Network Working Group                               N. Mavrogiannopoulos
Internet-Draft                                                   Red Hat
Updates: 5208 (if approved)                               August 8, 2017
Intended status: Informational
Expires: February 9, 2018

          Storing private key validation parameters in PKCS#8


   This memo describes a method of storing parameters needed for private
   key validation in the Private-Key Information Syntax Specification
   Version 1.2 [RFC5208] (PKCS#8) format.

Status of This Memo

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   This Internet-Draft will expire on February 9, 2018.

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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 Version 1.2 [RFC5208] format.

2.  Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   document are to be interpreted as described in [RFC2119].

3.  ValidationParams attribute

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

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

     ValidationParams ::= SEQUENCE {
         algorithm OBJECT IDENTIFIER,
         seed OCTET STRING

   The algorithm identifier in the ValidationParams should be a hash
   algorithm identifier for the [FIPS186-4] methods.

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
   (hex encoded).

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Internet-DrafStoring private key validation parameters in PK August 2017

   -----BEGIN PRIVATE KEY-----
   -----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.

   This document intentionally ignores [RFC5958] as it enhances PKCS#8
   [RFC5208] in a way that makes new keys incompatible with old parsers.

6.  Security Considerations

   All the considerations in [RFC5208] apply.

7.  IANA Considerations


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8.  References

8.1.  Normative References

   [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,

              Kerry, C. and P. Gallagher, "FIPS PUB 186-4: Digital
              Signature Standard (DSS)", FEDERAL INFORMATION PROCESSING
              STANDARDS PUBLICATION , July 2013.

8.2.  Informative References

   [RFC8017]  Moriarty, K., Ed., Kaliski, B., Jonsson, J., and A. Rusch,
              "PKCS #1: RSA Cryptography Specifications Version 2.2",
              RFC 8017, DOI 10.17487/RFC8017, November 2016,

   [RFC5958]  Turner, S., "Asymmetric Key Packages", RFC 5958,
              DOI 10.17487/RFC5958, August 2010,

Appendix A.  Acknowledgements


Author's Address

   Nikos Mavrogiannopoulos
   Red Hat, Inc.
   Czech Republic


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