Independent Submission                                         S. Turner
Request for Comments: 7169                                    IECA, Inc.
Category: Informational                                     1 April 2014
ISSN: 2070-1721


         The NSA (No Secrecy Afforded) Certificate Extension

Abstract

  This document defines the NSA (No Secrecy Afforded) certificate
  extension appropriate for use in certain PKIX (X.509 Pubic Key
  Certificates) digital certificates.  Historically, clients and
  servers strived to maintain the privacy of their keys; however, the
  secrecy of their private keys cannot always be maintained.  In
  certain circumstances, a client or a server might feel that they will
  be compelled in the future to share their keys with a third party.
  Some clients and servers also have been compelled to share their keys
  and wish to indicate to relying parties upon certificate renewal that
  their keys have in fact been shared with a third party.

Status of This Memo

  This document is not an Internet Standards Track specification; it is
  published for informational purposes.

  This is a contribution to the RFC Series, independently of any other
  RFC stream.  The RFC Editor has chosen to publish this document at
  its discretion and makes no statement about its value for
  implementation or deployment.  Documents approved for publication by
  the RFC Editor are not a candidate for any level of Internet
  Standard; see Section 2 of RFC 5741.

  Information about the current status of this document, any errata,
  and how to provide feedback on it may be obtained at
  http://www.rfc-editor.org/info/rfc7169.

Copyright Notice

  Copyright (c) 2014 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
  (http://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.



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RFC 7169              The NSA Certificate Extension         1 April 2014


1.  Introduction

  Insecurity abounds when clients and servers are unable to keep their
  private keys private.  Situations exist nonetheless where client and
  servers have shared their private keys with a third party.  An
  example of over-sharing might be lawful intercept.

  Just because the private key has been shared does not mean that the
  private key holder wants to conceal the fact they have shared their
  private key with a third party.  Overtly indicating that the private
  key may be or has been shared with a third party is the best way to
  indicate to relying parties that this sharing has occurred.
  Knowledge is power, after all.  Extensions for certificates [RFC5280]
  offer an excellent mechanism to indicate that the entities key(s)
  have been shared, and this document specifies one such certificate
  extension for use by entities that have shared their private key: the
  NSA (No Secrecy Afforded) certificate extension.

2.  The NSA Certificate Extension

  In order to allow entities that have shared their keys with a third
  party, the NSA certificate extension is defined herein.  ASN.1
  [X.680] for the extension follows:

  ext-KeyUsage EXTENSION ::= { SYNTAX
        BOOLEAN  IDENTIFIED BY id-pe-nsa }

  id-pe-nsa OBJECT IDENTIFIER ::=  { id-pe 23 }

  Making the boolean TRUE indicates that the key has been shared with a
  third party, and making the extension FALSE indicates that the key
  may have also been shared with a third party but the signer does not
  want to overtly indicate that the key has been shared.  This
  extension is always marked critical.

3.  Security Considerations

  Having to disclose keys is sometimes unavoidable.  Explicitly
  indicating that the keys have been shared is one way to mitigate the
  risk that the relying party might be unaware of this over share.
  Whatever the case for having shared the keys, the certificate signer
  needs to careful consider whether to include this extension.

  Any key with this extension must be trusted with care.  Lengthy
  deliberations about whether to trust the keys is necessary.  Rushing
  a security analysis is never a good thing.  Ultimately, the keys need
  not be trusted.  Secrecy is hard.




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RFC 7169              The NSA Certificate Extension         1 April 2014


4.  Normative References

  [RFC5280]  Cooper, D., Santesson, S., Farrell, S., Boeyen, S.,
             Housley, R., and W. Polk, "Internet X.509 Public Key
             Infrastructure Certificate and Certificate Revocation List
             (CRL) Profile", RFC 5280, May 2008.

  [X.680]    ITU-T, "Information technology - Abstract Syntax Notation
             One (ASN.1): Specification of basic notation", ITU-T
             Recommendation X.680 (2002) | ISO/IEC 8824-1:2002, 2002.

Author's Address

  Sean Turner
  IECA, Inc.
  3057 Nutley Street, Suite 106
  Fairfax, VA 22031
  USA

  EMail: [email protected]
  XMPP:  [email protected]






























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