encrypted-by-choice {
nacm:default-deny-write;
mandatory true;
description
"A choice amongst other symmetric or asymmetric keys.";
case symmetric-key-ref {
leaf symmetric-key-ref {
type ks:symmetric-key-ref;
description
"Identifies the symmetric key used to encrypt the
associated key.";
}
}
case asymmetric-key-ref {
leaf asymmetric-key-ref {
type ks:asymmetric-key-ref;
description
"Identifies the asymmetric key whose public key
encrypted the associated key.";
}
}
}
}
grouping asymmetric-key-certificate-ref-grouping {
description
"This grouping defines a reference to a specific certificate
associated with an asymmetric key stored in the Keystore.";
leaf asymmetric-key {
nacm:default-deny-write;
type ks: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.";
}
}
// local-or-keystore-* groupings
grouping local-or-keystore-symmetric-key-grouping {
description
"A grouping that expands to allow the symmetric key to be
either stored locally, i.e., within the using data model,
or a reference to a symmetric key stored in the Keystore.";
choice local-or-keystore {
nacm:default-deny-write;
mandatory true;
description
"A choice between an inlined definition and a definition
that exists in the Keystore.";
case local {
if-feature "local-definitions-supported";
container local-definition {
description
"Container to hold the local key definition.";
uses ct:symmetric-key-grouping;
}
}
case keystore {
if-feature "keystore-supported";
leaf keystore-reference {
type ks:symmetric-key-ref;
description
"A reference to an symmetric key that exists in
the Keystore.";
}
}
}
}
grouping local-or-keystore-asymmetric-key-grouping {
description
"A grouping that expands to allow the asymmetric key to be
either stored locally, i.e., within the using data model,
or a reference to an asymmetric key stored in the Keystore.";
choice local-or-keystore {
nacm:default-deny-write;
mandatory true;
description
"A choice between an inlined definition and a definition
that exists in the Keystore.";
case local {
if-feature "local-definitions-supported";
container local-definition {
description
"Container to hold the local key definition.";
uses ct:asymmetric-key-pair-grouping;
}
}
case keystore {
if-feature "keystore-supported";
leaf keystore-reference {
type ks:asymmetric-key-ref;
description
"A reference to an asymmetric key that exists in
the Keystore. The intent is to reference just the
asymmetric key without any regard for any certificates
that may be associated with it.";
}
}
}
}
grouping local-or-keystore-asymmetric-key-with-certs-grouping {
description
"A grouping that expands to allow an asymmetric key and
its associated certificates to be either stored locally,
i.e., within the using data model, or a reference to an
asymmetric key (and its associated certificates) stored
in the Keystore.";
choice local-or-keystore {
nacm:default-deny-write;
mandatory true;
description
"A choice between an inlined definition and a definition
that exists in the Keystore.";
case local {
if-feature "local-definitions-supported";
container local-definition {
description
"Container to hold the local key definition.";
uses ct:asymmetric-key-pair-with-certs-grouping;
}
}
case keystore {
if-feature "keystore-supported";
leaf keystore-reference {
type ks:asymmetric-key-ref;
description
"A reference to an asymmetric-key (and all of its
associated certificates) in the Keystore.";
}
}
}
}
grouping local-or-keystore-end-entity-cert-with-key-grouping {
description
"A grouping that expands to allow an end-entity certificate
(and its associated asymmetric key pair) to be either stored
locally, i.e., within the using data model, or a reference
to a specific certificate in the Keystore.";
choice local-or-keystore {
nacm:default-deny-write;
mandatory true;
description
"A choice between an inlined definition and a definition
that exists in the Keystore.";
case local {
if-feature "local-definitions-supported";
container local-definition {
description
"Container to hold the local key definition.";
uses ct:asymmetric-key-pair-with-cert-grouping;
}
}
case keystore {
if-feature "keystore-supported";
container keystore-reference {
uses asymmetric-key-certificate-ref-grouping;
description
"A reference to a specific certificate associated with
an asymmetric key stored in the Keystore.";
}
}
}
}
grouping keystore-grouping {
description
"Grouping definition enables use in other contexts. If ever
done, implementations SHOULD augment new 'case' statements
into local-or-keystore 'choice' statements to supply leafrefs
to the new location.";
container asymmetric-keys {
nacm:default-deny-write;
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;
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;
}
}
} // grouping keystore-grouping
/*********************************/
/* Protocol accessible nodes */
/*********************************/
container keystore {
description
"The Keystore contains 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-key/"
+ "encrypted-key/encrypted-by" {
description
"Augments in a choice statement enabling the encrypting
key to be any other symmetric or asymmetric key in the
keystore.";
uses encrypted-by-choice-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
keystore.";
uses encrypted-by-choice-grouping;
}
}
}
}
¶
<CODE ENDS>¶
In some implementations, a server may support built-in keys. 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., SSH) is enabled.¶
The primary characteristic of the built-in keys is that they are provided by the system, as opposed to configuration. As such, they are present in <operational>. The example below illustrates what the keystore in <operational> might look like for a server in its factory default state.¶
<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-key-format>
<public-key>base64encodedvalue==</public-key>
<hidden-private-key/>
<certificates>
<certificate>
<name>Manufacturer-Generated IDevID Cert</name>
<cert-data>base64encodedvalue==</cert-data>
</certificate>
</certificates>
</asymmetric-key>
</asymmetric-keys>
</keystore>
¶
In order for the built-in keys (and/or their associated built-in certificates) to be referenced by configuration, the referenced keys MUST first be copied into <running>. The keys SHOULD be copied into <running> using the same value for the list's "key" substatement, so that the server can bind the references to the built-in entries.¶
In addition to copying keys into the Keystore in <running>, cleartext and encrypted keys may be copied into other parts of configuration, but they will lose their connection to having been a built-in value. Note that hidden keys cannot be copied into other parts of the configuration because doing would lose the key's connection to the built-in key, where the key's secret value is stored. Built-in "encrypted" keys MAY be copied into other parts of the configuration so long as the reference to the other built-in key that encrypted them is maintained.¶
Only the referenced keys need to be copied; that is, the keys in <running> MAY be a subset, including the whole of the set, of the built-in keys defined in <operational>.¶
No new built-in keys may be added nor existing built-in changed, with exception for associating additional certificates to an existing built-in key.¶
A server MUST reject attempts to modify any aspect of built-in keys, with exception for associating additional certificates to a built-in key. That these keys are "configured" in <running> is an illusion, as they are strictly a read-only subset of that which must already exist in <operational>.¶
The following example illustrates how a single built-in key definition from the previous example has been propagated to <running>:¶
<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-key-format>
<public-key>base64encodedvalue==</public-key>
<hidden-private-key/>
<certificates>
<certificate>
<name>Manufacturer-Generated IDevID Cert</name>
<cert-data>base64encodedvalue==</cert-data>
</certificate>
<certificate>
<name>Deployment-Specific LDevID Cert</name>
<cert-data>base64encodedvalue==</cert-data>
</certificate>
</certificates>
</asymmetric-key>
</asymmetric-keys>
</keystore>
¶
After the above configuration is applied, <operational> should appear as follows:¶
<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-key-format>
<public-key>base64encodedvalue==</public-key>
<hidden-private-key/>
<certificates>
<certificate>
<name>Manufacturer-Generated IDevID Cert</name>
<cert-data>base64encodedvalue==</cert-data>
</certificate>
<certificate or:origin="or:intended">
<name>Deployment-Specific LDevID Cert</name>
<cert-data>base64encodedvalue==</cert-data>
</certificate>
</certificates>
</asymmetric-key>
</asymmetric-keys>
</keystore>
¶
This section describes an approach that enables both the symmetric and asymmetric keys on a server to be encrypted, such that traditional backup/restore procedures can be used without concern for the keys being compromised when in transit.¶
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 system. 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 MAY provide an API enabling the encryption of other keys or, alternatively, let the administrators do so themselves using the asymmetric key's public half.¶
A server MUST possess (or be able to possess, in case the KEK has been encrypted by another KEK) a KEK's cleartext value so that it can decrypt the other keys in the configurion at runtime.¶
Each time a new key is configured, it SHOULD be encrypted by a KEK.¶
In "ietf-crypto-types" [I-D.ietf-netconf-crypto-types], the format for an encrypted symmetric key is described by the "encrypted-one-symmetric-key-format" identity, while the format for an encrypted asymmetric key is described by the "encrypted-one-asymmetric-key-format" identity¶
Implementations SHOULD provide an API that simultaneously generates and encrypts a key (symmetric or asymmetric) using a KEK. Thusly newly generated key cleartext values are never known to the administrators generating the keys.¶
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 (e.g., an organization's crypto officer).¶
In either case, the encrypted key can be configured into the Keystore using either the "encrypted-key" (for symmetric keys) or the "encrypted-private-key" (for asymmetric keys) nodes. These two nodes contain both the encrypted value as well as a reference to the KEK that encrypted the key.¶
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 but, in many RMA 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 (e.g., NACM's "default-deny-all), 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 doesn't scale in production environments.¶
In order to decouple the crypto officers from the regular administrators, a special KEK, called the "master key" (MK), may be used.¶
A MK is commonly a globally-unique built-in (see Section 3) asymmetric key. The private key, due to its long lifetime, is hidden (i.e., "hidden-private-key" in Section 2.1.4.5. of [I-D.ietf-netconf-crypto-types]). The public key is often contained in an identity certificate (e.g., IDevID). How to configure a MK during the manufacturing process is outside the scope of this document.¶
It is highly RECOMMENDED that MKs are built-in and hidden but, if this is not possible, MKs highly restricted access mechanisms SHOULD be used to limit access to the MK's secret data to only highly authorized clients (e.g., an organization's crypto officer). In this case, it is RECOMMENDED that the MK is not built-in and hence is, effectively, just like a KEK.¶
Assuming the server has a MK, the MK 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 handoff the encrypted KEKs to the 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 MK |
| |
| |
| possesses \o |
+-------------- |\ |
/ \ shares with |
crypto +--------------------+
officer |
|
|
+----------------------+ | +----------------------+
| server-1 | | | server-2 |
| configuration | | | configuration |
| | | | |
| | | | |
| +----------------+ | | | +----------------+ |
| | MK-1 | | | | | MK-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) | |
| +----------------+ | | +----------------+ |
| | | |
+----------------------+ +----------------------+
¶
The YANG module defined in this document defines a mechanism called a "keystore" that, by its name, suggests that it will protect its contents from unauthorized disclosure and modification.¶
Security controls for the API (i.e., data in motion) are discussed in Section 5.2, but controls for the data at rest cannot be specified by the YANG module.¶
In order to satisfy the expectations of a "keystore", it is RECOMMENDED that implementations ensure that the keystore contents are encrypted when persisted to non-volatile memory.¶
The YANG module defined in this document is designed to be accessed via YANG based management protocols, such as NETCONF [RFC6241] and RESTCONF [RFC8040]. Both of these protocols have mandatory-to-implement secure transport layers (e.g., SSH, TLS) with mutual authentication.¶
The NETCONF access control model (NACM) [RFC8341] provides the means to restrict access for particular users to a pre-configured subset of all available protocol operations and content.¶
None of the readable data nodes defined in this YANG module are considered sensitive or vulnerable in network environments. The NACM "default-deny-all" extension has not been set for any data nodes defined in this module.¶
All of the writable data nodes defined by this 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 module does not define any RPCs, actions, or notifications, and thus the security consideration for such is not provided here.¶
This document registers one URI in the "ns" subregistry of the IETF XML Registry [RFC3688]. Following the format in [RFC3688], the following registration is requested:¶
URI: urn:ietf:params:xml:ns:yang:ietf-keystore Registrant Contact: The NETCONF WG of the IETF. XML: N/A, the requested URI is an XML namespace.¶
This document registers one YANG module in the YANG Module Names registry [RFC6020]. Following the format in [RFC6020], the following registration is requested:¶
name: ietf-keystore namespace: urn:ietf:params:xml:ns:yang:ietf-keystore prefix: ks reference: RFC CCCC¶
This section is to be removed before publishing as an RFC.¶
The authors would like to thank for following for lively discussions on list and in the halls (ordered by first name): Alan Luchuk, Andy Bierman, Benoit Claise, Bert Wijnen, Balazs Kovacs, David Lamparter, Eric Voit, Ladislav Lhotka, Liang Xia, Juergen Schoenwaelder, Mahesh Jethanandani, Magnus Nystroem, Martin Bjorklund, Mehmet Ersue, Phil Shafer, Radek Krejci, Ramkumar Dhanapal, Reshad Rahman, Sandra Murphy, Sean Turner, and Tom Petch.¶