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One of the most strategic problems still open in PKIX is locating
public data and services associated with a Certification Authority (CA).
This issue impacts interoperability and usability in PKIX.
This draft describes the PKI Resource Query Protocol (PRQP), its design,
definition, and its impact in already deployed PKIX protocols.
This Internet-Draft is submitted to IETF in full conformance with the provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet-Drafts.
Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as “work in progress.”
The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt.
The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html.
This Internet-Draft will expire on May 20, 2010.
Copyright (c) 2009 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. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the BSD License.
This document may contain material from IETF Documents or IETF Contributions published or made publicly available before November 10, 2008. The person(s) controlling the copyright in some of this material may not have granted the IETF Trust the right to allow modifications of such material outside the IETF Standards Process. Without obtaining an adequate license from the person(s) controlling the copyright in such materials, this document may not be modified outside the IETF Standards Process, and derivative works of it may not be created outside the IETF Standards Process, except to format it for publication as an RFC or to translate it into languages other than English.
1.
Requirements notation
2.
Introduction
2.1.
Overview of existing solutions
2.1.1.
Certificate Extensions
2.1.2.
DNS SRV records
2.1.3.
Local Network Oriented Solutions
3.
Protocol Details
3.1.
The Resource Query Authority (RQA)
3.2.
PRQP Overview
3.2.1.
PRQP Request
3.2.1.1.
Request Syntax
3.2.2.
PRQP Response
3.2.2.1.
Response Syntax
4.
Object Identifiers for PKI resources
4.1.
The RQA Service identifier
4.2.
The OCSP identifier
4.3.
The Subject's Certificate identifier
4.4.
The Issuer's Certificate identifier
4.5.
The Timestamping Service identifier
4.6.
The SCVP Server identifier
4.7.
The CRL Distribution Point identifier
4.8.
The Certificates Repository identifier
4.9.
The CRL Repository identifier
4.10.
The Cross Certificates Repository identifier
4.11.
The CMC Gateway identifier
4.12.
The CMP Gateway identifier
4.13.
The SCEP Gateway identifier
4.14.
The HTML Gateway identifier
4.15.
The XKMS Gateway identifier
4.16.
The Certificate Policy (CP) identifier
4.17.
The Certification Practice Statement (CPS) identifier
4.18.
The Endorsed Trust Anchors identifier
4.19.
The LOA Policy (LP) identifier
4.20.
The Certificate LOA Modifier identifier
4.21.
The HTML Certificate Request Service identifier
4.22.
The HTML Certificate Revoke Service identifier
4.23.
The HTML Certificate Renew Service identifier
4.24.
The HTML Certificate Suspend Service identifier
4.25.
The HTML Certificate Recovery Service Identifier
4.26.
The Grid Accreditation Body identifier
4.27.
The Grid Policy identifier
4.28.
The Grid Distribution Update identifier
4.29.
The Grid Accredited CA Certificates identifier
4.30.
The Apex Trust Anchor Update identifier
4.31.
The Trust Anchor Update identifier
4.32.
The CA Incident Report identifier
4.33.
The Private Resources identifier
5.
IANA Considerations
6.
PRQP Design Rationale
6.1.
Response Complexity
6.2.
RQA's URL distribution
6.3.
Security Considerations
6.4.
Time Validity
6.5.
Message Format
7.
Acknowledgments
8.
References
8.1.
Normative References
8.2.
Non-Normative References
Appendix A.
Transport Protocol Specifications for PRQP Messages
A.1.
PRQP over HTTP
A.1.1.
Request
A.1.2.
Response
A.1.3.
Message Caching
A.2.
PRQP over Peer-to-Peer Network
Appendix B.
RQA address Retrieval
B.1.
DHCP Specifications
B.1.1.
PRQP Servers IPv4 Option for DHCPv4
B.1.2.
PRQP Servers IPv6 Option for DHCPv6
B.1.3.
DHCP Configuration
B.1.4.
DHCP Client Processing
B.2.
DNS SRV Records
B.2.1.
SRV Record Format for PRQP
B.2.2.
Example: PRQP enabled zone file
Appendix C.
PRQP ASN1.1 Specification
§
Author's Address
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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] (Bradner, S., “Key words for use in RFCs to Indicate Requirement Levels,” March 1997.).
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An increasing number of services and protocols are being defined to
address different needs of users and administrators of PKIs. With
the deployment of new applications and services, the need to access
information and services provided by Certificate Service Providers
(CSPs) is critical. Currently Certification Authorities (CAs) barely
publish access details on their official web sites, this includes
URL of provided services and repositories.
Using the PRQP, resources provided by a CA can be automatically
and securely discovered by an application.
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Currently there are three options to find URLs providing access to PKI data:
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To provide pointers to published data it is possible to use
the Authority Information Access (AIA) Subject Information Access
(SIA) extensions defined by PKIX [RFC3280] (Housley, R., Polk, W., Ford, W., and D. Solo, “Internet X.509 Public Key Infrastructure Certificate and Certificate Revocation List (CRL) Profile,” April 2002.).
The former can provide information about services associated with
the issuer of the certificate,
while the latter carries information (inside a CA certificate) about
offered CA services.
AIA and SIA extensions are static, i.e. not modifiable unless the
certificate is re-issued.
If a CA inserts the AIA extension into every certificate it issues,
e.g., to identify the location of an OCSP
responder, then changing that location would require re-issuance of
all these certificates, a substantial barrier to such a change. If a CA
certificate is self-signed and used as a trust anchor, then re-issuing
the certificate to change the content of the SIA extension, e.g., to reflect
a change in the location of a time stamping server would be very disruptive.
In closed PKIs, e.g., enterprises,
use of these extensions may be replaced by manual configuration
and management of this data via ad hoc means.
Because of the centrally controlled nature of such environments,
the static nature of SIA and AIA extensions is not a concern.
However in order to promote interoperability between PKIs, PRQP enables
dynamic management of pointers to such services (e.g., adding/removing
or moving) without requiring changes in the certificate contents or
third parties to manually configure services in their applications.
Even in closed environments, PRQP could help manage PKI services
analogous the way DHCP facilitates network management.
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The SRV record technique provides pointers to servers via the
DNS [RFC1035] (Mockapetris, P., “Domain names - implementation and specification,” November 1987.).
As defined in [RFC2782] (Gulbrandsen, A., Vixie, P., and L. Esibov, “A DNS RR for specifying the location of services (DNS SRV),” February 2000.), the introduction of this
type of record allows
administrators to perform operations similar to what we require
in order to solve the problem we are addressing in this draft,
i.e., to provide URLs to services.
The problem in the adoption of this mechanism is that, in contrast to
the DNS environment, usually in PKIX there is no fixed mapping
between certificates and the DNS name space.
The only exception is when the
Domain Component (DC) attributes are used in the certificate's Subject.
Currently this approach is not widely adopted. Moreover, it is not
always easy to identify the right DNS to query to, when trying to find
a particular service provided by a CA, because of the lack of such
information in certificates.
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Another approach to provide reliable information is to use existing
protocols for service location such as Jini, Universal Plug and Play
protocol (UPnP) or Service Location Protocol (SLP) [RFC2608] (Guttman, E., Perkins, C., Veizades, J., and M. Day, “Service Location Protocol, Version 2,” June 1999.)
[RFC2609] (Guttman, E., Perkins, C., and J. Kempf, “Service Templates and Service: Schemes,” June 1999.).
The IETF defined the SLP to provide a service location mechanism
that is language and technology independent.
Some issues, however, make it not the right choice to solve our
problem, e.g., the protocol is quite complex to implement when
considering the scope of the problem we are addressing.
The definition of a specific and simple protocol for PKI service and
resource location is needed to ease PKI integration into existing and
future
applications, especially for mobile devices which have limited
computational power and communication bandwidth.
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The PRQP protocol is a request-response protocol, formed by the
exchanging of two messages, i.e., a request and a response between a
client and a server, called the Resource Query Authority (RQA).
The requesting entity (the client) may be any entity that needs
to access information about repositories and services related
to a certificate.
The RQA is the authority entitled to answer for a particular CA or to
act as a PRQP Trusted Authority (PTA) for a set of users, e.g., users
in an enterprise environment.
In the first case the RQA is directly designated by a CA to act
as an RQA, by having the CA issue a certificate to the RQA with a
specific value set in the extendedKeyUsage extension.
In this case the RQA provides authoritative
responses for requests regarding the CA that issued the RQA's
certificate.
When operating as a PTA, the RQA may provide responses about multiple CAs,
without the need to have been directly certified by them. To operate as
such, a specific extension (prqpTrustedAuthority) should be present in
RQA's certificate and its value should be set to TRUE.
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The Resource Query Authority is the designated authority to act as PRQP
responder. The RQA's signing key needs not to be the same as that of the
CA that designated it.
The CA may designate an RQA by issuing a certificate containing a unique
value for the extendedKeyUsage in RQA's certificate. The RQA may also act
as a trusted responder. PRQP signing delegation SHALL be designated by
the inclusion of id-kp-PRQPSigning in the extendedKeyUsage extension
within the PRQP response signer's certificate.
- id-kp-PRQPSigning OBJECT IDENTIFIER ::= {iso(1) identified-organization(2) dod(6) internet(1) security(5) mechanisms(5) pkix(7) kp(3) 11}
When operating as a PTA, the RQA may provide responses about multiple CAs, without the need to have been directly certified by them. To operate as a PTA a specific extension (prqpTrustedAuthority) should be present in RQA's certificate and its value should be set to TRUE.
- prqpTrustedAuthority ::= BOOLEAN DEFAULT TRUE
We also define two new OIDs to identify the PRQP protocol and the PTA extension as follows:
- id-prqp OBJECT IDENTIFIER ::= { id-pkix 23 }
- id-prqp-pta OBJECT IDENTIFIER ::= { id-prqp 1 }
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The protocol encompasses the exchange of a single round of messages between a client and an RQA:
Upon receiving the response the client MUST verify the status error
returned in the response. If no error is present, the client MUST
verify the
various fields contained in the ResourceResponseToken and the validity
of the associated digital signature (if present).
A nonce MAY be used to guarantee that the response is associated with a
specific request in order to avoid reply attacks.
The client also SHOULD check the validity period of the response. It
SHOULD NOT, in order to minimize the load on an RQA, request again the
location of the same resource within this interval to the same RQA.
If the response is signed, the client SHOULD check the RQA's certificate
validity.
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A PRQP request contains the following data:
The ASN.1 syntax imports terms defined in [RFC4210] (Adams, C., Farrell, S., Kause, T., and T. Mononen, “Internet X.509 Public Key Infrastructure Certificate Management Protocol (CMP),” September 2005.). For signature calculation, the data to be signed is encoded by using the DER format. ASN.1 EXPLICIT tagging is used as a default unless specified otherwise. The terms imported from [RFC3280] (Housley, R., Polk, W., Ford, W., and D. Solo, “Internet X.509 Public Key Infrastructure Certificate and Certificate Revocation List (CRL) Profile,” April 2002.) are: Extensions, Certificate, CertificateSerialNumber, SubjectPublicKeyInfo, Name, AlgorithmIdentifier.
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The PRQP request syntax is as follows:
PRQPRequest ::= SEQUENCE {
requestData TBSReqData,
signature [0] EXPLICIT Signature OPTIONAL }
TBSReqData ::= SEQUENCE {
version INTEGER { v(1) },
nonce [0] INTEGER OPTIONAL,
-- very large number
producedAt GeneralizedTime,
-- time when the request has been generated
serviceToken ResourceRequestToken,
-- token identifying the requested service
extensions [1] IMPLICIT Extensions OPTIONAL }
The version field (currently v1) describes the version of the PRQP request. The nonce field, if present, is an integer between 80 bits and 256 bit in length. The producedAt define the time-frame when the request has been generated.
ResourceRequestToken ::= SEQUENCE {
ca CertIdentifier,
servicesList [0] SET OF ResourceIdentifier OPTIONAL }
The ca field is of type CertIdentifier. This is used to identify
the certificate of the CA whose services are requested.
The CertIdentifier syntax is as follows:
BasicCertIdentifier ::= SEQUENCE {
issuerNameHash OCTET STRING,
serialNumber CertificateSerialNumber }
ExtendedCertInfo ::= SEQUENCE {
certificateHash OCTET STRING,
subjectKeyHash OCTET STRING,
subjectKeyIdentifier [0] KeyIdentifier OPTIONAL,
issuerKeyIdentifier [1] KeyIdentifier OPTIONAL }
CertIdentifier ::= SEQUENCE {
hashAlgorithm AlgorithmIdentifier,
basicCertIdentifier BasicCertIdentifier,
extInfo [0] ExtendedCertInfo OPTIONAL,
caCertificate [1] Certificate OPTIONAL,
issuedCertificate [2] Certificate OPTIONAL }
The resourceList specifies the resources or services being requested.
ResourceIdentifier ::= SEQUENCE {
resourceId OBJECT IDENTIFIER,
version [0] INTEGER OPTIONAL
--- version of the protocol or data format (if applicable)
oid [1] OBJECT IDENTIFIER OPTIONAL,
--- object identifier associated with the URL
--- (if applicable) }
The ResourceIdentifier is formed by an OID that identifies the service
or the data being requested (e.g. OCSP, LDAP, CRL, etc... ) and an optional
version number that may be used to better identify the requested resource.
All fields SHOULD be used whenever applicable.
If one or more ResourceIdentifier are provided in the request, the RQA
should report back the location for each of the requested services. If
no ResourceIdentifier is present in the request, the response should
carry all the available service locations for the specified CA (with
respect to the MaxResponse and optional parameters constrain).
The signature field is of type Signature and it is defined in
[RFC2560] (Myers, M., Ankney, R., Malpani, A., Galperin, S., and C. Adams, “X.509 Internet Public Key Infrastructure Online Certificate Status Protocol - OCSP,” June 1999.):
Signature ::= SEQUENCE {
signatureAlgorithm AlgorithmIdentifier,
signature BIT STRING,
certs [0] EXPLICIT SEQUENCE OF Certificate
OPTIONAL }
Extensions can be used for future protocol enhancement.
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The PRQP response contains the following data:
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The response syntax is as follows:
PRQPResponse ::= SEQUENCE {
respData TBSRespData,
signature [0] EXPLICIT Signature OPTIONAL }
TBSRespData ::= SEQUENCE {
version INTEGER { v(1)},
nonce [0] INTEGER OPTIONAL,
-- as duplicated from the request
producedAt GeneralizedTime,
-- time when the response has been generated
nextUpdate [1] GeneralizedTime OPTIONAL,
-- time till when the response should be considered valid
pkiStatus PKIStatusInfo,
-- status of the response
caCertId CertIdentifier,
-- identifier of the CA certificate that issued the
-- targeted certificate
responseToken [2] SEQUENCE OF ResourceResponseToken
OPTIONAL,
-- token carrying information about
-- requested services
extensions [3] EXPLICIT Extensions OPTIONAL }
The version field (currently v1) describes the version of the used PRQP
response. The nonce, if present, binds the response to a specific request.
The usage of the nonce is meaningful only in signed responses
and its value must be copied directly from the corresponding request.
If not present in the request, the nonce MUST be omitted.
The pkiStatus field is used to return useful information to the client on
the status of the query.
PKIStatusInfo ::= SEQUENCE {
status PKIStatus,
statusString [0] UTF8String OPTIONAL,
failInfo [1] PKIFailureInfo OPTIONAL,
referrals [2] EXPLICIT SEQUENCE OF IA5String
OPTIONAL }
If status has value zero, a responseToken MUST be present in the response. When the status value is non zero, the responseToken MUST be omitted and the reason code MUST be one of the values in PKIStatus. When the PKIStatus value is set to caNotPresent (2) or sytemFailure (3), a list referral URLs MAY be included in the response to facilitate the client in finding the required resource from other known servers.
PKIStatus ::= INTEGER {
ok (0),
-- when the PKIStatus contains the value zero one or
more responseToken is present
badRequest (1),
-- the request is badly formatted
caNotPresent (2),
-- the requested CA is not present
systemFailure (3)
-- a system failure has occurred }
The signature field is of type Signature and it is defined in [RFC2560] (Myers, M., Ankney, R., Malpani, A., Galperin, S., and C. Adams, “X.509 Internet Public Key Infrastructure Online Certificate Status Protocol - OCSP,” June 1999.):
Signature ::= SEQUENCE {
signatureAlgorithm AlgorithmIdentifier,
signature BIT STRING,
certs [0] EXPLICIT SEQUENCE OF Certificate
OPTIONAL }
The responseToken carries information about the services requested by
the client. For each of the requested service, the RQA should include
a ResourceResponseToken which bears the OID of the service and the
corresponding URI.
The ResourceResponseToken syntax is described below:
ResourceResponseToken ::= SEQUENCE {
resourceId OBJECT IDENTIFIER,
--- resource identifier
resourceLocatorList [0] EXPLICIT SEQUENCE OF IA5String,
--- sequence of resource locators (URI)
version [1] INTEGER OPTIONAL,
--- version of the protocol or data format (if applicable)
oid [2] OBJECT IDENTIFIER OPTIONAL,
--- object identifier associated with the URL
--- (if applicable)
resourceInfo [3] UTF8Sting OPTIONAL,
--- additional service Info (eg. technical contacts) }
The resourceId field value is copied from the corresponding request and it bears the OID of the service about which the client inquired. In section Section 4 (Object Identifiers for PKI resources) we define a list of default PKI resources.
The producedAt and nextUpdate define the time-frame when the response
data is to be considered valid. Within the defined period, the client
SHOULD NOT request for the same service. Use of wider time-frames values
can help the RQA avoid duplication of requests from the same client
thus potentially lowering the load of the responder. However, providing
this data to a client does not ensure a lower query rate, as a server
cannot rely on clients to obey the advice provided in the response.
The resourceLocator bears access information for the service identified
by the serviceId. The name MUST be an absolute URL, and it MUST follow
the URL syntax and encoding rules specified in [RFC4248] (Hoffman, P., “The telnet URI Scheme,” October 2005.)
and [RFC4266] (Hoffman, P., “The gopher URI Scheme,” November 2005.).
The resourceLocator
includes both a scheme (e.g., HTTP or FTP) and a scheme specific part.
The scheme specific part is supposed to carry information on how to
reach the requested service, this is, for example, a fully qualified
domain name or IP address as the host. If the requested service is not
available or it is unknown by the server, the resourceLocator value
should be empty.
Optional Extensions may be added if requested.
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The PRQP defines a set of standard OIDs that are used to identify resources related to a Certification Authority. In this section we provide a description for each of the defined OIDs.
The services are all defined under the id-ad-prqp OID which is defined as follows:
id-ad-prqp OBJECT IDENTIFIER ::= {id-ad 12}
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When id-ad-prqp-rqa is used in a PRQP message, the associated value in the response is the location of the PRQP server (i.e., an RQA) using the conventions in this document or subsequent updates.
id-ad-prqp-rqa OBJECT IDENTIFIER ::= {id-ad-prqp 0}
The version field, if used, indicates the supported PRQP protocol version.
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When id-ad-prqp-ocsp appears in a PRQP request or response, the associated value in the response is the location of the OCSP responder, using the conventions defined in [RFC2560] (Myers, M., Ankney, R., Malpani, A., Galperin, S., and C. Adams, “X.509 Internet Public Key Infrastructure Online Certificate Status Protocol - OCSP,” June 1999.). The version field, if used, indicates the supported protocol version.
id-ad-prqp-ocsp OBJECT IDENTIFIER ::= {id-ad-prqp 1 }
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When id-ad-subjectCert is used in a PRQP message, the associated value in the response is the location of the DER formatted certificate of the identified CA. The version field MAY be used to specify the version of the certificate pointed by the URL in a PRQP Response message. In order to enhance interoperability between applications and reduce development efforts, the URI should point directly to the certificate and not to a redirection service.
id-ad-prqp-subjectCert OBJECT IDENTIFIER ::= {id-ad-prqp 2 }
HTTP server implementations accessed via the URI SHOULD specify the media type "application/x-x509-ca-cert" in the content-type header field of the response.
This field allows applications to check for renewal of CA certificates. When the application wants to check if a new version of the identified certificate exists, it can use this service and download the certificate from the URL. If the downloaded certificate differs from the one already possesed by the client, two different cases are possible:
For more complex trust anchor operations, please refer to Section 4.18 (The Endorsed Trust Anchors identifier), Section 4.30 (The Apex Trust Anchor Update identifier) or Section 4.31 (The Trust Anchor Update identifier).
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When id-ad-issuerCert is used in a PRQP message, the associated value is in the response the location of the DER formatted certificate of the issuer of the identified CA. The version field MAY be used to specify the version of the certificate pointed by the URL in a PRQP Response message. In order to enhance interoperability between applications and reduce development efforts, the URI should point directly to the certificate and not to a redirection service.
id-ad-prqp-issuerCert OBJECT IDENTIFIER ::= {id-ad-prqp 3 }
HTTP server implementations accessed via the URI SHOULD specify the media type "application/x-x509-ca-cert" in the content-type header field of the response.
The content of this service is the same as the content of caIssuers when the provided URI refers to the CA Issuer's certificate [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,” May 2008.). This field allows applications to dynamically download and build validation paths and may be extremely useful when cross certificates are used (eg., in bridge CAs).
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When id-ad-timestamping is used in a PRQP message, the associated value in the response is the location of the Timestamping responder, using the conventions defined in [RFC3161] (Adams, C., Cain, P., Pinkas, D., and R. Zuccherato, “Internet X.509 Public Key Infrastructure Time-Stamp Protocol (TSP),” August 2001.). The version field, if used, indicates the supported protocol version.
id-ad-prqp-timestamping OBJECT IDENTIFIER ::= {id-ad-prqp 4 }
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When id-ad-prqp-scvp appears in a PRQP request or response, the associated value in the response is the location of the SCVP responder, using the conventions defined in [RFC5055] (Freeman, T., Housley, R., Malpani, A., Cooper, D., and W. Polk, “Server-Based Certificate Validation Protocol (SCVP),” December 2007.). The version field, if used, indicates the supported protocol version.
id-ad-prqp-scvp OBJECT IDENTIFIER ::= {id-ad-prqp 5 }
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When id-ad-prqp-crlDistribution appears in a PRQP message, the associated value in the response is a pointer to the current CRL. The URI MUST point to a single DER encoded CRL as specified in [RFC2585] (Housley, R. and P. Hoffman, “Internet X.509 Public Key Infrastructure Operational Protocols: FTP and HTTP,” May 1999.). The version field, if used, indicates the version of the pointed CRL. In order to enhance interoperability between applications and reduce development efforts, the URI should point directly to the CRL and not to a redirection service.
id-ad-prqp-crlDistribution OBJECT IDENTIFIER ::= {id-ad-prqp 6 }
HTTP server implementations accessed via the URI SHOULD specify the media type "application/pkix-crl" in the content-type header field of the response.
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When id-ad-prqp-certRepository appears in a PRQP message, the associated value in the response is a pointer to a set of certificates. The URI MUST point to a collection of certificates in a DER encoded "certs-only" CMS message as specified in [RFC5272] (Schaad, J. and M. Myers, “Certificate Management over CMS (CMC),” June 2008.).
id-ad-prqp-certRepository OBJECT IDENTIFIER ::= {id-ad-prqp 7 }
HTTP server implementations accessed via the URI SHOULD specify the media type "application/pkcs7-mime" [RFC5272] (Schaad, J. and M. Myers, “Certificate Management over CMS (CMC),” June 2008.) in the content-type header field of the response. The name of the returned file SHOULD have a suffix of ".p7c" [RFC5272] (Schaad, J. and M. Myers, “Certificate Management over CMS (CMC),” June 2008.).
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When id-ad-prqp-crlRepository appears in a PRQP message, the associated value is a pointer to a set of CRL. The URI MUST point to a collection of CRLs in a DER encoded CMS message. The type of message should be a Simple PKI Response where the CRLs are placed in the CRL bag.
id-ad-prqp-crlRepository OBJECT IDENTIFIER ::= {id-ad-prqp 8 }
HTTP server implementations accessed via the URI SHOULD specify the media type "application/pkcs7-mime" [RFC5272] (Schaad, J. and M. Myers, “Certificate Management over CMS (CMC),” June 2008.) in the content-type header field of the response. The name of the returned file SHOULD have a suffix of ".p7c"
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When id-ad-prqp-crossCertRepository appears in a PRQP message, the associated value in the response is a pointer to a set of Cross Certificates. The URI MUST point to a collection of certificates in DER encoded CertificatePair object defined as:
CertificatePair ::= SEQUENCE {
forward [0] Certificate OPTIONAL,
reverse [1] Certificate OPTIONAL,
-- at least one of the pair shall be present -- }
The id-ad-prqp-crossCertRepository is defined as follows:
id-ad-prqp-crossCertRepository
OBJECT IDENTIFIER ::= {id-ad-prqp 9 }
As defined in [RFC4523] (Zeilenga, K., “Lightweight Directory Access Protocol (LDAP) Schema Definitions for X.509 Certificates,” June 2006.), LDAP implementation store the CertificatePair in the crossCertificatePair attribute.
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When id-ad-prqp-cmcGateway appears in a PRQP message, the associated value in the response is the location of the CMM over CMS service, using the conventions defined in [RFC5272] (Schaad, J. and M. Myers, “Certificate Management over CMS (CMC),” June 2008.). As the [RFC5272] (Schaad, J. and M. Myers, “Certificate Management over CMS (CMC),” June 2008.) does not define a version for the protocol, if the version field is used to identify the service, applications SHOULD ignore it.
id-ad-prqp-cmcGateway OBJECT IDENTIFIER ::= {id-ad-prqp 10 }
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When id-ad-prqp-cmpGateway appears in a PRQP message, the associated value in the response is the location of the CMP over CMS service, using the conventions defined in [RFC4210] (Adams, C., Farrell, S., Kause, T., and T. Mononen, “Internet X.509 Public Key Infrastructure Certificate Management Protocol (CMP),” September 2005.). As the [RFC4210] (Adams, C., Farrell, S., Kause, T., and T. Mononen, “Internet X.509 Public Key Infrastructure Certificate Management Protocol (CMP),” September 2005.) defines the protocol version in the pvno field of PKIHeader, the version field MAY be used to to identify the required/supported service version.
id-ad-prqp-cmpGateway OBJECT IDENTIFIER ::= {id-ad-prqp 11 }
| TOC |
When id-ad-prqp-scepGateway appears in a PRQP message, the associated value in the response is the location of the CMS service gateway, using the conventions defined in [I‑D.nourse‑scep] (Liu, X., “Cisco Systems' Simple Certificate Enrollment Protocol,” June 2008.). The version field used to identify the service, if present, SHOULD be set to 0.
id-ad-prqp-scepGateway OBJECT IDENTIFIER ::= {id-ad-prqp 12 }
| TOC |
When id-ad-prqp-htmlGateway appears in a PRQP message, the associated value in the response is the location of a HTML CA service.
id-ad-prqp-htmlGateway OBJECT IDENTIFIER ::= {id-ad-prqp 13 }
The version field, if present, identifies the version of the HTML data as follows:
| Version Value | Data Type |
|---|---|
| 0 | HTML |
| 1 | XML |
| Table 1 |
| TOC |
When id-ad-prqp-xkmsGateway appears in a PRQP message, the associated value in the response is the location of an XKMS server, using the conventions defined in [W3C.xkms] (Ford, W., Hallam-Baker, P., Fox, B., Dillaway, B., LaMacchia, B., Epstein, J., and J. Lapp, “XML Key Management Specification (XKMS),” March 2001.) and [W3C.REC‑xkms2‑20050628] (Mysore, S. and P. Hallam-Baker, “XML Key Management Specification (XKMS 2.0),” June 2005.). The version field used to identify the service, if present, SHOULD be set to 1 for services compliant to [W3C.xkms] (Ford, W., Hallam-Baker, P., Fox, B., Dillaway, B., LaMacchia, B., Epstein, J., and J. Lapp, “XML Key Management Specification (XKMS),” March 2001.) and to 2 for services compliant to [W3C.REC‑xkms2‑20050628] (Mysore, S. and P. Hallam-Baker, “XML Key Management Specification (XKMS 2.0),” June 2005.).
id-ad-prqp-xkmsGateway OBJECT IDENTIFIER ::= {id-ad-prqp 14 }
| TOC |
When id-ad-prqp-certPolicy appears in a PRQP message, the associated value in the response is the location of a certificate Policy (CP). A CP may be used by a relying party to help in deciding whether a certificate, and the binding therein, are sufficiently trustworthy and otherwise appropriate for a particular application.
id-ad-prqp-certPolicy OBJECT IDENTIFIER ::= {id-ad-prqp 20 }
More information can be found in [RFC2527] (Chokhani, S. and W. Ford, “Internet X.509 Public Key Infrastructure Certificate Policy and Certification Practices Framework,” March 1999.).
In order to gather the correct policy under which a certificate is issued, the optional OID field in the PRQPRequest SHOULD be copied from the certificate Policy extension of the EE certificate (i.e., the certificate issued by the CA the client is querying for).
| TOC |
When id-ad-prqp-certPolicycertPracticeStatement appears in a PRQP message, the associated value in the response is the location of a Certification Practice Statement (CPS) published by the CA. A CPS is a document that details the practices and procedures established by a CA that will cover the life-cycle of certificates issued by the CA. That is it covers how the certificate will be generated, suspended and revoked. An internally focused document covering the internal environment of the CA.
id-ad-prqp-certPracticeStatement
OBJECT IDENTIFIER ::= {id-ad-prqp 21 }
More information can be found in [RFC2527] (Chokhani, S. and W. Ford, “Internet X.509 Public Key Infrastructure Certificate Policy and Certification Practices Framework,” March 1999.).
| TOC |
When id-ad-prqp-endorsedTA appears in a PRQP message, the associated value in the response is a pointer to a set of Trust Anchors (TA) in the form of certificates. The URI MUST point to a collection of certificates in a DER encoded CMS signedData message as specified in [RFC5272] (Schaad, J. and M. Myers, “Certificate Management over CMS (CMC),” June 2008.).
id-ad-prqp-endorsedTA OBJECT IDENTIFIER ::= {id-ad-prqp 22 }
HTTP server implementations accessed via the URI SHOULD specify the media type "application/pkcs7-mime" [RFC5272] (Schaad, J. and M. Myers, “Certificate Management over CMS (CMC),” June 2008.) in the content-type header field of the response. The name of the returned file SHOULD have a suffix of ".p7" [RFC5272] (Schaad, J. and M. Myers, “Certificate Management over CMS (CMC),” June 2008.). The returned data object SHOULD be signed directly by the CA or by an authorized Identity whose certificate has been issued by the CA (i.e., an EE certificate). The application SHOULD verify the signature on the CMS message before proceeding in accepting the set of TAs. Moreover the application MAY import the set of certificates in its own certificate store as trusted depending on previous trust settings or input from the user.
| TOC |
When id-ad-prqp-loaPolicy appears in a PRQP message, the associated value in the response is the location of a Level of Assurance Policy (LP) published by the CA. An LP is a document that details the practices and procedures established by a CA that will cover the requirements for each Level of Assurance. The OID field in the request/response MAY be used to identify a specific LOA Policy document.
id-ad-prqp-loaPolicy OBJECT IDENTIFIER ::= {id-ad-prqp 25 }
More information can be found in [RFC2527] (Chokhani, S. and W. Ford, “Internet X.509 Public Key Infrastructure Certificate Policy and Certification Practices Framework,” March 1999.).
| TOC |
When id-ad-prqp-certLOAModifier appears in a PRQP message, the associated value in the response is the location of a LOA Level Modifier. The LOA modifier service is used to identify the current LOA Level of the certificate (not the LOA under which the certificate has been issued).
id-ad-prqp-certLOAModifier OBJECT IDENTIFIER ::= {id-ad-prqp 26 }
| TOC |
When id-ad-prqp-htmlRequestCertificate appears in a PRQP message, the associated value in the response is the location of a HTML certificate request service. The version field, when present, identifies the version of the supported HTML format. See Table Table 1 for more details. As not standard exists that describes how to interact with a CA via HTML, this locator should be mainly used for browser-based certification requests.
id-ad-prqp-htmlRequestCertificate
OBJECT IDENTIFIER ::= {id-ad-prqp 30}
| TOC |
When id-ad-prqp-htmlRevokeCertificate appears in a PRQP message, the associated value in the response is the location of a HTML certificate revoking service. The version field, when present, identifies the version of the supported HTML format. See Table Table 1 for more details. As not standard exists that describes how to interact with a CA via HTML, this locator should be mainly used for browser-based certification requests.
id-ad-prqp-htmlRevokeCertificate
OBJECT IDENTIFIER ::= {id-ad-prqp 31}
| TOC |
When id-ad-prqp-htmlRenewCertificate appears in a PRQP message, the associated value in the response is the location of a HTML certificate renewal service. The version field, when present, identifies the version of the supported HTML format. Table 1 As not standard exists that describes how to interact with a CA via HTML, this locator should be mainly used for browser-based certificate renewal requests.
id-ad-prqp-htmlRenewCertificate
OBJECT IDENTIFIER ::= {id-ad-prqp 32}
| TOC |
When id-ad-prqp-htmlSuspendCertificate appears in a PRQP message, the associated value in the response is the location of a HTML certificate suspension service. The version field, when present, identifies the version of the supported HTML format. See Table Table 1 for more details. As not standard exists that describes how to interact with a CA via HTML, this locator should be mainly used for browser-based certificate suspension requests.
id-ad-prqp-htmlSuspendCertificate
OBJECT IDENTIFIER ::= {id-ad-prqp 33}
| TOC |
When id-ad-prqp-htmlRecoveryCertificate appears in a PRQP message, the associated value in the response is the location of a HTML certificate recovery service. The version field, when present, identifies the version of the supported HTML format. See Table Table 1 for more details. The recovery service is used when a user's local copy of their keys and key history is destroyed. The recovery service returns the user to a complete state (e.g. so they can decrypt messages that were encrypted with older keys). As not standard exists that describes how to interact with a CA via HTML, this locator should be mainly used for browser-based certificate recovery requests.
id-ad-prqp-htmlRecoveryCertificate
OBJECT IDENTIFIER ::= {id-ad-prqp 34}
| TOC |
When id-ad-prqp-grid-accreditationBody appears in a PRQP message, the associated value in the response is the location of the main information point of the Grid Policy Management Authority (GPMA) that accredited the CA. The pointer SHOULD NOT be present if the CA has not been accredited by the GPMA.
id-ad-prqp-grid-accreditationBody
OBJECT IDENTIFIER ::= {id-ad-prqp 50}
| TOC |
When id-ad-prqp-grid-accreditationPolicy appears in a PRQP message, the associated value in the response is the location of an Accreditation Policy published by a Grid Policy Management Authority (GPMA). The OID field SHOULD be used to uniquely identify the accreditation policy under which the CA has been accredited. The pointer SHOULD NOT be present if the CA has not been accredited by the GPMA. A Grid Policy (GP) is a document that details the practices and procedures required from a CA in order to be accredited by the GPMA.
id-ad-prqp-grid-accreditationPolicy
OBJECT IDENTIFIER ::= {id-ad-prqp 51}
| TOC |
When id-ad-prqp-grid-commonDistributionUpdate appears in a PRQP message, the associated value in the response is the location of the Grid Distribution Package associated with the Grid Policy Management Authority (GPMA) that accredited the CA. The OID field SHOULD be used to uniquely identify the accreditation policy under which the Grid Distribution Package has been released. The pointer SHOULD NOT be present if the CA has not been accredited by the GPMA.
id-ad-prqp-grid-commonDistributionUpdate
OBJECT_IDENTIFIER ::= {id-ad-prqp 53}
| TOC |
When id-ad-prqp-gridAccreditedCACerts appears in a PRQP message, the associated value in the response is a pointer to a set of Trust Anchors (TA) in the form of certificates accredited by the Grid body/bodies that the CA is participating to. The URI MUST point to a collection of certificates in a DER encoded CMS signedData message as specified in [RFC5272] (Schaad, J. and M. Myers, “Certificate Management over CMS (CMC),” June 2008.). The OID field SHOULD be used to uniquely identify the accreditation policy under which the set of CAs pointed by the URI have been accredited.
id-ad-prqp-grid-gridAccreditedCACerts
OBJECT_IDENTIFIER ::= {id-ad-prqp 54}
HTTP server implementations accessed via the URI SHOULD specify the media type "application/pkcs7-mime" [RFC5272] (Schaad, J. and M. Myers, “Certificate Management over CMS (CMC),” June 2008.) in the content-type header field of the response. The name of the returned file SHOULD have a suffix of ".p7" [RFC5272] (Schaad, J. and M. Myers, “Certificate Management over CMS (CMC),” June 2008.). The returned data object SHOULD be signed by the CA the endorsedTA service has been requested for. The application SHOULD verify the signature on the CMS message before proceeding in accepting the set of TAs. Moreover the application MAY import the set of certificates in its own certificate store as trusted depending on previous trust settings or input from the user.
| TOC |
When id-ad-prqp-apexTampUpdate appears in a PRQP message, the associated value in the response is the location of a Apex Trust Anchor Update (apexTrustAnchorUpdate) message as defined by using the conventions defined in [I‑D.pkix‑tamp] (Housley, R., Ashmore, S., and C. Wallace, “Trust Anchor Management Protocol (TAMP),” October 2008.). The version field used to identify the service, if present, SHOULD reflect the supported TAMP version.
id-ad-prqp-apexTampUpdate OBJECT IDENTIFIER ::= {id-ad-prqp 70}
| TOC |
When id-ad-prqp-tampUpdate appears in a PRQP message, the associated value in the response is the location of a Trust Anchor Update (trustAnchorUpdate) message as defined by using the conventions defined in [I‑D.pkix‑tamp] (Housley, R., Ashmore, S., and C. Wallace, “Trust Anchor Management Protocol (TAMP),” October 2008.). The version field used to identify the service, if present, SHOULD reflect the supported TAMP version.
id-ad-prqp-tampUpdate OBJECT IDENTIFIER ::= {id-ad-prqp 71 }
| TOC |
When id-ad-prqp-caIncidentReport appears in a PRQP message, the associated value in the response is the location of a Incident Report submission service. No standard mechanisms are currently defined for this type of service, therefore the The resourceInfo field in the response SHOULD be used to provide information on the provided Incident Report service. For example while the URI could point to a web-page carrying contacts information or a ticketing system for reporting CA-related incidents, the resourceInfo field could provide text carrying information that may be displayed to the user (e.g., a support phone number). This would allow support for a wide range of different devices and applications as long as they have the ability to display or read the content of the resourceInfo field to the user.
id-ad-prqp-caIncidentReport
OBJECT IDENTIFIER ::= {id-ad-prqp 90}
| TOC |
When an application wants to identify private resources, i.e. services that are not standardized in the PRQP standard definition, id-ad-prqp-private should be used as the base OID:
id-ad-prqp-private OBJECT IDENTIFIER ::= {id-ad-prqp 100}
The OIDs for a private resource can be identified as follows:
myPrivateResource OBJECT IDENTIFIER ::= {id-ad-prqp-private N}
| TOC |
IANA has assigned a value of TBD1 for the DHCP option code described in Section Appendix B.1.1 (PRQP Servers IPv4 Option for DHCPv4) of this document.
IANA has assigned a value of TBD2 for the DHCPv6 option code described in Section Appendix B.1.2 (PRQP Servers IPv6 Option for DHCPv6) of this document.
| TOC |
In this section we provide some considerations about the protocol design and its details.
| TOC |
An important design consideration is the complexity of messages. Some type
of services, e.g. delta CRLs, can be directly detected upon data
downloading. On the contrary if a client is looking for a specific
version of a protocol or data type, the definition of a fine-grained
query system would allow for data downloading only when it is actually
supported by the requesting client, thus reducing the server's load.
At present we think that keeping the protocol simple will encourage
its adoption in current environments because the flexibility introduced
by PRQP is a big enhancement over the current options.
Moreover, without requiring changes to the protocol, extensions could
be defined to provide more fine grained options.
Future versions of the protocol may implement extended request
and response types if required by applications.
| TOC |
The AIA and SIA extensions in certificates can be used to carry the
pointer to the RQA. If no RQA address is present in the certificate,
a client application could use a default configured URL.
Although this approach seems to contradict the criticism of Certificate
extensions use in Section 2.1.1 (Certificate Extensions), using only one extension
to locate the RQA would provide an easy way to distribute the RQA's URL.
The usage of PRQP will provide a gateway for all the other services
and data URLs.
| TOC |
The PRQP provides URLs for PKI resources. This means that it provides
locators to data and services, not the data per se. It still remains
the client's job to access the provided URLs to gather the needed data.
Both NONCEs and signatures are optional in order to provide flexibility
in how requests and responses are generated.
It is possible to provide pre-computed responses in case the NONCE is
not provided by the client. This allows the RQA to generate off-line
signatures for responses, an optimization used in OCSP.
Moreover if an authenticated secure channel is used at the transport level
between the client and the RQA (e.g. HTTPS or SFTP) signatures in requests
and responses can be safely omitted.
| TOC |
The time validity should reflect the frequency of updates in configured
URLs. An interesting aspect to be considered is how often would users
execute the protocol for a given set of data.
If the clients query the server often it could be a serious burden
on the server but, if executed rarely, clients would not be able to
discover changes in provided resources.
As described in more detail in Appendix A (Transport Protocol Specifications for PRQP Messages),
the adoption of a validity
time frame for responses can be used as a mean to balance the trade off
between this two aspects, but this is merely advisory
data for clients and thus not a guarantee against DoS attacks by clients.
| TOC |
Two different candidates have been considered. The first one is the
Extensible Markup Language (XML), while the second one is the
Distinguished Encoding Rules (DER).
The adoption of the Abstract Syntax Notation (ASN.1) to describe the
data structures allows a software developer to provide either DER or XML
based implementations of the protocol.
However we think that a DER based implementation of PRQP is the best
choice because of compatibility considerations with existing applications
and APIs. Moreover DER encoded messages are smaller in size then XML
encoded ones and almost all PKI aware applications already support it.
| TOC |
The authors would like to thank Stephen Kent for his insightful comments about PRQP and his help in writing this document.
| TOC |
| TOC |
| TOC |
| [I-D.nourse-scep] | Liu, X., “Cisco Systems' Simple Certificate Enrollment Protocol,” draft-nourse-scep-17 (work in progress), June 2008 (TXT). |
| [PEACH] | Pala, M. and S. Smith, “Peaches and Peers,” LNCS 5057, June 2008. |
| [RFC4523] | Zeilenga, K., “Lightweight Directory Access Protocol (LDAP) Schema Definitions for X.509 Certificates,” RFC 4523, June 2006 (TXT). |
| [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 (TXT). |
| [W3C.REC-xkms2-20050628] | Mysore, S. and P. Hallam-Baker, “XML Key Management Specification (XKMS 2.0),” World Wide Web Consortium Recommendation REC-xkms2-20050628, June 2005 (HTML). |
| [W3C.xkms] | Ford, W., Hallam-Baker, P., Fox, B., Dillaway, B., LaMacchia, B., Epstein, J., and J. Lapp, “XML Key Management Specification (XKMS),” W3C Note xkms, March 2001. |
| TOC |
| TOC |
This section describes the formatting needed in order to route PRQP request and response over HTTP.
| TOC |
HTTP based PRQP requests SHOULD use the POST method to submit their
requests. Where privacy is a requirement, PRQP transactions
exchanged using HTTP MAY be protected using either TLS/SSL or some
other lower layer protocol.
The required HTTP headers for the request are:
The Content-Type header SHOULD be set to "application/prqp-request". The Content-Transfer-Encoding SHOULD be set to "Binary", while the Content-Length SHOULD be set to the length (in bytes) of the body of the request. The body of the HTTP message MUST carry the binary value of the DER encoding of the PRQPRequest.
| TOC |
An HTTP-based PRQP response is composed of the appropriate HTTP
headers, followed by the binary value of the DER encoding of the
PRQPPResponse.
The required HTTP headers for the response are:
The Content-Type header SHOULD be set to "application/prqp-response". The Content-Transfer-Encoding SHOULD be set to "Binary", while the Content-Length SHOULD be set to the length (in bytes) of the body of the request. The body of the HTTP message MUST carry the binary value of the DER encoding of the PRQPResponse.
| TOC |
To minimize bandwidth usage, clients MUST locally cache authoritative
PRQP responses for the validity period of the request. To enable
proxy servers to be able to cache responses as well, additional HTTP
headers MAY be used in the response.
The PRQP responder MAY ease caching by setting the following headers:
In particular, the date field SHOULD carry the date at which the HTTP
response has been generated. The last-modified, instead, SHOULD bear the
date at which the response has been modified. This field SHOULD carry
the same date as the producedAt field of the PRQPResponse.
The expires field SHOULD carry the date till when the response is to be
considered valid. This field SHOULD carry the same date as in the
nextUpdate field of the PRQPResponse.
An example HTTP response would look like:
HTTP/1.0 200 OK
Content-Type: application/prqp-response
Content-Transfer-Encoding: Binary
Content-Length: 860
Date: Thu, 03 May 2007 04:43:43 GMT
Last-Modified: Thu, 03 May 2007 04:43:42 GMT
Expires: Thu, 04 May 2007 04:43:42 GMT
<...response data...>
PRQP clients SHOULD NOT included a no-cache header in PRQP request messages, unless the client encounters an expired response which may be a result of an intermediate proxy caching stale data.
| TOC |
PRQP offers a starting point for the development of a PKI Resource
Discovery Architecture where different RQAs cooperate to access data
not locally available.
One technology that already provides good results in data sharing is
Peer-to-Peer (P2P) networking.
Signed PRQP requests and responses can be routed also on existing P2P
networks or a PRQP-specific network can be setup to provide a World
Wide PKI Resources Discovery Architecture (PRDA), the definition of
which is out of the scope of this document.
An example of such an architecture is PEACH [PEACH] (Pala, M. and S. Smith, “Peaches and Peers,” June 2008.)
| TOC |
| TOC |
This section describes the needed steps to distribute RQAs addresses by using DHCP extensions. In particular we define the DHCP option needed to identify an RQA server and we suggest options parsing for DHCP server and clients.
| TOC |
We define a prqp-servers option for DHCPv4 that specifies a list of Resource Query Authorities (PRQP servers) available to the client. The RQA address MUST be expressed as IPv4 addresses. Servers SHOULD be listed in order of preference and clients MUST treat the list of PRQP servers as an ordered list.
The format for the prqp-servers option is as shown below:
Code Len Address 1 Address 2
+------+-----+-----+-----+-----+-----+-----+--
| TBD1 | n | a1 | a2 | a3 | a4 | a1 | ...
+------+-----+-----+-----+-----+-----+-----+--
The code for the pki resource query authority list option is TBD1. The minimum length for this option is 1 octets.
| TOC |
We define a prqp-servers option for DHCPv6 that specifies a list of Resource Query Authorities (PRQP servers) available to the client. The RQA address MUST be expressed as IPv6 addresses (128-bit). Servers SHOULD be listed in order of preference and clients MUST treat the list of PRQP servers as an ordered list.
The format for the prqp-servers option is as follows:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OPTION_RQA_LIST | option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| PRQP server (IPv6 address) |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| PRQP server (IPv6 address) |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
option-code: OPTION_PRQP_SERVERS (TBD2)
option-len: Length of the 'PRQP servers' field in octets; it must
be a multiple of 16
PRQP server: IPv6 address of Resource Query Authority (PRQP) Server
The RQA address(es) specified in the 'PRQP server' MUST be encoded as IPv6 addresses. The code for the prqp-servers option for IPv6 is TBD2. The minimum length for this option is 1 octets.
| TOC |
As reported in [I‑D.ietf‑dhc‑option‑guidelines] (Hankins, D., “Guidelines for Creating New DHCP Options,” October 2008.), one of the most deployed DHCP package is the ISC DHCP, mostly written by Ted Lemon in cooperation with Nominum, Inc. and now maintained by Internet Systems Consortium, Inc. ("ISC"). In order to provide developers and system administrators with deployment guidelines, we provide example configurations for both the server and the client.
Below is a sample configuration for the pki resource query authorities option that can be added both the dhclient.conf (on clients) and dhcpd.conf (on servers) for IPv4:
option prqp-servers code TBD1 = array of ip-address;
If your environment supports IPv6, you should provide the option as a list of IPv6 addresses as follows:
option prqp-servers code TBD2 = array of ipv6-address;
In addition to this, in order for the server to pass on the configuration to the clients, the following example configuration options could be used in the server's configuration file (typically /etc/dhcpd.conf):
...
subnet XXX.XXX.XXX.XXX netmask YYY.YYY.YYY.YYY {
...
option prqp-servers rqa.openca.org,
rqa3.dartmouth.edu,
rqa5.mydomain.org;
}
...
| TOC |
In order to provide applications deriving their configuration parameters from values provided by this DHCP option, the dhcp client needs to format the on-the-wire bits in a more digestible one. In particular for the "prqp-servers" option, a configuration file should be created as:
/etc/pki.conf
where the list of addresses can be stored. An example of such a file is reported below:
queryauthority rqa.openca.org
queryauthority rqa3.dartmouth.edu
queryauthority 127.0.0.1
where each line has the format:
queryauthority <ADDRESS>
| TOC |
This section describes the needed steps to distribute RQAs addresses by using DNS SRV records. In particular we define the format to use for the SRV records. As an example we also provide a sample zone file.
| TOC |
The format for DNS SRV records MUST be compliant with [RFC2782] (Gulbrandsen, A., Vixie, P., and L. Esibov, “A DNS RR for specifying the location of services (DNS SRV),” February 2000.). In particular, in order to support PRQP, a DNS server MUST use the following:
_Service._Proto.Name TTL Class SRV Priority Weight Port Target
Where:
| TOC |
In this section we provide a sample zone file for the domain .openca.org. In this example we configure service records for three different RQAs.
$ORIGIN openca.org.
@ SOA server.openca.org. root.openca.org. (
1995032001 3600 3600 604800 86400 )
NS server.openca.org.
NS ns1.ip-provider.net.
NS ns2.ip-provider.net.
; first two rqa server lines, they have the same priority,
; but different weight
_rqa._tcp SRV 0 1 830 rqa.openca.org.
SRV 0 3 830 rqa2.openca.org.
; last chance - lower priority because it is a very slow box
SRV 10 0 830 rqa-slow.openca.org.
rqa A 129.170.214.89
rqa2 A 129.170.212.31
rqa-slow A 64.233.167.99
; NO other services are supported
*._tcp SRV 0 0 0 .
*._udp SRV 0 0 0 .
| TOC |
PRQP DEFINITIONS EXPLICIT TAGS ::=
BEGIN
-- EXPORTS ALL --
IMPORTS
-- Directory Authentication Framework (X.509)
Certificate, AlgorithmIdentifier
FROM AuthenticationFramework { joint-iso-itu-t ds(5)
module(1) authenticationFramework(7) 3 }
-- PKIX Certificate Extensions
AuthorityKeyIdentifier, SubjectKeyIdentifier, KeyIdentifier,
FROM PKIX1Implicit88 {iso(1) identified-organization(3)
dod(6) internet(1) security(5) mechanisms(5) pkix(7)
id-mod(0) id-pkix1-implicit-88(2)}
CertificateSerialNumber, Extensions, id-kp, id-ad-prqp
FROM PKIX1Explicit88 {iso(1) identified-organization(3)
dod(6) internet(1) security(5) mechanisms(5) pkix(7)
id-mod(0) id-pkix1-explicit-88(1)};
PRQPRequest ::= SEQUENCE {
requestData TBSReqData,
signature [0] EXPLICIT Signature OPTIONAL }
TBSReqData ::= SEQUENCE {
version INTEGER { v(1) },
nonce [0] INTEGER OPTIONAL,
-- very large number
producedAt GeneralizedTime,
-- time when the request has been generated
serviceToken ResourceRequestToken,
-- token identifying the requested service
extensions [1] IMPLICIT Extensions OPTIONAL }
ResourceRequestToken ::= SEQUENCE {
ca CertIdentifier,
servicesList [0] SET OF ResourceIdentifier OPTIONAL }
BasicCertIdentifier ::= SEQUENCE {
issuerNameHash OCTET STRING,
serialNumber CertificateSerialNumber }
ExtenderCertInfo ::= SEQUENCE {
certificateHash OCTET STRING,
subjectKeyHash OCTET STRING,
subjectKeyIdentifier [0] KeyIdentifier OPTIONAL,
issuerKeyIdentifier [1] KeyIdentifier OPTIONAL }
CertIdentifier ::= SEQUENCE {
hashAlgorithm AlgorithmIdentifier,
basicCertIdentifier BasicCertIdentifier,
extInfo [0] ExtendedCertInfo OPTIONAL,
caCertificate [1] Certificate OPTIONAL,
issuedCertificate [2] Certificate OPTIONAL }
ResourceIdentifier ::= SEQUENCE {
resourceId OBJECT IDENTIFIER,
version [0] INTEGER OPTIONAL
--- version of the protocol or data format (if applicable)
oid [1] OBJECT IDENTIFIER OPTIONAL,
--- object identifier associated with the URL
--- (if applicable) }
PRQPResponse ::= SEQUENCE {
respData TBSRespData,
signature [0] EXPLICIT Signature OPTIONAL }
TBSRespData ::= SEQUENCE {
version INTEGER { v(1)},
nonce INTEGER OPTIONAL,
-- as duplicated from the request
producedAt GeneralizedTime,
-- time when the response has been generated
nextUpdate [0] GeneralizedTime OPTIONAL,
-- time till when the response should be considered
-- valid
pkiStatus PKIStatusInfo,
-- status of the response
caCertId CertIdentifier,
-- identifier of the CA the targeted certificate is
-- issued from
responseToken SEQUENCE OF ResourceResponseToken
OPTIONAL,
-- token carrying information about
-- requested services
extensions [0] EXPLICIT Extensions OPTIONAL }
PKIStatusInfo ::= SEQUENCE {
status PKIStatus,
statusString [0] UTF8String OPTIONAL,
failInfo [1] PKIFailureInfo OPTIONAL,
referrals [2] EXPLICIT SEQUENCE OF IA5String
OPTIONAL }
PKIStatus ::= INTEGER {
ok (0),
-- when the PKIStatus contains the value zero one or
more responseToken is present
badRequest (1),
-- the request is badly formatted
caNotPresent (2),
-- the requested CA is not present
systemFailure (3)
-- a system failure has occourred }
Signature ::= SEQUENCE {
signatureAlgorithm AlgorithmIdentifier,
signature BIT STRING,
certs [0] EXPLICIT SEQUENCE OF Certificate
OPTIONAL }
ResourceResponseToken ::= SEQUENCE {
resourceId OBJECT IDENTIFIER,
--- resource identifier
resourceLocatorList [0] EXPLICIT SEQUENCE OF IA5String,
--- sequence of resource locators (URI)
version [1] INTEGER OPTIONAL,
--- version of the protocol or data format (if applicable)
oid [2] OBJECT IDENTIFIER OPTIONAL,
--- object identifier associated with the URL
--- (if applicable)
resourceInfo [3] UTF8Sting OPTIONAL,
--- additional service Info (eg. technical contacts) }
-- Object Identifiers
id-kp-PRQPSigning OBJECT IDENTIFIER ::= { id-kp 11 }
id-prqp OBJECT IDENTIFIER ::= { id-pkix 23 }
id-prqp-pta OBJECT IDENTIFIER ::= { id-prqp 1 }
id-ad-prqp OBJECT IDENTIFIER ::= {id-ad 12 }
id-ad-prqp-rqa OBJECT IDENTIFIER ::= {id-ad-prqp 0}
id-ad-prqp-ocsp OBJECT IDENTIFIER ::= {id-ad-prqp 1}
id-ad-prqp-subjectCert OBJECT IDENTIFIER ::= {id-ad-prqp 2}
id-ad-prqp-issuerCert OBJECT IDENTIFIER ::= {id-ad-prqp 3}
id-ad-prqp-timestamping OBJECT IDENTIFIER ::= {id-ad-prqp 4}
id-ad-prqp-scvp OBJECT IDENTIFIER ::= {id-ad-prqp 5}
id-ad-prqp-crlDistribution OBJECT IDENTIFIER ::= {id-ad-prqp 6}
id-ad-prqp-certRepository OBJECT IDENTIFIER ::= {id-ad-prqp 7}
id-ad-prqp-crlRepository OBJECT IDENTIFIER ::= {id-ad-prqp 8}
id-ad-prqp-crossCertRepository OBJECT IDENTIFIER ::= {id-ad-prqp 9}
id-ad-prqp-cmcGateway OBJECT IDENTIFIER ::= {id-ad-prqp 10}
id-ad-prqp-cmpGateway OBJECT IDENTIFIER ::= {id-ad-prqp 11}
id-ad-prqp-scepGateway OBJECT IDENTIFIER ::= {id-ad-prqp 12}
id-ad-prqp-htmlGateway OBJECT IDENTIFIER ::= {id-ad-prqp 13}
id-ad-prqp-xkmsGateway OBJECT IDENTIFIER ::= {id-ad-prqp 14}
id-ad-prqp-certPolicy OBJECT IDENTIFIER ::= {id-ad-prqp 20}
id-ad-prqp-certPracticesStatement OBJECT IDENTIFIER ::= {id-ad-prqp 21}
id-ad-prqp-endorsedTA OBJECT IDENTIFIER ::= {id-ad-prqp 22}
id-ad-prqp-loaPolicy OBJECT IDENTIFIER ::= {id-ad-prqp 25}
id-ad-prqp-certLOALevel OBJECT IDENTIFIER ::= {id-ad-prqp 26}
id-ad-prqp-htmlRequestCertificate OBJECT IDENTIFIER ::= {id-ad-prqp 30}
id-ad-prqp-htmlRevokeCertificate OBJECT IDENTIFIER ::= {id-ad-prqp 31}
id-ad-prqp-htmlRenewCertificate OBJECT IDENTIFIER ::= {id-ad-prqp 32}
id-ad-prqp-htmlSuspendCertificate OBJECT IDENTIFIER ::= {id-ad-prqp 33}
id-ad-prqp-htmlRecoveryCertificate OBJECT IDENTIFIER ::= {id-ad-prqp 34}
id-ad-prqp-gridAccreditationBody OBJECT IDENTIFIER ::= {id-ad-prqp 50}
id-ad-prqp-gridAccreditationPolicy OBJECT IDENTIFIER ::= {id-ad-prqp 51}
id-ad-prqp-gridAccreditationStatus OBJECT IDENTIFIER ::= {id-ad-prqp 52}
id-ad-prqp-gridDistributionUpdate OBJECT IDENTIFIER ::= {id-ad-prqp 53}
id-ad-prqp-gridAccreditedCACerts OBJECT IDENTIFIER ::= {id-ad-prqp 54}
id-ad-prqp-apexTampUpdate OBJECT IDENTIFIER ::= {id-ad-prqp 70}
id-ad-prqp-tampUpdate OBJECT IDENTIFIER ::= {id-ad-prqp 71}
id-ad-prqp-caIncidentReport OBJECT IDENTIFIER ::= {id-ad-prqp 90}
id-ad-prqp-private OBJECT IDENTIFIER ::= {id-ad-prqp 100}
| TOC |
| Massimiliano Pala | |
| Dartmouth College | |
| 6211 Sudikoff PKI/Trust Lab | |
| Hanover, NH 03755 | |
| US | |
| Email: | pala@cs.dartmouth.edu |
| URI: | http://www.openca.org |