Internet Engineering Task Force D. Linsenbardt
Internet-Draft S. Pontius
April 2002 SPYRUS
Expires: October 2002
Warranty Certificate Extension
<draft-ietf-pkix-warranty-extn-00.txt>
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Abstract
This document describes a certificate extension to explicitly state
the warranty offered by a Certificate Authority (CA) for a the
certificate containing the extension.
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].
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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 legal liability of the CA, in favor of the subscriber. The
certificate warranty primarily concerns the use, storage, and reliance
on a certificate by a third party and the CA. It is common for a CA
to limit liability by establishing 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
has the effect of undermining the confidence that commerce requires to
gainfully use certificates.
Alternatively a CA may provide extended liability 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.
When a certificate contains a warranty certificate extension, the
extension MUST be non-critical, and it MUST contain base warranty
data. The extension MAY contain optional qualifiers.
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-warrantyData.
id-pe-warrantyData OBJECT IDENTIFIER ::= { id-pe <<TBD>> }
The 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
liability limitations 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
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considered independently.
The warranty extension permits inclusion of two optional warranty
qualifiers. The first qualifier provides extended warranty information.
The second qualifier 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
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 pointer is always a uniform resource locator (URL).
The URL MUST be a non-relative URL, and it MUST follow the URL syntax
and encoding rules specified in RFC 1738 [URL].
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 }
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-- CurrencyAmount specifies the currency and a monetary value.
-- Currency codes are defined in ISO 4217. The monetary value
-- is: amount * (10 ** amtExp10), and the exponent MUST be the
-- minor unit of currency specified in ISO 4217.
CurrencyAmount ::= SEQUENCE {
currency INTEGER (1..999),
amount INTEGER (0..MAX),
amtExp10 INTEGER (0..MAX) }
WarrantyType ::= INTEGER {
aggregated (0),
perTransaction (1) }
TermsAndConditionsURL ::= IA5String
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 the
warranty that is provided.
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.
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 period
of the warranty MUST be exactly the same as the validity period of the
certificate. 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 warranty validity
period and the certificate validity period 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.
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ValidityPeriod is a SEQUENCE of two GeneralizedTime values. The first
(notBefore) GeneralizedTime value MUST indicate the date and time that
the warranty become valid, and the second (notAfter) GeneralizedTime
value MUST indicate the date and time that the warranty expires.
CurrencyAmount is a SEQUENCE if three integers. Together the integers
specify the currency and a monetary value. The first integer
(currency) MUST indicate the currency using one of the currency codes
defined in ISO 4217. 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 it
MUST be the minor unit of currency specified in ISO 4217. 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 certificate that is
issued. 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 unexpected liabilities for the CA.
4. References
ISO 4217 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.
URL Berners-Lee, T., Masinter, L., and M. McCahill. "Uniform
Resource Locators (URL)", RFC 1738, December 1994.
X.208-88 CCITT. Recommendation X.208: Specification of Abstract
Syntax Notation One (ASN.1). 1988.
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X.209-88 CCITT. Recommendation X.209: Specification of Basic
Encoding Rules for Abstract Syntax Notation One (ASN.1).
1988.
X.509-97 ITU-T. Recommendation X.509: The Directory -
Authentication Framework. 1997.
Acknowledgements
This Internet-Draft was developed with the expertise and support of Russ Housley,
RSA Laboratories, and Dr. Adrian McCullagh, Freehills Australia.
Author's Address
Duane Linsenbardt
Sue Pontius
SPYRUS
2355 Oakland Road
Suite 1
San Jose CA 95131
USA
dlinsenbardt@spyrus.com
spontius@spyrus.com
Person & email address to contact for further information:
Alice Sturgeon <asturgeon@spyrus.com>
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