Network Working Group                                     D. Linsenbardt
Request for Comments: 4059                                    S. Pontius
Category: Informational                                      A. Sturgeon
                                                                  SPYRUS
                                                                May 2005

                Internet X.509 Public Key Infrastructure
                     Warranty Certificate Extension

Status of This Memo

   This memo provides information for the Internet community.  It does
   not specify an Internet standard of any kind.  Distribution of this
   memo is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (2005).

Abstract

   This document describes a certificate extension to explicitly state
   the warranty offered by a Certificate Authority (CA) for the
   certificate containing the extension.

1.  Introduction

   The warranty certificate extension identifies the warranty policy
   associated with a X.509 public key certificate [X.509-97, PROFILE].
   Often the Certificate Authority (CA) will obtain an insurance policy
   to ensure coverage of the warranty.

   The certificate warranty provides an extended monetary coverage for
   the end entities.  The certificate warranty primarily concerns the
   use, storage, and reliance on a certificate by a subscriber, a
   relying party, and the CA.  It is common for a CA to establish
   reliance limits on the use of a certificate.  It is not uncommon for
   a CA to attempt through contractual means to exclude its liability
   entirely.  However, this undermines the confidence that commerce
   requires to gainfully use certificates.

   Alternatively a CA may provide extended coverage for the use of the
   certificate.  Usually, the subscriber pays for the extended warranty
   coverage.  In turn, subscribers are covered by an appropriately
   drafted insurance policy.  The certificate warranty is backed by an
   insurance policy issued by a licensed insurance company, which
   results in a financial backing that is far greater than that of the

   CA.  This extra financial backing provides a further element of
   confidence necessary to encourage the use of certificates in
   commerce.

   A relying party that has a warranty from a CA may obtain compensation
   from a CA depending on the conditions for such compensation expressed
   in either the CA's Certificate Policy, the CA's insurance policy, or
   both.  Evidence of an extended warranty, provided through the
   certificate extension, will give the relying party additional
   confidence that compensation is possible, and therefore will enhance
   trust in the process.  Risk for a non-subscriber relying party may be
   reduced by the presence of a warranty extension with an explicit
   warranty stated.  The warranty extension allows this aspect of risk
   management to be automated.

   When a certificate contains a warranty certificate extension, the
   extension MUST be non-critical, and MUST contain either a NULL to
   indicate that no warranty is provided or base warranty data to
   indicate that a warranty is provided.  The extension MAY contain
   optional qualifiers.

1.1.  Conventions Used in This Document

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in [RFC2119].

2.  Warranty Extension Format

   Like all X.509 certificate extensions, the warranty certificate
   extension is defined using ASN.1 [X.208-88, X.209-88].

   The non-critical warranty extension is identified by id-pe-warranty.

   PKIX Object Identifier Registry
   id-pkix OBJECT IDENTIFIER ::= { iso(1) identified-organization(3)
              dod(6) internet(1) security(5) mechanisms(5) pkix(7) }

   PKIX Arcs
   id-mod  OBJECT IDENTIFIER ::= { id-pkix 0 }    -- modules
   id-pe   OBJECT IDENTIFIER ::= { id-pkix 1 }    -- private
   certificate extensions

   PKIX modules
   id-mod-warranty-extn         OBJECT IDENTIFIER ::= { id-mod 27 }

   id-pe-warranty OBJECT IDENTIFIER  ::=  { id-pe 16 }

   A non-null warranty always includes a base warranty.  The warranty
   information includes the period during which the warranty applies, a
   warranty value, and a warranty type.  The warranty type tells the
   warranty limit against claims.  The extension definition supports two
   alternatives: aggregated and per-transaction.  With aggregation,
   claims are fulfilled until a ceiling value is reached.  After that,
   no further claims are fulfilled.  With per-transaction, a ceiling
   value is imposed on each claim, but each transaction is considered
   independently.

   The warranty extension permits inclusion of two optional warranty
   qualifiers.  The first qualifier provides extended warranty
   information, the second provides a pointer to the warranty terms and
   conditions.

   When present, the extended warranty information provides information
   about coverage beyond the scope of the base warranty.  Like the base
   warranty information, the extended warranty information includes the
   period during which the warranty applies, a warranty value, and a
   warranty type.

   When present, the terms and conditions pointer provides a reference
   to a document containing the terms and conditions associated with the
   warranty.  The document may be a Certificate Policy that contains
   this information, a document specifically about the warranty, or a
   Relying Party Agreement.  The pointer is always a uniform resource
   locator (URL).  The URL MUST be a non-relative URL using the http
   scheme.  The URL MUST follow the URL syntax and encoding rules
   specified in RFC 3986 [URI].

2.1.  Warranty Extension Syntax

   The syntax for the warranty extension is:

   Warranty  ::=  CHOICE  {
     none                 NULL,            -- No warranty provided
     wData                WarrantyData  }  -- Explicit warranty

   WarrantyData  ::=  SEQUENCE  {
     base                 WarrantyInfo,
     extended             WarrantyInfo OPTIONAL,
     tcURL                TermsAndConditionsURL OPTIONAL  }

   WarrantyInfo  ::=  SEQUENCE  {
     validity             WarrantyValidityPeriod,
     amount               CurrencyAmount,
     wType                WarrantyType  }

   WarrantyValidityPeriod  ::=  CHOICE  {
     sameAsCertificate    NULL,
     explicitPeriod       ValidityPeriod  }

   ValidityPeriod  ::=  SEQUENCE  {
     notBefore            GeneralizedTime,
     notAfter             GeneralizedTime  }

   -- CurrencyAmount specifies the currency and a monetary value.
   -- Currency codes are defined in [ISO4217].  The monetary value
   -- is: amount / (10 ** amtExp10), and the exponent MUST be the
   -- minor unit of currency specified in [ISO4217].

   CurrencyAmount  ::=  SEQUENCE  {
     currency             INTEGER (1..999),
     amount               INTEGER (0..MAX),
     amtExp10             INTEGER (0..MAX)  }

   WarrantyType  ::=  INTEGER  {
     aggregated           (0),
     perTransaction       (1)  }

   TermsAndConditionsURL  ::=  IA5String  -- MUST use http scheme

2.2.  Warranty Extension Semantics

   Warranty is a CHOICE; it is represented either by NULL or
   WarrantyData.  If the CA selects NULL, then the CA is explicitly
   stating that no warranty is provided.  If the CA selects
   WarrantyData, then the CA is explicitly stating that a warranty is
   provided, and the fields within the WarrantyData type MUST provide
   details about that warranty.

   WarrantyData MUST contain information about the base warranty.
   WarrantyData MAY contain information about an extended warranty.
   Both base warranty and extended warranty information is provided
   using the WarrantyInfo type.  WarrantyData MAY contain a URL that
   points to the terms and conditions of the warranty.  The URL is
   provided using the TermsAndConditionsURL type, which is an IA5
   string.  The IA5String MUST contain a URI [URI] using the http
   scheme, such as "http://www.example.com/warranty/t_and_c.html".

   WarrantyInfo MUST contain the warranty validity period, the currency
   amount of the warranty, and the type of warranty.  The warranty
   validity period is provided using the WarrantyValidityPeriod type.
   The currency amount of the warranty is provided using the
   CurrencyAmount type.  The type of warranty is provided using the
   WarrantyType type.

   WarrantyValidityPeriod is a CHOICE; it is represented either by NULL
   or ValidityPeriod.  If the CA selects NULL, then the validity periods
   of the warranty and the certificate MUST be exactly the same.  If the
   CA selects ValidityPeriod, then the CA is explicitly stating a
   warranty validity period that is different than the validity period
   of the certificate.  If the validity periods of the warranty and the
   certificate are the same, then the CA MUST select the NULL choice.
   The validity periods are expected to be the same in the vast majority
   of the cases.  ValidityPeriod is a SEQUENCE of two GeneralizedTime
   values.  The first (notBefore) GeneralizedTime value MUST indicate
   the date and time that the warranty becomes valid, and the second
   (notAfter) GeneralizedTime value MUST indicate the date and time that
   the warranty expires.

   CurrencyAmount is a SEQUENCE of three integers which together specify
   the currency and a monetary value.  The first integer (currency) MUST
   indicate the currency using one of the currency codes defined in
   [ISO4217].  The second integer (amount) MUST indicate the value of
   the warranty.  The third integer (amtExp10) MUST indicate the correct
   placement of the decimal point in the monetary value, and MUST be the
   minor unit of currency specified in [ISO4217].  For example
   $48,525.50 (in US dollars) is represented as:

      currency =      840
      amount   =  4852550
      amtExp10 =        2

   WarrantyType is an integer.  A value of zero indicates that claims
   against the warranty will be aggregated, and once the value of
   fulfilled claims reaches the warranty currency amount, then no
   further claim will be fulfilled.  A value of one indicates that each
   claim is handled independently, but no individual claim can exceed
   the warranty currency amount.  The CA MUST select either zero or one
   for this integer value.

3.  Security Considerations

   The procedures and practices employed by the CA MUST ensure that the
   correct values for the warranty are inserted in each issued
   certificate.  Relying parties and users may accept or reject a
   particular certificate for an intended use based on the information
   provided in warranty extension.  Incorrect representation of the
   actual warranty may result in otherwise avoidable warranty claims for
   the CA.

4.  IANA Considerations

   Certificate extensions and extended key usage values are identified
   by object identifiers (OIDs).  The OIDs used in this document are
   derived from X.509 [X.509-97].  No further action by the IANA is
   necessary for this document or any anticipated updates.

5.  ASN.1 Module

   WarrantyExtn
     { iso(1) identified-organization(3) dod(6) internet(1)
       security(5) mechanisms(5) pkix(7) id-mod(0)
       id-mod-warranty-extn(27) }

   DEFINITIONS IMPLICIT TAGS ::=
   BEGIN


   -- OID Arcs

   id-pe  OBJECT IDENTIFIER  ::=
      { iso(1) identified-organization(3) dod(6) internet(1)
        security(5) mechanisms(5) pkix(7) 1 }

   -- Warranty Extension

   id-pe-warranty-extn  OBJECT IDENTIFIER  ::=  { id-pe 16 }

   Warranty ::= CHOICE  {
       none                 NULL,            -- No warranty provided
       wData                WarrantyData  }  -- Explicit warranty

   WarrantyData ::= SEQUENCE  {
       base                 WarrantyInfo,
       extended             WarrantyInfo OPTIONAL,
       tcURL                TermsAndConditionsURL OPTIONAL  }

   WarrantyInfo ::= SEQUENCE  {
       validity             WarrantyValidityPeriod,
       amount               CurrencyAmount,
       wType                WarrantyType  }

   WarrantyValidityPeriod ::= CHOICE  {
       sameAsCertificate    NULL,
       explicitPeriod       ValidityPeriod  }

   ValidityPeriod ::= SEQUENCE  {
       notBefore            GeneralizedTime,
       notAfter             GeneralizedTime  }

   -- CurrencyAmount specifies the currency and a monetary value.
   -- Currency codes are defined in [ISO4217].  The monetary value
   -- is: amount / (10 ** amtExp10), and the exponent MUST be the
   -- minor unit of currency specified in [ISO4217].

   CurrencyAmount ::= SEQUENCE  {
       currency             INTEGER (1..999),
       amount               INTEGER (0..MAX),
       amtExp10             INTEGER (0..MAX)  }

   WarrantyType ::= INTEGER {
       aggregated           (0),
       perTransaction       (1)  }

   TermsAndConditionsURL ::= IA5String

   END

6.  Normative References

   [ISO4217]   ISO. "Codes for the Representation of Currencies and
               Funds", ISO 4217. 1995.

   [PROFILE]   Housley, R., Ford, W., Polk, W., and D. Solo, "Internet
               X.509 Public Key Infrastructure Certificate and CRL
               Profile", RFC 2459, January 1999.

   [URI]       Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
               Resource Identifier (URI): Generic Syntax", STD 66, RFC
               3986, January 2005.

   [X.208-88]  CCITT.  Recommendation X.208: Specification of Abstract
               Syntax Notation One (ASN.1).  1988.

   [X.209-88]  CCITT.  Recommendation X.209: Specification of Basic
               Encoding Rules for Abstract Syntax Notation One (ASN.1).
               1988.

7. Informative References

   [X.509-97]  ITU-T.  Recommendation X.509: The Directory-
               Authentication Framework.  1997.

Acknowledgements

   This document was developed with the expertise and support of Russ
   Housley, Vigil Security LLC, and Dr. Adrian McCullagh, Freehills
   Australia.

Authors' Addresses

   Duane Linsenbardt
   SPYRUS
   2355 Oakland Road
   Suite 1
   San Jose CA 95131
   USA

   EMail: dlinsenbardt@spyrus.com


   Sue Pontius
   SPYRUS
   2355 Oakland Road
   Suite 1
   San Jose CA 95131
   USA

   EMail: spontius@spyrus.com


   Alice Sturgeon
   SPYRUS
   Suite 1502, 222 Queen St.,
   Ottawa ON K0A 2T0
   Canada

   EMail: asturgeon@spyrus.com

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