Watsen Networks

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Operations NETCONF Working Group This document defines three YANG 1.1 modules: the first defines features and groupings common to both TLS clients and TLS servers, the second defines a grouping for a generic TLS client, and the third defines a grouping for a generic TLS server. 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:

• 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
• FFFF --> 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:

• 2022-07-18 --> the publication date of this draft

The following Appendix section is to be removed prior to publication:

• . Change Log

Introduction This document defines three YANG 1.1 modules: the first defines features and groupings common to both TLS clients and TLS servers, the second defines a grouping for a generic TLS client, and the third defines a grouping for a generic TLS server. Any version of TLS may be configured. TLS 1.0 and TLS 1.1 are historic and hence the YANG "feature" statements enabling them are marked "status obsolete". TLS 1.2 is obsoleted by TLS 1.3 but still in common use, and hence its "feature" statement is marked "status deprecated". All the feature statements for 1.0, 1.1, and 1.3 have "description" statements stating that it is NOT RECOMMENDED to enable obsolete protocol versions. It is intended that the YANG groupings will be used by applications needing to configure TLS client and server protocol stacks. For instance, these groupings are used to help define the data model for HTTPS and NETCONF over TLS based clients and servers in and respectively. The client and server YANG modules in this document each define one grouping, which is focused on just TLS-specific configuration, and specifically avoids any transport-level configuration, such as what ports to listen-on or connect-to. This affords applications the opportunity to define their own strategy for how the underlying TCP connection is established. For instance, applications supporting NETCONF Call Home could use the "tls-server-grouping" grouping for the TLS parts it provides, while adding data nodes for the TCP-level call-home configuration.

Relation to other RFCs This document presents one or more YANG modules that are part of a collection of RFCs that work together to, ultimately, enable the configuration of the clients and servers of both the NETCONF and RESTCONF 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. Label to RFC Mapping

Label in Diagram	Originating RFC
crypto-types
truststore
keystore
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.

Adherence to the NMDA This document is compliant with the Network Management Datastore Architecture (NMDA) . For instance, as described in and , trust anchors and keys installed during manufacturing are expected to appear in <operational>.

Conventions Various examples used in this document use a placeholder value for binary data that has been base64 encoded (e.g., "BASE64VALUE="). This placeholder value is used as real base64 encoded structures are often many lines long and hence distracting to the example being presented.

The "ietf-tls-common" Module The TLS common model presented in this section contains features and groupings common to both TLS clients and TLS servers. The "hello-params-grouping" grouping can be used to configure the list of TLS algorithms permitted by the TLS client or TLS server. The lists of algorithms are ordered such that, if multiple algorithms are permitted by the client, the algorithm that appears first in its list that is also permitted by the server is used for the TLS transport layer connection. The ability to restrict the algorithms allowed is provided in this grouping for TLS clients and TLS servers that are capable of doing so and may serve to make TLS clients and TLS servers compliant with local security policies. This model supports both TLS 1.2 and TLS 1.3 . Thus, in order to support both TLS1.2 and TLS1.3, the cipher-suites part of the "hello-params-grouping" grouping should include three parameters for configuring its permitted TLS algorithms, which are: TLS Cipher Suites, TLS SignatureScheme, TLS Supported Groups. Note that TLS1.2 only uses TLS Cipher Suites.

Data Model Overview This section provides an overview of the "ietf-tls-common" module in terms of its features, identities, and groupings.

Features The following diagram lists all the "feature" statements defined in the "ietf-tls-common" module:

Identities The following diagram illustrates the relationship amongst the "identity" statements defined in the "ietf-tls-common" module: Comments:

• The diagram shows that there are two base identities.
• One base identity is used to specific TLS versions, while the other is used to specify cipher-suites.
• These base identities are "abstract", in the object oriented programming sense, in that they only define a "class" of things, rather than a specific thing.

Groupings The "ietf-tls-common" module defines the following "grouping" statement:

• hello-params-grouping

This grouping is presented in the following subsection.

The "hello-params-grouping" Grouping The following tree diagram illustrates the "hello-params-grouping" grouping: Comments:

• This grouping is used by both the "tls-client-grouping" and the "tls-server-grouping" groupings defined in and , respectively.
• This grouping enables client and server configurations to specify the TLS versions and cipher suites that are to be used when establishing TLS sessions.
• The "cipher-suites" list is "ordered-by user".

Protocol-accessible Nodes The following tree diagram lists all the protocol-accessible nodes defined in the "ietf-tls-common" module, without expanding the "grouping" statements: The following tree diagram lists all the protocol-accessible nodes defined in the "ietf-tls-common" module, with all "grouping" statements expanded, enabling the module's full structure to be seen: 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-tls-common" module are limited to the RPC "generate-public-key", which is additionally constrained by the feature "public-key-generation".
• The "encrypted-by-choice-grouping" grouping is discussed in .
• The "asymmetric-key-pair-grouping" grouping is discussed in .

Example Usage The following example illustrates the "hello-params-grouping' grouping when populated with some data. tlscmn:tls11 tlscmn:tls12 tlscsa:tls-ecdhe-ecdsa-with-aes-256-cbc-sha tlscsa:tls-dhe-rsa-with-aes-128-cbc-sha256 tlscsa:tls-rsa-with-3des-ede-cbc-sha ]]> The following example illustrates the "generate-public-key" RPC. tlscsa:tls-ecdhe-psk-with-aes-128-gcm-sha256 521 hidden-asymmetric-key ]]>

YANG Module This YANG module has a normative references to , , , , and FIPS PUB 180-4. This YANG module has a informative references to , , , and . <CODE BEGINS> file "ietf-tls-common@2022-07-18.yang" WG Web: https://datatracker.ietf.org/wg/netconf Author: Kent Watsen Author: Jeff Hartley Author: Gary Wu "; description "This module defines a common features and groupings for Transport Layer Security (TLS). Copyright (c) 2022 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 FFFF (https://www.rfc-editor.org/info/rfcFFFF); 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 2022-07-18 { description "Initial version"; reference "RFC FFFF: YANG Groupings for TLS Clients and TLS Servers"; } // Features feature tls10 { status "obsolete"; description "TLS Protocol Version 1.0 is supported. TLS 1.0 is obsolete and thus it is NOT RECOMMENDED to enable this feature."; reference "RFC 2246: The TLS Protocol Version 1.0"; } feature tls11 { status "obsolete"; description "TLS Protocol Version 1.1 is supported. TLS 1.1 is obsolete and thus it is NOT RECOMMENDED to enable this feature."; reference "RFC 4346: The Transport Layer Security (TLS) Protocol Version 1.1"; } feature tls12 { status "deprecated"; description "TLS Protocol Version 1.2 is supported TLS 1.2 is obsolete and thus it is NOT RECOMMENDED to enable this feature."; reference "RFC 5246: The Transport Layer Security (TLS) Protocol Version 1.2"; } feature tls13 { description "TLS Protocol Version 1.3 is supported."; reference "RFC 8446: The Transport Layer Security (TLS) Protocol Version 1.3"; } feature hello-params { description "TLS hello message parameters are configurable."; } feature public-key-generation { description "Indicates that the server implements the 'generate-public-key' RPC."; } // Identities identity tls-version-base { description "Base identity used to identify TLS protocol versions."; } identity tls10 { if-feature "tls10"; base tls-version-base; status "obsolete"; description "TLS Protocol Version 1.0."; reference "RFC 2246: The TLS Protocol Version 1.0"; } identity tls11 { if-feature "tls11"; base tls-version-base; status "obsolete"; description "TLS Protocol Version 1.1."; reference "RFC 4346: The Transport Layer Security (TLS) Protocol Version 1.1"; } identity tls12 { if-feature "tls12"; base tls-version-base; status "deprecated"; description "TLS Protocol Version 1.2."; reference "RFC 5246: The Transport Layer Security (TLS) Protocol Version 1.2"; } identity tls13 { if-feature "tls13"; base tls-version-base; description "TLS Protocol Version 1.3."; reference "RFC 8446: The Transport Layer Security (TLS) Protocol Version 1.3"; } typedef epsk-supported-hash { type enumeration { enum sha-256 { description "The SHA-256 Hash."; } enum sha-384 { description "The SHA-384 Hash."; } } description "As per Section 4.2.11 of RFC 8446, the hash algorithm supported by an instance of an External Pre-Shared Key (EPSK)."; reference "RFC 8446: The Transport Layer Security (TLS) Protocol Version 1.3 I-D.ietf-tls-external-psk-importer: Importing External PSKs for TLS I-D.ietf-tls-external-psk-guidance: Guidance for External PSK Usage in TLS"; } // Groupings grouping hello-params-grouping { description "A reusable grouping for TLS hello message parameters."; reference "RFC 5246: The Transport Layer Security (TLS) Protocol Version 1.2 RFC 8446: The Transport Layer Security (TLS) Protocol Version 1.3"; container tls-versions { description "Parameters regarding TLS versions."; leaf-list tls-version { type identityref { base tls-version-base; } description "Acceptable TLS protocol versions. If this leaf-list is not configured (has zero elements) the acceptable TLS protocol versions are implementation- defined."; } } container cipher-suites { description "Parameters regarding cipher suites."; leaf-list cipher-suite { type identityref { base tlscsa:cipher-suite-alg-base; } ordered-by user; description "Acceptable cipher suites in order of descending preference. The configured host key algorithms should be compatible with the algorithm used by the configured private key. Please see Section 5 of RFC FFFF for valid combinations. If this leaf-list is not configured (has zero elements) the acceptable cipher suites are implementation- defined."; reference "RFC FFFF: YANG Groupings for TLS Clients and TLS Servers"; } } } // hello-params-grouping rpc generate-public-key { if-feature "public-key-generation"; description "Requests the device to generate an public key using the specified key algorithm."; input { leaf algorithm { type tlscsa:cipher-suite-algorithm-ref; mandatory true; description "The cipher suite algorithm that the generated key is to work with. Implementations derive the public key algorithm from the cipher suite algorithm. Example: cipher suite 'tls-rsa-with-aes-256-cbc-sha256' maps to the RSA public key."; } leaf bits { type uint16; description "Specifies the number of bits in the key to create. For RSA keys, the minimum size is 1024 bits and the default is 3072 bits. Generally, 3072 bits is considered sufficient. DSA keys must be exactly 1024 bits as specified by FIPS 186-2. For elliptical keys, the 'bits' value determines the key length of the curve (e.g., 256, 384 or 521), where valid values supported by the server are conveyed via an unspecified mechanism. For some public algorithms, the keys have a fixed length and the 'bits' value, if specified, will be ignored."; } choice private-key-encoding { default cleartext; description "A choice amongst optional private key handling."; case cleartext { leaf cleartext { type empty; description "Indicates that the private key is to be returned as a cleartext value."; } } case encrypt { if-feature "ct:private-key-encryption"; container encrypt-with { description "Indicates that the key is to be encrypted using the specified symmetric or asymmetric key."; uses ks:encrypted-by-choice-grouping; } } case hide { if-feature "ct:hidden-keys"; leaf hide { type empty; description "Indicates that the private key is to be hidden. Unlike the 'cleartext' and 'encrypt' options, the key returned is a placeholder for an internally stored key. See the 'Support for Built-in Keys' section in RFC CCCC for information about hidden keys."; } } } } output { uses ct:asymmetric-key-pair-grouping; } } // end generate-public-key } ]]> <CODE ENDS>

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

Data Model Overview This section provides an overview of the "ietf-tls-client" module in terms of its features and groupings.

Features The following diagram lists all the "feature" statements defined in the "ietf-tls-client" module:

Groupings The "ietf-tls-client" module defines the following "grouping" statement:

• tls-client-grouping

This grouping is presented in the following subsection.

The "tls-client-grouping" Grouping The following tree diagram illustrates the "tls-client-grouping" grouping: Comments:

• The "client-identity" node, which is optionally configured (as client authentication MAY occur at a higher protocol layer), configures identity credentials, each enabled by a "feature" statement defined in .
• The "server-authentication" node configures trust anchors for authenticating the TLS server, with each option enabled by a "feature" statement.
• The "hello-params" node, which must be enabled by a feature, configures parameters for the TLS sessions established by this configuration.
• The "keepalives" node, which must be enabled by a feature, configures a "presence" container for testing the aliveness of the TLS server. The aliveness-test occurs at the TLS protocol layer.
• For the referenced grouping statement(s):
  • The "local-or-keystore-end-entity-cert-with-key-grouping" grouping is discussed in .
  • The "local-or-keystore-asymmetric-key-grouping" grouping is discussed in .
  • The "local-or-keystore-symmetric-key-grouping" grouping is discussed in .
  • The "local-or-truststore-certs-grouping" grouping is discussed in .
  • The "local-or-truststore-public-keys-grouping" grouping is discussed in .
  • The "hello-params-grouping" grouping is discussed in in this document.

Protocol-accessible Nodes The "ietf-tls-client" module defines only "grouping" statements that are used by other modules to instantiate protocol-accessible nodes.

Example Usage This section presents two examples showing the "tls-client-grouping" grouping populated with some data. These examples are effectively the same except the first configures the client identity using a local key while the second uses a key configured in a keystore. Both examples are consistent with the examples presented in Section 2 of and Section 3.2 of . The following configuration example uses local-definitions for the client identity and server authentication: ct:subject-public-key-info-format\ BASE64VALUE= ct:rsa-private-key-format BASE64VALUE= BASE64VALUE= Server Cert Issuer #1 BASE64VALUE= Server Cert Issuer #2 BASE64VALUE= My Application #1 BASE64VALUE= My Application #2 BASE64VALUE= corp-fw1 ct:subject-public-key-info-fo\ rmat BASE64VALUE= corp-fw2 ct:subject-public-key-info-fo\ rmat BASE64VALUE= 30 3 ]]> The following configuration example uses keystore-references for the client identity and truststore-references for server authentication: from the keystore: rsa-asymmetric-key ex-rsa-cert trusted-server-ca-certs trusted-server-ee-certs Raw Public Keys for TLS Servers 30 3 ]]>

YANG Module This YANG module has normative references to and , and Informative references to , , and . <CODE BEGINS> file "ietf-tls-client@2022-07-18.yang" WG Web: https://datatracker.ietf.org/wg/netconf Author: Kent Watsen Author: Jeff Hartley Author: Gary Wu "; description "This module defines reusable groupings for TLS clients that can be used as a basis for specific TLS client instances. Copyright (c) 2022 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 FFFF (https://www.rfc-editor.org/info/rfcFFFF); 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 2022-07-18 { description "Initial version"; reference "RFC FFFF: YANG Groupings for TLS Clients and TLS Servers"; } // Features feature tls-client-keepalives { description "Per socket TLS keepalive parameters are configurable for TLS clients on the server implementing this feature."; } feature client-ident-x509-cert { description "Indicates that the client supports identifying itself using X.509 certificates."; reference "RFC 5280: Internet X.509 Public Key Infrastructure Certificate and Certificate Revocation List (CRL) Profile"; } feature client-ident-raw-public-key { description "Indicates that the client supports identifying itself using raw public keys."; reference "RFC 7250: Using Raw Public Keys in Transport Layer Security (TLS) and Datagram Transport Layer Security (DTLS)"; } feature client-ident-tls12-psk { description "Indicates that the client supports identifying itself using TLS-1.2 PSKs (pre-shared or pairwise-symmetric keys)."; reference "RFC 4279: Pre-Shared Key Ciphersuites for Transport Layer Security (TLS)"; } feature client-ident-tls13-epsk { description "Indicates that the client supports identifying itself using TLS-1.3 External PSKs (pre-shared keys)."; reference "RFC 8446: The Transport Layer Security (TLS) Protocol Version 1.3"; } feature server-auth-x509-cert { description "Indicates that the client supports authenticating servers using X.509 certificates."; reference "RFC 5280: Internet X.509 Public Key Infrastructure Certificate and Certificate Revocation List (CRL) Profile"; } feature server-auth-raw-public-key { description "Indicates that the client supports authenticating servers using raw public keys."; reference "RFC 7250: Using Raw Public Keys in Transport Layer Security (TLS) and Datagram Transport Layer Security (DTLS)"; } feature server-auth-tls12-psk { description "Indicates that the client supports authenticating servers using PSKs (pre-shared or pairwise-symmetric keys)."; reference "RFC 4279: Pre-Shared Key Ciphersuites for Transport Layer Security (TLS)"; } feature server-auth-tls13-epsk { description "Indicates that the client supports authenticating servers using TLS-1.3 External PSKs (pre-shared keys)."; reference "RFC 8446: The Transport Layer Security (TLS) Protocol Version 1.3"; } // Groupings grouping tls-client-grouping { description "A reusable grouping for configuring a TLS client without any consideration for how an underlying TCP session is established. Note that this grouping uses fairly typical descendant node names such that a stack of 'uses' statements will have name conflicts. It is intended that the consuming data model will resolve the issue (e.g., by wrapping the 'uses' statement in a container called 'tls-client-parameters'). This model purposely does not do this itself so as to provide maximum flexibility to consuming models."; container client-identity { nacm:default-deny-write; presence "Indicates that a TLS-level client identity has been configured. This statement is present so the mandatory descendant do not imply that this node must be configured."; description "Identity credentials the TLS client MAY present when establishing a connection to a TLS server. If not configured, then client authentication is presumed to occur a protocol layer above TLS. When configured, and requested by the TLS server when establishing a TLS session, these credentials are passed in the Certificate message defined in Section 7.4.2 of RFC 5246 and Section 4.4.2 in RFC 8446."; reference "RFC 5246: The Transport Layer Security (TLS) Protocol Version 1.2 RFC 8446: The Transport Layer Security (TLS) Protocol Version 1.3 RFC CCCC: A YANG Data Model for a Keystore"; choice auth-type { mandatory true; description "A choice amongst authentication types, of which one must be enabled (via its associated 'feature') and selected."; case certificate { if-feature "client-ident-x509-cert"; container certificate { description "Specifies the client identity using a certificate."; uses ks:local-or-keystore-end-entity-cert-with-key-grouping{ refine "local-or-keystore/local/local-definition" { must 'public-key-format' + ' = "ct:subject-public-key-info-format"'; } refine "local-or-keystore/keystore/keystore-reference" + "/asymmetric-key" { must 'deref(.)/../ks:public-key-format' + ' = "ct:subject-public-key-info-format"'; } } } } case raw-public-key { if-feature "client-ident-raw-public-key"; container raw-private-key { description "Specifies the client identity using a raw private key."; uses ks:local-or-keystore-asymmetric-key-grouping { refine "local-or-keystore/local/local-definition" { must 'public-key-format' + ' = "ct:subject-public-key-info-format"'; } refine "local-or-keystore/keystore" + "/keystore-reference" { must 'deref(.)/../ks:public-key-format' + ' = "ct:subject-public-key-info-format"'; } } } } case tls12-psk { if-feature "client-ident-tls12-psk"; container tls12-psk { description "Specifies the client identity using a PSK (pre-shared or pairwise-symmetric key)."; uses ks:local-or-keystore-symmetric-key-grouping; leaf id { type string; description "The key 'psk_identity' value used in the TLS 'ClientKeyExchange' message."; reference "RFC 4279: Pre-Shared Key Ciphersuites for Transport Layer Security (TLS)"; } } } case tls13-epsk { if-feature "client-ident-tls13-epsk"; container tls13-epsk { description "An External Pre-Shared Key (EPSK) is established or provisioned out-of-band, i.e., not from a TLS connection. An EPSK is a tuple of (Base Key, External Identity, Hash). External PSKs MUST NOT be imported for (D)TLS 1.2 or prior versions. When PSKs are provisioned out of band, the PSK identity and the KDF hash algorithm to be used with the PSK MUST also be provisioned. The structure of this container is designed to satisfy the requirements of RFC 8446 Section 4.2.11, the recommendations from I-D ietf-tls-external-psk-guidance Section 6, and the EPSK input fields detailed in I-D draft-ietf-tls-external-psk-importer Section 3.1. The base-key is based upon ks:local-or-keystore-symmetric-key-grouping in order to provide users with flexible and secure storage options."; reference "RFC 8446: The Transport Layer Security (TLS) Protocol Version 1.3 I-D.ietf-tls-external-psk-importer: Importing External PSKs for TLS I-D.ietf-tls-external-psk-guidance: Guidance for External PSK Usage in TLS"; uses ks:local-or-keystore-symmetric-key-grouping; leaf external-identity { type string; mandatory true; description "As per Section 4.2.11 of RFC 8446, and Section 4.1 of I-D. ietf-tls-external-psk-guidance: A sequence of bytes used to identify an EPSK. A label for a pre-shared key established externally."; reference "RFC 8446: The Transport Layer Security (TLS) Protocol Version 1.3 I-D.ietf-tls-external-psk-guidance: Guidance for External PSK Usage in TLS"; } leaf hash { type tlscmn:epsk-supported-hash; mandatory true; description "As per Section 4.2.11 of RFC 8446, for externally established PSKs, the Hash algorithm MUST be set when the PSK is established or default to SHA-256 if no such algorithm is defined. The server MUST ensure that it selects a compatible PSK (if any) and cipher suite. Each PSK MUST only be used with a single hash function."; reference "RFC 8446: The Transport Layer Security (TLS) Protocol Version 1.3"; } leaf context { type string; description "As per Section 4.1 of I-D. ietf-tls-external-psk-guidance: Context may include information about peer roles or identities to mitigate Selfie-style reflection attacks [Selfie]. If the EPSK is a key derived from some other protocol or sequence of protocols, context MUST include a channel binding for the deriving protocols [RFC5056]. The details of this binding are protocol specific."; reference "I-D.ietf-tls-external-psk-importer: Importing External PSKs for TLS I-D.ietf-tls-external-psk-guidance: Guidance for External PSK Usage in TLS"; } leaf target-protocol { type uint16; description "As per Section 3.1 of I-D. ietf-tls-external-psk-guidance: The protocol for which a PSK is imported for use."; reference "I-D.ietf-tls-external-psk-importer: Importing External PSKs for TLS"; } leaf target-kdf { type uint16; description "As per Section 3.1 of I-D. ietf-tls-external-psk-guidance: The specific Key Derivation Function (KDF) for which a PSK is imported for use."; reference "I-D.ietf-tls-external-psk-importer: Importing External PSKs for TLS"; } } } } } // container client-identity container server-authentication { nacm:default-deny-write; must 'ca-certs or ee-certs or raw-public-keys or tls12-psks or tls13-epsks'; description "Specifies how the TLS client can authenticate TLS servers. Any combination of credentials is additive and unordered. Note that no configuration is required for PSK (pre-shared or pairwise-symmetric key) based authentication as the key is necessarily the same as configured in the '../client- identity' node."; container ca-certs { if-feature "server-auth-x509-cert"; presence "Indicates that CA certificates have been configured. This statement is present so the mandatory descendant nodes do not imply that this node must be configured."; description "A set of certificate authority (CA) certificates used by the TLS client to authenticate TLS server certificates. A server certificate is authenticated if it has a valid chain of trust to a configured CA certificate."; reference "RFC BBBB: A YANG Data Model for a Truststore"; uses ts:local-or-truststore-certs-grouping; } container ee-certs { if-feature "server-auth-x509-cert"; presence "Indicates that EE certificates have been configured. This statement is present so the mandatory descendant nodes do not imply that this node must be configured."; description "A set of server certificates (i.e., end entity certificates) used by the TLS client to authenticate certificates presented by TLS servers. A server certificate is authenticated if it is an exact match to a configured server certificate."; reference "RFC BBBB: A YANG Data Model for a Truststore"; uses ts:local-or-truststore-certs-grouping; } container raw-public-keys { if-feature "server-auth-raw-public-key"; presence "Indicates that raw public keys have been configured. This statement is present so the mandatory descendant nodes do not imply that this node must be configured."; description "A set of raw public keys used by the TLS client to authenticate raw public keys presented by the TLS server. A raw public key is authenticated if it is an exact match to a configured raw public key."; reference "RFC BBBB: A YANG Data Model for a Truststore"; uses ts:local-or-truststore-public-keys-grouping { refine "local-or-truststore/local/local-definition" + "/public-key" { must 'public-key-format' + ' = "ct:subject-public-key-info-format"'; } refine "local-or-truststore/truststore" + "/truststore-reference" { must 'deref(.)/../*/ts:public-key-format' + ' = "ct:subject-public-key-info-format"'; } } } leaf tls12-psks { if-feature "server-auth-tls12-psk"; type empty; description "Indicates that the TLS client can authenticate TLS servers using configure PSKs (pre-shared or pairwise-symmetric keys). No configuration is required since the PSK value is the same as PSK value configured in the 'client-identity' node."; } leaf tls13-epsks { if-feature "server-auth-tls13-epsk"; type empty; description "Indicates that the TLS client can authenticate TLS servers using configured external PSKs (pre-shared keys). No configuration is required since the PSK value is the same as PSK value configured in the 'client-identity' node."; } } // container server-authentication container hello-params { nacm:default-deny-write; if-feature "tlscmn:hello-params"; uses tlscmn:hello-params-grouping; description "Configurable parameters for the TLS hello message."; } // container hello-params container keepalives { nacm:default-deny-write; if-feature "tls-client-keepalives"; description "Configures the keepalive policy for the TLS client."; leaf peer-allowed-to-send { type empty; description "Indicates that the remote TLS server is allowed to send HeartbeatRequest messages, as defined by RFC 6520 to this TLS client."; reference "RFC 6520: Transport Layer Security (TLS) and Datagram Transport Layer Security (DTLS) Heartbeat Extension"; } container test-peer-aliveness { presence "Indicates that the TLS client proactively tests the aliveness of the remote TLS server."; description "Configures the keep-alive policy to proactively test the aliveness of the TLS server. An unresponsive TLS server is dropped after approximately max-wait * max-attempts seconds. The TLS client MUST send HeartbeatRequest messages, as defined by RFC 6520."; reference "RFC 6520: Transport Layer Security (TLS) and Datagram Transport Layer Security (DTLS) Heartbeat Extension"; leaf max-wait { type uint16 { range "1..max"; } units "seconds"; default "30"; description "Sets the amount of time in seconds after which if no data has been received from the TLS server, a TLS-level message will be sent to test the aliveness of the TLS server."; } leaf max-attempts { type uint8; default "3"; description "Sets the maximum number of sequential keep-alive messages that can fail to obtain a response from the TLS server before assuming the TLS server is no longer alive."; } } } } // grouping tls-client-grouping } ]]> <CODE ENDS>

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

Data Model Overview This section provides an overview of the "ietf-tls-server" module in terms of its features and groupings.

Features The following diagram lists all the "feature" statements defined in the "ietf-tls-server" module:

Groupings The "ietf-tls-server" module defines the following "grouping" statement:

• tls-server-grouping

This grouping is presented in the following subsection.

The "tls-server-grouping" Grouping The following tree diagram illustrates the "tls-server-grouping" grouping: Comments:

• The "server-identity" node configures identity credentials, each of which is enabled by a "feature".
• The "client-authentication" node, which is optionally configured (as client authentication MAY occur at a higher protocol layer), configures trust anchors for authenticating the TLS client, with each option enabled by a "feature" statement.
• The "hello-params" node, which must be enabled by a feature, configures parameters for the TLS sessions established by this configuration.
• The "keepalives" node, which must be enabled by a feature, configures a flag enabling the TLS client to test the aliveness of the TLS server, as well as a "presence" container for testing the aliveness of the TLSi client. The aliveness-tests occurs at the TLS protocol layer.
• For the referenced grouping statement(s):
  • The "local-or-keystore-end-entity-cert-with-key-grouping" grouping is discussed in .
  • The "local-or-keystore-asymmetric-key-grouping" grouping is discussed in .
  • The "local-or-keystore-symmetric-key-grouping" grouping is discussed in .
  • The "local-or-truststore-public-keys-grouping" grouping is discussed in .
  • The "local-or-truststore-certs-grouping" grouping is discussed in .
  • The "hello-params-grouping" grouping is discussed in in this document.

Protocol-accessible Nodes The "ietf-tls-server" module defines only "grouping" statements that are used by other modules to instantiate protocol-accessible nodes.

Example Usage This section presents two examples showing the "tls-server-grouping" grouping populated with some data. These examples are effectively the same except the first configures the server identity using a local key while the second uses a key configured in a keystore. Both examples are consistent with the examples presented in Section 2 of and Section 3.2 of . The following configuration example uses local-definitions for the server identity and client authentication: ct:subject-public-key-info-format\ BASE64VALUE= ct:rsa-private-key-format BASE64VALUE= BASE64VALUE= Identity Cert Issuer #1 BASE64VALUE= Identity Cert Issuer #2 BASE64VALUE= Application #1 BASE64VALUE= Application #2 BASE64VALUE= User A ct:subject-public-key-info-fo\ rmat BASE64VALUE= User B ct:subject-public-key-info-fo\ rmat BASE64VALUE= ]]> The following configuration example uses keystore-references for the server identity and truststore-references for client authentication: from the keystore: rsa-asymmetric-key ex-rsa-cert trusted-client-ca-certs trusted-client-ee-certs Raw Public Keys for TLS Clients ]]>

YANG Module This YANG module has normative references to and , and Informative references to , , and . <CODE BEGINS> file "ietf-tls-server@2022-07-18.yang" WG Web: https://datatracker.ietf.org/wg/netconf Author: Kent Watsen Author: Jeff Hartley Author: Gary Wu "; description "This module defines reusable groupings for TLS servers that can be used as a basis for specific TLS server instances. Copyright (c) 2022 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 FFFF (https://www.rfc-editor.org/info/rfcFFFF); 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 2022-07-18 { description "Initial version"; reference "RFC FFFF: YANG Groupings for TLS Clients and TLS Servers"; } // Features feature tls-server-keepalives { description "Per socket TLS keepalive parameters are configurable for TLS servers on the server implementing this feature."; } feature server-ident-x509-cert { description "Indicates that the server supports identifying itself using X.509 certificates."; reference "RFC 5280: Internet X.509 Public Key Infrastructure Certificate and Certificate Revocation List (CRL) Profile"; } feature server-ident-raw-public-key { description "Indicates that the server supports identifying itself using raw public keys."; reference "RFC 7250: Using Raw Public Keys in Transport Layer Security (TLS) and Datagram Transport Layer Security (DTLS)"; } feature server-ident-tls12-psk { description "Indicates that the server supports identifying itself using TLS-1.2 PSKs (pre-shared or pairwise-symmetric keys)."; reference "RFC 4279: Pre-Shared Key Ciphersuites for Transport Layer Security (TLS)"; } feature server-ident-tls13-epsk { description "Indicates that the server supports identifying itself using TLS-1.3 External PSKs (pre-shared keys)."; reference "RFC 8446: The Transport Layer Security (TLS) Protocol Version 1.3"; } feature client-auth-supported { description "Indicates that the configuration for how to authenticate clients can be configured herein. TLS-level client authentication may not be needed when client authentication is expected to occur only at another protocol layer."; } feature client-auth-x509-cert { description "Indicates that the server supports authenticating clients using X.509 certificates."; reference "RFC 5280: Internet X.509 Public Key Infrastructure Certificate and Certificate Revocation List (CRL) Profile"; } feature client-auth-raw-public-key { description "Indicates that the server supports authenticating clients using raw public keys."; reference "RFC 7250: Using Raw Public Keys in Transport Layer Security (TLS) and Datagram Transport Layer Security (DTLS)"; } feature client-auth-tls12-psk { description "Indicates that the server supports authenticating clients using PSKs (pre-shared or pairwise-symmetric keys)."; reference "RFC 4279: Pre-Shared Key Ciphersuites for Transport Layer Security (TLS)"; } feature client-auth-tls13-epsk { description "Indicates that the server supports authenticating clients using TLS-1.3 External PSKs (pre-shared keys)."; reference "RFC 8446: The Transport Layer Security (TLS) Protocol Version 1.3"; } // Groupings grouping tls-server-grouping { description "A reusable grouping for configuring a TLS server without any consideration for how underlying TCP sessions are established. Note that this grouping uses fairly typical descendant node names such that a stack of 'uses' statements will have name conflicts. It is intended that the consuming data model will resolve the issue (e.g., by wrapping the 'uses' statement in a container called 'tls-server-parameters'). This model purposely does not do this itself so as to provide maximum flexibility to consuming models."; container server-identity { nacm:default-deny-write; description "A locally-defined or referenced end-entity certificate, including any configured intermediate certificates, the TLS server will present when establishing a TLS connection in its Certificate message, as defined in Section 7.4.2 in RFC 5246 and Section 4.4.2 in RFC 8446."; reference "RFC 5246: The Transport Layer Security (TLS) Protocol Version 1.2 RFC 8446: The Transport Layer Security (TLS) Protocol Version 1.3 RFC CCCC: A YANG Data Model for a Keystore"; choice auth-type { mandatory true; description "A choice amongst authentication types, of which one must be enabled (via its associated 'feature') and selected."; case certificate { if-feature "server-ident-x509-cert"; container certificate { description "Specifies the server identity using a certificate."; uses ks:local-or-keystore-end-entity-cert-with-key-grouping{ refine "local-or-keystore/local/local-definition" { must 'public-key-format' + ' = "ct:subject-public-key-info-format"'; } refine "local-or-keystore/keystore/keystore-reference" + "/asymmetric-key" { must 'deref(.)/../ks:public-key-format' + ' = "ct:subject-public-key-info-format"'; } } } } case raw-private-key { if-feature "server-ident-raw-public-key"; container raw-private-key { description "Specifies the server identity using a raw private key."; uses ks:local-or-keystore-asymmetric-key-grouping { refine "local-or-keystore/local/local-definition" { must 'public-key-format' + ' = "ct:subject-public-key-info-format"'; } refine "local-or-keystore/keystore/keystore-reference"{ must 'deref(.)/../ks:public-key-format' + ' = "ct:subject-public-key-info-format"'; } } } } case tls12-psk { if-feature "server-ident-tls12-psk"; container tls12-psk { description "Specifies the server identity using a PSK (pre-shared or pairwise-symmetric key)."; uses ks:local-or-keystore-symmetric-key-grouping; leaf id_hint { type string; description "The key 'psk_identity_hint' value used in the TLS 'ServerKeyExchange' message."; reference "RFC 4279: Pre-Shared Key Ciphersuites for Transport Layer Security (TLS)"; } } } case tls13-epsk { if-feature "server-ident-tls13-epsk"; container tls13-epsk { description "An External Pre-Shared Key (EPSK) is established or provisioned out-of-band, i.e., not from a TLS connection. An EPSK is a tuple of (Base Key, External Identity, Hash). External PSKs MUST NOT be imported for (D)TLS 1.2 or prior versions. When PSKs are provisioned out of band, the PSK identity and the KDF hash algorithm to be used with the PSK MUST also be provisioned. The structure of this container is designed to satisfy the requirements of RFC 8446 Section 4.2.11, the recommendations from I-D ietf-tls-external-psk-guidance Section 6, and the EPSK input fields detailed in I-D draft-ietf-tls-external-psk-importer Section 3.1. The base-key is based upon ks:local-or-keystore-symmetric-key-grouping in order to provide users with flexible and secure storage options."; reference "RFC 8446: The Transport Layer Security (TLS) Protocol Version 1.3 I-D.ietf-tls-external-psk-importer: Importing External PSKs for TLS I-D.ietf-tls-external-psk-guidance: Guidance for External PSK Usage in TLS"; uses ks:local-or-keystore-symmetric-key-grouping; leaf external-identity { type string; mandatory true; description "As per Section 4.2.11 of RFC 8446, and Section 4.1 of I-D. ietf-tls-external-psk-guidance: A sequence of bytes used to identify an EPSK. A label for a pre-shared key established externally."; reference "RFC 8446: The Transport Layer Security (TLS) Protocol Version 1.3 I-D.ietf-tls-external-psk-guidance: Guidance for External PSK Usage in TLS"; } leaf hash { type tlscmn:epsk-supported-hash; mandatory true; description "As per Section 4.2.11 of RFC 8446, for externally established PSKs, the Hash algorithm MUST be set when the PSK is established or default to SHA-256 if no such algorithm is defined. The server MUST ensure that it selects a compatible PSK (if any) and cipher suite. Each PSK MUST only be used with a single hash function."; reference "RFC 8446: The Transport Layer Security (TLS) Protocol Version 1.3"; } leaf context { type string; description "As per Section 4.1 of I-D. ietf-tls-external-psk-guidance: Context may include information about peer roles or identities to mitigate Selfie-style reflection attacks [Selfie]. If the EPSK is a key derived from some other protocol or sequence of protocols, context MUST include a channel binding for the deriving protocols [RFC5056]. The details of this binding are protocol specific."; reference "I-D.ietf-tls-external-psk-importer: Importing External PSKs for TLS I-D.ietf-tls-external-psk-guidance: Guidance for External PSK Usage in TLS"; } leaf target-protocol { type uint16; description "As per Section 3.1 of I-D. ietf-tls-external-psk-guidance: The protocol for which a PSK is imported for use."; reference "I-D.ietf-tls-external-psk-importer: Importing External PSKs for TLS"; } leaf target-kdf { type uint16; description "As per Section 3.1 of I-D. ietf-tls-external-psk-guidance: The specific Key Derivation Function (KDF) for which a PSK is imported for use."; reference "I-D.ietf-tls-external-psk-importer: Importing External PSKs for TLS"; } } } } } // container server-identity container client-authentication { if-feature "client-auth-supported"; nacm:default-deny-write; must 'ca-certs or ee-certs or raw-public-keys or tls12-psks or tls13-epsks'; presence "Indicates that client authentication is supported (i.e., that the server will request clients send certificates). If not configured, the TLS server SHOULD NOT request the TLS clients provide authentication credentials."; description "Specifies how the TLS server can authenticate TLS clients. Any combination of credentials is additive and unordered. Note that no configuration is required for PSK (pre-shared or pairwise-symmetric key) based authentication as the key is necessarily the same as configured in the '../server- identity' node."; container ca-certs { if-feature "client-auth-x509-cert"; presence "Indicates that CA certificates have been configured. This statement is present so the mandatory descendant nodes do not imply that this node must be configured."; description "A set of certificate authority (CA) certificates used by the TLS server to authenticate TLS client certificates. A client certificate is authenticated if it has a valid chain of trust to a configured CA certificate."; reference "RFC BBBB: A YANG Data Model for a Truststore"; uses ts:local-or-truststore-certs-grouping; } container ee-certs { if-feature "client-auth-x509-cert"; presence "Indicates that EE certificates have been configured. This statement is present so the mandatory descendant nodes do not imply that this node must be configured."; description "A set of client certificates (i.e., end entity certificates) used by the TLS server to authenticate certificates presented by TLS clients. A client certificate is authenticated if it is an exact match to a configured client certificate."; reference "RFC BBBB: A YANG Data Model for a Truststore"; uses ts:local-or-truststore-certs-grouping; } container raw-public-keys { if-feature "client-auth-raw-public-key"; presence "Indicates that raw public keys have been configured. This statement is present so the mandatory descendant nodes do not imply that this node must be configured."; description "A set of raw public keys used by the TLS server to authenticate raw public keys presented by the TLS client. A raw public key is authenticated if it is an exact match to a configured raw public key."; reference "RFC BBBB: A YANG Data Model for a Truststore"; uses ts:local-or-truststore-public-keys-grouping { refine "local-or-truststore/local/local-definition" + "/public-key" { must 'public-key-format' + ' = "ct:subject-public-key-info-format"'; } refine "local-or-truststore/truststore" + "/truststore-reference" { must 'deref(.)/../*/ts:public-key-format' + ' = "ct:subject-public-key-info-format"'; } } } leaf tls12-psks { if-feature "client-auth-tls12-psk"; type empty; description "Indicates that the TLS server can authenticate TLS clients using configured PSKs (pre-shared or pairwise-symmetric keys). No configuration is required since the PSK value is the same as PSK value configured in the 'server-identity' node."; } leaf tls13-epsks { if-feature "client-auth-tls13-epsk"; type empty; description "Indicates that the TLS 1.3 server can authenticate TLS clients using configured external PSKs (pre-shared keys). No configuration is required since the PSK value is the same as PSK value configured in the 'server-identity' node."; } } // container client-authentication container hello-params { nacm:default-deny-write; if-feature "tlscmn:hello-params"; uses tlscmn:hello-params-grouping; description "Configurable parameters for the TLS hello message."; } // container hello-params container keepalives { nacm:default-deny-write; if-feature "tls-server-keepalives"; description "Configures the keepalive policy for the TLS server."; leaf peer-allowed-to-send { type empty; description "Indicates that the remote TLS client is allowed to send HeartbeatRequest messages, as defined by RFC 6520 to this TLS server."; reference "RFC 6520: Transport Layer Security (TLS) and Datagram Transport Layer Security (DTLS) Heartbeat Extension"; } container test-peer-aliveness { presence "Indicates that the TLS server proactively tests the aliveness of the remote TLS client."; description "Configures the keep-alive policy to proactively test the aliveness of the TLS client. An unresponsive TLS client is dropped after approximately max-wait * max-attempts seconds."; leaf max-wait { type uint16 { range "1..max"; } units "seconds"; default "30"; description "Sets the amount of time in seconds after which if no data has been received from the TLS client, a TLS-level message will be sent to test the aliveness of the TLS client."; } leaf max-attempts { type uint8; default "3"; description "Sets the maximum number of sequential keep-alive messages that can fail to obtain a response from the TLS client before assuming the TLS client is no longer alive."; } } } // container keepalives } // grouping tls-server-grouping } ]]> <CODE ENDS>

Security Considerations

The "iana-tls-cipher-suite-algs" Module The "iana-tls-cipher-suite-algs" YANG module defines a data model that is designed to be accessed via YANG based management protocols, such as NETCONF and RESTCONF . Both of these protocols have mandatory-to-implement secure transport layers (e.g., SSH, TLS) with mutual authentication. The NETCONF access control model (NACM) provides the means to restrict access for particular users to a pre-configured subset of all available protocol operations and content. This YANG module defines YANG identities, for a public IANA-maintained registry, and a single protocol-accessible read-only node for the subset of those identities supported by a server. YANG identities are not security-sensitive, as they are statically defined in the publicly-accessible YANG module. The protocol-accessible read-only node for the algorithms supported by a server is mildly sensitive, but not to the extent that special NACM annotations are needed to prevent read-access to regular authenticated administrators. This module does not define any writable-nodes, RPCs, actions, or notifications, and thus the security consideration for such is not provided here.

The "ietf-tls-common" YANG Module The "ietf-tls-common" YANG module defines "grouping" statements that are designed to be accessed via YANG based management protocols, such as NETCONF and RESTCONF . Both of these protocols have mandatory-to-implement secure transport layers (e.g., SSH, TLS) with mutual authentication. The NETCONF access control model (NACM) provides the means to restrict access for particular users to a pre-configured subset of all available protocol operations and content. Since the module in this document only define groupings, these considerations are primarily for the designers of other modules that use these groupings. 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. None of the writable data nodes defined in this YANG module are considered sensitive or vulnerable in network environments. The NACM "default-deny-write" extension has not been set for any 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.

The "ietf-tls-client" YANG Module The "ietf-tls-client" YANG module defines "grouping" statements that are designed to be accessed via YANG based management protocols, such as NETCONF and RESTCONF . Both of these protocols have mandatory-to-implement secure transport layers (e.g., SSH, TLS) with mutual authentication. The NETCONF access control model (NACM) provides the means to restrict access for particular users to a pre-configured subset of all available protocol operations and content. Since the module in this document only define groupings, these considerations are primarily for the designers of other modules that use these groupings. 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 the writable data nodes defined by this module 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.

The "ietf-tls-server" YANG Module The "ietf-tls-server" YANG module defines "grouping" statements that are designed to be accessed via YANG based management protocols, such as NETCONF and RESTCONF . Both of these protocols have mandatory-to-implement secure transport layers (e.g., SSH, TLS) with mutual authentication. The NETCONF access control model (NACM) provides the means to restrict access for particular users to a pre-configured subset of all available protocol operations and content. Since the module in this document only define groupings, these considerations are primarily for the designers of other modules that use these groupings. 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 the writable data nodes defined by this module 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.

IANA Considerations

The "IETF XML" Registry This document registers four URIs in the "ns" subregistry of the IETF XML Registry . Following the format in , the following registrations are requested:

The "YANG Module Names" Registry This document registers four YANG modules in the YANG Module Names registry . Following the format in , the following registrations are requested:

The "iana-tls-cipher-suite-algs" Module IANA is requested to maintain a YANG module called "iana-tls-cipher-suite-algs" that shadows the "TLS Cipher Suites" sub-registry of the "Transport Layer Security (TLS) Parameters" registry . This registry defines a YANG identity for each cipher suite algorithm, and a "base" identity from which all of the other identities are derived. An initial version of this module can be found in .

• Please note that this module was created on June 16th, 2022, and that additional entries may have been added in the interim before this document's publication. If this is that case, IANA may either publish just an updated module containing the new entries, or publish the initial module as is immediately followed by a "revision" containing the additional algorithm names.
• Please also note that the "status" statement has been set to "deprecated", if the "RECOMMENDED" column in the registry had the value 'N', and to "obsolete", if the "References" column included Moving single-DES and IDEA TLS ciphersuites to Historic reference.

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. This memo describes the use of the Advanced Encryption Standard (AES) in Galois/Counter Mode (GCM) as a Transport Layer Security (TLS) authenticated encryption operation. GCM provides both confidentiality and data origin authentication, can be efficiently implemented in hardware for speeds of 10 gigabits per second and above, and is also well-suited to software implementations. This memo defines TLS cipher suites that use AES-GCM with RSA, DSA, and Diffie-Hellman-based key exchange mechanisms. [STANDARDS-TRACK] RFC 4492 describes elliptic curve cipher suites for Transport Layer Security (TLS). However, all those cipher suites use HMAC-SHA-1 as their Message Authentication Code (MAC) algorithm. This document describes sixteen new cipher suites for TLS that specify stronger MAC algorithms. Eight use Hashed Message Authentication Code (HMAC) with SHA-256 or SHA-384, and eight use AES in Galois Counter Mode (GCM). This memo provides information for the Internet community. 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) provides mechanisms to install, manipulate, and delete the configuration of network devices. This document describes how to use the Transport Layer Security (TLS) protocol with mutual X.509 authentication to secure the exchange of NETCONF messages. This revision of RFC 5539 documents the new message framing used by NETCONF 1.1 and it obsoletes RFC 5539. 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). 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 describes key exchange algorithms based on Elliptic Curve Cryptography (ECC) for the Transport Layer Security (TLS) protocol. In particular, it specifies the use of Ephemeral Elliptic Curve Diffie-Hellman (ECDHE) key agreement in a TLS handshake and the use of the Elliptic Curve Digital Signature Algorithm (ECDSA) and Edwards-curve Digital Signature Algorithm (EdDSA) as authentication mechanisms. This document obsoletes RFC 4492. 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. Informative References This memo describes how to use Transport Layer Security (TLS) to secure Hypertext Transfer Protocol (HTTP) connections over the Internet. This memo provides information for the Internet community. This document specifies Version 1.0 of the Transport Layer Security (TLS) protocol. The TLS protocol provides communications privacy over the Internet. The protocol allows client/server applications to communicate in a way that is designed to prevent eavesdropping, tampering, or message forgery. 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. This document specifies Version 1.1 of the Transport Layer Security (TLS) protocol. The TLS protocol provides communications security over the Internet. The protocol allows client/server applications to communicate in a way that is designed to prevent eavesdropping, tampering, or message forgery. This document specifies Version 1.2 of the Transport Layer Security (TLS) protocol. The TLS protocol provides communications security over the Internet. The protocol allows client/server applications to communicate in a way that is designed to prevent eavesdropping, tampering, or message forgery. [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] 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). This RFC presents NETCONF Call Home and RESTCONF Call Home, which enable a NETCONF or RESTCONF server to initiate a secure connection to a NETCONF or RESTCONF client, respectively. 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.

YANG Modules for IANA The module contained in this section was generated by scripts using the contents of the associated sub-registry as they existed on June 16th, 2022.

Initial Module for the "TLS Cipher Suites" Registry

Data Model Overview This section provides an overview of the "iana-tls-cipher-suite-algs" module in terms of its identities and protocol-accessible nodes.

Identities The following diagram lists the base "identity" statements defined in the module, of which there is just one, and illustrates that all the derived identity statements are generated from the associated IANA-maintained registry . ]]>

Typedefs The following diagram illustrates the "typedef" statements defined in the "iana-tls-cipher-suite-algs" module: Comments:

• The typedef defined in the "iana-tls-cipher-suite-algs" module extends the "identityref" type defined in .

Protocol-accessible Nodes The following tree diagram lists all the protocol-accessible nodes defined in the "iana-tls-cipher-suite-alg" module: Comments:

• Protocol-accessible nodes are those nodes that are accessible when the module is "implemented", as described in .

Example Usage The following example illustrates operational state data indicating the TLS cipher suite algorithms supported by the server: tlscsa:tls-ecdhe-ecdsa-with-aes-256-cbc-sha tlscsa:tls-dhe-rsa-with-aes-128-cbc-sha256 tlscsa:tls-rsa-with-3des-ede-cbc-sha tlscsa:tls-ecdhe-psk-with-aes-256-gcm-sha384<\ /supported-algorithm> tlscsa:tls-dhe-psk-with-chacha20-poly1305-sha\ 256 tlscsa:tls-eccpwd-with-aes-256-gcm-sha384 tlscsa:tls-psk-with-aes-256-ccm tlscsa:tls-dhe-psk-with-camellia-256-cbc-sha3\ 84 tlscsa:tls-ecdh-rsa-with-aes-256-cbc-sha384 tlscsa:tls-ecdh-rsa-with-3des-ede-cbc-sha tlscsa:tls-dh-dss-with-aes-128-gcm-sha256 ]]>

YANG Module Following are the complete contents to the initial IANA-maintained YANG module. Please note that the date "2022-06-16" reflects the day on which the extraction occurred. <CODE BEGINS> file "iana-tls-cipher-suite-algs@2022-06-16.yang" <CODE ENDS>

Change Log

00 to 01

• Noted that '0.0.0.0' and '::' might have special meanings.
• Renamed "keychain" to "keystore".

01 to 02

• Removed the groupings containing transport-level configuration. Now modules contain only the transport-independent groupings.
• Filled in previously incomplete 'ietf-tls-client' module.
• Added cipher suites for various algorithms into new 'ietf-tls-common' module.

02 to 03

• Added a 'must' statement to container 'server-auth' asserting that at least one of the various auth mechanisms must be specified.
• Fixed description statement for leaf 'trusted-ca-certs'.

03 to 04

• Updated title to "YANG Groupings for TLS Clients and TLS Servers"
• Updated leafref paths to point to new keystore path
• Changed the YANG prefix for ietf-tls-common from 'tlscom' to 'tlscmn'.
• Added TLS protocol verions 1.0 and 1.1.
• Made author lists consistent
• Now tree diagrams reference ietf-netmod-yang-tree-diagrams
• Updated YANG to use typedefs around leafrefs to common keystore paths
• Now inlines key and certificates (no longer a leafref to keystore)

04 to 05

• Merged changes from co-author.

05 to 06

• Updated to use trust anchors from trust-anchors draft (was keystore draft)
• Now Uses new keystore grouping enabling asymmetric key to be either locally defined or a reference to the keystore.

06 to 07

• factored the tls-[client|server]-groupings into more reusable groupings.
• added if-feature statements for the new "x509-certificates" feature defined in draft-ietf-netconf-trust-anchors.

07 to 08

• Added a number of compatibility matrices to Section 5 (thanks Frank!)
• Clarified that any configured "cipher-suite" values need to be compatible with the configured private key.

08 to 09

• Updated examples to reflect update to groupings defined in the keystore draft.
• Add TLS keepalives features and groupings.
• Prefixed top-level TLS grouping nodes with 'tls-' and support mashups.
• Updated copyright date, boilerplate template, affiliation, and folding algorithm.

09 to 10

• Reformatted the YANG modules.

10 to 11

• Collapsed all the inner groupings into the top-level grouping.
• Added a top-level "demux container" inside the top-level grouping.
• Added NACM statements and updated the Security Considerations section.
• Added "presence" statements on the "keepalive" containers, as was needed to address a validation error that appeared after adding the "must" statements into the NETCONF/RESTCONF client/server modules.
• Updated the boilerplate text in module-level "description" statement to match copyeditor convention.

11 to 12

• In server model, made 'client-authentication' a 'presence' node indicating that the server supports client authentication.
• In the server model, added a 'required-or-optional' choice to 'client-authentication' to better support protocols such as RESTCONF.
• In the server model, added a 'local-or-external' choice to 'client-authentication' to better support consuming data models that prefer to keep client auth with client definitions than in a model principally concerned with the "transport".
• In both models, removed the "demux containers", floating the nacm:default-deny-write to each descendant node, and adding a note to model designers regarding the potential need to add their own demux containers.
• Fixed a couple references (section 2 --> section 3)

12 to 13

• Updated to reflect changes in trust-anchors drafts (e.g., s/trust-anchors/truststore/g + s/pinned.//)

12 to 13

• Removed 'container' under 'client-identity' to match server model.
• Updated examples to reflect change grouping in keystore module.

13 to 14

• Removed the "certificate" container from "client-identity" in the ietf-tls-client module.
• Updated examples to reflect ietf-crypto-types change (e.g., identities --> enumerations)

14 to 15

• Updated "server-authentication" and "client-authentication" nodes from being a leaf of type "ts:certificates-ref" to a container that uses "ts:local-or-truststore-certs-grouping".

15 to 16

• Removed unnecessary if-feature statements in the -client and -server modules.
• Cleaned up some description statements in the -client and -server modules.
• Fixed a canonical ordering issue in ietf-tls-common detected by new pyang.

16 to 17

• Removed choice local-or-external by removing the 'external' case and flattening the 'local' case and adding a "client-auth-supported" feature.
• Removed choice required-or-optional.
• Updated examples to include the "*-key-format" nodes.
• Augmented-in "must" expressions ensuring that locally-defined public-key-format are "ct:tls-public-key-format" (must expr for ref'ed keys are TBD).

17 to 18

• Removed the unused "external-client-auth-supported" feature.
• Made client-indentity optional, as there may be over-the-top auth instead.
• Added augment to uses of local-or-keystore-symmetric-key-grouping for a psk "id" node.
• Added missing presence container "psks" to ietf-tls-server's "client-authentication" container.
• Updated examples to reflect new "bag" addition to truststore.
• Removed feature-limited caseless 'case' statements to improve tree diagram rendering.
• Refined truststore/keystore groupings to ensure the key formats "must" be particular values.
• Switched to using truststore's new "public-key" bag (instead of separate "ssh-public-key" and "raw-public-key" bags).
• Updated client/server examples to cover ALL cases (local/ref x cert/raw-key/psk).

18 to 19

• Updated the "keepalives" containers in part to address Michal Vasko's request to align with RFC 8071, and in part to better align to RFC 6520.
• Removed algorithm-mapping tables from the "TLS Common Model" section
• Removed the 'algorithm' node from the examples.
• Renamed both "client-certs" and "server-certs" to "ee-certs"
• Added a "Note to Reviewers" note to first page.

19 to 20

• Modified the 'must' expression in the "ietf-tls-client:server-authention" node to cover the "raw-public-keys" and "psks" nodes also.
• Added a "must 'ca-certs or ee-certs or raw-public-keys or psks'" statement to the ietf-tls-server:client-authentication" node.
• Added "mandatory true" to "choice auth-type" and a "presence" statement to its ancestor.
• Expanded "Data Model Overview section(s) [remove "wall" of tree diagrams].
• Moved the "ietf-tls-common" module section to proceed the other two module sections.
• Updated the Security Considerations section.

20 to 21

• Updated examples to reflect new "cleartext-" prefix in the crypto-types draft.

21 to 22

• In both the "client-authentication" and "server-authentication" subtrees, replaced the "psks" node from being a P-container to a leaf of type "empty".
• Cleaned up examples (e.g., removed FIXMEs)
• Fixed issues found by the SecDir review of the "keystore" draft.
• Updated the "psk" sections in the "ietf-tls-client" and "ietf-tls-server" modules to more correctly reflect RFC 4279.

22 to 23

• Addressed comments raised by YANG Doctor in the ct/ts/ks drafts.

23 to 24

• Added missing reference to "FIPS PUB 180-4".
• Added identity "tls-1.3" and updated description statement in other identities indicating that the protocol version is obsolete and enabling the feature is NOT RECOMMENDED.
• Added XML-comment above examples explaining the reason for the unexpected top-most element's presence.
• Added missing "client-ident-raw-public-key" and "client-ident-psk" featutes.
• Aligned modules with `pyang -f` formatting.
• Fixed nits found by YANG Doctor reviews.
• Added a 'Contributors' section.

24 to 25

• Added TLS 1.3 references.
• Clarified support for various TLS protocol versions.
• Moved algorithms in ietf-tls-common (plus more) to IANA-maintained modules
• Added "config false" lists for algorithms supported by the server.
• Fixed issues found during YANG Doctor review.

25 to 26

• Replaced "base64encodedvalue==" with "BASE64VALUE=" in examples.
• Minor editorial nits

26 to 27

• Fixed up the 'WG Web' and 'WG List' lines in YANG module(s)
• Fixed up copyright (i.e., s/Simplified/Revised/) in YANG module(s)
• Created identityref-based typedef for the IANA alg identity base.
• Major update to support TLS 1.3.

27 to 28

• Fixed draft text to refer to new "identity" values (e.g., s/tls-1.3/tls13).
• Added ietf-tls-common:generate-public-key() RPC.

28 to 29

• Updated modules to IANA-maintained module in Appendix A to 2022-06-16.

Acknowledgements 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, Balazs Kovacs, Benoit Claise, Bert Wijnen, David Lamparter, Dhruv Dhody, Gary Wu, Henk Birkholz, Juergen Schoenwaelder, Ladislav Lhotka, Liang Xia, Martin Bjoerklund, Mehmet Ersue, Michal Vasko, Phil Shafer, Radek Krejci, Sean Turner, and Tom Petch.

Contributors Special acknowledgement goes to Gary Wu who contributed the "ietf-tls-common" module, and Tom Petch who carefully ensured that references were set correctly throughout.