Internet-Draft ACVP KDFs April 2024
Celi Expires 25 October 2024 [Page]
Workgroup:
Network Working Group
Internet-Draft:
draft-gold-acvp-kdf-01
:
Published:
Intended Status:
Informational
Expires:
Author:
C. Celi, Ed.

ACVP SP800-108 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 25 October 2024.

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Table of Contents

1. Acknowledgements

There are no acknowledgements.

2. Abstract

This document defines the JSON schema for testing SP 800-108 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 SP 800-108 KDF implementations using ACVP.

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

5. Supported SP 800-108 KDFs

The following key derivation functions MAY be advertised by the ACVP compliant cryptographic module:

6. Test Types and Test Coverage

This section describes the design of the tests used to validate SP 800-108 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 [SP800-108r1].

6.2.1. Requirements Covered

  • The ACVP server tests the IUT's ability to derive keying material using the "modes of iteration" defined in sections 5.1, 5.2 and 5.3 of [SP800-108r1]. The server supports testing the IUT against the various MACs or PRFs listed in Section 7.3.3. It also supports testing varying 1) the location of the counter within the input data, 2) the length of the derived keying material, and 3) the counter length.

6.2.2. Requirements Not Covered

  • The tests described in this document do not validate the construction of the fixed input data string described in [SP800-108r1] Sections 5, 7.5 and 7.6.

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 SP 800-108 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

Table 1: Prerequisite Properties
JSON Property Description JSON Type
algorithm a prerequisite algorithm string
valValue algorithm validation number string

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

"prereqVals":
[
  {
    "algorithm": "Alg1",
    "valValue": "Val-1234"
  },
  {
    "algorithm": "Alg2",
    "valValue": "same"
  }
]

7.2. Required Prerequisite Algorithms for SP 800-108r1 KDF Validations

Each SP800-108r1 KDF implementation relies on other cryptographic primitives. For example, the KDF must utilize an underlying MAC algorithm. 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:

Table 2: SP800-108r1 KDF Required Prerequisites
JSON Value Description JSON Type Valid Values
algorithm A prerequisite algorithm string AES, DRBG, CMAC, HMAC
valValue Algorithm validation number string Actual number or "same"
prereqAlgVal Prerequisite algorithm validation object with algorithm and valValue properties See above
prereqVals Prerequisite algorithm validations array of prereqAlgVal objects See above

7.3. Property Registration

Each algorithm capability advertised is a self-contained JSON object using the following values.

Two algorithm registrations are possible to test SP 800-108r1 KDFs. The first is for the "KDF" / "1.0" which covers the counter, feedback, and double pipeline iteration key derivation functions. The second is for "KDF" / "KMAC" / "Sp800-108r1" which covers the KMAC function when used as a key derivation function, introduced in the new revision, SP 800-108r1. A registration SHALL use these properties:

Table 3: Registration Properties
JSON Property Description JSON Type Valid Values
algorithm The KDF to be validated. string "KDF"
mode The KDF mode to be validated. string "KMAC" or ""
revision The algorithm testing revision to use. string "1.0" when "mode" is not included, or "Sp800-108r1" when "mode" is set to "KMAC"
prereqVals Prerequisite algorithm validations array of prereqAlgVal objects See Section 7.2
capabilities Array of JSON objects, each with fields pertaining to the KDF mode identified uniquely by the combination of the "kdfMode" and indicated properties array of JSON objects See Section 7.3.2

7.3.1. Supported SP 800-108r1 KDF Modes

The following SP800-108 KDF modes or "modes of iteration" may be advertised by the ACVP compliant crypto module as the "kdfMode" property:

  • counter
  • feedback
  • double pipeline iteration

7.3.2. Supported KDF Modes Capabilities

The KDF mode capabilities are advertised as JSON objects within the 'capabilities' value of the ACVP registration message - see Table 2. The 'capabilities' value is an array, where each array element is a JSON object corresponding to a particular KDF mode defined in this section. The 'capabilities' value is part of the 'capability_exchange' element of the ACVP JSON registration message. See the ACVP specification [ACVP] for details on the registration message.

Each KDF mode's capabilities are advertised as JSON objects.

The following table describes the capabilities that may be advertised by the ACVP compliant crypto module for "KDF" / / "1.0":

Table 4: KDF Mode Capabilities
JSON Value Description JSON Type Valid Values
kdfMode The type of SP800-108r1 KDF or "mode of iteration" string See Section 7.3.1
macMode The MAC or PRF algorithm used array of string See Section 7.3.3
supportedLengths The supported derived keying material lengths in bits domain Min: 1, Max: 4096
fixedDataOrder Describes where the counter appears in the fixed data array Any non-empty subset of {"none", "after fixed data", "before fixed data", "middle fixed data", "before iterator"}
counterLength The length of the counter in bits array Any non-empty subset of {0, 8, 16, 24, 32}
supportsEmptyIv Whether or not the IUT supports an empty IV boolean true/false
requiresEmptyIv Whether or not the IUT requires an empty IV boolean true/false
customKeyInLength Optional value used to control the length of the keyIn produced by the ACVP server for the capability. This field cannot be used to alter the keyIn length for AES/TDES based macModes, as the keyIns expected by those algorithms is fixed. integer 112-4096

The following table describes the capabilities that may be advertisd by the ACVP compliant crypto module for "KDF" / "KMAC" / "Sp800-108r1":

Table 5: KDF KMAC Mode Capabilities
JSON Value Description JSON Type Valid Values
macMode The MAC or PRF algorithm used array of string See Section 7.3.3
keyDerivationKeyLength The lengths of the key derivation key in bits domain Min: 112, Max: 4096, Inc: 8
contextLength The lengths of the context field in bits domain Min: 8, Max: 4096, Inc: 8
labelLength The lengths of the label field in bits. This field can be excluded if no label is used. domain Min: 8, Max: 4096, Inc: 8
derivedKeyLength The lengths of the derived keys in bits domain Min: 112, Max: 4096, Inc: 8

7.3.3. Supported SP 800-108r1 KDF MACs

The following MAC or PRF functions MAY be advertised by an ACVP compliant client

  • CMAC-AES128
  • CMAC-AES192
  • CMAC-AES256
  • CMAC-TDES
  • HMAC-SHA1
  • HMAC-SHA2-224
  • HMAC-SHA2-256
  • HMAC-SHA2-384
  • HMAC-SHA2-512
  • HMAC-SHA2-512/224
  • HMAC-SHA2-512/256
  • HMAC-SHA3-224
  • HMAC-SHA3-256
  • HMAC-SHA3-384
  • HMAC-SHA3-512
  • KMAC-128
  • KMAC-256

7.4. Registration Example

The following is a example JSON object advertising support for "KDF" / / "1.0".

{
    "algorithm": "KDF",
    "revision": "1.0",
    "prereqVals": [
        {
            "algorithm": "SHA",
            "valValue": "123456"
        },
        {
            "algorithm": "DRBG",
            "valValue": "123456"
        }
    ],
    "capabilities": [
        {
            "kdfMode": "counter",
            "macMode": [
                "CMAC-AES128",
                "CMAC-AES192",
                "CMAC-AES256",
                "CMAC-TDES",
                "HMAC-SHA-1",
                "HMAC-SHA2-224",
                "HMAC-SHA2-256",
                "HMAC-SHA2-384",
                "HMAC-SHA2-512"
            ],
            "supportedLengths": [
                {
                    "min": 8,
                    "max": 1024,
                    "increment": 1
                }
            ],
            "fixedDataOrder": [
                "after fixed data",
                "before fixed data",
                "middle fixed data"
            ],
            "counterLength": [
                8,
                16,
                24,
                32
            ],
            "supportsEmptyIv": false
        },
        {
            "kdfMode": "feedback",
            "macMode": [
                "CMAC-AES128",
                "CMAC-AES192",
                "CMAC-AES256",
                "CMAC-TDES",
                "HMAC-SHA-1",
                "HMAC-SHA2-224",
                "HMAC-SHA2-256",
                "HMAC-SHA2-384",
                "HMAC-SHA2-512"
            ],
            "supportedLengths": [
                {
                    "min": 8,
                    "max": 1024,
                    "increment": 1
                }
            ],
            "fixedDataOrder": [
                "none",
                "after fixed data",
                "before fixed data",
                "before iterator"
            ],
            "counterLength": [
                0,
                8,
                16,
                24,
                32
            ],
            "supportsEmptyIv": true,
            "requiresEmptyIv": false
        },
        {
            "kdfMode": "double pipeline iteration",
            "macMode": [
                "CMAC-AES128",
                "CMAC-AES192",
                "CMAC-AES256",
                "CMAC-TDES",
                "HMAC-SHA-1",
                 "HMAC-SHA2-224",
                "HMAC-SHA2-256",
                "HMAC-SHA2-384",
                "HMAC-SHA2-512"
            ],
            "supportedLengths": [
                {
                    "min": 8,
                    "max": 1024,
                    "increment": 1
                }
            ],
            "fixedDataOrder": [
                "none",
                "after fixed data",
                "before fixed data",
                "before iterator"
            ],
            "counterLength": [
                0,
                8,
                16,
                24,
                32
            ],
            "supportsEmptyIv": false
        }
    ]
}
Figure 1

The following is a example JSON object advertising support for a "KDF" / "KMAC" / "Sp800-108r1".

{
    "algorithm": "KDF",
    "mode": "KMAC",
    "revision": "Sp800-108r1",
    "macMode": [
        "KMAC-128",
        "KMAC-256"
    ],
    "keyDerivationKeyLength": [
        {
            "min": 112,
            "max": 4096,
            "increment": 8
        }
    ],
    "contextLength": [
        {
            "min": 8,
            "max": 4096,
            "increment": 8
        }
    ],
    "labelLength": [
        {
            "min": 8,
            "max": 4096,
            "increment": 8
        }
    ],
    "derivedKeyLength": [
        {
            "min": 112,
            "max": 4096,
            "increment": 8
        }
    ]
}
Figure 2

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 algorithm defined during the capability exchange. This section describes the JSON schema for a test vector set used with SP 800-108 KDF algorithms.

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.

Table 6: Top Level Test Vector JSON Elements
JSON Values Description JSON Type
acvVersion Protocol version identifier string
vsId Unique numeric vector set identifier integer
algorithm Algorithm defined in the capability exchange string
mode Mode defined in the capability exchange string
revision Protocol test revision selected string
testGroups Array of test groups containing test data, see Section 8.1 array

An example of this would look like this

[
  {
    "acvVersion": <version>
  },
  {
    "vsId": 1,
    "algorithm": "Alg1",
    "mode": "Mode1",
    "revision": "Revision1.0",
    "testGroups": [ ... ]
  }
]

8.1. Test Groups JSON Schema

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 SP 800-108 KDF JSON elements of the Test Group JSON object for "KDF" / / "1.0".

Table 7: Test Group JSON Object
JSON Values Description JSON Type
tgId Test group identifier integer
kdfMode The kdfMode used for the test group string
macMode Psuedorandom function (PRF) HMAC, CMAC, or KMAC used string
counterLocation "none", "after fixed data", "before fixed data", "middle fixed data", or "before iterator" string
keyOutLength Expected length of the derived keying material or key in bits integer
counterLength Expected length of the counter in bits integer
zeroLengthIv Whether or not the group utilizes a null IV boolean
testType Describes the operation being performed string
tests Array of individual test cases array

For "KDF" / "KMAC" / "Sp800-108r1" the following table describes the JSON elements of the Test Group JSON object.

Table 8: Test Group JSON Object for "KDF" / "KMAC" / "Sp800-108r1"
JSON Values Description JSON Type
tgId Test group identifier integer
macMode Psuedorandom function (PRF) KMAC used string
testType Describes the operation being performed string
tests Array of individual test cases array

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' the group is addressing.

8.2. Test Case JSON Schema

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 SP 800-108 KDF "KDF" / / "1.0" test vector.

Table 9: Test Case JSON Object
JSON Values Description JSON Type
tcId Test case idenfitier integer
keyIn Input key hex
iv The initialization vector used only for feedback KDFs hex

The following table describes the JSON elements for each "KDF" / "KMAC" / "Sp800-108r1" test vector.

Table 10: Test Case JSON Object
JSON Values Description JSON Type
tcId Test case idenfitier integer
keyDerivationKey Input key hex
context The context value used hex
label The label value used hex
derivedKeyLength The expected length of the derived key integer

8.3. Example Test Vector JSON Object

The following is a example JSON object for SP 800-108r1 KDF "KDF" / / "1.0" test vectors sent from the ACVP server to the crypto module.

[
    {
        "acvVersion": "v1.0"
    },
    {
        "vsId": 1564,
        "algorithm": "counterMode",
        "revision": "1.0",
        "testGroups": [{
            "tgId": 1,
            "kdfMode": "counter",
            "macMode": "CMAC-AES128",
            "counterLocation": "after fixed data",
            "keyOutLength": 1024,
            "counterLength": 8,
            "tests": [{
                    "tcId": 1,
                    "keyIn": "5DA38931E8D9174BC3279C8942D2DB82",
                    "deferred": false
                },
                {
                    "tcId": 2,
                    "keyIn": "58F5426A40E3D5D2C94F0F97EB30C739",
                    "deferred": false
                }
            ]
        }]
    }
]
Figure 3

The following is a example JSON object for "KDF" / "KMAC" / "Sp800-108r1" test vectors sent from the ACVP server to the crypto module.

[
    {
        "acvVersion": "v1.0"
    },
{
    "vsId": 0,
    "algorithm": "KDF",
    "mode": "KMAC",
    "revision": "Sp800-108r1",
    "isSample": false,
    "testGroups": [
        {
            "tgId": 1,
            "testType": "AFT",
            "macMode": "KMAC-128",
            "tests": [
                {
                    "tcId": 1,
                    "keyDerivationKey": "FA4E...",
                    "context": "4476...",
                    "label": "146EE...",
                    "derivedKeyLength": 112
                },
                {
                    "tcId": 2,
                    "keyDerivationKey": "2BE6...",
                    "context": "5E2E...",
                    "label": "0DD6...",
                    "derivedKeyLength": 112
                }
            ]
        }
    }
]
Figure 4

9. Test Vector 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.

Table 11: Vector Set Response Properties
JSON Property Description JSON Type
acvVersion The version of the protocol string
vsId The vector set identifier integer
testGroups The test group data array

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.

Table 12: Vector Set Group Response Properties
JSON Property Description JSON Type
tgId The test group identifier integer
tests The test case data array

An example of this is the following

{
    "tgId": 1,
    "tests": [ ... ]
}

The testCase 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.

The following table describes the JSON properties that represent a test case response for "KDF" / / "1.0".

Table 13: Test Case Results JSON Properties
JSON Property Description JSON Type
tcId The test case identifier integer
breakLocation The bit location in the fixed data where the counter is placed. breakLocation is only applicable and SHALL be included for test cases where counterLocation is "middle fixed data". integer
fixedData The fixed input data used by the IUT hex
keyOut The outputted keying material or key hex

The following table describes the JSON properties that represent a test case response for "KDF" / "KMAC" / "Sp800-108r1".

Table 14: Test Case Results JSON Properties for "KDF" / "KMAC" / "Sp800-108r1"
JSON Property Description JSON Type
tcId The test case identifier integer
derivedKey The outputted keying material or key hex

9.1. Example Test Vector Response JSON

The following is an abbreviated example of a JSON object for "KDF" / / "1.0" test results sent from the crypto module to the ACVP server.

[
    {
        "acvVersion": <acvp-version>
    },
    {
        "vsId": 1564,
        "testGroups": [
            {
                "tgId": 1,
                "tests": [
                    {
                        "tcId": 1,
                        "keyOut": "94D58F...",
                        "fixedData": "FBF14DF02EE6C7DABCA6EF9AF59BB9A2"
                    }
                ]
            }
        ]
    }
]
Figure 5

The following is an example of a JSON object for "KDF" / "KMAC" / "Sp800-108r1" test results sent from the crypto module to the ACVP server.

[
    {
        "acvVersion": <acvp-version>
    },
    {
        "vsId": 0,
        "algorithm": "KDF",
        "mode": "KMAC",
        "revision": "Sp800-108r1",
        "testGroups": [
            {
                "tgId": 1,
                "tests": [
                    {
                        "tcId": 1,
                        "derivedKey": "A639..."
                    },
                    {
                        "tcId": 2,
                        "derivedKey": "A328..."
                    }
                ]
            }
        ]
    }
]
Figure 6

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. Normative References

[RFC2119]
Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", RFC 2119, RFC 2119, DOI 10.17487/RFC2119, , <https://www.rfc-editor.org/info/rfc2119>.
[RFC7991]
Hoffman, P., "The "xml2rfc" Version 3 Vocabulary", RFC 7991, RFC 7991, DOI 10.17487/RFC7991, , <https://www.rfc-editor.org/info/rfc7991>.
[RFC8174]
Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", RFC 8174, RFC 8174, DOI 10.17487/RFC8174, , <https://www.rfc-editor.org/info/rfc8174>.
[SP800-108]
Chen, L., "Recommendation for Key Derivation Using Pseudorandom Functions (Revised)", NIST SP 800-108, , <https://csrc.nist.gov/pubs/sp/800/108/upd1/final>.
[SP800-108r1]
Chen, L., "Recommendation for Key Derivation Using Pseudorandom Functions", NIST SP 800-108 Rev. 1, , <https://csrc.nist.gov/pubs/sp/800/108/r1/upd1/final>.
[ACVP]
Fussell, B., Vassilev, A., and H. Booth, "Automatic Cryptographic Validation Protocol", ACVP, .

Author's Address

Christopher Celi (editor)