Network Working Group N. Mavrogiannopoulos
Internet-Draft Red Hat
Intended status: Informational Mar 29, 2018
Expires: September 30, 2018

Storing validation parameters in PKCS#8
draft-mavrogiannopoulos-pkcs8-validated-parameters-02

Abstract

This memo describes a method of storing parameters needed for private key validation in the Private-Key Information Syntax Specification as defined in RFC5208 (PKCS#8) format. It is equally applicable the alternative implementation of the Private-Key Information Syntax Specification as defined in RFC 5958.

Status of This Memo

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Copyright Notice

Copyright (c) 2018 IETF Trust and the persons identified as the document authors. All rights reserved.

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1. Introduction

RSA or DSA private keys generated using the Shawe-Taylor prime generation algorithm describled in [FIPS186-4] allow for parameter validation, i.e., verify whether the primes are actually prime, and were correctly generated. That is done by generating the parameters from a known seed and a selected hash algorithm.

Storing these parameters in a private key format such as the RSA Private Key Syntax from PKCS#1 [RFC8017], or common representations for DSA private keys, does not allow attaching information on the parameters needed for validation. The purpose of the document is to describe such a method using the Private-Key Information Syntax Specification as defined in [RFC5208], as well as on the alternative specification on [RFC5958].

2. Terminology

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 BCP14 [RFC2119][RFC8174] when, and only when, they appear in all capitals, as shown here.

3. ValidationParams attribute

The information related to the validation parameters is stored as an attribute in the PrivateKeyInfo structure. The attribute is identified by the id-attr-validation-parameters object identifier and contains as AttributeValue a single ValidationParams structure.

  id-attr-validation-parameters OBJECT IDENTIFIER ::=
                                           {1 3 6 1 4 1 2312 18 8 1}

  ValidationParams ::= SEQUENCE {
      hashAlgo OBJECT IDENTIFIER,
      seed OCTET STRING
  }

The algorithm identifier in the ValidationParams should be a hash algorithm identifier for the [FIPS186-4] methods. The ValidationParams sequence must be DER encoded [CCITT.X690.2002].

4. Example Structure

The following structure contains an RSA key generated using the [FIPS186-4] section B.3.3 algorithm with SHA2-384 hash. The seed used is '8af4328c87bebcec31e303b8f5537effcb6a91d947084d99a369823b36f01462' (hex encoded).

-----BEGIN PRIVATE KEY-----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-----END PRIVATE KEY-----

5. Compatibility notes

For compatibility it is RECOMMENDED that implementations following this document, support generation and validation using the SHA2-384 hash algorithm.

The extension defined in this document is applicable both to the Private-Key Information Syntax Specification defined in [RFC5958] and PKCS#8 [RFC5208].

6. Security Considerations

All the considerations in [RFC5208] and [RFC5958] apply.

7. IANA Considerations

None.

8. References

8.1. Normative References

[CCITT.X680.2002] International International Telephone and Telegraph Consultative Committee, "Abstract Syntax Notation One (ASN.1): Specification of basic notation", CCITT Recommendation X.680, July 2002.
[CCITT.X690.2002] International International Telephone and Telegraph Consultative Committee, "ASN.1 encoding rules: Specification of basic encoding Rules (BER), Canonical encoding rules (CER) and Distinguished encoding rules (DER)", CCITT Recommendation X.690, July 2002.
[FIPS186-4] Kerry, C. and P. Gallagher, "FIPS PUB 186-4: Digital Signature Standard (DSS)", FEDERAL INFORMATION PROCESSING STANDARDS PUBLICATION , July 2013.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997.
[RFC5208] Kaliski, B., "Public-Key Cryptography Standards (PKCS) #8: Private-Key Information Syntax Specification Version 1.2", RFC 5208, DOI 10.17487/RFC5208, May 2008.
[RFC5958] Turner, S., "Asymmetric Key Packages", RFC 5958, DOI 10.17487/RFC5958, August 2010.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017.

8.2. Informative References

[RFC5912] Hoffman, P. and J. Schaad, "New ASN.1 Modules for the Public Key Infrastructure Using X.509 (PKIX)", RFC 5912, DOI 10.17487/RFC5912, June 2010.
[RFC8017] Moriarty, K., Kaliski, B., Jonsson, J. and A. Rusch, "PKCS #1: RSA Cryptography Specifications Version 2.2", RFC 8017, DOI 10.17487/RFC8017, November 2016.

Appendix A. Acknowledgements

The author would like to thank Russ Housley for his comments and for the ASN.1 module appendix.

Appendix B. ASN.1 module

This appendix provides non-normative ASN.1 definitions for the structures described in this specification using ASN.1 as defined in [CCITT.X680.2002] and [RFC5912].

   PrivateKeyValidationAttrV1
     { iso(1) identified-organization(3) dod(6) internet(1)
       private(4) enterprise(1) 2312 18 1 1 }

   DEFINITIONS IMPLICIT TAGS ::=

   BEGIN

   -- EXPORTS ALL

   IMPORTS

   ATTRIBUTE
    FROM PKIX-CommonTypes-2009  --  [RFC5912]
      { iso(1) identified-organization(3) dod(6) internet(1)
        security(5) mechanisms(5) pkix(7) id-mod(0)
        id-mod-pkixCommon-02(57) } ;

   -- PrivateKeyInfo is defined in [RFC5208].
   -- This definition adds the validation parameters attribute
   -- to the set of allowed attributes.

   PrivateKeyInfo ATTRIBUTE ::= {
     at-validation-parameters, ... }

   at-validation-parameters ATTRIBUTE ::= {
     TYPE ValidationParams
     IDENTIFIED BY id-attr-validation-parameters }

   id-attr-validation-parameters OBJECT IDENTIFIER ::=
     { 1 3 6 1 4 1 2312 18 8 1 }

   ValidationParams ::= SEQUENCE {
     hashAlg OBJECT IDENTIFIER,
     seed OCTET STRING }

   END

Author's Address

Nikos Mavrogiannopoulos Red Hat, Inc. Brno, Czech Republic EMail: nmav@redhat.com

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