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rfc:rfc4809

Network Working Group C. Bonatti, Ed. Request for Comments: 4809 S. Turner, Ed. Category: Informational IECA

                                                      G. Lebovitz, Ed.
                                                               Juniper
                                                         February 2007
     Requirements for an IPsec Certificate Management Profile

Status of This Memo

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

Copyright Notice

 Copyright (C) The IETF Trust (2007).

Abstract

 This informational document describes and identifies the requirements
 for transactions to handle Public Key Certificate (PKC) lifecycle
 transactions between Internet Protocol Security (IPsec) Virtual
 Private Network (VPN) Systems using Internet Key Exchange (IKE)
 (versions 1 and 2) and Public Key Infrastructure (PKI) Systems.
 These requirements are designed to meet the needs of enterprise-scale
 IPsec VPN deployments.  It is intended that a standards track profile
 of a management protocol will be created to address many of these
 requirements.

Bonatti, et al. Informational [Page 1] RFC 4809 Reqs for IPsec Certificate Mgmt Profile February 2007

Table of Contents

 1. Introduction ....................................................4
    1.1. Scope ......................................................5
    1.2. Non-Goals ..................................................6
    1.3. Definitions ................................................6
    1.4. Requirements Terminology ...................................8
 2. Architecture ....................................................9
    2.1. VPN System .................................................9
         2.1.1. IPsec Peer(s) .......................................9
         2.1.2. VPN Administration Function (Admin) .................9
    2.2. PKI System ................................................10
    2.3. VPN-PKI Interaction .......................................11
 3. Requirements ...................................................13
    3.1. General Requirements ......................................13
         3.1.1. One Protocol .......................................13
         3.1.2. Secure Transactions ................................13
         3.1.3. Admin Availability .................................13
         3.1.4. PKI Availability ...................................14
         3.1.5. End-User Transparency ..............................14
         3.1.6. PKC Profile for PKI Interaction ....................14
                3.1.6.1. Identity ..................................15
                3.1.6.2. Key Usage .................................15
                3.1.6.3. Extended Key Usage ........................15
                3.1.6.4. Revocation Information Location ...........15
         3.1.7. Error Handling .....................................15
    3.2. Authorization .............................................15
         3.2.1. One Protocol .......................................15
         3.2.2. Bulk Authorization .................................16
         3.2.3. Authorization Scenario .............................16
         3.2.4. Authorization Request ..............................17
                3.2.4.1. Specifying Fields within the PKC ..........17
                3.2.4.2. Authorizations for Rekey, Renewal,
                         and Update ................................18
                3.2.4.3. Other Authorization Elements ..............18
                3.2.4.4. Cancel Capability .........................19
         3.2.5. Authorization Response .............................19
                3.2.5.1. Error Handling for Authorization ..........20
    3.3. Generation ................................................20
         3.3.1. Generation Method 1: IPsec Peer Generates Key Pair,
                Constructs PKC Request, and Signs PKC Request ......21
         3.3.2. Generation Method 2: IPsec Peer Generates Key Pair,
                Admin Constructs PKS Request, Admin Signs PKC
                Request ............................................22
         3.3.3. Generation Method 3: Admin Generates Key Pair,
                Constructs PKC Request, and Signs PKC Request ......23
         3.3.4. Method 4: PKI Generates Key Pair ...................24
         3.3.5. Error Handling for Generation ......................25

Bonatti, et al. Informational [Page 2] RFC 4809 Reqs for IPsec Certificate Mgmt Profile February 2007

    3.4. Enrollment ................................................25
         3.4.1. One Protocol .......................................25
         3.4.2. On-line Protocol ...................................25
         3.4.3. Single Connection with Immediate Response ..........25
         3.4.4. Manual Approval Option .............................25
         3.4.5. Enrollment Method 1: Peer Enrolls to PKI Directly ..26
         3.4.6. Enrollment Method 2a: Peer Enrolls through Admin ...27
         3.4.7. Enrollment Method 2b: Peer Enrolls through Admin ...28
         3.4.8. Enrollment Method 3a: Admin Authorizes and
                Enrolls Directly to PKI ............................30
         3.4.9. Enrollment Method 3b: Admin Requests and PKI
                Generates and Sends PKC ............................31
         3.4.10. Confirmation Handshake ............................32
         3.4.11. Error Handling for Enrollment .....................33
    3.5. Lifecycle .................................................34
         3.5.1. One Protocol .......................................34
         3.5.2. PKC Rekeys, Renewals, and Updates ..................35
                3.5.2.1. Rekey Request .............................36
                3.5.2.2. Renew Request .............................36
                3.5.2.3. Update Request ............................37
                3.5.2.4. Error Handling for Rekey, Renewal,
                         and Update ................................38
                3.5.2.5. Confirmation Handshakes ...................38
         3.5.3. Revocation .........................................38
    3.6. Repositories ..............................................39
         3.6.1. Lookups ............................................39
         3.6.2. Error Handling for Repository Lookups ..............40
    3.7. Trust .....................................................40
         3.7.1. Trust Anchor PKC Acquisition .......................40
         3.7.2. Certification Path Validation ......................41
         3.7.3. Revocation Checking and Status Information .........41
         3.7.4. Error Handling in Revocation Checking and
                Certificate Path Validation ........................42
 4. Security Considerations ........................................42
 5. References .....................................................43
    5.1. Normative References ......................................43
    5.2. Informative References ....................................43
 6. Acknowledgements ...............................................43

Bonatti, et al. Informational [Page 3] RFC 4809 Reqs for IPsec Certificate Mgmt Profile February 2007

1. Introduction

 This document describes and identifies the requirements for
 transactions to handle PKC lifecycle transactions between [IPsec] VPN
 Systems using IKE ([IKEv1] and [IKEv2]) and PKI Systems.  This
 document contains requirements for a transaction-based approach.
 Other models are conceivable, for example, a directory-centric
 approach, but their requirements are beyond the scope of this
 document.
 This document enumerates requirements for Public Key Certificate
 (PKC) lifecycle transactions between different VPN System and PKI
 System products in order to better enable large scale, PKI-enabled
 IPsec deployments with a common set of transactions.  Requirements
 for both the IPsec and the PKI products are discussed.  The
 requirements are carefully designed to achieve security without
 compromising ease of management and deployment, even where the
 deployment involves tens of thousands of IPsec users and devices.
 The requirements address transactions for the entire PKC lifecycle
 for PKI-enabled VPN System: authorization (of PKC issuance),
 generation (public-private key pair and PKC request), enrollment (PKC
 request, PKC response, and confirmation), maintenance (rekey, renew,
 update, revoke, and confirm), and repository lookups.  These
 transactions enable a VPN Operator to:
  1. Use a VPN Administration function (Admin), which is introduced in

this document, to manage PKC authorization and possibly act as

     the sole interface for the VPN System and the PKI System.
  1. Authorize individual or batches of PKC issuances based on a pre-

agreed template (i.e., both types of authorization requests refer

     to the pre-agreed template).  These authorizations can occur
     either prior to the enrollment or in the same transaction as the
     enrollment.
  1. Provision PKI-based user or machine identity to IPsec Peers, on a

large scale.

  1. Set the corresponding gateway or client authorization policy for

remote access and site-to-site connections.

  1. Establish policies for automatic PKC rekeys, renewals, and

updates.

  1. Ensure timely revocation information is available for PKCs used

in IKE exchanges.

Bonatti, et al. Informational [Page 4] RFC 4809 Reqs for IPsec Certificate Mgmt Profile February 2007

 These requirements are intended to be used to profile a certificate
 management protocol that the VPN System will use to communicate with
 the PKI System.  Note that this profile will be in another document.
 The certificate management profile will also clarify and constrain
 existing PKIX (PKI for X.509 Certificates) and IPsec standards to
 limit the complexity of deployment.  Some requirements may require
 either a new protocol, or changes or extensions to an existing
 protocol.
 The desired outcome of the requirements and profile documents is that
 both IPsec and PKI vendors create interoperable products to enable
 large-scale IPsec System deployments, and do so as quickly as
 possible.  For example, a VPN Operator should be able to use any
 conforming IPsec implementation (VPN Administration or IPsec Peer) of
 the certificate management profile with any conforming PKI vendor's
 implementation to perform the VPN rollout and management.

1.1. Scope

 The document addresses requirements on transactions between the VPN
 Systems and the PKI Systems and between the VPN Administration and
 IPsec Peers.  The requirements strive to meet eighty percent of the
 market needs for large-scale deployments (i.e., VPNs including
 hundreds or thousands of managed VPN gateways or VPN remote access
 clients).  Environments will understandably exist in which large-
 scale deployment tools are desired, but local security policy
 stringency will not allow for the use of such commercial tools.  The
 solution will possibly miss the needs of the highest ten percent of
 stringency and the lowest ten percent of convenience requirements.
 Use cases will be considered or rejected based upon this eighty
 percent rule.  The needs of small deployments are a stated non-goal;
 however, service providers employing the scoped solution and applying
 it to many smaller deployments in aggregate may address them.
 Gateway-to-gateway access and end-user remote access (to a gateway)
 are both covered.  End-to-end communications are not necessarily
 excluded, but are intentionally not a focus.
 Only VPN-PKI transactions that ease and enable scalable PKI-enabled
 IPsec deployments are addressed.

Bonatti, et al. Informational [Page 5] RFC 4809 Reqs for IPsec Certificate Mgmt Profile February 2007

1.2. Non-Goals

 The scenario for PKC cross-certification will not be addressed.
 The protocol specification for the VPN-PKI interactions will not be
 addressed.
 The protocol specification for the VPN Administrator to Peer
 transactions will not be addressed.  These interactions are
 considered vendor proprietary.  These interactions may be
 standardized later to enable interoperability between VPN
 Administration function stations and IPsec Peers from different
 vendors, but are far beyond the scope of this current effort, and
 will be described as opaque transactions in this document.
 The protocol specification for Registration Authority - Certificate
 Authority (RA-CA), CA-Repository, and RA-Repository interactions will
 not be addressed.

1.3. Definitions

 VPN System
 The VPN System is comprised of the VPN Administration function
 (defined below), the IPsec Peers, and the communication mechanism
 between the VPN Administration and the IPsec Peers.  VPN System is
 defined in more detail in Section 2.1.
 PKI System
 The PKI System, or simply PKI, is the set of functions needed to
 authorize, issue, and manage PKCs.  PKI System is defined in more
 detail in Section 2.2.
 (VPN) Operator
 The Operator is the person or group of people that define security
 policy and configure the VPN System to enforce that policy, with the
 VPN Administration function.
 IPsec Peer (Gateway or Client)
 For the purposes of this document, an IPsec Peer, or simply "Peer",
 is any VPN System component that communicates IKE and IPsec to
 another Peer in order to create an IPsec Security Association for
 communications.  It can be either a traditional security gateway
 (with two network interfaces, one for the protected network and one
 for the unprotected network) or an IPsec client (with a single
 network interface).  In both cases, the Peer can pass traffic with no
 IPsec protection, and can add IPsec protection to chosen traffic
 streams.  See Section 2.1.1 for more details.

Bonatti, et al. Informational [Page 6] RFC 4809 Reqs for IPsec Certificate Mgmt Profile February 2007

 (VPN) Admin
 The Admin is the VPN System function that interacts with the PKI
 System to establish PKC provisioning for the VPN connections.  See
 Section 2.1.2 for more details.
 End Entity
 An end entity is the entity or subject that is identified in a PKC.
 The end entity is the one entity that will finally use a private key
 associated with a PKC to digitally sign data.  In this document, an
 IPsec Peer is certainly an end entity, but the VPN Admin can also
 constitute an end entity.  Note that end entities can have different
 PKCs for different purposes (e.g., signature vs. key exchange,
 Admin-functions vs. Peer-functions).
 PKC Rekey
 The routine procedure for replacement of a PKC with a new PKC with a
 new public key for the same subject name.  A rekey process can rely
 on the existing key pair to bootstrap authentication for the new
 enrollment.
 PKC Renewal
 The acquisition of a new PKC with the same public key due to the
 expiration of an existing PKC.  Renewal occurs prior to the
 expiration of the existing PKC to avoid any connection outages.  A
 renewal process can rely on the existing key pair to bootstrap
 authentication for the new enrollment.
 PKC Update
 A special case of a renewal-like occurrence where a PKC needs to be
 changed prior to expiration due to some change in its subject's
 information.  Examples might include change in the address, telephone
 number, or name change due to marriage of the end entity.  An update
 process can rely on the existing key pair to bootstrap authentication
 for the new enrollment.
 Registration Authority (RA)
 An optional entity in a PKI System given responsibility for
 performing some of the administrative tasks necessary in the
 registration of end entities, such as confirming the subject's
 identity and verifying that the subject has possession of the private
 key associated with the public key requested for a PKC.
 Certificate Authority (CA)
 An authority in a PKI System that is trusted by one or more users to
 create and sign PKCs.  It is important to note that the CA is
 responsible for the PKCs during their whole lifetime, not just for
 issuing them.

Bonatti, et al. Informational [Page 7] RFC 4809 Reqs for IPsec Certificate Mgmt Profile February 2007

 Repository
 An Internet-accessible server in a PKI System that stores and makes
 available for retrieval PKCs and Certificate Revocation Lists (CRLs).
 Root CA/Trust Anchor
 A CA that is directly trusted by an end entity; that is, securely
 acquiring the value of a Root CA public key requires some out-of-band
 step(s).  This term is not meant to imply that a Root CA is
 necessarily at the top of any hierarchy, simply that the CA in
 question is trusted directly.
 Certificate Revocation List (CRL)
 A CRL is a CA-signed, timestamped list identifying revoked PKCs and
 made freely available in a repository.  Peers retrieve the CRL to
 verify that a PKC being presented to them as the identity in an IKE
 transaction has not been revoked.
 CRL Distribution Point (CDP)
 The CDP is a PKC extension that identifies the location from which
 end entities should retrieve CRLs to check status information.
 Authority Info Access (AIA)
 The AIA is a PKC extension that indicates how to access CA
 information and services for the issuer of the PKC in which the
 extension appears.  Information and services may include on-line
 validation services and Certificate Policy (CP) data.

1.4. Requirements 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 [MUSTSHOULD].

Bonatti, et al. Informational [Page 8] RFC 4809 Reqs for IPsec Certificate Mgmt Profile February 2007

2. Architecture

 This section describes the overall architecture for a PKI-supported
 IPsec VPN deployment.  First, an explanation of the VPN System is
 presented.  Second, key points about the PKI System are stated.
 Third, the VPN-PKI architecture is presented.

2.1. VPN System

 The VPN System consists of the IPsec Peers and the VPN Administration
 function, as depicted in Figure 1.
          +---------------------------------------------------+
          |                                                   |
          |                      +----------+                 |
          |                      |   VPN    |                 |
          |          +---------->|  Admin   |<-------+        |
          |          |           | Function |        |        |
          |          |           +----------+        |        |
          |          v                               v        |
          |  +---------+                         +---------+  |
          |  |  IPsec  |                         |  IPsec  |  |
          |  |  Peer 1 |<=======================>|  Peer 2 |  |
          |  +---------+                         +---------+  |
          |                                                   |
          |                     VPN System                    |
          +---------------------------------------------------+
                           Figure 1: VPN System

2.1.1. IPsec Peer(s)

 The Peers are two entities between which establishment of an IPsec
 Security Association is required.  Two Peers are shown in Figure 1,
 but implementations can support an actual number in the hundreds or
 thousands.  The Peers can be gateway-to-gateway, remote-access-host-
 to-gateway, or a mix of both.  The Peers authenticate themselves in
 the IKE negotiation using digital signatures generated with PKCs from
 a PKI System.

2.1.2. VPN Administration Function (Admin)

 This document defines the notion of a VPN Administration function,
 hereafter referred to as Admin, and gives the Admin great
 responsibility within the VPN System.  The Admin is a centralized
 function used by the Operator to interact with the PKI System to
 establish PKI policy (e.g., algorithms, key lengths, lifecycle
 options, and PKC fields) for groups of IPsec Peers.  The Admin also

Bonatti, et al. Informational [Page 9] RFC 4809 Reqs for IPsec Certificate Mgmt Profile February 2007

 authorizes PKC issuance and can act as the Peer's PKI System
 interface, which allows the Admin to perform many RA-like functions.
 It is important to note that, within this document, the Admin is
 neither a device nor a person; rather, it is a function.  Every
 large-scale VPN deployment will contain the Admin function.  The
 function can be performed on a stand-alone workstation, on a gateway,
 or on an administration software component.  The Admin function can
 also be one and the same as the gateway, client device, or software.
 They are represented in the architectural diagram as different
 functions, but they need not be different physical entities.  As
 such, the Admin's architecture and the means by which it interacts
 with the participating IPsec Peers will vary widely from
 implementation to implementation.  However, some basic functions of
 the Admin are assumed.
  1. It, and not the PKI, will define the Certificate Policy (CP)

[FRAME] for use in a VPN System. The PKC's characteristics and

     contents are a function of the CP.  In VPN Systems, the Operator
     chooses to strengthen the VPN by using PKI; PKI is a bolt-on to
     the VPN System.  The Operator will configure local security
     policy in part through the Admin and its authorized PKI-enabled
     Peers.
  1. It will interact directly with the PKI System to initiate

authorization for end entity PKCs by sending the parameters and

     contents for individual PKCs or batches of PKCs based on a pre-
     agreed template (i.e., both types of authorization requests refer
     to the pre-agreed template).  Templates will be agreed in an
     out-of-band mechanism by the VPN Operator and the PKI Operator.
     It will receive back from the PKI a unique tuple of authorization
     identifiers and one-time authorization tokens that will authorize
     Peers to request a PKC.
  1. It will deliver instructions to the IPsec Peers, and the Peers

will carry out those instructions (e.g., Admin passes Peer

     information necessary to generate keys and PKC request).

2.2. PKI System

 The PKI System, as depicted in Figure 2, can be set up and operated
 by the Operator (in-house), be provided by third party PKI providers
 to which connectivity is available at the time of provisioning
 (managed PKI service), or be integrated with the VPN product.

Bonatti, et al. Informational [Page 10] RFC 4809 Reqs for IPsec Certificate Mgmt Profile February 2007

             +---------------------------------------------+
             |        +-------------------------+          |
             |        v                         |          |
             |   +--------------+               v          |
             |   |  Repository  |    +----+   +----+       |
             |   | Certs & CRLs |<-> | CA |<->| RA |       |
             |   +--------------+    +----+   +----+       |
             |                                             |
             +---------------------------------------------+
                            Figure 2: PKI System
 This framework assumes that all components of the VPN obtain PKCs
 from a single PKI community.  An IPsec Peer can accept a PKC from a
 Peer that is from a CA outside of the PKI community, but the auto
 provision and life cycle management for such a PKC or its trust
 anchor PKC fall out of scope.
 The PKI System contains a mechanism for handling Admin's
 authorization requests and PKC enrollments.  This mechanism is
 referred to as the Registration Authority (RA).  The PKI System
 contains a Repository for Peers to retrieve each other's PKCs and
 revocation information.  Last, the PKI System contains the core
 function of a CA that uses a public and private key pair and signs
 PKCs.

2.3. VPN-PKI Interaction

 The interaction between the VPN System and the PKI System is the key
 focus of this requirements document, as shown in Figure 3.
 Therefore, it is sensible to consider the steps necessary to set up,
 use, and manage PKCs for one Peer to establish an association with
 another Peer.

Bonatti, et al. Informational [Page 11] RFC 4809 Reqs for IPsec Certificate Mgmt Profile February 2007

        +-----------------------------------------------+
        |                  PKI System                   |
        |                                               |
        |   +--------------+                            |
        |   |  Repository  |     +----+    +----+       |
        |   | Certs & CRLs |     | CA |    | RA |       |
        |   +--------------+     +----+    +----+       |
        |                                               |
        +-----------------------------------------------+
             ^                  ^                   ^
             |[G]               |[A]                |[G]
             |[E]               |[G]                |[E]
             |[L]               |[E]                |[L]
             |[R]               |[R]                |[R]
             |                  |[L]                |
       +-----+------------------+-------------------+-------+
       |     |                  v                   |       |
       |     |             +----------+             |       |
       |     | [G][E][L][R]|   VPN    |[G][E][L][R] |       |
       |     | +---------->|  Admin   |<----------+ |       |
       |     | |           | Function |           | |       |
       |     | |           +----------+           | |       |
       |     v v                                  v v       |
       |  +---------+                          +---------+  |
       |  |  IPsec  |          [I]             |  IPsec  |  |
       |  |  Peer 1 |<========================>|  Peer 2 |  |
       |  +---------+                          +---------+  |
       |                                                    |
       |                     VPN System                     |
       +----------------------------------------------------+
 [A] = Authorization: PKC issuance
 [G] = Generation: Public key, private key, and PKC request
 [E] = Enrollment: Sending PKC request, verifying PKC response, and
       confirming PKC response
 [I] = IKE and IPsec communication
 [L] = Lifecycle: Rekey, renewal, update, revocation, and confirmation
 [R] = Repository: Posting and lookups
      Figure 3.  Architectural Framework for VPN-PKI Interaction
 Requirements for each of the interactions, [A], [G], [E], [L], and
 [R], are addressed in Sections 3.2 through 3.6.  However, only
 requirements for [A], [E], [L], and [R] will be addressed by the
 certificate management profile.  Requirements for [I] transactions
 are beyond the scope of this document.  Additionally, the act of
 certification (i.e., binding the public key to the name) is performed
 at the CA and is not shown in the figure.

Bonatti, et al. Informational [Page 12] RFC 4809 Reqs for IPsec Certificate Mgmt Profile February 2007

3. Requirements

3.1. General Requirements

3.1.1. One Protocol

 The target profile, to be based on this requirements document, MUST
 call for ONE PROTOCOL or ONE USE PROFILE for each main element of the
 [A], [E], [L], and [R] interactions.  In order to reduce complexity
 and improve interoperability, having multiple competing protocols or
 profiles to solve the same requirement should be avoided whenever
 possible.
 Meeting some of the requirements may necessitate the creation of a
 new protocol or new extension for an existing protocol; however, the
 latter is much preferred.

3.1.2. Secure Transactions

 The target certificate management profile MUST specify the [A], [E],
 [L], and [R] transactions between VPN and PKI Systems.  To support
 these transactions, the Admin and PKI MUST exchange policy details,
 identities, and keys.  As such, the method of communication for [A],
 [E], and [L] transactions MUST be secured in a manner that ensures
 privacy, authentication, and message data integrity.  The
 communication method MUST require that mutual trust be established
 between the PKI and the Admin (see Section 3.7.1).  [R] transactions
 do not require authentication or message data integrity because the
 responses (i.e., PKCs and CRLs) are already digitally signed.
 Whether [R] transactions require privacy is determined by the local
 security policy.
 The target certificate management profile will not specify [G]
 transactions.  However, these transactions MUST be secured in a
 manner that ensures privacy, authentication, and message data
 integrity because these transactions are the basis for the other
 transactions.

3.1.3. Admin Availability

 The Admin MUST be reachable by the Peers.  Most implementations will
 meet this requirement by ensuring Peers can connect to the Admin from
 anywhere on the network or Internet.  However, communication between
 the Admin and Peers can be "off-line".  It can, in some environments,
 be "moving media" (i.e., the configuration or data is loaded on to a
 floppy disk or other media and physically moved to the IPsec Peers).
 Likewise, it can be entered directly on the IPsec Peer via a User
 Interface (UI).  In this case, the Admin function is co-located on

Bonatti, et al. Informational [Page 13] RFC 4809 Reqs for IPsec Certificate Mgmt Profile February 2007

 the Peer device itself.  Most requirements and scenarios in this
 document assume on-line availability of the Admin for the life of the
 VPN System.

3.1.4. PKI Availability

 Availability is REQUIRED initially for authorization transactions
 between the PKI and Admin.  Further availability is required in most
 cases, but the extent of this availability is a decision point for
 the Operator.  Most requirements and scenarios in this document
 assume on-line availability of the PKI for the life of the VPN
 System.
 Off-line interaction between the VPN and PKI Systems (i.e., where
 physical media is used as the transport method) is beyond the scope
 of this document.

3.1.5. End-User Transparency

 PKI interactions are to be transparent to the user.  Users SHOULD NOT
 even be aware that PKI is in use.  First time connections SHOULD
 consist of no more than a prompt for some identification and pass
 phrase, and a status bar notifying the user that setup is in
 progress.

3.1.6. PKC Profile for PKI Interaction

 A PKC used for identity in VPN-PKI transactions MUST include all the
 [CERTPROFILE] mandatory fields.  It MUST also contain contents
 necessary to support path validation and certificate status checking.
 It is preferable that the PKC profiles for IPsec transactions
 [IKECERTPROFILE] and VPN-PKI transactions (in the certificate
 management profile) are the same so that one PKC could be used for
 both transaction sets.  If the profiles are inconsistent, then
 different PKCs (and perhaps different processing requirements) might
 be required.  However, the authors urge that progress continue on
 other aspects of this standardization effort regardless of the status
 of efforts to achieve PKC profile consensus.

Bonatti, et al. Informational [Page 14] RFC 4809 Reqs for IPsec Certificate Mgmt Profile February 2007

3.1.6.1. Identity

 PKCs MUST support identifying (i.e., naming) Peers and Admins.  The
 following name forms MUST be supported:
  1. Fully-Qualified Domain Name (FQDN)
  2. RFC 822 (also called USER FQDN)
  3. IPv4 Address
  4. IPv6 Address

3.1.6.2. Key Usage

 PKCs MUST support indicating the purposes for which the key (i.e.,
 digital signature) can be used.  Further, PKCs MUST always indicate
 that relying parties (i.e., Peers) need to understand the indication.

3.1.6.3. Extended Key Usage

 Extended Key Usage (EKU) indications are not required.  The presence
 or lack of an EKU MUST NOT cause an implementation to fail an IKE
 connection.

3.1.6.4. Revocation Information Location

 PKCs MUST indicate the location of CRL such that any Peer who holds
 the PKC locally will know exactly where to go and how to request the
 CRL.

3.1.7. Error Handling

 The protocol for the VPN-PKI transactions MUST specify error handling
 for each transaction.  Thorough error condition descriptions and
 handling instructions will greatly aid interoperability efforts
 between the PKI and VPN System products.

3.2. Authorization

 This section refers to the [A] elements labeled in Figure 3.

3.2.1. One Protocol

 One protocol MUST be specified for the Admin to PKI (RA/CA)
 interactions.  This protocol MUST support privacy, authorization,
 authentication, and integrity.  PKCs for authorization of the Admin
 can be initialized through an out-of-band mechanism.
 The transport used to carry the authorization SHOULD be reliable
 (TCP).

Bonatti, et al. Informational [Page 15] RFC 4809 Reqs for IPsec Certificate Mgmt Profile February 2007

 The protocol SHOULD be as lightweight as possible.

3.2.2. Bulk Authorization

 Bulk authorization MUST be supported by the certificate management
 profile.  Bulk authorization occurs when the Admin requests of the
 PKI that authorization be established for several different subjects
 with almost the same contents.  A minimum of one value (more is also
 acceptable) differs per subject.  Because the authorizations may
 occur before any keys have been generated, the only way to ensure
 unique authorization identifiers are issued is to have at least one
 value differ per subject.
 Authorization can occur prior to a PKC enrollment request, or the
 authorization and the PKC enrollment request can be presented to the
 PKI at the same time.  Both of these authorization scenarios MUST be
 supported.
 A bulk authorization SHOULD occur in one single connection to the PKI
 (RA/CA), with the number of subjects being one or greater.
 Implementations SHOULD be able to handle one thousand subjects in a
 batch authorization.

3.2.3 Authorization Scenario

 The authorization scenario for VPN-PKI transactions involves a two-
 step process: an authorization request and an authorization response.
 Figure 4 shows the salient interactions to perform authorization
 transactions.

Bonatti, et al. Informational [Page 16] RFC 4809 Reqs for IPsec Certificate Mgmt Profile February 2007

     +--------------+     +-----------------------+
     |  Repository  |     |         CA/RA         |
     +--------------+     +-----------------------+
                                      ^
                                      | 1
                                    2 |
                                      v
                                   +-------+
                                   | Admin |
                                   +-------+
              +--------------------+          +--------+
              |       IPsec        |          | IPsec  |
              |      Peer 1        |          | Peer 2 |
              +--------------------+          +--------+
                Figure 4.  Authorization Transactions
 1) Authorization Request [A].  Admin sends a list of identities and
    PKC contents for the PKI System to authorize enrollment.  See
    Section 3.2.4.
 2) Authorization Response [A].  The PKI returns a list of unique
    authorization identifiers and one-time authorization tokens to be
    used for the enrollment of each PKC (1).  Response may indicate
    success, failure, or errors for any particular authorization.  See
    Section 3.2.5.

3.2.4. Authorization Request

3.2.4.1. Specifying Fields within the PKC

 The Admin authorizes individual PKCs or batches of PKC issuances
 based on a pre-agreed template.  This template is agreed by the VPN
 Operator and PKI Operator and is referred to in each authorization
 request.  This allows the authorization requests to include the
 minimal amount of information necessary to support a VPN System.
 The Admin can send the PKI System the set of PKC contents that it
 wants the PKI to issue to a group of IPsec Peers.  In other words, it
 tells the PKI System, "if you see a PKC request that looks like this,
 from this person, process it and issue the PKC."
 Requirements for PKC fields used in IPsec transactions are specified
 in [IKECERTPROFILE].

Bonatti, et al. Informational [Page 17] RFC 4809 Reqs for IPsec Certificate Mgmt Profile February 2007

 Requirements for PKC fields used in VPN-PKI transactions are
 specified in Section 3.1.6.

3.2.4.2. Authorizations for Rekey, Renewal, and Update

 When the VPN Operator and PKI Operator pre-agree on a template, they
 MUST also agree on the local policy regarding PKC renewal and PKC
 update.  These are:
  1. Admin MUST specify if automatic renewals are allowed, that is,

the Admin authorizes the PKI to process a future renewal for the

     specified Peer PKC.
  1. Admin MUST specify if PKC update is allowed, that is, the Admin

authorizes the PKI to accept a future request for a new PKC with

     changes to non-key-related fields.
     If a PKC renewal is authorized, the Admin MUST further specify:
  1. Who can renew, that is, can only the Admin send a renewal request

or can the Peer send a request directly to the PKI, or either.

  1. How long before the PKC expiration date the PKI will accept and

process a renewal (i.e., N% of validity period, or the UTC time

     after which renewal is permitted).
 If a PKC update is authorized, the Admin MUST further specify:
  1. The aspects of non-key-related fields that are changeable.
  1. The entity that can send the PKC Update request, that is, only

the Admin, only the Peer, or either.

  1. How long before the PKC expiration date the PKI will accept and

process an update (i.e., N% of validity period, or the UTC time

     after which update is permitted).
 A new authorization by the Admin is REQUIRED for PKC rekey.  No
 parameters of prior authorizations need be considered.

3.2.4.3. Other Authorization Elements

 The Admin MUST have the ability to specify the format for the
 authorization ID and one-time authorization token.  The one-time
 authorization token SHOULD be unique per authorization ID.  The more
 randomness that can be achieved in the relationship between an
 authorization ID and its one-time authorization token, the better.
 The one-time authorization token MUST be in UTF-8 format to avoid

Bonatti, et al. Informational [Page 18] RFC 4809 Reqs for IPsec Certificate Mgmt Profile February 2007

 incompatibilities that may occur due to international characters.  It
 MUST support normalization as in [CERTPROFILE].  The Admin MUST have
 the ability to constrain the UTF-8 character set.
 There MUST be an option to specify a validation period for the
 authorization ID and its one-time authorization token.  If such a
 validation period is set, any PKC requests using the authorization ID
 and one-time authorization token that arrive at the PKI outside of
 the validation period MUST be dropped, and the event logged.
 The Protocol SHOULD consider what happens when Admin-requested
 information conflicts with PKI settings such that the Admin request
 cannot be issued as requested (e.g., Admin requests validation period
 = 3 weeks and CA is configured to only allow validation periods = 1
 week).  Proper conflict handling MUST be specified.

3.2.4.4. Cancel Capability

 Either the Admin or the Peer can send a cancel authorization message
 to PKI.  The canceling entity MUST provide the authorization ID and
 one-time authorization token in order to cancel the authorization.
 At that point, the authorization will be erased from the PKI, and a
 log entry of the event written.
 After the cancellation has been verified (a Cancel, Cancel ACK, ACK
 type of a process is REQUIRED to cover a lost connections scenario),
 the PKI will accept a new authorization request with the exact same
 contents as the canceled one, except that the identifier MUST be new.
 The PKI MUST NOT process duplicate authorization requests.
 Note that if the PKI has already issued a PKC associated with an
 authorization, then cancellation of the authorization is not possible
 and the authorization request SHOULD be refused by the PKI.  Once a
 PKC has been issued it MUST be revoked in accordance with Section
 3.6.

3.2.5. Authorization Response

 If the authorization request is acceptable, the PKI will respond to
 the Admin with a unique authorization identifier per subject
 authorization requested and a one-time authorization token per
 authorization ID.  See Section 3.2.4.3 for additional authorization
 ID and one-time authorization token requirements.
 The PKI can alter parameters of the authorization request submitted
 by the Admin.  In that event, the PKI MUST return all the contents of
 the authorization request (as modified) to the Admin with the
 confirmation of authorization success.  This will allow the Admin to

Bonatti, et al. Informational [Page 19] RFC 4809 Reqs for IPsec Certificate Mgmt Profile February 2007

 perform an "operational test" to verify that the issued PKCs will
 meet its requirements.  If the Admin determines that the modified
 parameters are unacceptable, then the authorization should be
 cancelled in accordance with Section 3.2.4.4.
 After receiving a bulk authorization request from the Admin, the PKI
 MUST be able to reply YES to those individual PKC authorizations that
 it has satisfied and NO or FAILED for those requests that cannot be
 satisfied, along with sufficient reason or error codes.
 A method is REQUIRED to identify if there is a change in PKI settings
 between the time the authorization is granted and the PKC request
 occurs, and what to do about the discrepancy.

3.2.5.1. Error Handling for Authorization

 Thorough error condition descriptions and handling instructions MUST
 be provided to the Admin for each transaction in the authorization
 process.  Providing such error codes will greatly aid
 interoperability efforts between the PKI and IPsec products.

3.3. Generation

 This section refers to the [G] elements labeled in Figure 3.
 Once the PKI System has responded with authorization identifiers and
 authorization tokens (see Section 3.2), and this information is
 received at the Admin, the next step is to generate public and
 private key pairs and to construct PKC requests using those key
 pairs.  The key generations can occur at one of three places,
 depending on local requirements: at the IPsec Peer, at the Admin, or
 at the PKI.  The PKC request can come from either the IPsec Peer, a
 combination of the Peer and the Admin, or not at all.

Bonatti, et al. Informational [Page 20] RFC 4809 Reqs for IPsec Certificate Mgmt Profile February 2007

3.3.1. Generation Method 1: IPsec Peer Generates Key Pair, Constructs

      PKC Request, and Signs PKC Request
 This option will be used most often in the field.  This is the most
 secure method for keying, as the keys are generated on the end entity
 and the private key never leaves the end entity.  However, it is the
 most computationally intensive for the Peer, as it must be "ASN.1
 aware" to support generating and digitally signing the PKC request.
     +--------------+     +-----------------------+
     |  Repository  |     |         CA/RA         |
     +--------------+     +-----------------------+
                                   +-------+
                           +------>| Admin |
                           |       +-------+
                           |
                           | 1
                           V
              +--------------------+          +--------+
            2 |       IPsec        |          | IPsec  |
              |      Peer 1        |          | Peer 2 |
              +--------------------+          +--------+
                Figure 5.  Generation Interactions:
    IPsec Peer Generates Key Pair and Constructs PKC Request
 1) Opaque transaction [G].  Admin sends authorization identifier,
    one-time authorization token, and any other parameters needed by
    the Peer to generate the PKC request, including key type and size.
 2) Generation [G].  Peer receives authorization identifier, one-time
    authorization token, and any parameters.  Peer generates key pair
    and constructs PKC request.
 Steps prior to these can be found in Section 3.2.  The next step,
 enrollment, can occur either directly between the Peer and PKI (see
 Section 3.4.5) or through the Admin (see Section 3.4.6).

Bonatti, et al. Informational [Page 21] RFC 4809 Reqs for IPsec Certificate Mgmt Profile February 2007

3.3.2. Generation Method 2: IPsec Peer Generates Key Pair, Admin

      Constructs PKC Request, Admin Signs PKC Request
 This option also supports IPsec Peer generation of a key pair, but
 removes the requirement for the Peer to be ASN.1 aware because it
 does not have to construct or digitally sign the PKC request.  The
 drawback is that the key pair does need to be provided to the Admin.
 In the most probable cases where the Admin function is remotely
 located from the peer, this means that the private key will leave the
 cryptographic boundary of the peer, which is a significant security
 trade-off consideration.  Whenever possible, it is always better to
 have private keys generated and never leave the cryptographic
 boundary of the generating system.
     +--------------+     +-----------------------+
     |  Repository  |     |         CA/RA         |
     +--------------+     +-----------------------+
                                 3 +-------+
                           +------>| Admin | 4
                           |       +-------+
                           |
                           | 1
                           V
              +--------------------+          +--------+
            2 |       IPsec        |          | IPsec  |
              |      Peer 1        |          | Peer 2 |
              +--------------------+          +--------+
                Figure 6.  Generation Interactions:
    IPsec Peer Generates Key Pair, Admin Constructs PKC Request
 1) Opaque transaction [G].  Admin sends command to Peer to generate
    key pair, based on parameters provided in the command.
 2) Generation [G].  Peer generates key pair.
 3) Opaque transaction [G].  Peer returns key pair to Admin.
 4) Generation [G].  Admin constructs and digitally signs PKC request.
 Steps prior to these can be found in Section 3.2.  The next step,
 enrollment, occurs through the Admin (see Section 3.4.7).

Bonatti, et al. Informational [Page 22] RFC 4809 Reqs for IPsec Certificate Mgmt Profile February 2007

3.3.3. Generation Method 3: Admin Generates Key Pair, Constructs PKC

      Request, and Signs PKC Request
 This option exists for deployments where Peers cannot generate their
 own key pairs.  Some examples are for PDAs and handsets where to
 generate an RSA key would be operationally impossible due to
 processing and battery constraints.  Another case covers key recovery
 requirements, where the same PKCs are used for other functions in
 addition to IPsec, and key recovery is required (e.g., local data
 encryption), therefore key escrow is needed from the Peer.  If key
 escrow is performed then the exact requirements and procedures for it
 are beyond the scope of this document.
     +--------------+     +-----------------------+
     |  Repository  |     |         CA/RA         |
     +--------------+     +-----------------------+
                                   +-------+
                                   | Admin | 1
                                   +-------+
              +--------------------+          +--------+
              |       IPsec        |          | IPsec  |
              |      Peer 1        |          | Peer 2 |
              +--------------------+          +--------+
                Figure 7.  Generation Interactions:
       Admin Generates Key Pair and Constructs PKC Request
 1) Generation [G].  Admin generates key pair, constructs PKC request,
    and digitally signs PKC request.
 Steps prior to these can be found in Section 3.2.  The next step,
 enrollment, occurs through the Admin (see Section 3.4.8).
 Note that separate authorizations steps are still of value even
 though the Admin is also performing the key generation.  The PKC
 template, Subject fields, SubjectAltName fields, and more are part of
 the request, and must be communicated in some way from the Admin to
 the PKI.  Instead of creating a new mechanism, the authorization
 schema can be reused.  This also allows for the feature of role-based

Bonatti, et al. Informational [Page 23] RFC 4809 Reqs for IPsec Certificate Mgmt Profile February 2007

 administration, where Operator 1 is the only one allowed to have the
 Admin function pre-authorize PKCs, but Operator 2 is the one doing
 batch enrollments and VPN device configurations.

3.3.4. Method 4: PKI Generates Key Pair

 This option exists for deployments where end entities cannot generate
 their own key pairs and the Admin function is a minimal
 implementation.  The PKI and Admin pre-agree to have the PKI generate
 key pairs and PKCs.  This is, in all likelihood, the easiest way to
 deploy PKCs, though it sacrifices some security since both the CA and
 the Admin have access to the private key.  However, in cases where
 key escrow is required, this may be acceptable.  The Admin
 effectively acts as a proxy for the Peer in the PKC enrollment
 process.
     +--------------+     +-----------------------+
     |  Repository  |     |         CA/RA         | 1
     +--------------+     +-----------------------+
                                   +-------+
                                   | Admin |
                                   +-------+
              +--------------------+          +--------+
              |       IPsec        |          | IPsec  |
              |      Peer 1        |          | Peer 2 |
              +--------------------+          +--------+
                Figure 8.  Generation Interactions:
    IPsec Peer Generates Key Pair, Admin Constructs PKC Request
 1) Generation [G] The PKI generates the key pair.
 Steps prior to these can be found in Section 3.2.  The next step,
 enrollment, occurs through the Admin (see Section 3.4.9).

Bonatti, et al. Informational [Page 24] RFC 4809 Reqs for IPsec Certificate Mgmt Profile February 2007

3.3.5. Error Handling for Generation

 Thorough error condition descriptions and handling instructions MUST
 be provided for each transaction in the key generation and PKC
 request construction process.  Providing such error codes will
 greatly aid interoperability efforts between the PKI and IPsec
 products.
 Error conditions MUST be communicated to the Admin regardless of who
 generated the key or PKC request.

3.4. Enrollment

 This section refers to the [E] elements labeled in Figure 3.
 Regardless of where the keys were generated and the PKC request
 constructed, an enrollment process will need to occur to request that
 the PKI issue a PKC and the corresponding PKC be returned.
 The protocol MUST be exactly the same regardless of whether the
 enrollment occurs from the Peer to the PKI or from the Admin to the
 PKI.

3.4.1. One Protocol

 One protocol MUST be specified for enrollment requests, responses,
 and confirmations.

3.4.2. On-line Protocol

 The protocol MUST support enrollment that occurs over the Internet
 and without the need for manual intervention.

3.4.3. Single Connection with Immediate Response

 Enrollment requests and responses MUST be able to occur in one on-
 line connection between the Admin on behalf of the Peer or the Peer
 itself and the PKI (RA/CA).

3.4.4. Manual Approval Option

 Manual approval of PKC enrollments is too time consuming for large
 scale implementations, and is therefore not required.

Bonatti, et al. Informational [Page 25] RFC 4809 Reqs for IPsec Certificate Mgmt Profile February 2007

3.4.5. Enrollment Method 1: Peer Enrolls to PKI Directly

 In this case, the IPsec Peer only communicates with the PKI after
 being commanded to do so by the Admin.  This enrollment mode is
 depicted in Figure 9 and the letters in the following description
 refer to Figure 3.  Prior authorization (Section 3.2) and generation
 (Section 3.3.1) steps are not shown.
 Most IPsec Systems have enough CPU power to generate a public and
 private key pair of sufficient strength for secure IPsec.  In this
 case, the end entity needs to prove to the PKI that it has such a key
 pair; this is normally done by the PKI sending the end entity a
 nonce, which the end entity signs and returns to the Admin along with
 the end entity's public key.
     +--------------+     +-----------------------+
     |  Repository  |     |         CA/RA         |
     +--------------+     +-----------------------+
                             ^
                         1,3 |
                             |
                             |
                             |     +-------+
                             |     | Admin |
                             |     +-------+
                             |
                         2,4 |
                             v
              +--------------------+          +--------+
              |       IPsec        |          | IPsec  |
              |      Peer 1        |          | Peer 2 |
              +--------------------+          +--------+
                Figure 9.  VPN-PKI Interaction Steps:
              IPsec Peer Generates Keys and PKC Request,
                       Enrolls Directly with PKI
 1) Enrollment Request [E].  The IPsec Peer sends PKC requests to the
    PKI, providing the generated public key.
 2) Enrollment Response [E].  The PKI responds to the enrollment
    request, providing either the new PKC that was generated or a
    suitable error indication.
 3) Enrollment Confirmation [E].  Peer positively acknowledges receipt
    of new PKC back to the Admin.

Bonatti, et al. Informational [Page 26] RFC 4809 Reqs for IPsec Certificate Mgmt Profile February 2007

 4) Enrollment Confirmation Receipt [E].  PKI sends enrollment
    confirmation receipt back to the Peer.

3.4.6 Enrollment Method 2a: Peer Enrolls through Admin

 In this case, the IPsec Peer has generated the key pair and the PKC
 request, but does not enroll directly to the PKI System.  Instead, it
 automatically sends its request to the Admin, and the Admin redirects
 the enrollment to the PKI System.  The PKI System does not care where
 the enrollment comes from, as long as it is a valid enrollment.  Once
 the Admin receives the PKC response, it automatically forwards it to
 the IPsec Peer.
 Most IPsec Systems have enough CPU power to generate a public and
 private key pair of sufficient strength for secure IPsec.  In this
 case, the end entity needs to prove to the Admin that it has such a
 key pair; this is normally done by the Admin sending the end entity a
 nonce, which the end entity signs and returns to the Admin along with
 the end entity's public key.
 This enrollment mode is depicted in Figure 10 and the letters in the
 following description refer to Figure 3.  Prior authorization
 (Section 3.2) and generation (Section 3.3.1) steps are not shown.
     +--------------+     +-----------------------+
     |  Repository  |     |         CA/RA         |
     +--------------+     +-----------------------+
                                      ^ 2,6
                                      |
                                      |
                                      v 3,7
                              1,5  +-------+
                                +> | Admin |
                                |  +-------+
                                |
                                |
                            4,8 v
              +--------------------+          +--------+
              |       IPsec        |          | IPsec  |
              |      Peer 1        |          | Peer 2 |
              +--------------------+          +--------+
                Figure 10.  VPN-PKI Interaction Steps:
              IPsec Peer Generates Keys and PKC Request,
                       Enrolls Through Admin
 1) Opaque Transaction [E].  The IPsec Peer requests a PKC from the
    Admin, providing the generated public key.

Bonatti, et al. Informational [Page 27] RFC 4809 Reqs for IPsec Certificate Mgmt Profile February 2007

 2) Enrollment Request [E].  The Admin forwards the enrollment request
    to the PKI.
 3) Enrollment Response [E].  The PKI responds to the enrollment
    request, providing either the new PKC that was generated or a
    suitable error indication.
 4) Opaque Transaction [E].  The Admin forwards the enrollment
    response back to the IPsec Peer.
 5) Opaque Transaction [E].  Peer positively acknowledges receipt of
    new PKC back to the Admin.
 6) Enrollment Confirmation [E].  Admin forwards enrollment
    confirmation back to the PKI.
 7) Enrollment Confirmation Receipt [E].  PKI sends enrollment
    confirmation receipt back to the Admin.
 8) Opaque Transaction [E].  Admin forwards PKI's enrollment
    confirmation receipt back to the Peer.

3.4.7. Enrollment Method 2b: Peer Enrolls through Admin

 In this case, the IPsec Peer has generated the key pair, but the PKC
 request is constructed and signed by the Admin.  The PKI System does
 not care where the enrollment comes from, as long as it is a valid
 enrollment.  Once the Admin retrieves the PKC, it then automatically
 forwards it to the IPsec Peer along with the key pair.
 Some IPsec Systems do not have enough CPU power to generate a public
 and private key pair of sufficient strength for secure IPsec.  In
 this case, the Admin needs to prove to the PKI that it has such a key
 pair; this is normally done by the PKI sending the Admin a nonce,
 which the Admin signs and returns to the PKI along with the end
 entity's public key.  A drawback to this case is that the private key
 will eventually be sent over the wire (though hopefully securely so)
 from Admin to the IPsec Peer; whenever possible, it is preferred to
 keep a key within its cryptographic boundary of origin.  Failing to
 do so opens the system to risk of the private keys being sniffed and
 discerned.
 This enrollment mode is depicted in Figure 11 and the letters in the
 following description refer to Figure 3.  Prior authorization
 (Section 3.2) and generation (Section 3.3.2) steps are not shown.

Bonatti, et al. Informational [Page 28] RFC 4809 Reqs for IPsec Certificate Mgmt Profile February 2007

     +--------------+     +-----------------------+
     |  Repository  |     |         CA/RA         |
     +--------------+     +-----------------------+
                                      ^ 1,5
                                      |
                                      |
                                      v 2,6
                                4  +-------+
                                +->| Admin |
                                |  +-------+
                                |
                                |
                            3,7 v
              +--------------------+          +--------+
              |       IPsec        |          | IPsec  |
              |      Peer 1        |          | Peer 2 |
              +--------------------+          +--------+
                Figure 11.  VPN-PKI Interaction Steps:
         IPsec Peer Generates Keys, Admin Constructs and
             Signs PKC Request, Enrolls through Admin
 1) Enrollment Request [E].  The Admin requests a PKC from the PKI,
    providing the generated public key.
 2) Enrollment Response [E].  The PKI responds to the enrollment
    request, providing either the new PKC that was generated or a
    suitable error indication.
 3) Opaque Transaction [E].  The Admin forwards the enrollment
    response back to the IPsec Peer.
 4) Opaque Transaction [E].  Peer positively acknowledges receipt of
    new PKC back to the Admin.
 5) Enrollment Confirmation [E].  Admin forwards enrollment
    confirmation back to the PKI.
 6) Enrollment Confirmation Receipt [E].  PKI sends enrollment
    confirmation receipt back to the Admin.
 7) Opaque Transaction [E].  Admin forwards PKI's enrollment
    confirmation receipt back to the Peer.

Bonatti, et al. Informational [Page 29] RFC 4809 Reqs for IPsec Certificate Mgmt Profile February 2007

3.4.8. Enrollment Method 3a: Admin Authorizes and Enrolls Directly to

      PKI
 In this case, the Admin generates the key pair, PKC request, and
 digitally signs the PKC request.  The PKI System does not care where
 the enrollment comes from, as long as it is a valid enrollment.  Once
 the Admin retrieves the PKC, it then automatically forwards it to the
 IPsec Peer along with the key pair.
 Some IPsec Systems do not have enough CPU power to generate a public
 and private key pair of sufficient strength for secure IPsec.  In
 this case, the Admin needs to prove to the PKI that it has such a key
 pair; this is normally done by the PKI sending the Admin a nonce,
 which the Admin signs and returns to the PKI along with the end
 entity's public key.  A drawback to this case is that the private key
 will eventually be sent over the wire (though hopefully securely so)
 from Admin to the IPsec Peer; whenever possible, it is preferred to
 keep a key within its cryptographic boundary of origin.  Failing to
 do so opens the system to risk of the private keys being sniffed and
 discerned.
 This enrollment mode is depicted in Figure 12 and the letters in the
 following description refer to Figure 3.  Prior authorization
 (Section 3.2) and generation (Section 3.3.3) steps are not shown.
     +--------------+     +-----------------------+
     |  Repository  |     |         CA/RA         |
     +--------------+     +-----------------------+
                                      ^ 1,5
                                      |
                                      |
                                      v 2,6
                                4  +-------+
                                +->| Admin |
                                |  +-------+
                                |
                                |
                            3,7 v
              +--------------------+          +--------+
              |       IPsec        |          | IPsec  |
              |      Peer 1        |          | Peer 2 |
              +--------------------+          +--------+
                Figure 12.  VPN-PKI Interaction Steps:
      Admin Generates Keys and PKC Request, and Enrolls Directly
                            with PKI

Bonatti, et al. Informational [Page 30] RFC 4809 Reqs for IPsec Certificate Mgmt Profile February 2007

 1) Enrollment Request [E].  The Admin requests a PKC from the PKI,
    providing the generated public key.
 2) Enrollment Response [E].  The PKI responds to the enrollment
    request, providing either the new PKC that was generated or a
    suitable error indication.
 3) Opaque Transaction [E].  The Admin forwards the enrollment
    response back to the IPsec Peer, along with the keys.
 4) Opaque Transaction [E].  Peer positively acknowledges receipt of
    new PKC back to the Admin.
 5) Enrollment Confirmation [E].  Admin forwards enrollment
    confirmation back to the PKI.
 6) Enrollment Confirmation Receipt [E].  PKI sends enrollment
    confirmation receipt back to the Admin.
 7) Opaque Transaction [E].  Admin forwards PKI's enrollment
    confirmation receipt back to the Peer.

3.4.9. Enrollment Method 3b: Admin Requests and PKI Generates and

      Sends PKC
 In this instance, the PKI and Admin have previously agreed to have
 the PKI generate keys and certificates when the PKI receives an
 authorization request.  The PKI returns to the IPsec Peer through the
 Admin, the final product of a key pair and PKC.  Again, the mechanism
 for the Peer to Admin communication is opaque.
 A drawback to this case is that the private key will eventually be
 sent over the wire (though hopefully securely so) from Admin to the
 IPsec Peer; whenever possible, it is preferred to keep a key within
 its cryptographic boundary of origin.  Failing to do so opens the
 system to risk of the private keys being sniffed and discerned.
 This enrollment mode is depicted in Figure 13 and the letters in the
 following description refer to Figure 3.  Prior authorization
 (Section 3.2) and generation (Section 3.3.4) steps are not shown.

Bonatti, et al. Informational [Page 31] RFC 4809 Reqs for IPsec Certificate Mgmt Profile February 2007

     +--------------+     +-----------------------+
     |  Repository  |     |         CA/RA         |
     +--------------+     +-----------------------+
                                      ^ 4
                                      |
                                      |
                                      v 1,5
                                3  +-------+
                                +->| Admin |
                                |  +-------+
                                |
                                |
                            2,6 v
              +--------------------+        +--------+
              |       IPsec        |        | IPsec  |
              |      Peer 1        |        | Peer 2 |
              +--------------------+        +--------+
                Figure 13.  VPN-PKI Interaction Steps:
             PKI Generates Keys, PKC Request, and Enrolls
                           Directly with PKI
 1) Enrollment Response [E].  The PKI responds to the authorization
    request sent, providing either the new PKC and public-private key
    pair that were generated or a suitable error indication.
 2) Opaque Transaction [E].  The Admin forwards the enrollment
    response back to the IPsec Peer, along with the keys.
 3) Opaque Transaction [E].  Peer positively acknowledge receipt of
    new PKC back to the Admin.
 4) Enrollment Confirmation [E].  Admin forwards enrollment
    confirmation back to the PKI.
 5) Enrollment Confirmation Receipt [E].  PKI sends enrollment
    confirmation receipt back to the Admin.
 6) Opaque Transaction [E].  Admin forwards PKI's enrollment
    confirmation receipt back to the Peer.

3.4.10. Confirmation Handshake

 Any time a new PKC is issued by the PKI, a confirmation of PKC
 receipt MUST be sent back to the PKI by the Peer or the Admin
 (forwarding the Peer's confirmation).

Bonatti, et al. Informational [Page 32] RFC 4809 Reqs for IPsec Certificate Mgmt Profile February 2007

 Operationally, the Peer MUST send a confirmation to the PKI verifying
 that it has received the PKC, loaded it, and can use it effectively
 in an IKE exchange.  This requirement exists so that:
  1. The PKI does not publish the new PKC in the repository for others

until that PKC is able to be used effectively by the Peer, and

  1. A revocation may be invoked if the PKC is not received and

operational within an allowable window of time.

 To assert such proof, the Peer MUST sign a portion of data with the
 new key.  The result MUST be sent to the PKI.  The entity that
 actually sends the result to the PKI MAY be either the Peer (sending
 it directly to the PKI) or Admin (the Peer would send it to Admin,
 and Admin can, in turn, send it to the PKI).
 The Admin MUST acknowledge the successful receipt of the
 confirmation, thus signaling to the Peer that it may proceed using
 this PKC in IKE connections.  The PKI MUST complete all the
 processing necessary to enable the Peer's operational use of the new
 PKC (for example, writing the PKC to the repository) before sending
 the confirmation acknowledgement.  The Peer MUST NOT begin using the
 PKC until the PKI's confirmation acknowledgement has been received.

3.4.11. Error Handling for Enrollment

 Thorough error condition descriptions and handling instructions are
 REQUIRED for each transaction in the enrollment process.  Providing
 such error codes will greatly aid interoperability efforts between
 the PKI and IPsec products.
 The profile will clarify what happens if the request and retrieval
 fails for some reason.  The following cases MUST be covered:
  1. Admin or Peer cannot send the request.
  1. Admin or Peer sent the request, but the PKI did not receive the

request.

  1. PKI received the request, but could not read it effectively.
  1. PKI received and read the request, but some contents of the

request violated the PKI's configured policy such that the PKI

     was unable to generate the PKC.
  1. The PKI System generated the PKC, but could not send it.

Bonatti, et al. Informational [Page 33] RFC 4809 Reqs for IPsec Certificate Mgmt Profile February 2007

  1. The PKI sent the PKC, but the requestor (Admin or Peer) did not

receive it.

  1. The Requestor (Admin or Peer) received the PKC, but could not

process it due to incorrect contents, or other PKC-construction-

     related problem.
  1. The Requestor failed trying to generate the confirmation.
  1. The Requestor failed trying to send the confirmation.
  1. The Requestor sent the confirmation, but the PKI did not receive

it.

  1. The PKI received the confirmation but could not process it.
 In each case the following questions MUST be addressed:
  1. What does Peer do?
  2. What does Admin do?
  3. What does PKI do?
  4. Is Authorization used?
 If a failure occurs after the PKI sends the PKC and before the Peer
 receives it, then the Peer MUST re-request with the same
 authorization ID and one-time authorization token.  The PKI, seeing
 the authorization ID and authorization token, MUST send the PKC
 again.
 Enrollment errors MUST be sent to the Admin regardless of the entity
 that generated the enrollment request.

3.5. Lifecycle

 This section refers to the [L] elements labeled in Figure 3.
 Once the PKI has issued a PKC for the end entity Peer, the Peer MUST
 be able to either contact the PKI directly or through the Admin for
 any subsequent rekeys, renewals, updates, or revocations.  The PKI
 MUST support either case for renewals, updates, and revocations.
 Rekeys are Admin initiated; therefore, Peer initiated rekeys MUST be
 transferred via the Admin.

3.5.1. One Protocol

 One protocol MUST be specified for rekey, renew, and update requests,
 responses, and confirmations.  It MUST be the same protocol as is
 specified in Section 3.4.

Bonatti, et al. Informational [Page 34] RFC 4809 Reqs for IPsec Certificate Mgmt Profile February 2007

 Revocation requests MAY use the same protocol as rekey, renew, and
 update operations.  Revocation requests MAY also occur via email,
 telephone, Instant Messaging, etc.

3.5.2. PKC Rekeys, Renewals, and Updates

 Rekeys, renewals, and updates are variants of a PKC enrollment
 request scenario with unique operational and management requirements.
  1. A PKC rekey replaces an end entity's PKC with a new PKC that has

a new public key for the same SubjectName and SubjectAltName

     contents before the end entity's currently held PKC expires.
  1. A PKC renewal replaces an end entity's PKC with the same public

key for the same SubjectName and SubjectAlternativeName contents

     as an existing PKC before that PKC expires.
  1. A PKC update is defined as a new PKC issuance with the same

public key for an altered SubjectName or SubjectAlternativeName

     before expiration of the end entity's current PKC.
 When sending rekey, renew, or update requests, the entire contents of
 the PKC request needs to be sent to the PKI, not just the changed
 elements.
 The rekey, renew, and update requests MUST be signed by the private
 key of the old PKC.  This will allow the PKI to verify the identity
 of the requestor, and ensure that an attacker does not submit a
 request and receive a PKC with another end entity's identity.
 Whether or not a new key is used for the new PKC in a renew or update
 scenario is a matter of local security policy, and MUST be specified
 by the Admin to the PKI in the original authorization request.
 Reusing the same key is permitted, but not encouraged.  If a new key
 is used, the update or renew request must be signed by both the old
 key -- to prove the right to make the request -- and the new key --
 to use for the new PKC.
 The new PKC resulting from a rekey, renew, or update will be
 retrieved in-band, using the same mechanism as a new PKC request.
 For the duration of time after a rekey, renew, or update has been
 processed and before PKI has received confirmation of the Peer's
 successful receipt of the new PKC, both PKCs (the old and the new)
 for the end entity will be valid.  This will allow the Peer to
 continue with uninterrupted IKE connections with the previous PKC
 while the rekey, renewal, or update process occurs.

Bonatti, et al. Informational [Page 35] RFC 4809 Reqs for IPsec Certificate Mgmt Profile February 2007

 After the rekey, renewal, or update occurs, the question now exists
 for the PKI of what to do about the old PKC.  If the old PKC is to be
 made unusable, the PKI will need to add it to the revocation list,
 removed from the repository; however this should only occur once all
 connections that used the old PKC have expired.  The decision about
 if the old PKC should be made unusable is determined by local policy.
 Either the PKI or the Admin MUST specify this parameter during the
 authorization phase.  In this case, the PKI or the Admin MUST also
 specify the length of time from when the PKI receives the end entity
 Peer's confirmation (of receipt of the PKC) until when the old PKC is
 made unusable.
 In the case where the new keys were generated for a renew or update
 request and for rekey requests, once the Peer receives the
 confirmation acknowledgement from the PKI, it is good practice for
 the old key pair to be destroyed as soon as possible.  Deletion can
 occur once all connections that used the old PKC have expired.
 If a PKC has been revoked, it MUST NOT be allowed a rekey, renewal,
 or update.
 Should the PKC expire without rekey, renewal, or update, an entirely
 new request MUST be made.

3.5.2.1. Rekey Request

 Admins manage rekeys to ensure uninterrupted use of the VPN by Peers
 with new keys.  Rekeys can occur automatically if the Admin is
 configured to initiate a new authorization for the rekey.
 Scenarios for rekey are omitted as they use the same scenarios used
 in the original PKC enrollment from Sections 3.2, 3.3, and 3.4.

3.5.2.2. Renew Request

 Admins manage renewals to ensure uninterrupted use of the VPN by
 Peers with the same key pair.
 At the time of authorization, certain details about renewal
 acceptance will be conveyed by the Admin to the PKI, as stated in
 Section 3.2.4.2.  The renewal request MUST match the conditions that
 were specified in the original authorization for:
  1. Keys: New, existing, or either.
  2. Requestor: End entity Peer, Admin, or either.
  3. Period: How soon before PKC expiry.
  4. Time: Length of time before making the old PKC unusable.

Bonatti, et al. Informational [Page 36] RFC 4809 Reqs for IPsec Certificate Mgmt Profile February 2007

 If any of these conditions are not met, the PKI must reject the
 renewal and log the event.
 Scenarios for renewal are omitted as they use the same scenarios used
 in the original PKC enrollment from Sections 3.2, 3.3, and 3.4.

3.5.2.3. Update Request

 An update to the contents of a PKC will be necessary when details
 about an end entity Peer's identity change, but the Operator does not
 want to generate a new PKC from scratch, requiring a whole new
 authorization.  For example, a gateway device may be moved from one
 site to another.  Its IPv4 Address will change in the SubjectAltName
 extension, but all other information could stay the same.  Another
 example is an end user who gets married and changes the last name or
 moves from one department to another.  In either case, only one field
 (the Surname or Organizational Unit (OU) in the DN) need change.
 An update differs from a rekey or a renewal in a few ways:
  1. A new key is not necessary
  1. The timing of the update event is not predictable, as is the case

with a scheduled rekey or renewal.

  1. The update request may occur at any time during a PKC's period of

validity.

  1. Once the update is completed, and the new PKC is confirmed, the

old PKC should cease to be usable, as its contents no longer

     accurately describe the subject.
 At the time of authorization, certain details about update acceptance
 can be conveyed by the Admin to the PKI, as stated in Section
 3.2.4.2.  The update request MUST match the conditions that were
 specified in the original authorization for:
  1. Keys: new, existing, or either.
  2. Requestor: End entity Peer, Admin, or either.
  3. The fields in the Subject and SubjectAltName that are changeable.
  4. Time: Length of time before making the old PKC unusable.
 If any of these conditions are not met, the PKI MUST reject the
 update and log the event.
 If an update authorization was not made at the time of original
 authorization, one can be made from Admin to the PKI at any time
 during the PKC's valid life.  When such an update is desired, Admin

Bonatti, et al. Informational [Page 37] RFC 4809 Reqs for IPsec Certificate Mgmt Profile February 2007

 must notify the PKI System that an update is authorized for the end
 entity and must specify the new contents.  Admin then initiates the
 update request with the given contents in whichever mechanism the VPN
 System employs (direct from end entity to PKI, from end entity
 through Admin, or directly from Admin).
 Scenarios for update are omitted as they use the same scenarios used
 in the original PKC enrollment from Sections 3.2, 3.3, and 3.4.

3.5.2.4. Error Handling for Rekey, Renewal, and Update

 Thorough error condition descriptions and handling instructions are
 required for each transaction in the rekey, renewal, or update
 process.  Providing such error codes will greatly aid
 interoperability efforts between the PKI and IPsec products.

3.5.2.5. Confirmation Handshakes

 The confirmation handshake requirements are the same as in Sections
 3.2, 3.3, and 3.4 except that depending on the Administrative policy
 the PKI MUST also issue a revocation on the original PKC before
 sending the confirmation response.

3.5.3. Revocation

 The Peer MUST be able to initiate revocation for its own PKC.  In
 this case the revocation request MUST be signed by the Peer's current
 key pair for the PKC it wishes to revoke.  Whether the actual
 revocation request transaction occurs directly with the PKI or is
 first sent to Admin (who proxies or forwards the request to the PKI)
 is a matter of implementation.
 The Admin MUST be able to initiate revocation for any PKC issued
 under a template it controls.  The Admin will identify itself to the
 PKI by use of its own PKC; it MUST sign any revocation request to the
 PKI with the private key from its own PKC.  The PKI MUST have the
 ability to configure Admin(s) with revocation authority, as
 identified by its PKC.  Any PKC authorizations must specify if said
 PKC may be revoked by the Admin (see Section 3.2.3.2 for more
 details).
 The profile MUST identify the one protocol or transaction within a
 protocol to be used for both Peer and Admin initiated revocations.
 The profile MUST identify the size of CRL the client will be prepared
 to support.

Bonatti, et al. Informational [Page 38] RFC 4809 Reqs for IPsec Certificate Mgmt Profile February 2007

 Below are guidelines for revocation in specific transactions:
  1. AFTER RENEW, BEFORE EXPIRATION: The PKI MUST be responsible for

the PKC revocation during a renew transaction. PKI MUST revoke

     the PKC after receiving the confirm notification from the Peer,
     and before sending the confirm-ack to the Peer.  The Peer MUST
     NOT revoke its own PKC in this case.
  1. AFTER UPDATE, BEFORE EXPIRATION: The PKI MUST be responsible for

the PKC revocation during an update transaction. PKI MUST revoke

     the PKC after receiving the confirm notification from the Peer,
     and before sending the confirm-ack to the Peer.  The Peer MUST
     NOT revoke its own PKC in this case.

3.6. Repositories

 This section refers to the [R] elements labeled in Figure 3.

3.6.1. Lookups

 The PKI System SHOULD be built so that lookups resolve directly and
 completely at the URL indicated in a CDP or AIA.  The PKI SHOULD be
 built such that URL contents do not contain referrals to other hosts
 or URLs, as such referral lookups will increase the time to complete
 the IKE negotiation, and can cause implementations to timeout.
 CDP MUST be flagged as required in the authorization request.  The
 method MUST also be specified: the HTTP method MUST be method; the
 Lightweight Directory Access Protocol (LDAP) method MAY be supported.
 The complete hierarchical PKC chain (except the trust anchor) MUST be
 able to be searched in their respective repositories.  The
 information to accomplish these searches MUST be adequately
 communicated in the PKCs sent during the IKE transaction.
 All PKCs must be retrievable through a single protocol.  The final
 specification will identify one protocol as a "MUST", others MAY be
 listed as "OPTIONAL".
 The general requirements for the retrieval protocol include:
  1. The protocol can be easily firewalled (including Network Address

Translation (NAT) or Port Address Translation (PAT)).

  1. The protocol can easily perform some query against a remote

repository on a specific ID element that was given to it in a

     standard PKC field.

Bonatti, et al. Informational [Page 39] RFC 4809 Reqs for IPsec Certificate Mgmt Profile February 2007

 Other considerations include:
  1. Relative speed
  2. Relative ease of administration
  3. Scalability
 Intermediate PKCs will be needed for the case of re-keying of the CA,
 or a PKI System where multiple CAs exist.
 PKCs MAY have extendedKeyusage to help identify the proper PKC for
 IPsec, though the default behavior is to not use them (see 3.1.5.3).
 IPsec Peers MUST be able to resolve Internet domain names and support
 the mandatory repository access protocol at the time of starting up
 so they can perform the PKC lookups.
 IPsec Peers should cache PKCs to reduce latency in setting up Phase
 1.  Note that this is an operational issue, not an interoperability
 issue.
 The use case for accomplishing lookups when PKCs are not sent in IKE
 is a stated non-goal of the profile at this time.

3.6.2. Error Handling for Repository Lookups

 Thorough error condition descriptions and handling instructions are
 required for each transaction in the repository lookup process.
 Providing such error codes will greatly aid interoperability efforts
 between the PKI and IPsec products.

3.7. Trust

3.7.1. Trust Anchor PKC Acquisition

 The root PKC MUST arrive on the Peer via one of two methods:
 (a) Peer can get the root PKC via its secure communication with
     Admin.  This requires the Peer to know less about interaction
     with the PKI.
 (b) Admin can command Peer to retrieve the root cert directly from
     the PKI.  How retrieval of the root cert takes place is beyond
     the scope of this document, but is assumed to occur via an
     unauthenticated but confidential enrollment protocol.

Bonatti, et al. Informational [Page 40] RFC 4809 Reqs for IPsec Certificate Mgmt Profile February 2007

3.7.2. Certification Path Validation

 The IPsec Peer MUST perform identity verification based on the fields
 of the PKC and parameters applicable to the VPN Security Association.
 The fields of the PKC used for verification MAY include either the
 X.500 Distinguished Name (DN) within the Subject Name, or a specific
 field within the Extension SubjectAltName (per [DOI] 4.6.2.1
 Identification Type Values).  Usage descriptions for each follow.
 The Peers or a Simple Certificate Validation Protocol (SCVP) server
 MUST validate the certification path, as per RFC 3280.  The contents
 necessary in the PKC to allow this will be enumerated in the profile
 document.
 The Peer MAY have the ability to construct the certification path
 itself; however, Admin MUST be able to supply Peers with the trust
 anchor and any chaining PKCs necessary.  The Admin MAY ensure the
 template uses the AIA extension in PKCs as a means of facilitating
 path validation.
 DNS MUST be supported by the Peers in order to support resolving URLs
 present in CDPs and AIA extensions.

3.7.3. Revocation Checking and Status Information

 The PKI System MUST provide a mechanism whereby Peers can check the
 revocation status of PKCs that are presented to it for IKE identity.
 The mechanism should allow for access to extremely fresh revocation
 information.  CRLs have been chosen as the mechanism for
 communicating this information.  Operators are RECOMMENDED to refresh
 CRLs as often as logistically possible.
 A single mandatory protocol mechanism for performing CRL lookups MUST
 be specified by the final specification.
 All PKCs used in IKE MUST have cRLDistributionPoint and
 authorityInfoAccess fields populated with valid URLs.  This will
 allow all recipients of the PKC to know immediately how revocation is
 to be accomplished, and where to find the revocation information.
 The AIA is needed in an environment where multiple layers of CAs
 exist and for the case of a CA key roll-over.
 IPsec Systems have an OPTION to turn off revocation checking.  Such
 may be desired when the two Peers are communicating over a network
 without access to the CRL service, such as at a trade show, in a lab,
 or in a demo environment.  If revocation checking is OFF, the
 implementation MUST proceed to use the PKC as valid identity in the
 exchange and need not perform any check.

Bonatti, et al. Informational [Page 41] RFC 4809 Reqs for IPsec Certificate Mgmt Profile February 2007

 If the revocation of a PKC is used as the only means of deactivation
 of access authorization for the Peer (or user), then the speed of
 deactivation will be as rapid as the refresh rate of the CRL issued
 and published by the PKI.  If more immediate deactivation of access
 is required than the CRL refreshing can provide, then another
 mechanism for authorization that provides more immediate access
 deactivation should be layered into the VPN deployment.  Such a
 second mechanism is out of the scope of this profile.  (Examples are
 Xauth, L2TP's authentication, etc.)

3.7.4. Error Handling in Revocation Checking and Certificate Path

      Validation
 Thorough error condition descriptions and handling instructions are
 required for each transaction in the revocation checking and path
 validation process.  Providing such error codes will greatly aid
 interoperability efforts between the PKI and IPsec products.

4. Security Considerations

 This requirements document does not specify a concrete solution, and
 as such has no system-related security considerations per se.
 However, the intent of the PKI4IPSEC WG was to profile and use
 concrete protocols for certificate management (e.g., Cryptographic
 Message Syntax (CMS), Certificate Management over CMS (CMC),
 Certificate Request Message Format (CRMF)).  The individual security
 considerations of these protocols should be carefully considered in
 the profiling effort.
 In addition, this document allows significant flexibility in the
 allocation of functions between the roles of Peer and Admin.  This
 functional allocation is crucial both to achieving successful
 deployment, and to maintaining the integrity of the PKI enrollment
 and management processes.  However, much of the responsibility for
 this allocation necessarily falls to product implementers and system
 operators through the selection of applicable use cases and
 development of security policy constraints.  These factors must be
 carefully considered to ensure the security of PKI4IPSEC certificate
 management.

Bonatti, et al. Informational [Page 42] RFC 4809 Reqs for IPsec Certificate Mgmt Profile February 2007

5. References

5.1. Normative References

 [MUSTSHOULD]     Bradner, S., "Key words for use in RFCs to Indicate
                  Requirement Levels", BCP 14, RFC 2119, March 1997.

5.2. Informative References

 [CERTPROFILE]    Housley, R., Polk, W., Ford, W., and D. Solo,
                  "Internet X.509 Public Key Infrastructure
                  Certificate and Certificate Revocation List (CRL)
                  Profile", RFC 3280, April 2002.
 [DOI]            Piper, D., "The Internet IP Security Domain of
                  Interpretation for ISAKMP", RFC 2407, November 1998.
 [FRAME]          Chokhani, S., Ford, W., Sabett, R., Merrill, C., and
                  S. Wu, "Internet X.509 Public Key Infrastructure
                  Certificate Policy and Certification Practices
                  Framework", RFC 3647, November 2003.
 [IKECERTPROFILE] Korver, B., "The Internet IP Security PKI Profile of
                  IKEv1/ISAKMP, IKEv2, and PKIX", Work in Progress,
                  February 2007.
 [IKEv1]          Harkins, D. and D. Carrel, "The Internet Key
                  Exchange (IKE)", RFC 2409, November 1998.
 [IKEv2]          Kaufman, C., "Internet Key Exchange (IKEv2)
                  Protocol", RFC 4306, December 2005.
 [IPsec]          Kent, S. and K. Seo, "Security Architecture for the
                  Internet Protocol", RFC 4301, December 2005.

6. Acknowledgements

 This RFC is substantially based on a prior document developed by
 Project Dploy.  The principle editor of that document was Gregory M.
 Lebovitz (NetScreen/Juniper).  Contributing authors included
 Lebovitz, Paul Hoffman (VPN Consortium), Hank Mauldin (Cisco
 Systems), and Jussi Kukkonen (SSH Communications Security).
 Substantial editorial contributions were made by Leo Pluswick (ICSA),
 Tim Polk (NIST), Chris Wells (SafeNet), Thomas Hardjono (VeriSign),
 Carlisle Adams (Entrust), and Michael Shieh (NetScreen/Juniper).

Bonatti, et al. Informational [Page 43] RFC 4809 Reqs for IPsec Certificate Mgmt Profile February 2007

 Once brought to the IETF's PKI4IPSEC WG, the following people made
 substantial contributions: Jim Schaad and Stefan Santesson.

Editors' Addresses

 Chris Bonatti
 IECA, Inc.
 EMail: Bonattic@ieca.com
 Sean Turner
 IECA, Inc.
 EMail: Turners@ieca.com
 Gregory M. Lebovitz
 Juniper
 EMail: gregory.ietf@gmail.com

Bonatti, et al. Informational [Page 44] RFC 4809 Reqs for IPsec Certificate Mgmt Profile February 2007

Full Copyright Statement

 Copyright (C) The IETF Trust (2007).
 This document is subject to the rights, licenses and restrictions
 contained in BCP 78, and except as set forth therein, the authors
 retain all their rights.
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Bonatti, et al. Informational [Page 45]

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