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Keywords: cmc, suite b x.509 public key certificates
Internet Engineering Task Force (IETF) L. Zieglar
Request for Comments: 6403 NSA
Category: Informational S. Turner
ISSN: 2070-1721 IECA
M. Peck
November 2011
Suite B Profile of Certificate Management over CMS
Abstract
The United States government has published guidelines for "NSA
Suite B Cryptography", which defines cryptographic algorithm policy
for national security applications. This document specifies a
profile of the Certificate Management over CMS (CMC) protocol for
managing Suite B X.509 public key certificates. This profile is a
refinement of RFCs 5272, 5273, and 5274.
Status of This Memo
This document is not an Internet Standards Track specification; it is
published for informational purposes.
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Not all documents
approved by the IESG are 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/rfc6403.
Copyright Notice
Copyright (c) 2011 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
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RFC 6403 Suite B CMC Profile November 2011
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 Simplified BSD License.
1. Introduction
This document specifies a profile for using the Certificate
Management over CMS (CMC) protocol, defined in [RFC5272], [RFC5273],
and [RFC5274], and updated by [RFC6402], to manage X.509 public key
certificates compliant with the United States National Security
Agency's Suite B Cryptography as defined in the Suite B Certificate
and Certificate Revocation List (CRL) Profile [RFC5759]. This
document specifically focuses on defining CMC interactions for both
initial enrollment and rekey of Suite B public key certificates
between a client and a Certification Authority (CA). One or more
Registration Authorities (RAs) may act as intermediaries between the
client and the CA. This profile may be further tailored by specific
communities to meet their needs. Specific communities will also
define Certificate Policies that implementations need to comply with.
2. Terminology
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].
The terminology in [RFC5272] Section 2.1 applies to this profile.
3. Requirements and Assumptions
All key pairs are on either the curve P-256 or the curve P-384. FIPS
186-3 [DSS], Appendix B.4, provides useful guidance for elliptic
curve key pair generation that SHOULD be followed by systems that
conform to this document.
This document assumes that the required trust anchors have been
securely provisioned to the client and, when applicable, to any RAs.
All requirements in [RFC5272], [RFC5273], [RFC5274], and [RFC6402]
apply, except where overridden by this profile.
This profile was developed with the scenarios described in Appendix A
in mind. However, use of this profile is not limited to just those
scenarios.
The term "client" in this profile typically refers to an end-entity.
However, it may instead refer to a third party acting on the end-
entity's behalf. The client may or may not be the entity that
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actually generates the key pair, but it does perform the CMC protocol
interactions with the RA and/or CA. For example, the client may be a
token management system that communicates with a cryptographic token
through an out-of-band secure protocol.
This profile uses the term "rekey" in the same manner as does CMC
(defined in Section 2 of [RFC5272]). The profile makes no specific
statements about the ability to do "renewal" operations; however, the
statements applicable to rekey should be applied to renewal as well.
This profile may be used to manage RA and/or CA certificates. In
that case, the RA and/or CA whose certificate is being managed is
considered to be the end-entity.
This profile does not support key establishment certification
requests from cryptographic modules that cannot generate a one-time
signature with a key establishment key for proof-of-possession
purposes. In that case, a separate profile would be needed to define
the use of another proof-of-possession technique.
4. Client Requirements: Generating PKI Requests
This section specifies the conventions employed when a client
requests a certificate from a Public Key Infrastructure (PKI).
The Full PKI Request MUST be used; it MUST be encapsulated in a
SignedData; and the SignedData MUST be constructed as defined in
[RFC6318]. The PKIData content type complies with [RFC5272] with the
following additional requirements:
o controlSequence SHOULD be present, and it SHOULD include the
following CMC controls: Transaction ID and Sender Nonce. Other
CMC controls MAY be included. If the request is being
authenticated using a shared-secret, then the following
requirements in this paragraph apply: Identity Proof Version 2
control, as defined in [RFC5272], MUST be included; hashAlgId MUST
be id-sha256 or id-sha384 for P-256 certification requests, and
MUST be id-sha384 for P-384 certification requests (both algorithm
OIDs are defined in [RFC5754]); macAlgId MUST be HMAC-SHA256 when
the hashAlgId is id-sha256, and MUST be HMAC-SHA384 when the
hashAlgId is id-sha384 (both HMAC algorithms are defined in
[RFC4231]). If the subject included in the certification request
is NULL or otherwise does not uniquely identify the end-entity,
then the POP Link Random control MUST be included, and the POP
Link Witness Version 2 control MUST be included in the inner PKCS
#10 or Certificate Request Message Format (CRMF) request as
described in Sections 4.1 and 4.2.
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o reqSequence MUST be present. It MUST include at least one tcr
(see Section 4.1) or crm (see Section 4.2) TaggedRequest. Support
for the orm choice is OPTIONAL.
If the Full PKI Request contains a P-256 public key certification
request, then the SignedData encapsulating the Full PKI Request MUST
be generated using either SHA-256 and ECDSA on P-256 or using SHA-384
and ECDSA on P-384. If the Full PKI Request contains a P-384 public
key certification request, then the SignedData MUST be generated
using SHA-384 and ECDSA on P-384.
A Full PKI Request MUST be signed using the private key that
corresponds to the public key of an existing signature certificate
unless an appropriate signature certificate does not yet exist, such
as during initial enrollment.
If an appropriate signature certificate does not yet exist, and if a
Full PKI Request includes one or more certification requests and is
authenticated using a shared-secret (because no appropriate
certificate exists yet to authenticate the request), the Full PKI
Request MUST be signed using the private key corresponding to the
public key of one of the requested certificates. When necessary
(i.e., because there is no existing signature certificate and there
is no signature certification request included), a Full PKI Request
MAY be signed using a key pair intended for use in a key
establishment certificate. However, servers are not required to
allow this behavior.
4.1. Tagged Certification Request
The reqSequence tcr choice conveys PKCS #10 [RFC2986] syntax. The
CertificateRequest MUST comply with [RFC5272], Section 3.2.1.2.1,
with the following additional requirements:
o certificationRequestInfo:
* subjectPublicKeyInfo MUST be set as defined in Section 4.4 of
[RFC5759];
* attributes:
- The ExtensionReq attribute MUST be included with its
contents as follows:
o The Key Usage extension MUST be included, and it MUST be
set as defined in [RFC5759].
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o For rekey requests, the SubjectAltName extension MUST be
included and set equal to the SubjectAltName of the
certificate that is being used to sign the SignedData
encapsulating the request (i.e., not the certificate
being rekeyed) if the Subject field of the certificate
being used to generate the signature is NULL.
o Other extension requests MAY be included as desired.
- The ChangeSubjectName attribute, as defined in [RFC6402],
MUST be included if the Full PKI Request encapsulating this
Tagged Certification Request is being signed by a key for
which a certificate currently exists and the existing
certificate's Subject or SubjectAltName does not match the
desired Subject or SubjectAltName of this certification
request.
- The POP Link Witness Version 2 attribute MUST be included if
the request is being authenticated using a shared-secret and
the Subject in the certification request is NULL or
otherwise does not uniquely identify the end-entity. In the
POP Link Witness Version 2 attribute, keyGenAlgorithm MUST
be id-sha256 or id-sha384 for P-256 certification requests
and MUST be id-sha384 for P-384 certification requests, as
defined in [RFC5754]; macAlgorithm MUST be HMAC-SHA256 when
the keyGenAlgorithm is id-sha256 and MUST be HMAC-SHA384
when the keyGenAlgorithm is id-sha384, as defined in
[RFC4231].
* signatureAlgorithm MUST be ecdsa-with-sha256 for P-256
certification requests and MUST be ecdsa-with-sha384 for P-384
certification requests;
* signature MUST be generated using the private key corresponding
to the public key in the CertificationRequestInfo, for both
signature and key establishment certification requests. The
signature provides proof-of-possession of the private key to
the Certification Authority.
4.2. Certificate Request Message
The reqSequence crm choice conveys Certificate Request Message Format
(CRMF) [RFC4211] syntax. The CertReqMsg MUST comply with [RFC5272],
Section 3.2.1.2.2, with the following additional requirements:
o popo MUST be included using the signature (POPOSigningKey) proof-
of-possession choice and set as defined in [RFC4211], Section 4.1,
for both signature and key establishment certification requests.
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The POPOSigningKey poposkInput field MUST be omitted. The
POPOSigningKey algorithmIdentifier MUST be ecdsa-with-sha256 for
P-256 certification requests and MUST be ecdsa-with-sha384 for
P-384 certification requests. The signature MUST be generated
using the private key corresponding to the public key in the
CertTemplate.
The CertTemplate MUST comply with [RFC5272], Section 3.2.1.2.2, with
the following additional requirements:
o version MAY be included and, if included, it MUST be set to 2 as
defined in Section 4.3 of [RFC5759];
o publicKey MUST be set as defined in Section 4.4 of [RFC5759];
o extensions:
* The Key Usage extension MUST be included, and it MUST be set as
defined in [RFC5759].
* For rekey requests, the SubjectAltName extension MUST be
included and set equal to the SubjectAltName of the certificate
that is being used to sign the SignedData encapsulating the
request (i.e., not the certificate being rekeyed) if the
Subject field of the certificate being used to generate the
signature is NULL.
* Other extension requests MAY be included as desired.
o controls:
* The ChangeSubjectName attribute, as defined in [RFC6402], MUST
be included if the Full PKI Request encapsulating this Tagged
Certification Request is being signed by a key for which a
certificate currently exists and the existing certificate's
Subject or SubjectAltName does not match the desired Subject or
SubjectAltName of this certification request.
* The POP Link Witness Version 2 attribute MUST be included if
the request is being authenticated using a shared-secret, and
the Subject in the certification request is NULL or otherwise
does not uniquely identify the end-entity. In the POP Link
Witness Version 2 attribute, keyGenAlgorithm MUST be id-sha256
or id-sha384 for P-256 certification requests and MUST be
id-sha384 for P-384 certification requests; macAlgorithm MUST
be HMAC-SHA256 when keyGenAlgorithm is id-sha256 and MUST be
HMAC-SHA384 when keyGenAlgorithm is id-sha384.
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5. RA Requirements
This section addresses the optional case where one or more RAs act as
intermediaries between the client and CA as described in Section 7 of
[RFC5272]. In this section, the term "client" refers to the entity
from which the RA received the PKI Request. This section is only
applicable to RAs.
5.1. RA Processing of Requests
RAs conforming to this document MUST ensure that only the permitted
signature, hash, and MAC algorithms described throughout this profile
are used in requests; if they are not, the RA MUST reject those
requests. The RA SHOULD return a CMCFailInfo with the value of
badAlg [RFC5272].
When processing end-entity-generated SignedData objects, RAs MUST NOT
perform Cryptographic Message Syntax (CMS) Content Constraints (CCC)
certificate extension processing [RFC6010].
Other RA processing is as in [RFC5272].
5.2. RA-Generated PKI Requests
If the RA encapsulates the client-generated PKI Request in a new RA-
signed PKI Request, it MUST create a Full PKI Request encapsulated in
a SignedData, and the SignedData MUST be constructed as defined in
[RFC6318]. The PKIData content type complies with [RFC5272] with the
following additional requirements:
o controlSequence MUST be present. It MUST include the following
CMC controls: Transaction ID, Sender Nonce, and Batch Requests.
Other appropriate CMC controls MAY be included.
o cmsSequence MUST be present. It contains the original, unmodified
request(s) received from the client.
RA certificates are authorized to sign Full PKI Requests with an
Extended Key Usage (EKU) and/or with the CCC certificate extension
[RFC6010]. Certificates may also be authorized through local
configuration. Authorized certificates SHOULD include the
id-kp-cmcRA EKU from [RFC6402]. Authorized certificates MAY also
include the CCC certificate extension [RFC6010], or the authorized
certificate MAY just include the CCC certificate extension. If the
RA is authorized via the CCC extension, then the CCC extension MUST
include the object identifier for the PKIData content type. CCC
SHOULD be included if constraints are to be placed on the content
types generated.
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If the RA-signed PKI Request contains a certification request for a
P-256 public key, then the SignedData MUST be generated using either
SHA-256 and ECDSA on P-256 or SHA-384 and ECDSA on P-384. If the
request contains a certification request for a P-384 public key, then
the SignedData MUST be generated using SHA-384 and ECDSA on P-384.
If the RA-signed PKI Request contains requests for certificates on
the P-256 and P-384 curve, then the SignedData MUST be generated
using SHA-384 and ECDSA on P-384. If the Full PKI Response is a
successful response to a PKI Request that only contained a Get
Certificate or Get CRL control, then the SignedData MUST be signed by
either SHA-256 and ECDSA on P-256 or SHA-384 and ECDSA on P-384, the
algorithm used in the response MUST match the algorithm used in the
request.
5.3. RA-Generated Errors
RA certificates authorized with the CCC certificate extension
[RFC6010] MUST include the object identifier for the PKIResponse
content type to authorize them to generate responses.
6. CA Requirements
This section specifies the requirements for CAs that receive PKI
Requests and that generate PKI Responses.
6.1. CA Processing of PKI Requests
CAs conforming to this document MUST ensure that only the permitted
signature, hash, and MAC algorithms described throughout this profile
are used in requests; if they are not, the CA MUST reject those
requests. The CA SHOULD return a CMCStatusInfoV2 control with
CMCStatus of failed and a CMCFailInfo with the value of badAlg
[RFC5272].
For requests involving an RA, the CA MUST verify the RA's
authorization. The following certificate fields MUST NOT be
modifiable using the Modify Certification Request control: publicKey
and the key usage extension. The request MUST be rejected if an
attempt to modify those certification request fields is present. The
CA SHOULD return a CMCStatusInfoV2 control with CMCStatus of failed
and a CMCFailInfo with a value of badRequest.
When processing end-entity-generated SignedData objects, CAs MUST NOT
perform CCC certificate extension processing [RFC6010].
If the client-generated PKI Request includes a ChangeSubjectName
attribute either in the CertRequest controls field for a CRMF request
or in the tcr attributes field for a PKCS#10 request, then the CA
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MUST ensure that name change is authorized. The mechanism for
ensuring that the name change is authorized is out of scope. If the
CA performs this check, and the name change is not authorized, then
the CA MUST reject the PKI Request. The CA SHOULD return a
CMCStatusInfoV2 control with CMCStatus of failed.
Other processing of PKIRequests is as in [RFC5272].
6.2. CA-Generated PKI Responses
If a Full PKI Response is returned, it MUST be encapsulated in a
SignedData, and the SignedData MUST be constructed as defined in
[RFC6318].
If the PKI Response is in response to an RA-encapsulated PKI Request,
then the above PKI Response is encapsulated in another CA-generated
PKI Response. That PKI Response MUST be encapsulated in a SignedData
and the SignedData MUST be constructed as defined in [RFC6318]. The
above PKI Response is placed in the encapsulating PKI Response
cmsSequence field. The other fields are as above with the addition
of the batch response control in controlSequence. The following
illustrates a successful CA response to an RA-encapsulated PKI
Request, both of which include Transaction IDs and Nonces:
SignedData (applied by the CA)
PKIData
controlSequence (Transaction ID, Sender Nonce, Recipient
Nonce, Batch Response)
cmsSequence
SignedData (applied by CA and includes returned
certificates)
PKIData
controlSequence (Transaction ID, Sender Nonce,
Recipient Nonce)
The same private key used to sign certificates MUST NOT be used to
sign Full PKI Response messages. Instead, a separate certificate
authorized to sign CMC responses MUST be used. Certificates are
authorized to sign Full PKI Responses with an EKU and/or with the CCC
certificate extension [RFC6010]. Certificates may also be authorized
through local configuration. Authorized certificates SHOULD include
the id-kp-cmcCA EKU from [RFC6402]. Authorized certificates MAY also
include the CCC certificate extension [RFC6010], or the authorized
certificate MAY just include the CCC certificate extension. If the
CA is authorized via the CCC extension, then the CCC extension MUST
include the object identifier for the PKIResponse content type. CCC
SHOULD be included if constraints are to be placed on the content
types generated.
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The signature on the SignedData MUST be generated using either ECDSA
P-256 on SHA-256 or ECDSA P-384 on SHA-384. If the Full PKI Response
is a successful response to a P-256 public key certification request,
then the SignedData MUST be generated using either SHA-256 and ECDSA
on P-256 or SHA-384 and ECDSA on P-384. If the Full PKI Response is
a successful response to a P-384 public key certification request,
then the SignedData MUST be generated using SHA-384 and ECDSA on
P-384. If the Full PKI Response is a successful response to
certification requests on both the P-256 and P-356 curves, then the
SignedData MUST be generated using SHA-384 and ECDSA on P-384. If
the Full PKI Response is an unsuccessful response to a PKI Request,
then the SignedData MUST be signed by either SHA-256 and ECDSA on
P-256 or SHA-384 and ECDSA on P-384, the algorithm used in the
response MUST match the algorithm used in the request. If the Full
PKI Response is an unsuccessful response to certification requests on
both the P-256 and P-356 curves, then the SignedData MUST be
generated using SHA-384 and ECDSA on P-384. If the Full PKI Response
is a successful response to a PKI Request that only contained a Get
Certificate or Get CRL control, then the SignedData MUST be signed by
either SHA-256 and ECDSA on P-256 or SHA-384 and ECDSA on P-384, the
algorithm used in the response MUST match the algorithm used in the
request.
If the PKI Response is in response to an RA-encapsulated PKI Request,
the signature algorithm for each SignedData is selected
independently.
7. Client Requirements: Processing PKI Responses
Clients conforming to this document MUST ensure that only the
permitted signature, hash, and MAC algorithms described throughout
this profile are used in responses; if they are not, the client MUST
reject those responses.
Clients MUST authenticate all Full PKI Responses. This includes
verifying that the PKI Response is signed by an authorized CA or RA
whose certificate validates back to a trust anchor. The authorized
CA certificate MUST include the id-kp-cmcCA EKU and/or include a CCC
extension that includes the object identifier for the PKIResponse
content type. Or, the CA is determined to be authorized to sign
responses through an implementation-specific mechanism. The PKI
Response can be signed by an RA if it is an error message, if it is a
response to a Get Certificate or Get CRL request, or if the PKI
Response contains an inner PKI Response signed by a CA. In the last
case, each layer of PKI Response MUST still contain an authorized,
valid signature signed by an entity with a valid certificate that
verifies back to an acceptable trust anchor. The authorized RA
certificate MUST include the id-kp-cmcRA EKU and/or include a CCC
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extension that includes the object identifier for the PKIResponse
content type. Or, the RA is determined to be authorized to sign
responses through an implementation-specific mechanism.
When a newly issued certificate is included in the PKI Response, the
client MUST verify that the newly issued certificate's public key
matches the public key that the client requested. The client MUST
also ensure that the certificate's signature is valid and that the
signature validates back to an acceptable trust anchor.
Clients MUST reject PKI Responses that do not pass these tests.
Local policy will determine whether the client returns a Full PKI
Response with an Extended CMC Status Info control with CMCStatus set
to failed to a user console, error log, or the server.
If the Full PKI Response contains an Extended Status Info with a
CMCStatus set to failed, then local policy will determine whether the
client resends a duplicate certification request back to the server
or an error state is returned to a console or error log.
8. Shared-Secrets
When the Identity Proof V2 and POP Link Witness V2 controls are used,
the shared-secret MUST be randomly generated and securely
distributed. The shared-secret MUST provide at least 128 bits of
strength for P-256 certification requests and at least 192 bits of
strength for P-384 certification requests.
9. Security Considerations
Protocol security considerations are found in [RFC2986], [RFC4211],
[RFC6318], [RFC5272], [RFC5273], [RFC5274], [RFC5759], and [RFC6402].
When CCC is used to authorize RA and CA certificates, then the
security considerations in [RFC6010] also apply. Algorithm security
considerations are found in [RFC6318].
Compliant with NIST Special Publication 800-57 [SP80057], this
profile defines proof-of-possession of a key establishment private
key by performing a digital signature. Except for one-time proof-of-
possession, a single key pair MUST NOT be used for both signature and
key establishment.
This specification requires implementations to generate key pairs and
other random values. The use of inadequate pseudo-random number
generators (PRNGs) can result in little or no security. The
generation of quality random numbers is difficult. NIST Special
Publication 800-90 [SP80090], FIPS 186-3 [DSS], and [RFC4086] offer
random number generation guidance.
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When RAs are used, the list of authorized RAs must be securely
distributed out-of-band to CAs.
Presence of the POP Link Witness Version 2 and POP Link Random
attributes protects against substitution attacks.
The Certificate Policy for a particular environment will specify
whether expired certificates can be used to sign certification
requests.
10. Acknowledgments
Michael Peck wishes to acknowledge that he was employed at the
National Security Agency during much of the work on this document.
11. References
11.1. Normative References
[DSS] National Institute of Standards and Technology (NIST),
FIPS 186-3: Digital Signature Standard (DSS), June 2009.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2986] Nystrom, M. and B. Kaliski, "PKCS #10: Certification
Request Syntax Specification Version 1.7", RFC 2986,
November 2000.
[RFC4086] Eastlake 3rd, D., Schiller, J., and S. Crocker,
"Randomness Requirements for Security", BCP 106, RFC 4086,
June 2005.
[RFC4211] Schaad, J., "Internet X.509 Public Key Infrastructure
Certificate Request Message Format (CRMF)", RFC 4211,
September 2005.
[RFC4231] Nystrom, M., "Identifiers and Test Vectors for HMAC-
SHA-224, HMAC-SHA-256, HMAC-SHA-384, and HMAC-SHA-512",
RFC 4231, December 2005.
[RFC5272] Schaad, J. and M. Myers, "Certificate Management over CMS
(CMC)", RFC 5272, June 2008.
[RFC5273] Schaad, J. and M. Myers, "Certificate Management over CMS
(CMC): Transport Protocols", RFC 5273, June 2008.
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RFC 6403 Suite B CMC Profile November 2011
[RFC5274] Schaad, J. and M. Myers, "Certificate Management Messages
over CMS (CMC): Compliance Requirements", RFC 5274, June
2008.
[RFC5754] Turner, S., "Using SHA2 Algorithms with Cryptographic
Message Syntax", RFC 5754, January 2010.
[RFC5759] Solinas, J. and L. Zieglar, "Suite B Certificate and
Certificate Revocation List (CRL) Profile", RFC 5759,
January 2010.
[RFC6010] Housley, R., Ashmore, S., and C. Wallace, "Cryptographic
Message Syntax (CMS) Content Constraints Extension", RFC
6010, September 2010.
[RFC6318] Housley, R. and J. Solinas, "Suite B in
Secure/Multipurpose Internet Mail Extensions (S/MIME)",
RFC 6318, June 2011.
[RFC6402] Schaad, J., "Certificate Management over CMS (CMC)
Updates", RFC 6402, November 2011.
11.2. Informative References
[SP80057] National Institute of Standards and Technology (NIST),
Special Publication 800-57 Part 1: Recommendation for Key
Management, March 2007.
[SP80090] National Institute of Standards and Technology (NIST),
Special Publication 800-90: Recommendation for Random
Number Generation Using Deterministic Random Number Bits
Generators (Revised), March 2007.
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Appendix A. Scenarios
This section illustrates several potential certificate enrollment and
rekey scenarios supported by this profile. This section does not
intend to place any limits or restrictions on the use of CMC.
A.1. Initial Enrollment
This section describes three scenarios for authenticating initial
enrollment requests:
1. Previously installed signature certificate (e.g., Manufacturer
Installed Certificate);
2. Shared-secret distributed securely out-of-band;
3. RA authentication.
A.1.1. Previously Installed Signature Certificate
In this scenario, the end-entity has had a signature certificate
installed by the cryptographic module manufacturer. As the end-
entity already has a signature certificate, it can be used to
authenticate a request for a new certificate. The end-entity signs
the Full PKI Request with the private key that corresponds to the
subject public key of a previously installed signature certificate.
The CA will recognize the authorization of the previously installed
certificate and issue an appropriate certificate to the end-entity.
A.1.2. Shared-Secret Distributed Securely Out-of-Band
In this scenario, the CA distributes a shared-secret out-of-band to
the end-entity that the end-entity uses to authenticate its
certification request. The end-entity signs the Full PKI Request
with the private key for which the certification is being requested.
The end-entity includes the Identity Proof Version 2 control to
authenticate the request using the shared-secret. The CA uses either
the Identification control or the Subject in the end-entity's
enclosed PKCS #10 or CRMF certification request message to identify
the request. The end-entity performs either the POP Link Witness
Version 2 mechanism as described in [RFC5272], Section 6.3.1.1, or
the Shared-Subject/Subject Distinguished Name (DN) linking mechanism
as described in [RFC5272], Section 6.3.2. The Subject in the
enclosed PKCS #10 or CRMF certification request does not necessarily
match the issued certificate, as it may be used just to help identify
the request (and corresponding shared-secret) to the CA.
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A.1.3. RA Authentication
In this scenario, the end-entity does not automatically authenticate
its enrollment request to the CA, either because the end-entity has
nothing to authenticate the request with or because organizational
policy requires RA involvement. The end-entity creates a Full PKI
Request and sends it to an RA. The RA verifies the authenticity of
the request, then, if approved, encapsulates and signs the request as
described in Section 5.2, forwarding the new request on to the CA.
The Subject in the PKCS #10 or CRMF certification request is not
required to match the issued certificate, it may be used just to help
identify the request to the RA and/or CA.
A.2. Rekey
There are two scenarios to support the rekey of certificates that are
already enrolled. One addresses the rekey of signature certificates
and the other addresses the rekey of key establishment certificates.
Typically, organizational policy will require certificates to be
currently valid to be rekeyed, and it may require initial enrollment
to be repeated when rekey is not possible. However, some
organizational policies might allow a grace period during which an
expired certificate could be used to rekey.
A.2.1. Rekey of Signature Certificates
When a signature certificate is rekeyed, the PKCS #10 or CRMF
certification request message enclosed in the Full PKI Request will
include the same Subject as the current signature certificate. The
Full PKI Request will be signed by the current private key
corresponding to the current signature certificate.
A.2.2. Rekey of Key Establishment Certificates
When a key establishment certificate is rekeyed, the Full PKI Request
will generally be signed by the current private key corresponding to
the current signature certificate. If there is no current signature
certificate, one of the initial enrollment options in Appendix A.1
may be used.
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Authors' Addresses
Lydia Zieglar
National Information Assurance Research Laboratory
National Security Agency
EMail: llziegl@tycho.ncsc.mil
Sean Turner
IECA, Inc.
3057 Nutley Street, Suite 106
Fairfax, VA 22031
USA
EMail: turners@ieca.com
Michael Peck
EMail: mpeck@alumni.virginia.edu
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