Network Working Group C. Celi, Ed. Internet-Draft 1 November 2024 Intended status: Informational Expires: 5 May 2025 ACVP SSH Key Derivation Function JSON Specification Status of This Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at https://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." This Internet-Draft will expire on 5 May 2025. Copyright Notice Copyright (c) 2024 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/ license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Revised BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Revised BSD License. Table of Contents 1. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 2 2. Abstract . . . . . . . . . . . . . . . . . . . . . . . . . . 2 3. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 4. Conventions . . . . . . . . . . . . . . . . . . . . . . . . . 3 4.1. Notation conventions . . . . . . . . . . . . . . . . . . 3 4.2. Terms and Definitions . . . . . . . . . . . . . . . . . . 3 4.2.1. Prompt . . . . . . . . . . . . . . . . . . . . . . . 3 Celi Expires 5 May 2025 [Page 1] Internet-Draft ACVP KDF SSH November 2024 4.2.2. Registration . . . . . . . . . . . . . . . . . . . . 3 4.2.3. Response . . . . . . . . . . . . . . . . . . . . . . 3 4.2.4. Test Case . . . . . . . . . . . . . . . . . . . . . . 3 4.2.5. Test Group . . . . . . . . . . . . . . . . . . . . . 3 4.2.6. Test Vector Set . . . . . . . . . . . . . . . . . . . 3 4.2.7. Validation . . . . . . . . . . . . . . . . . . . . . 3 5. Supported KDFs . . . . . . . . . . . . . . . . . . . . . . . 4 6. Test Types and Test Coverage . . . . . . . . . . . . . . . . 4 6.1. Test Types . . . . . . . . . . . . . . . . . . . . . . . 4 6.2. Test Coverage . . . . . . . . . . . . . . . . . . . . . . 4 6.2.1. SSH Requirements Covered . . . . . . . . . . . . . . 4 6.2.2. SSH Requirements Not Covered . . . . . . . . . . . . 4 7. Capabilities Registration . . . . . . . . . . . . . . . . . . 5 7.1. Prerequisites . . . . . . . . . . . . . . . . . . . . . . 5 7.2. Property Registration . . . . . . . . . . . . . . . . . . 6 7.2.1. Valid Hash Functions . . . . . . . . . . . . . . . . 7 8. Test Vectors . . . . . . . . . . . . . . . . . . . . . . . . 7 8.1. Test Groups . . . . . . . . . . . . . . . . . . . . . . . 9 8.2. Test Cases . . . . . . . . . . . . . . . . . . . . . . . 9 9. Responses . . . . . . . . . . . . . . . . . . . . . . . . . . 10 10. Security Considerations . . . . . . . . . . . . . . . . . . . 13 11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13 12. References . . . . . . . . . . . . . . . . . . . . . . . . . 13 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 13 1. Acknowledgements There are no acknowledgements. 2. Abstract This document defines the JSON schema for testing SP800-135 SSH KDF implementations with the ACVP specification. 3. Introduction The Automated Crypto Validation Protocol (ACVP) defines a mechanism to automatically verify the cryptographic implementation of a software or hardware crypto module. The ACVP specification defines how a crypto module communicates with an ACVP server, including crypto capabilities negotiation, session management, authentication, vector processing and more. The ACVP specification does not define algorithm specific JSON constructs for performing the crypto validation. A series of ACVP sub-specifications define the constructs for testing individual crypto algorithms. Each sub- specification addresses a specific class of crypto algorithms. This sub-specification defines the JSON constructs for testing SP800-135 SSH KDF implementations using ACVP. Celi Expires 5 May 2025 [Page 2] Internet-Draft ACVP KDF SSH November 2024 4. Conventions 4.1. Notation conventions 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 of [RFC2119] and [RFC8174] when, and only when, they appear in all capitals, as shown here. 4.2. Terms and Definitions 4.2.1. Prompt JSON sent from the server to the client describing the tests the client performs 4.2.2. Registration The initial request from the client to the server describing the capabilities of one or several algorithm, mode and revision combinations 4.2.3. Response JSON sent from the client to the server in response to the prompt 4.2.4. Test Case An individual unit of work within a prompt or response 4.2.5. Test Group A collection of test cases that share similar properties within a prompt or response 4.2.6. Test Vector Set A collection of test groups under a specific algorithm, mode, and revision 4.2.7. Validation JSON sent from the server to the client that specifies the correctness of the response Celi Expires 5 May 2025 [Page 3] Internet-Draft ACVP KDF SSH November 2024 5. Supported KDFs The following key derivation functions MAY be advertised by the ACVP compliant cryptographic module: * kdf-components / ssh / 1.0 6. Test Types and Test Coverage This section describes the design of the tests used to validate SP800-135 SSH KDF implementations. 6.1. Test Types There is only one test type: functional tests. Each has a specific value to be used in the testType field. The testType field definition is: * "AFT" - Algorithm Functional Test. These tests can be processed by the client using a normal 'derive_key' operation. AFTs cause the implementation under test to exercise normal operations on a single block, multiple blocks, or partial blocks. In all cases, random data is used. The functional tests are designed to verify that the logical components of the key deriviation process are operating correctly. 6.2. Test Coverage The tests described in this document have the intention of ensuring an implementation is conformant to [SP800-135]. 6.2.1. SSH Requirements Covered In [SP800-135], TBD. 6.2.2. SSH Requirements Not Covered Some requirements in the outlined specification are not easily tested. Often they are not ideal for black-box testing such as the ACVP. In [SP800-135], TBD. Celi Expires 5 May 2025 [Page 4] Internet-Draft ACVP KDF SSH November 2024 7. Capabilities Registration ACVP requires crypto modules to register their capabilities. This allows the crypto module to advertise support for specific algorithms, notifying the ACVP server which algorithms need test vectors generated for the validation process. This section describes the constructs for advertising support of SSH KDF algorithms to the ACVP server. The algorithm capabilities MUST be advertised as JSON objects within the 'algorithms' value of the ACVP registration message. The 'algorithms' value is an array, where each array element is an individual JSON object defined in this section. The 'algorithms' value is part of the 'capability_exchange' element of the ACVP JSON registration message. See the ACVP specification [ACVP] for more details on the registration message. 7.1. Prerequisites Each algorithm implementation MAY rely on other cryptographic primitives. For example, RSA Signature algorithms depend on an underlying hash function. Each of these underlying algorithm primitives must be validated, either separately or as part of the same submission. ACVP provides a mechanism for specifying the required prerequisites: Prerequisites, if applicable, MUST be submitted in the registration as the prereqVals JSON property array inside each element of the algorithms array. Each element in the prereqVals array MUST contain the following properties +===============+=============================+===========+ | JSON Property | Description | JSON Type | +===============+=============================+===========+ | algorithm | a prerequisite algorithm | string | +---------------+-----------------------------+-----------+ | valValue | algorithm validation number | string | +---------------+-----------------------------+-----------+ Table 1: Prerequisite Properties A "valValue" of "same" SHALL be used to indicate that the prerequisite is being met by a different algorithm in the capability exchange in the same registration. An example description of prerequisites within a single algorithm capability exchange looks like this Celi Expires 5 May 2025 [Page 5] Internet-Draft ACVP KDF SSH November 2024 "prereqVals": [ { "algorithm": "Alg1", "valValue": "Val-1234" }, { "algorithm": "Alg2", "valValue": "same" } ] 7.2. Property Registration The SSH KDF mode capabilities are advertised as JSON objects within the 'capabilities_exchange' property. A registration SHALL use these properties +===============+=======================+========+==================+ | JSON | Description | JSON | Valid Values | | Property | | Type | | +===============+=======================+========+==================+ | algorithm | Name of the algorithm | string | "kdf-components" | | | to be validated | | | +---------------+-----------------------+--------+------------------+ | mode | Mode of the algorithm | string | "ssh" | | | to be validated | | | +---------------+-----------------------+--------+------------------+ | revision | ACVP Test version | string | "1.0" | +---------------+-----------------------+--------+------------------+ | cipher | Block ciphers | array | TDES, AES-128, | | | supported | | AES-192, AES-256 | +---------------+-----------------------+--------+------------------+ | hashAlg | Valid hash algorithms | array | See | | | used by the IUT | | Section 7.2.1 | +---------------+-----------------------+--------+------------------+ Table 2: SSH KDF Mode Capabilities JSON Values An example registration within an algorithm capability exchange looks like this. Celi Expires 5 May 2025 [Page 6] Internet-Draft ACVP KDF SSH November 2024 "capability_exchange": [ { "algorithm": "kdf-components", "mode": "ssh", "revision": "1.0", "hashAlg": [ "SHA-1", "SHA2-224", "SHA2-256", "SHA2-384", "SHA2-512" ], "cipher": [ "TDES", "AES-128", "AES-192", "AES-256" ] } ] 7.2.1. Valid Hash Functions The following hash functions MAY be advertised by an ACVP compliant client under the 'hashAlg' property * SHA-1 * SHA2-224 * SHA2-256 * SHA2-384 * SHA2-512 8. Test Vectors The ACVP server provides test vectors to the ACVP client, which are then processed and returned to the ACVP server for validation. A typical ACVP validation test session would require multiple test vector sets to be downloaded and processed by the ACVP client. Each test vector set represents an individual cryptographic algorithm defined during the capability exchange. This section describes the JSON schema for a test vector set used with SP800-135 SSH KDF algorithms. Celi Expires 5 May 2025 [Page 7] Internet-Draft ACVP KDF SSH November 2024 The test vector set JSON schema is a multi-level hierarchy that contains meta data for the entire vector set as well as individual test vectors to be processed by the ACVP client. The following table describes the JSON elements at the top level of the hierarchy. +=============+======================================+===========+ | JSON Values | Description | JSON Type | +=============+======================================+===========+ | acvVersion | Protocol version identifier | string | +-------------+--------------------------------------+-----------+ | vsId | Unique numeric vector set identifier | integer | +-------------+--------------------------------------+-----------+ | algorithm | Algorithm defined in the capability | string | | | exchange | | +-------------+--------------------------------------+-----------+ | mode | Mode defined in the capability | string | | | exchange | | +-------------+--------------------------------------+-----------+ | revision | Protocol test revision selected | string | +-------------+--------------------------------------+-----------+ | testGroups | Array of test group JSON objects, | array | | | which are defined in Section 8.1 | | +-------------+--------------------------------------+-----------+ Table 3: Top Level Test Vector JSON Elements An example of this would look like this [ { "acvVersion": }, { "vsId": 1, "algorithm": "Alg1", "mode": "Mode1", "revision": "Revision1.0", "testGroups": [ ... ] } ] Celi Expires 5 May 2025 [Page 8] Internet-Draft ACVP KDF SSH November 2024 8.1. Test Groups The testGroups element at the top level in the test vector JSON object is an array of test groups. Test vectors are grouped into similar test cases to reduce the amount of data transmitted in the vector set. For instance, all test vectors that use the same key size would be grouped together. The Test Group JSON object contains meta data that applies to all test vectors within the group. The following table describes the SP800-135 SSH KDF JSON elements of the Test Group JSON object +============+=================================+===========+ | JSON Value | Description | JSON Type | +============+=================================+===========+ | tgId | Test group identifier | integer | +------------+---------------------------------+-----------+ | testType | Test operations to be performed | string | +------------+---------------------------------+-----------+ | hashAlg | The SHA value used | string | +------------+---------------------------------+-----------+ | cipher | The encryption method used | string | +------------+---------------------------------+-----------+ | tests | Array of individual test cases | array | +------------+---------------------------------+-----------+ Table 4: Test Group JSON Object The 'tgId', 'testType' and 'tests' objects MUST appear in every test group element communicated from the server to the client as a part of a prompt. Other properties are dependent on which 'testType' (see Section 6) the group is addressing. 8.2. Test Cases Each test group contains an array of one or more test cases. Each test case is a JSON object that represents a single test vector to be processed by the ACVP client. The following table describes the JSON elements for each SP800-135 SSH KDF test vector. Celi Expires 5 May 2025 [Page 9] Internet-Draft ACVP KDF SSH November 2024 +============+=============================+===========+ | JSON Value | Description | JSON Type | +============+=============================+===========+ | tcId | Test case idenfitier | integer | +------------+-----------------------------+-----------+ | k | Shared secret value in | hex | | | MPINT format, see [RFC4251] | | +------------+-----------------------------+-----------+ | h | Hash value | hex | +------------+-----------------------------+-----------+ | sessionId | Session ID value | hex | +------------+-----------------------------+-----------+ Table 5: Test Case JSON Object Here is an abbreviated yet fully constructed example of the prompt. { "vsId": 1, "algorithm": "kdf-components", "mode": "ssh", "revision": "1.0", "testGroups": [ { "tgId": 1, "cipher": "TDES", "hashAlg": "SHA-1", "tests": [ { "tcId": 1, "k": "00000100074F0CA30BDF...", "h": "44A4FFE335663340FE1E...", "sessionId": "76B601459363..." } ] } ] } 9. Responses After the ACVP client downloads and processes a vector set, it must send the response vectors back to the ACVP server. The following table describes the JSON object that represents a vector set response. Celi Expires 5 May 2025 [Page 10] Internet-Draft ACVP KDF SSH November 2024 +===============+=============================+===========+ | JSON Property | Description | JSON Type | +===============+=============================+===========+ | acvVersion | The version of the protocol | string | +---------------+-----------------------------+-----------+ | vsId | The vector set identifier | integer | +---------------+-----------------------------+-----------+ | testGroups | The test group data | array | +---------------+-----------------------------+-----------+ Table 6: Vector Set Response JSON Object An example of this is the following. { "acvVersion": "version", "vsId": 1, "testGroups": [ ... ] } The testGroups section is used to organize the ACVP client response in a similar manner to how it receives vectors. Several algorithms SHALL require the client to send back group level properties in their response. This structure helps accommodate that. +===============+===========================+===========+ | JSON Property | Description | JSON Type | +===============+===========================+===========+ | tgId | The test group identifier | integer | +---------------+---------------------------+-----------+ | tests | The test case data | array | +---------------+---------------------------+-----------+ Table 7: Vector Set Group Response JSON Object An example of this is the following. { "tgId": 1, "tests": [ ... ] } The following table describes the JSON object that represents a test case response for a SP800-135 SSH KDF. Celi Expires 5 May 2025 [Page 11] Internet-Draft ACVP KDF SSH November 2024 +=====================+=================================+===========+ | JSON Property | Description | JSON Type | +=====================+=================================+===========+ | tcId | The test case identifier | integer | +---------------------+---------------------------------+-----------+ | initialIvClient | Client to server initial IV | hex | +---------------------+---------------------------------+-----------+ | initialIvServer | Server to client initial IV | hex | +---------------------+---------------------------------+-----------+ | encryptionKeyClient | Client to server encryption | hex | | | key | | +---------------------+---------------------------------+-----------+ | encryptionKeyServer | Server to client | hex | | | eencryption key | | +---------------------+---------------------------------+-----------+ | integrityKeyClient | Client to server integrity | hex | | | key | | +---------------------+---------------------------------+-----------+ | integrityKeyServer | Server to client integrity | hex | | | key | | +---------------------+---------------------------------+-----------+ Table 8: Test Case Results JSON Object Here is an abbreviated example of the response. { "vsId": 1, "testResults": [ { "tgId": 1, "tests": [ { "tcId": 1, "initialIvClient": "D58275F599E68471", "encryptionKeyClient": "D1B16D92ED9AB...", "integrityKeyClient": "E7F57D7BFFFB58...", "initialIvServer": "3F48A283BF85F147", "encryptionKeyServer": "289241764AB45...", "integrityKeyServer": "9EE185ACDFE192..." } ] } ] } Celi Expires 5 May 2025 [Page 12] Internet-Draft ACVP KDF SSH November 2024 10. Security Considerations There are no additional security considerations outside of those outlined in the ACVP document. 11. IANA Considerations This document does not require any action by IANA. 12. References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", RFC 2119, RFC 2119, DOI 10.17487/RFC2119, March 1997, . [RFC4251] Ylonen, T. and C. Lonvick, Ed., "The Secure Shell (SSH) Protocol Architecture", RFC 4251, RFC 4251, DOI 10.17487/RFC4251, January 2006, . [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", RFC 8174, RFC 8174, DOI 10.17487/RFC8174, May 2017, . [SP800-135] Dang, Q. H., "Recommendation for Existing Application- Specific Key Derivation Functions", NIST SP 800-135 Rev. 1, December 2011, . [ACVP] Fussell, B., Vassilev, A., and H. Booth, "Automatic Cryptographic Validation Protocol", ACVP, 1 July 2019. Author's Address Christopher Celi (editor) Email: christopher.celi@nist.gov Celi Expires 5 May 2025 [Page 13]