PKIX M. Pritikin, Ed.
Internet-Draft Cisco Systems, Inc.
Intended status: Standards Track P. Yee, Ed.
Expires: April 25, 2013 AKAYLA, Inc.
D. Harkins, Ed.
Aruba Networks
October 22, 2012
Enrollment over Secure Transport
draft-ietf-pkix-est-03
Abstract
This document profiles certificate enrollment for clients using
Certificate Management over CMS (CMC) messages over a secure
transport. This profile, called Enrollment over Secure Transport
(EST), describes a simple yet functional certificate management
protocol targeting Public Key Infrastructure (PKI) clients that need
to acquire client certificate(s) and associated Certification
Authority (CA) certificate(s).
Status of this Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on April 25, 2013.
Copyright Notice
Copyright (c) 2012 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
Pritikin, et al. Expires April 25, 2013 [Page 1]
Internet-Draft EST October 2012
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 5
2. Operational Scenario Overviews . . . . . . . . . . . . . . . . 5
2.1. Obtaining CA Certificates . . . . . . . . . . . . . . . . 6
2.2. Initial Enrollment . . . . . . . . . . . . . . . . . . . . 7
2.2.1. Previously Installed Client Certificate . . . . . . . 7
2.2.2. Username/Password Distributed Out-of-Band . . . . . . 7
2.3. Client Certificate Re-issuance . . . . . . . . . . . . . . 8
2.3.1. Re-issuance of Signature Certificates . . . . . . . . 8
2.3.2. Re-issuance of Key Exchange Certificates . . . . . . . 8
2.4. Server Key Generation . . . . . . . . . . . . . . . . . . 8
2.5. Full PKI Request messages . . . . . . . . . . . . . . . . 8
2.6. CSR (Certificate Signing Request) Attributes Request . . . 8
3. Protocol Design and Layering . . . . . . . . . . . . . . . . . 9
3.1. Application Layer Design . . . . . . . . . . . . . . . . . 12
3.2. HTTP Layer Design . . . . . . . . . . . . . . . . . . . . 12
3.2.1. HTTP headers for control . . . . . . . . . . . . . . . 12
3.2.2. HTTP URIs for control . . . . . . . . . . . . . . . . 13
3.2.3. HTTP-Based Client Authentication . . . . . . . . . . . 14
3.2.4. Message types . . . . . . . . . . . . . . . . . . . . 15
3.3. TLS Layer Design . . . . . . . . . . . . . . . . . . . . . 16
3.3.1. TLS for transport security . . . . . . . . . . . . . . 17
3.3.1.1. TLS-Based Server Authentication . . . . . . . . . 17
3.3.1.2. TLS-Based Client Authentication . . . . . . . . . 17
3.3.1.3. Certificate-less TLS Mutual Authentication . . . . 18
3.4. Proof-of-Possession . . . . . . . . . . . . . . . . . . . 18
3.5. Linking Identity and POP information . . . . . . . . . . . 18
4. Protocol Exchange Details . . . . . . . . . . . . . . . . . . 20
4.1. Server Authorization . . . . . . . . . . . . . . . . . . . 20
4.2. Client Authorization . . . . . . . . . . . . . . . . . . . 20
4.3. Distribution of CA certificates . . . . . . . . . . . . . 21
4.3.1. Distribution of CA certificates request . . . . . . . 21
4.3.2. Bootstrap Distribution of CA certificates . . . . . . 21
4.3.3. Distribution of CA certificates response . . . . . . . 22
4.4. Client Certificate Request Functions . . . . . . . . . . . 23
4.4.1. Simple Enrollment of Clients . . . . . . . . . . . . . 23
4.4.2. Simple Re-Enrollment of Clients . . . . . . . . . . . 24
4.4.3. Simple Enroll and Re-Enroll Response . . . . . . . . . 24
4.5. Full CMC . . . . . . . . . . . . . . . . . . . . . . . . . 25
Pritikin, et al. Expires April 25, 2013 [Page 2]
Internet-Draft EST October 2012
4.5.1. Full CMC Request . . . . . . . . . . . . . . . . . . . 25
4.5.2. Full CMC Response . . . . . . . . . . . . . . . . . . 26
4.6. Server-side Key Generation . . . . . . . . . . . . . . . . 26
4.6.1. Server-side Key Generation Request . . . . . . . . . . 27
4.6.2. Server-side Key Generation Response . . . . . . . . . 27
4.7. CSR Attributes . . . . . . . . . . . . . . . . . . . . . . 28
4.7.1. CSR Attributes Request . . . . . . . . . . . . . . . . 28
4.7.2. CSR Attributes Response . . . . . . . . . . . . . . . 28
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 29
6. Security Considerations . . . . . . . . . . . . . . . . . . . 31
7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 32
7.1. Normative References . . . . . . . . . . . . . . . . . . . 32
7.2. Informative References . . . . . . . . . . . . . . . . . . 35
Appendix A. Operational Scenario Example Messages . . . . . . . . 36
A.1. Obtaining CA Certificates . . . . . . . . . . . . . . . . 36
A.2. Previously Installed Signature Certificate . . . . . . . . 37
A.3. Username/Password Distributed Out-of-Band . . . . . . . . 39
A.4. Re-Enrollment . . . . . . . . . . . . . . . . . . . . . . 42
A.5. Server Key Generation . . . . . . . . . . . . . . . . . . 43
A.6. CSR Attributes . . . . . . . . . . . . . . . . . . . . . . 47
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 47
Pritikin, et al. Expires April 25, 2013 [Page 3]
Internet-Draft EST October 2012
1. Introduction
This document profiles certificate enrollment for clients using
Certificate Management over CMS (CMC) [RFC5272] messages over a
secure transport. Enrollment over Secure Transport (EST) describes
the use of TLS 1.1 [RFC4346] (or a later version) and HTTP 1.1
[RFC2616] to provide an authenticated and authorized channel for
Simple PKI Requests and Responses [RFC5272].
Architecturally the EST service is located between a CA and the
client device. It performs several functions traditionally allocated
to the PKI role of the Registration Authority (RA). The nature of
the communication of EST server to CA is not described in this
document.
EST adopts the CMP [RFC4210] model for CA certificate rollover, but
does not use the CMP message syntax or protocol. EST servers are
extensible in that new functions may be defined to provide additional
capabilities not specified in CMC [RFC5272]. Non-CMC-based
extensions such as the requesting of Certificate Signing Request
attributes and requests for server generated keys are defined in this
document.
EST specifies the transferring of messages securely over HTTPS
[RFC2818] where the HTTP headers and content types are used in
conjunction with TLS. HTTPS operates over TCP; this document does
not specify EST over DTLS/UDP. Figure 1 shows how the layers build
upon each other.
Pritikin, et al. Expires April 25, 2013 [Page 4]
Internet-Draft EST October 2012
EST Layering:
Protocols:
+--------------------------------------------+
| |
| EST messages for request/response messages |
| |
+--------------------------------------------+
| |
| HTTP for message transfer and signaling |
| |
+--------------------------------------------+
| |
| TLS for transport security |
| |
+--------------------------------------------+
| |
| TCP for transport |
| |
+--------------------------------------------+
Figure 1
[[EDNOTE: Comments such as this one, included within double brackets
and initiated with an 'EDNOTE', are for editorial use and shall be
removed as the document is polished.]]
1.1. 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].
It is assumed that the reader is familiar with the terms and concepts
described in PKCS#10 [RFC2314], HTTPS [RFC2818], CMP [RFC4210], CMC
[RFC5272][RFC5273][RFC5274], and TLS [RFC5246].
2. Operational Scenario Overviews
This section provides an informative overview of the operational
scenarios to better introduce the reader to the protocol discussion.
This section does not include [RFC2119] key words.
Both the EST clients and server are configured with information that
will be the basis of authentication and authorization. The specific
initialization data depends on the methods available in the client
device and server, but can include shared secrets, network service
Pritikin, et al. Expires April 25, 2013 [Page 5]
Internet-Draft EST October 2012
names and locations (e.g. a URI [RFC3986]), trust anchor information
(e.g. current CA certificate or third party TA(s) or a hash of the
CA's root certificate), and enrollment keys and certificates.
Depending on the enterprise's acquisition and network management
practices, some initialization may be performed by the vendor prior
to client delivery. In that case, the client device vendor will
provide data, such as trust anchors, to the enterprise via a secure
procedural mechanism. The distribution of this initial information
is out of scope.
Distribution of trust anchors and certificates can be made through
the EST server. However, nothing can be inferred about the
authenticity of these trust anchors and certificates until an out-of-
band mechanism from the above list is used to verify them.
Sections 2.1-2.3 very closely mirror the text of the Scenarios
Appendix of [RFC6403] with such modifications as are appropriate for
this profile. (Our thanks are extended to the authors of that
document). More importantly, Sections 2.1-2.6 mirror the set of EST
functions (see Figure 4) and provide an informative overview of EST's
capabilities.
The client device begins by initiating a TLS-secured HTTP session
with the EST server. The specific EST service requested is named in
an operational URI portion. The client device and server
authenticate each other, and the client ascertains the authorization
of the server. The server ascertains the authorization of the client
and services the request.
2.1. Obtaining CA Certificates
The EST client can request a copy of the current CA certificates.
The EST client is assumed to perform this operation before performing
other operations.
The EST client authenticates and authorizes the EST server when
requesting the current CA certificates. As detailed in
Section 3.3.1.1 and Section 3.3.1.3) the available options include:
o Verifying the EST server's HTTPS URI against the EST server's
certificate using third party TAs (similar to a common HTTPS
exchange). This allows the EST server and client to leverage
existing TAs that might be known to the EST client.
o The client can leverage a previously distributed trust anchor
specific to the EST server. This allows the EST client to use an
existing, potentially older, CA certificate to request more recent
CA certificates.
Pritikin, et al. Expires April 25, 2013 [Page 6]
Internet-Draft EST October 2012
o For bootstrapping the the EST client can accept manual
authentication performed by the end user as detailed in
Section 4.3.2.
Client authentication is not required for this exchange, so it is
trivially supported by the EST server.
2.2. Initial Enrollment
After authenticating an EST server and verifying that it is
authorized to provide services to the client, an EST client can
acquire a certificate by submitting an enrollment request to that
server.
The EST server authenticates and authorizes the EST client as
specified in Section 3.3.1.2 and Section 4.2. The methods described
in the normative text that are expanded on in this overview include:
o Previously installed certificate (e.g., Manufacturer Installed
Certificate or 3rd party issued certificate);
o Username/password distributed out-of-band
2.2.1. Previously Installed Client Certificate
If the EST client has a previously installed certificate that was
issued by a 3rd party this certificate can be used to authenticate
the client's request for a certificate from the EST server's CA. An
EST client responds to the EST server's TLS certificate request
message with the existing certificate (i.e., it provides the
previously issued certificate to the EST server). The EST server
will authenticate the client's existing certificate and authorize the
client's request as described in Section 3.3.1.2.
2.2.2. Username/Password Distributed Out-of-Band
When the EST client is not authenticated during the TLS handshake
(see Section 3.3.1.2), or if the EST server wishes additional
authentication information, the EST server can requests that the EST
client submit a username/password using the HTTP Basic or Digest
Authentication methods. See Section 3.2.3.
Alternately, the server and client can mutually authenticate using
certificate-less TLS authentication (Section 3.3.1.3).
Pritikin, et al. Expires April 25, 2013 [Page 7]
Internet-Draft EST October 2012
2.3. Client Certificate Re-issuance
An EST client can renew/rekey an existing client certificate by
submitting a re-enrollment request to an EST server. As with initial
enrollment, the EST server authenticates the client using any
combination of the existing client certificate (see Section 3.3.1.2)
and/or HTTP Basic or Digest Authentication with a username/password
(see Section 3.2.3).
Two common renew/rekey scenarios for clients that are already
enrolled are described here. One addresses the renew/rekey of
signature certificates and the other addresses the renew/rekey of key
exchange certificates. The certification request message includes
the same Subject and SubjectAltName as the current key exchange
certificate with name changes handled as specified in Section 4.4.2.
2.3.1. Re-issuance of Signature Certificates
When a signature certificate is re-issued, the existing certificate
can be used by an EST client for authentication.
2.3.2. Re-issuance of Key Exchange Certificates
When a key exchange certificate is re-issued an existing signature
certificate is used by an EST client for authentication. If there is
no current signature certificate available, the EST server falls back
on the HTTP authentication method (Section 3.2.3).
2.4. Server Key Generation
The EST client can request a server-generated certificate and key
pair.
2.5. Full PKI Request messages
Full PKI Request messages can be transported via EST with the Full
CMC Request function, allowing access to functionality not provided
by the Simple Enrollment of Clients functions. Full PKI Request
messages are defined in Sections 3.2 and 4.2 of [RFC5272]. See
Section 4.5 for a discussion of how EST provides a transport for
these functions.
2.6. CSR (Certificate Signing Request) Attributes Request
Prior to sending an enrollment request to an EST server, an EST
client can query the EST server for the set of additional
attribute(s) that the client is requested to supply in the subsequent
enrollment request(s).
Pritikin, et al. Expires April 25, 2013 [Page 8]
Internet-Draft EST October 2012
3. Protocol Design and Layering
Figure 2 provides an expansion of Figure 1 describing how the layers
are used. Each aspect is described in more detail in the sections
that follow.
EST Layering:
Protocols and uses:
+---------------------------------------------------+
| |
| Message types: |
| - "Simple PKI" messages |
| (incorporating proof-of-possession) |
| - CA certificate retrieval |
| - "Full PKI" messages (OPTIONAL) |
| - CSR attribute request (OPTIONAL) |
| - Server-generated key request (OPTIONAL) |
| |
+---------------------------------------------------+
| |
| HTTP: |
| - HTTP headers and URIs for control |
| - Content-Type headers specify message type |
| - Headers for control/error messages |
| - URIs for selecting functions |
| - Basic or Digest authentication if no |
| client certificate |
| |
+---------------------------------------------------+
| |
| TLS for transport security |
| - Authentication is REQUIRED for EST server |
| OPTIONAL for EST clients |
| - Indirectly provides proof-of-identity for EST |
| - Provides communications integrity |
| - Channel Binding [RFC5929] to link |
| proof-of-identity with message-based |
| proof-of-possession. (OPTIONAL) |
| |
+---------------------------------------------------+
Figure 2
Specifying HTTPS as the secure transport for enrollment messages
introduces two 'layers' to communicate authentication and control
messages: TLS and HTTP.
Pritikin, et al. Expires April 25, 2013 [Page 9]
Internet-Draft EST October 2012
The TLS layer provides message authentication and integrity during
transport. The proof-of-identity is supplied by either the
certificate exchange during the TLS handshake or within the HTTP
layer headers. The message type along with control/error messages
are included in the HTTP headers.
The TLS and HTTP layer provided proof-of-identity means the CMC
[RFC5272] Section 3.1 note that "the Simple PKI Request MUST NOT be
used if a proof-of-identity needs to be included" is not applicable
and thus the Simple PKI message types are used.
The TLS layer certificate exchange provides a method for authorizing
client enrollment requests using existing certificates. Such
existing certificates may have been issued by the CA (from which the
client is requesting a certificate) or they may have been issued
under a distinct PKI (e.g., an IEEE 802.1AR IDevID [IDevID]
credential).
Proof-of-possession is a distinct issue from proof-of-identity and is
included in the Simple PKI message type as described in Section 3.4.
A method of linking proof-of-identity and proof-of-possession is
described in Section 3.5.
This document also defines transport for CMC [RFC5272] specification
compliant with CMC Transport Protocols [RFC5273].
During the protocol operations various different certificates can be
used. The following table provides an informative overview. End-
entities MAY have one or more certificates of each type listed in
Figure 3:
Pritikin, et al. Expires April 25, 2013 [Page 10]
Internet-Draft EST October 2012
Certificates/Trust-anchors and their corresponding uses:
+--------------+--------------------+-------------------------------+
| Certificate/ | Issuer | Use |
| TA database | | |
+==============+====================+===============================+
| EST server | The CA served by | Presented by the EST server |
| certificate | the EST server | during the TLS handshake |
| | | |
| | | Section: 3.3.1.1 |
+--------------+--------------------+-------------------------------+
| EST server | An unrelated CA | Presented by the EST server |
| certificate | e.g., a Web site | during the TLS handshake |
| | CA | |
| | | Section: 3.3.1.1 |
+--------------+--------------------+-------------------------------+
| EST client | Trust anchor for | EST clients use this |
| Trust Anchor | the CA issuing | trust anchor database to |
| Database | certificates. | authenticate certificates |
| | | issued by the CA, including |
| | | EST server certificates |
| | | Section 3.3.1.1 |
+--------------+--------------------+-------------------------------+
| EST client | Trust anchors for | EST clients can use this |
| third party | third party CAs | trust anchor database to |
| Trust Anchor | e.g., a list of | authenticate an EST server |
| Database | Web site CA root | that uses an externally |
| | certificates | issued certificate |
| | | Section: 3.3.1.1 |
+--------------+--------------------+-------------------------------+
| EST client | An unrelated CA | Presented by the EST client |
| certificate | e.g., a device | to the EST server by clients |
| | manufacturer | that have not yet enrolled |
| | | Section: 3.3.1.2 |
+--------------+--------------------+-------------------------------+
| EST client | The CA served by | Presented by the EST client |
| certificate | the EST server | to PKI End Entities. |
| | | Including to the EST server |
| | | during future EST operations |
| | | Section: 3.3.1.2 |
+--------------+--------------------+-------------------------------+
| EST client | The CA served by | Clients can obtain certs |
| certificate | the EST server | that can not be used for |
| | | EST authentication |
| | | (e.g., Key Encryption certs) |
| | | Section: 4.4.1 |
+--------------+--------------------+-------------------------------+
Pritikin, et al. Expires April 25, 2013 [Page 11]
Internet-Draft EST October 2012
Figure 3
3.1. Application Layer Design
An EST client SHOULD have its own client certificate suitable for TLS
client authentication (e.g., the digitalSignature bit is set). The
client certificate, if available, MUST be used when authenticating to
the EST server. If a client does not have a certificate, then the
client MUST use HTTP Basic or Digest authentication credentials (see
Section 3.2.3). HTTP authentication provides a bootstrap for clients
that have not yet been issued a certificate. EST clients obtaining a
certificates for other protocol purposes are RECOMMENDED to first
obtain an appropriate certificate for use when authenticating to the
EST server.
The client also SHOULD also have a CA certificate that will be used
to authenticate the EST server.
An EST client MUST be capable of generating and parsing Simple PKI
messages (see Section 4.4). Generating and parsing Full PKI messages
is OPTIONAL (see Section 4.5). The client MUST also be able to
request CA certificates from the EST server and parse the returned
"bag" of certificates (see Section 4.3). Requesting CSR attributes
and parsing the returned list of attributes is OPTIONAL (see
Section 4.7).
3.2. HTTP Layer Design
HTTP is used to transfer EST messages. URIs are provisioned for
handling each media type (i.e., message type) as described in
Section 3.2.2. HTTP is also used for client authentication services
when TLS client authentication is not available due to lack of a
client certificate suitable for use by TLS, as detailed in Section
Section 3.2.3. Registered media types are used to convey EST
messages as specified in Figure 5.
HTTP 1.1 [RFC2616] and above support persistent connections. As
given in Section 8.1 of that RFC persistent connections may be used
to reduce network and processing load associated with multiple HTTP
requests. EST does not require or preclude persistent HTTP
connections and their use is out of scope of this specification.
3.2.1. HTTP headers for control
This document profiles the HTTP content-type header (as defined in
[RFC2046], but see Figure 5 for specific values) to indicate the
media type for EST messages and to specify control messages for EST.
The HTTP Status value is used to communicate success or failure of
Pritikin, et al. Expires April 25, 2013 [Page 12]
Internet-Draft EST October 2012
EST functions Support for the HTTP authentication methods is
available for a client that does not have a certificate.
CMC uses the same messages for certificate renewal and certificate
rekey. This specification defines the renewal and rekey behavior of
both the client and server. It does so by using the HTTP control
mechanisms employed by the client and server as opposed to using CMC.
Various media types as indicated in the HTTP content-type header are
used to transfer EST messages. Media types used by EST are specified
in Section 3.2.4.
3.2.2. HTTP URIs for control
This profile supports six operations indicated by specific URIs:
Operations and their corresponding URIs:
+------------------------+-----------------+-------------------+
| Operation |Operation Path | Details |
+========================+=================+===================+
| Distribution of CA | /CACerts | Section 4.3 |
| certificates (MUST) | | |
+------------------------+-----------------+-------------------+
| Enrollment of new | /simpleEnroll | Section 4.4 |
| clients (MUST) | | |
+------------------------+-----------------+-------------------+
| Re-Enrollment of | /simpleReEnroll | Section 4.4.1 |
| existing clients (MUST)| | |
+------------------------+-----------------+-------------------+
| Full CMC (OPTIONAL) | /fullCMC | Section 4.5 |
+------------------------+-----------------+-------------------+
| Server-side Key | /serverKeyGen | Section 4.6 |
| Generation (OPTIONAL) | | |
+------------------------+-----------------+-------------------+
| Request CSR attributes | /CSRAttrs | Section 4.7 |
| (OPTIONAL) | | |
+------------------------+-----------------+-------------------+
Figure 4
An HTTP base path common for all of an EST server's requests is
defined in the form of an path-absolute ([RFC3986], section 3.3).
The operation path (Figure 4 is appended to the base path to form the
URI used with HTTP GET or POST to perform the desired EST operation.
An example:
With a base path of "/arbitrary/path" and an operation path of
Pritikin, et al. Expires April 25, 2013 [Page 13]
Internet-Draft EST October 2012
"/CACerts", the EST client would combine them to form an absolute
path of "/arbitrary/path/CACerts". Thus, to retrieve the CA's
certificates, the EST client would use the following HTTP request:
GET /arbitrary/path/CACerts HTTP/1.1
Likewise, to request a new certificate in this example scheme, the
EST client would use the following request:
POST /arbitrary/path/simpleEnroll HTTP/1.1
The mechanisms by which the EST server interacts with an HTTPS server
to handle GET and POST operations at these URIs is outside the scope
of this document. The use of distinct operation paths simplifies
implementation for servers that do not perform client authentication
when distributing /CACerts responses.
EST clients are provided with the base path URI of the EST server.
Potential methods of distributing the URI are discussed within the
Security Considerations (see Section 6 and Section 4.1).
An EST server MAY provide additional, services using other URIs.
An EST server MAY use multiple base paths in order to provide service
for multiple CAs. Each CA would use a distinct base path, but
operations are otherwise the same as specified for an EST server
operating on behalf of only one CA.
3.2.3. HTTP-Based Client Authentication
An EST server that has authenticated itself to the client MAY request
HTTP-based client authentication. This request can be in addition to
successful TLS client authentication (Section 3.3.1.2) if EST server
policy requires additional authentication (for example the EST server
wishes to confirm the EST client "knows" a password in addition to
"having" an existing client certificate). Or HTTP-based client
authentication can be an EST server policy specified fallback in
situations where the EST client did not successfully complete the TLS
client authentication (for example if the EST client is enrolling for
the first time or the existing EST client certificates can not be
used for TLS client authentication).
HTTP Basic and Digest authentication MUST only be performed over TLS
1.1 [RFC4346] (or later). As specified in CMC: Transport Protocols
[RFC5273] the server "MUST NOT assume client support for any type of
HTTP authentication such as cookies, Basic authentication, or Digest
authentication". Clients intended for deployments where password
authentication is advantageous SHOULD support the Basic and Digest
Pritikin, et al. Expires April 25, 2013 [Page 14]
Internet-Draft EST October 2012
authentication mechanism. Servers MAY provide configuration
mechanisms for administrators to enable Basic and Digest
authentication methods.
Servers that wish to use Basic and Digest authentication reject the
HTTP request using the HTTP defined WWW-Authenticate response-header
([RFC2616], Section 14.47). At that point the client SHOULD repeat
the request, including the appropriate Authorization Request Header
([RFC2617], Section 3.2.2) if the client is capable of using the
Basic or Digest authentication. If the client is not capable then
the client MUST terminate the connection.
Clients MAY set the username to the empty string ("") if they wish to
present a "one-time password" or "PIN" that is not associated with a
username.
Support for HTTP-based client authentication has security
ramifications as discussed in Section 6. The client MUST NOT respond
to the server's HTTP authentication request unless the client has
authenticated the EST server (as per Section 4.1).
3.2.4. Message types
This document uses existing media types for the messages as specified
by [RFC2585], [RFC5967], and CMC [RFC5272]. To support distribution
of multiple certificates for the CA certificate chain, the [RFC2046]
multipart/mixed media type is used.
The message type is specified in the HTTP Content-Type header with a
media type. The use herein is consistent with [RFC5273].
For reference the messages and their corresponding media types are:
Pritikin, et al. Expires April 25, 2013 [Page 15]
Internet-Draft EST October 2012
+--------------------+--------------------------+-------------------+
| Message type |Request media type | Request section |
| |Response media type | Response section |
| |Source(s) of types | |
+====================+==========================+===================+
| CA certificate | N/A | Section 4.3 |
| request | application/pkcs7-mime | Section 4.3.1 |
| | [RFC5751] | |
+--------------------+--------------------------+-------------------+
| Cert enroll/renew/ | application/pkcs10 | Section 4.4/4.4.1 |
| rekey | application/pkcs7-mime | Section 4.4.2 |
| | [RFC5967] [RFC5751] | |
+--------------------+--------------------------+-------------------+
| Full CMC | application/pkcs7-mime | Section 4.5.1 |
| | application/pkcs7-mime | Section 4.5.2 |
| | [RFC5751] | |
+--------------------+--------------------------+-------------------+
| Server-side Key | application/pkcs10 | Section 4.6.1 |
| Generation | multipart/mixed | Section 4.6.2 |
| | (application/pkcs7-mime &| |
| | application/pkcs8) | |
| | [RFC5967] [RFC5751] | |
+--------------------+--------------------------+-------------------+
| Request CSR | N/A | Section 4.7.1 |
| attributes | application/csrattrs | Section 4.7.2 |
| | This RFC | |
+--------------------+--------------------------+-------------------+
Figure 5
3.3. TLS Layer Design
TLS provides communications security for the layers above it. The
integrity and authentication services it provides are leveraged to
supply proof-of-identity and to allow authorization decisions to be
made. The higher layer EST server and EST client are responsible for
ensuring that an acceptable cipher suite is used and that
bidirectional authentication has been established. Alternately,
certificate-less TLS authentication-- where neither the client nor
server present a certificate-- is also an acceptable method for EST
server and client authentication.
When the EST server uses a certificate for authentication, TLS client
authentication is the preferred method for identifying EST clients.
If the EST client does not yet have a suitable client certificate the
EST server can request HTTP Basic or Digest authentication protected
by the TLS encryption. Alternately, certificate-less TLS
Pritikin, et al. Expires April 25, 2013 [Page 16]
Internet-Draft EST October 2012
authentication-- where neither the client nor server present a
certificate-- is also an acceptable method for EST client
authentication.
TLS channel binding information may be optionally inserted into a
certificate request as detailed in Section 3.5 in order to provide
the EST server with assurance that the authenticated TLS client
entity has possession of the private key for the certificate being
requested.
3.3.1. TLS for transport security
HTTPS [RFC2818] and specifies how HTTP messages are carried over TLS.
HTTPS MUST be used. TLS 1.1 [RFC4346] (or later) SHOULD be
supported. TLS session resumption [RFC5077] SHOULD be supported.
3.3.1.1. TLS-Based Server Authentication
The EST client authenticates the EST server as appropriate for the
cipher suite negotiated. The following provides details assuming the
TLS 1.1 [RFC4346] Section 9 Mandatory Cipher Suite
TLS_RSA_WITH_3DES_EDE_CBC_SHA with a TLS server certificate presented
during the TLS 1.1 [RFC4346] (or later) exchange-defined Server
Certificate message. As an alternative to authentication using a
certificate, an EST client MAY support certificate-less TLS
authentication (Section 3.3.1.3).
Certificate validation MUST be performed as given in [RFC5280] and
[RFC6125]. The EST server certificate MUST conform to the [RFC5280]
certificate profile.
The client validates the TLS server certificate using local TAs,
which may be in the form of certificates. If certificate
verification fails the client MAY follow the procedure outlined in
Section 4.3.2 for bootstrap distribution of CA certificates.
The EST client MUST perform authorization checks as specified in
Section 4.1.
3.3.1.2. TLS-Based Client Authentication
The EST server MUST authenticate the EST client as appropriate for
the cipher suite negotiated. The following provides details assuming
the TLS 1.1 [RFC4346] Section 9 Mandatory Cipher Suite
TLS_RSA_WITH_3DES_EDE_CBC_SHA with a TLS client certificate presented
during the TLS 1.1 [RFC4346] (or later) exchange-defined Client
certificate message. As an alternative to authentication using a
certificate, an EST server MAY support certificate-less TLS
Pritikin, et al. Expires April 25, 2013 [Page 17]
Internet-Draft EST October 2012
authentication. (Section 3.3.1.3)
Clients SHOULD support [RFC4346]-defined (or later) Certificate
request (section 7.4.4). As required by [RFC4346], the client
certificate needs to indicate support for digital signatures. The
client SHOULD support this method in order to leverage
/simpleReEnroll using client authentication by existing certificate.
If a client does not support TLS client authentication, then it MUST
support HTTP-based client authentication. (Section 3.2.3).
The EST server MUST perform authorization checks as specified in
Section 4.2.
3.3.1.3. Certificate-less TLS Mutual Authentication
The client and server MAY negotiate a certificate-less cipher suite
for mutual authentication. When using certificate-less mutual
authentication in TLS for enrollment, the cipher suite MUST be
resistant to dictionary attack and MUST provide sufficient
information to perform the authorization checks. For example if the
cipher suite uses a pre-shared secret, provisioned in an out-of-band
fashion, as a credential to perform mutual authentication then
knowledge of the pre-shared secret implies authorization as a peer in
the exchange.
3.4. Proof-of-Possession
As defined in Section 2.1 of CMC [RFC5272], Proof-of-possession (POP)
"refers to a value that can be used to prove that the private key
corresponding to the public key is in the possession and can be used
by an end-entity."
The signed enrollment request provides a "Signature"-based proof-of-
possession. The mechanism described in Section 3.5 strengthens this
by optionally including "Direct"-based proof-of-possession by
including TLS session specific information within the data covered by
the enrollment request signature (thus linking the enrollment request
to the authenticated end-point of the TLS connection).
3.5. Linking Identity and POP information
This specification provides an OPTIONAL method of linking identity
and proof-of-possession by including information specific to the
current authenticated TLS session within the signed certification
request. Clients MAY use this method as a result of client
configuration. If configuration is not possible the client can
determine that this method is required by parsing the error responses
Pritikin, et al. Expires April 25, 2013 [Page 18]
Internet-Draft EST October 2012
or by examining the CSR Attributes Response (see Section 4.7.2).
Linking identity and proof-of-possession proves to the server that
the authenticated TLS client has possession of the private key
associated with the certification request and that the client was
able to sign the certification request after the TLS session was
established. This is an alternative to the [RFC5272] Section 6.3-
defined "Linking Identity and POP information" method available if
Full PKI messages are used.
The client generating the request obtains the tls-unique value as
defined in Channel Bindings for TLS [RFC5929] from the TLS subsystem.
The tls-unique specification includes a synchronization issue as
described in Channel Bindings for TLS [RFC5929] section 3.1. To
avoid this problem EST implementations MUST use the tls-unique value
from the first TLS handshake. EST clients and servers use their tls-
unique implementation specific synchronization methods to obtain this
first tls-unique value. TLS "secure_renegotiation" [RFC5746] MUST be
used. This maintains the binding from the first tls-unique value
across renegotiations to the most recently negotiated connection.
The tls-unique value is Base 64 encoded as specified in Section 4 of
[RFC4648] and the resulting string is placed in the certification
request challenge-password field ([RFC2985], Section 5.4.1). If tls-
unique information is not embedded within the certification request
the challenge-password field MUST be empty to indicate that the
client did not include the optional channel-binding information (any
value submitted is verified by the server as tls-unique information).
The EST server MUST verify the tls-unique information embedded within
the certification request according to server policy regarding the
authenticated client. If the EST server forwards the request to
back-end infrastructure for processing it is RECOMMENDED that the
results of this verification be communicated. (For example this
communication might use the CMC "RA POP Witness Control" in a CMC
Full PKI Request message or the back-end infrastructure might
authenticate the EST server as being a trusted infrastructure element
that does not forward invalid requests. A detailed discussion of
back-end processing is out of scope).
When rejecting requests the EST server response is as described for
all enroll responses (Section 4.4.3). If a Full PKI Response is
included the CMCFailInfo MUST be set to popFailed. If a human
readable reject message is included it SHOULD include an informative
text message indicating that linking of identity and POP information
is required.
Pritikin, et al. Expires April 25, 2013 [Page 19]
Internet-Draft EST October 2012
4. Protocol Exchange Details
Before processing a request, an EST server determines if the client
is authorized to receive the requested services. Likewise, the
client determines if it will accept services from the EST server.
These authorization decisions are described in the next two sections.
Assuming that both sides of the exchange are authorized, then the
actual operations are as described in the sections that follow.
4.1. Server Authorization
The client MUST check the EST server authorization before accepting
any server responses or responding to HTTP authentication requests.
When the server authenticates with a certificate the client MUST
check the URI "against the server's identity as presented in the
server's Certificate message" (HTTP Over TLS Section 3.1 "Server
Identity" [RFC2818] and [RFC6125]). The provisioned URI provides the
authorization statement and the server's authenticated identity
confirms it is the authorized server. Successful authentication
using a certificate-less cipher suite implies authorization of the
server.
If the URI does not match the server identity check then the TLS
server certificate MUST contain the id-kp-cmcRA [CMC RFC6402]
extended key usage extension and the TLS server certificate MUST be
issued by the CA the EST server is providing services for.
The client MUST maintain the distinction between the EST specific TA
for the CA issuing certificates and the TAs for third party CAs in
order to make this determination (see, Section 3).
If these checks fail then authorization of the EST server does not
occur except for as specified in Section 4.3.2.
4.2. Client Authorization
When the EST server receives a Simple PKI Request or rekey/renew
message, the decision to issue a certificate is always the CA's. The
EST server configuration reflects the CA policy and can use any data
it wishes in determining whether to issue the certificate (e.g. CSR
attributes, client identity, linking of client identity and proof-of-
possession, etc). The details are out-of-scope. EST provides the
EST server access to client's authenticated identity-- e.g. the TLS
client's certificate in addition to any HTTP user authentication
credentials-- to help in implementing configured policy.
If the client's authenticated certificate was issued by the EST
Pritikin, et al. Expires April 25, 2013 [Page 20]
Internet-Draft EST October 2012
server CA and includes the id-kp-cmcRA [RFC6402] extended key usage
extension then the CA SHOULD apply policy consistent with a client
that is acting as an RA (such as policy to support enrollment
requests initiated either by the RA itself or by clients that are in
communication with the RA).
4.3. Distribution of CA certificates
The EST client can request a copy of the current CA certificates and
this function is generally performed before other EST functions.
4.3.1. Distribution of CA certificates request
EST clients MAY request TA information of the CA (in the form of
certificates) with an HTTPS GET message with an operation path of
"/CACerts". EST clients and servers MUST support the /CACerts
function. Clients SHOULD request an up-to-date response before
stored information has expired in order to maintain continuity of
trust.
The EST server SHOULD NOT require client authentication or
authorization to reply to this request.
The client MUST authenticate the EST server as specified in
Section 3.3.1 and check the server's authorization as given in
Section 4.1 or follow the procedure outlined in Section 4.3.2.
4.3.2. Bootstrap Distribution of CA certificates
If the TLS authentication or authorization fails then the client MAY
provisionally continue the TLS handshake to completion for the
purposes of accessing the /CACerts or /fullCMC method. If the EST
client continues with an unauthenticated connection the EST client
MUST extract the HTTP content data from the response (Section 4.3.3
or Section 4.5.2) and engage the end-user to authorize the CA
certificate using out-of-band pre-configuration data such as a CA
certificate "fingerprint" (e.g., a SHA-1, SHA-256, SHA-512 [SHS], or
MD5 [RFC1321] hash on the whole CA certificate). In a /fullCMC
response it is the Publish Trust Anchors control within the Full PKI
Response that must be accepted manually. It is incumbent on the end
user to properly verify the fingerprint or to provide valid out-of-
band data necessary to verify the fingerprint.
HTTP authentication requests MUST NOT be responded to since the
server is unauthenticated. The EST client uses the /CACerts response
to build the trust anchor for subsequent TLS server authentication.
EST clients MUST NOT make any other protocol exchange until after the
/CACerts response has been accepted and a new TLS session
Pritikin, et al. Expires April 25, 2013 [Page 21]
Internet-Draft EST October 2012
established.
4.3.3. Distribution of CA certificates response
The EST server responds to the client HTTPS GET request with an HTTP
GET response that includes CA trust anchor information, in the form
of certificates within the Simple PKI Response. If the certificates
are successfully returned, the server response MUST have an HTTP 200
response code with a content-type of "application/pkcs7-mime". Any
other response code indicates an error and the client should abort
the protocol.
The EST server MUST include the current CA certificate in the
response. The EST server MUST include any additional certificates
the client would need to build a chain to the current root CA
certificate. For example if the EST server is configured to use a
subordinate CA when signing new client requests then the appropriate
subordinate CA certificates to chain to the root CA are included in
this response.
If support for the CMP root certificate update mechanism is provided
by the CA then the server MUST include the three "Root CA Key Update"
certificates OldWithOld, OldWithNew, and NewWithOld. These are
defined in Section 4.4 of CMP [RFC4210].
The client can always find the current TA in the form of a self-
signed certificate by examining the received certificates. The CA's
most recent self signed certificate (e.g. NewWithNew certificate) is
self-signed and has the latest NotAfter date.
The most recent CA certificate is the certificate that is extracted
and authorized using out-of-band information as described in
Section 4.3.2. After out-of-band validation occurs each of the other
certificates MUST be validated using normal [RFC5280] certificate
path validation (using the most recent CA certificate as the TA)
before they can be used to build certificate paths during certificate
validation.
The response format is the CMC Simple PKI Response as defined in
[RFC5272]. The HTTP content-type of "application/pkcs7-mime" is
used. The Simple PKI response is Base64 encoded, as specified in
Section 4 of [RFC4648], and sandwiched between headers:
Pritikin, et al. Expires April 25, 2013 [Page 22]
Internet-Draft EST October 2012
-----BEGIN PKCS7-----
MIIBhDCB7gIBADBFMQswCQYDVQQGEwJBVTETMBEGA1UECBMKU29tZS1TdGF0ZTEh
Simplified example of Base64 encoding of CMC Simple PKI Response
ED8rf3UDF6HjloiV3jBnpetx4JjZH/BlmD9HMqofVEryb1e4iZgMUvuIgwEjQwpD
8J4OhHvLh1o=
-----END PKCS7-----
4.4. Client Certificate Request Functions
EST clients MAY request a certificate from the EST server with an
HTTPS POST using the operation path value of "/simpleEnroll". The
EST server MUST support the /simpleEnroll function. EST clients MAY
request a renew/rekey of existing certificates with an HTTP POST
using the operation path value of "/simpleReEnroll". The EST server
SHOULD support the /simpleReEnroll function.
The client is RECOMMENDED to have obtained the current CA
certificates using Section 4.3 before performing certificate request
functions to ensure it can validate the EST server certificate. The
client MUST authenticate the EST server as specified in
Section 3.3.1.1. The client MUST authorize the EST server as
specified in Section 4.1.
The server MUST check client authentication as specified in
Section 3.3.1.2. The server MUST check client authorization as
specified in Section 4.2. The EST server MUST check the tls-unique
value as described in Section 3.5.
The server MAY accept the certificate request for manual
authorization by the administrator. (Section 4.4.3 describes the use
of an HTTP 202 response to the EST client if this occurs).
4.4.1. Simple Enrollment of Clients
When HTTPS POSTing to /simpleEnroll the client MUST include a Simple
PKI Request as specified in CMC Section 3.1 (i.e., a PKCS#10
Certification Request).
The Certification Request signature provides proof-of-possession of
the private key to the EST server. If the requested KeyUsage
extensions support digital signing operations then the certification
request signature MUST be generated using the private key
corresponding to the public key in the CertificationRequestInfo. If
the requested KeyUsage extensions do not allow for digital signing
operations the request MAY sign the certificate request, however the
private key MUST NOT be used to perform signature operations after
certificate issuance. The use of /fullCMC operations provides access
to more advanced proof-of-possession methods that SHOULD be used when
Pritikin, et al. Expires April 25, 2013 [Page 23]
Internet-Draft EST October 2012
the keys are not available for digital signing operations. This is
consistent with the recommendations concerning submission of proof-
of-possession to an RA or CA as described in [SP-800-57-Part-1].
The HTTP content-type of "application/pkcs10" is used. The format of
the message is as specified in Section 6.4 of [RFC4945].
The client MAY request an additional certificate even when using an
existing certificate in the TLS client authentication. For example
the client can use an existing signature certificate to request a key
exchange certificate.
4.4.2. Simple Re-Enrollment of Clients
EST clients renew/rekey certificates with an HTTPS POST using the
operation path value of "/simpleReEnroll". EST clients and server
MUST support the /simpleReEnroll function.
The certificate request is the same format as for the "simpleEnroll"
request with the same HTTP content-type. The request Subject and
SubjectAltName field(s) MUST contain the identity of the certificate
being renewed/rekeyed. The ChangeSubjectName attribute, as defined
in [RFC6402], MAY be included in the certificate request.
If the public key information in the certification request is the
same as the currently issued certificate the EST server performs a
renew operation. If the public key information is different than the
currently issued certificate then the EST server performs a rekey
operation. The specifics of these operations are out of scope of
this profile.
4.4.3. Simple Enroll and Re-Enroll Response
If the enrollment is successful, the server response MUST have an
HTTP 200 response code with a content-type of "application/
pkcs7-mime". The response data is a degenerate certs-only Simple PKI
Response containing only the certificate issued. The Simple PKI
response is Base64 encoded and sandwiched between headers:
-----BEGIN PKCS7-----
MIIBhDCB7gIBADBFMQswCQYDVQQGEwJBVTETMBEGA1UECBMKU29tZS1TdGF0ZTEh
Simplified example of Base64 encoding of CMC Simple PKI Response
ED8rf3UDF6HjloiV3jBnpetx4JjZH/BlmD9HMqofVEryb1e4iZgMUvuIgwEjQwpD
8J4OhHvLh1o=
-----END PKCS7-----
When rejecting a request the server MUST specify either an HTTP 4xx/
401 error, or an HTTP 5xx error. A PKI Response with an HTTP
Pritikin, et al. Expires April 25, 2013 [Page 24]
Internet-Draft EST October 2012
content-type of "application/pkcs7-mime" (see Section 4.5.2) MAY be
included in the response data for any error response. If the
content-type is not set, the response data MUST be a plain text
human-readable error message containing informative information
concerning why the request was rejected (for example indicating that
CSR attributes are incomplete). A client MAY elect not to parse a
CMC error response in favor of a generic error message.
If the server responds with an HTTP [RFC2616] 202 this indicates that
the request has been accepted for processing but that a response is
not yet available. The server MUST include a Retry-After header as
defined for HTTP 503 responses and MAY include informative human-
readable content. The client MUST wait at least the specified
'retry-after' time before repeating the same request. The client
repeats the initial enrollment request after the appropriate 'retry-
after' interval has expired. The client SHOULD log or inform the end
user of this event. The server is responsible for maintaining all
state necessary to recognize and handle retry operations as the
client is stateless in this regard (it simply sends the same request
repeatedly until it receives a different response code).
All other return codes are handled as specified in HTTP [RFC2616].
If the EST client has not obtained the current CA certificates using
Section 4.3 then it may not be able to validate the certificate
received.
4.5. Full CMC
EST clients can also request a certificate from the EST server with
an HTTPS POST using the operation path value of "/fullCMC". Support
for the /fullCMC function is OPTIONAL.
The client SHOULD authenticate the server as specified in Server
Authentication (Section 3.3.1.1). Bootstrap distribution of CA
certificates is specified in Section 4.3.2.
The server SHOULD authenticate the client as specified in
Section 3.3.1. The server MAY depend on CMC client authentication
methods instead.
4.5.1. Full CMC Request
If the HTTP POST to /fullCMC is not a valid Full PKI Request, the
server MUST reject the message. The HTTP content-type used is
"application/pkcs7-mime", as specified in [RFC5273].
Pritikin, et al. Expires April 25, 2013 [Page 25]
Internet-Draft EST October 2012
4.5.2. Full CMC Response
The server responds with the client's newly issued certificate or
provides an error response.
If the enrollment is successful the server response MUST have an HTTP
200 response code with a content-type of "application/pkcs7-mime" as
specified in [RFC5273]. The response data includes either the Simple
PKI Response or the Full PKI Response.
When rejecting a request the server MAY specify either an HTTP 4xx/
401 error or an HTTP 5xx error. A CMC response with content-type of
"application/pkcs7-mime" SHOULD be included in the response data for
any CMC error response. The client parses the CMC response to
determine the current status.
All other return codes are handled as specified in Section 4.4.3 or
HTTP [RFC2616]. For example the client interprets a HTTP 404 or 501
response to indicate that this service is not implemented.
The Full PKI Response is Base64 encoded and sandwiched between
headers:
-----BEGIN PKCS7-----
MIIBhDCB7gIBADBFMQswCQYDVQQGEwJBVTETMBEGA1UECBMKU29tZS1TdGF0ZTEh
Simplified example of Base64 encoding of CMC Full PKI Response
ED8rf3UDF6HjloiV3jBnpetx4JjZH/BlmD9HMqofVEryb1e4iZgMUvuIgwEjQwpD
8J4OhHvLh1o=
-----END PKCS7-----
4.6. Server-side Key Generation
[[EDNOTE: This section includes references
[draft-ietf-pkix-cmc-serverkeygeneration-00] which has not yet been
published.]]
EST clients request a "private" key and associated certificate from
the EST server with an HTTPS POST using the operation path value of
"/serverKeyGen". Support for the /serverKeyGen function is OPTIONAL.
The client MUST authenticate the server as specified in
Section 3.3.1.1. The EST client is RECOMMENDED to have obtained the
current CA certificates using Section 4.3 to ensure it can validate
the EST server certificate.
The EST server MUST authenticate the client as specified in
Section 3.3.1. The server SHOULD use TLS-Based Client Authentication
for authorization purposes. The EST server applies whatever
Pritikin, et al. Expires April 25, 2013 [Page 26]
Internet-Draft EST October 2012
authorization or policy logic it chooses to determine if the
"private" key and certificate should be generated.
Proper random number and key generation [RFC4086] as well as storage
is a server implementation responsibility. The key pair and
certificate are transferred over the TLS session; the EST server MUST
verify that the current cipher suite is acceptable for securing the
key data.
4.6.1. Server-side Key Generation Request
The certificate request is HTTPS POSTed and is the same format as for
the "/simpleEnroll" and "/simpeReEnroll" path extensions with the
same content-type.
The Subject and SubjectAltName field(s) or ChangeSubjectName
attribute in the request MAY, as can all fields in a CSR, be ignored
by the server as these are only requests. The server uses these
fields, along with the authenticated client identity and server
policy, to determine if it wishes to generate a new "private" key
when servicing the request or re-use an escrowed "private" key. The
client MAY request multiple keys and certificates.
In all respects the server SHOULD treat the request as it would any
enroll or re-enroll request; with the only distinction being that the
server MUST ignore the public key values of the certificate request
and the request signature. These are included in the request only to
allow re-use of existing codebases for generating and parsing such
requests.
4.6.2. Server-side Key Generation Response
If the request is successful the server response MUST have an HTTP
200 response code with a content-type of "multipart/mixed" consisting
of two parts. One part is the "private" key data and the other part
is the certificate data.
The "private" key data MAY be an "application/pkcs8" consisting of
the Base64 encoded DER-encoded PrivatekeyInfo sandwiched between the
headers as described in [RFC5958]. Alternatively the "private" key
data SHOULD be an "application/pkcs7-mime" containing a CMS [RFC5652]
message (also as described in [RFC5958]). The content of this
message is an EncryptedData or EnvelopedData content type containing
the binary DER-encoded PrivatekeyInfo. The RecipientInfo MAY use any
valid key management technique as determined by server policy and
authenticated client identity. For example when the client uses a
TLS client certificate for authentication the server can use this as
the KeyTransRecipientInfo rid. The use of a CMS provides security to
Pritikin, et al. Expires April 25, 2013 [Page 27]
Internet-Draft EST October 2012
the AsymmetricKeyPackage:
-----BEGIN PRIVATE KEY-----
MIIBhDCB7gIBADBFMQswCQYDVQQGEwJBVTETMBEGA1UECBMKU29tZS1TdGF0ZTEh
Simplified example of Base64 encoding of DER-encoded PrivateKeyInfo
ED8rf3UDF6HjloiV3jBnpetx4JjZH/BlmD9HMqofVEryb1e4iZgMUvuIgwEjQwpD
8J4OhHvLh1o=
-----END PRIVATE KEY-----
The certificate data part is an "application/pkcs7-mime" and exactly
matches the certificate response to /simpleEnroll. If both parts are
"application/pkcs7-mime" the client checks each (one will be a certs-
only Simple PKI response and the other will be the CMS message with
the encrypted data).
When rejecting a request the server MUST specify either an HTTP 4xx/
401 error, or an HTTP 5xx error. If the content-type is not set the
response data MUST be a plain text human-readable error message.
Future work might define addtional certification request attributes
to communicate key management information in addition to using the
client's authenticated identity. Such attributes are out-of-scope of
this document.
4.7. CSR Attributes
The CA MAY want to include client-provided attributes in certificates
that it issues and some of these attributes may describe information
that is not available to the CA. For this reason, the EST client MAY
request a set of attributes from the EST server to include in its
certification request.
4.7.1. CSR Attributes Request
The EST Client MAY request a list of CA-desired CSR attributes from
the CA by sending an HTTPS GET message to the EST server with an
operations path of "/CSRAttrs". Clients SHOULD request such a list
if they have no a priori knowledge of what attributes are desired by
the CA in an enrollment request or when dictated by policy.
4.7.2. CSR Attributes Response
If policy for the authenticated EST client indicates a CSR Attributes
Response will be provided the server response MUST have an HTTP 200
response code. An HTTP response code of 204 or 404 indicates that a
CSR Attributes Response is not available. Regardless of the response
code the EST server and CA MAY reject any subsequent enrollment
requests for any reason, including incomplete CSR attributes in the
Pritikin, et al. Expires April 25, 2013 [Page 28]
Internet-Draft EST October 2012
request.
Responses to attribute request messages MUST be encoded as content
type "application/csrattrs". The syntax for application/csrattrs
body is as follows:
Csrattrs ::= SEQUENCE SIZE (0..MAX) OF OBJECT IDENTIFIER { }
Servers include zero or more object identifiers that they wish the
client to include in their certification request. When the server
encodes Csrattrs as an empty SEQUENCE it means that the server has no
specific additional attributes it wants in the client certification
requests (this is functionally equivalent to an HTTP response code of
204 or 404). The sequence is DER (preferred) or BER encoded and then
base64 encoded (section 4 of [RFC4648]). The resulting text forms
the application/csrattr body, without headers.
For example, if a CA wishes the authenticated client to submit a
certification request containing the MAC address [RFC2397] of a
device and the challengePassword (indicating that Linking of Identity
and POP information is requested, see Section 3.5) it takes the
following object identifiers:
o macAddress: 1.3.6.1.1.1.1.22
o challengePassword: 1.2.840.113549.1.9.7
and encodes them into an ASN.1 SEQUENCE to produce:
30 14 06 07 2B 06 01 01 01 01 16 06 09 2A 86 48 86 F7 0D 01 09 07
and then base64 encodes the resulting ASN.1 SEQUENCE to produce:
MBQGBysGAQEBARYGCSqGSIb3DQEJBw==
The EST client parses the response OID's and handles each OID
independently on a best effort basis. When an OID indicates a known
CSR attribute type the client SHOULD include that CSR attribute in
the subsequent CSR submitted, either in the CSR attributes or in any
other appropriate CSR field. When an OID is of an unknown type the
OID MAY be ignored by the client.
5. IANA Considerations
(This section is incomplete)
IANA is requested to register the following:
Pritikin, et al. Expires April 25, 2013 [Page 29]
Internet-Draft EST October 2012
IANA SHALL update the Application Media Types registry with the
following filled-in template from [RFC4288].
The media subtype for Attributes in a CertificationRequest is
application/csrattrs.
Type name: application
Subtype name: csrattrs
Required parameters: None
Optional parameters: None
Encoding considerations: binary;
Security Considerations:
Clients request a list of attributes that servers wish to be in
certification requests. The request/response SHOULD be done in
a TLS-protected tunnel.
Interoperability considerations: None
Published specification: This memo.
Applications which use this media type:
Enrollment over Secure Transport (EST)
Additional information:
Magic number(s): None
File extension: None
Macintosh File Type Code(s):
Person & email address to contact for further information:
Dan Harkins <dharkins@arubanetworks.com>
Restrictions on usage: None
Author: Dan Harkins <dharkins@arubanetworks.com>
Intended usage: COMMON
Pritikin, et al. Expires April 25, 2013 [Page 30]
Internet-Draft EST October 2012
Change controller: The IESG
6. Security Considerations
Support for Basic authentication as specified in HTTP [RFC2617]
allows the server access to the client's cleartext password. This
provides integration with legacy username/password databases but
requires exposing the plaintext password to the EST server. Use of a
PIN or one-time-password can help mitigate concerns but EST clients
are RECOMMENDED to use such credentials only once to obtain an
appropriate client certificate to be used during future interactions
with the EST server.
When the client uses a third party trust anchor database for
certificate validation (see Section 3) then authorization proceeds as
specified in Section 4.1. In this situation the client has validated
the server as being a valid responder for the URI configured but can
not directly verify that the responder is authorized as an RA within
the to-be-enrolled-in PKI hierarchy. Possible avenues for an attack
could be an erroneous URI injected into the client via an initial
configuration method, or the server could have compromised a third
party trust anchor to obtain an apparently valid server certificate.
Clients using a third party trust anchor database are RECOMMENDED to
only use TLS-based client authentication (to prevent leaking HTTP-
based Client Authentication information). Such clients are
RECOMMENDED to include "Linking Identity and POP information"
(Section 3.5) in requests (to minimize the chance that such requests
could be proxied to the real EST server). Additionally it is
RECOMMENDED that the third party trust anchor database available for
EST server authentication be carefully constructed (to reduce the
risk of improperly managed third party CAs).
When using a certificate-less TLS cipher suite, the shared secret
used for authentication and authorization MUST be known only to the
two parties to the exchange-- the client and the server. Any sharing
of secrets completely voids the security afforded by a certificate-
less cipher suite. Exposure of a shared secret used by a
certificate-less cipher suite to a third party enables client
impersonation that can results in corruption of a client's trust
anchor database.
Any certificate-less TLS cipher suite used with EST MUST be resistant
to dictionary attack. This means that the advantage an adversary
gains through attack MUST be related to interaction and not
computation. Certificate-less TLS cipher suites used with EST MUST
also be based on a zero knowledge protocol to enable proof of
knowledge of the shared secret without exposure of the shared secret
Pritikin, et al. Expires April 25, 2013 [Page 31]
Internet-Draft EST October 2012
(or any derived data which can be used to determine the secret).
These requirements mean that the adversary gains advantage solely
through active attack and the only thing learned from each active
attack is whether a single guess of the secret is successful or not.
Implementations of EST that support certificate-less TLS cipher
suites SHOULD provide countermeasures-- for example, exponential back
off after failed attempts or locking of an account after a certain
number of unsuccessful attempts-- to mitigate repeated active
attacks.
As described in CMC Section 6.7, "For keys that can be used as
signature keys, signing the certification request with the private
key serves as a POP on that key pair". The inclusion of tls-unique
within the certification request links the proof-of-possession to the
TLS proof-of-identity by enforcing that the POP operation occured
while the TLS session is active. This strongly implies to the server
that it is the authenticated client that has possession of the
private key. If client authentication indicates a client with
specific known behaviour this implication is strengthened but not
proven.
The server-side key generation method allows keys to be transported
over the TLS connection to the client. The distribution of "private"
key material is inherently risky and servers are NOT RECOMMENDED to
support this operation by default. Clients are NOT RECOMMENDED to
request this service unless there is a compelling operational
benefit. Use of a third party trust anchor database is NOT
RECOMMENDED for server-side key generation. The use of an encrypted
CMS Server-side Key Generation Response is RECOMMENDED.
Regarding the CSR attributes that the CA may list for inclusion in an
enrollment request, there are no real inherent security issues with
the content being conveyed but an adversary who is able to interpose
herself into the conversation could exclude attributes that a server
may want, include attributes that a server may not want, and render
meaningless other attributes that a server may want.
7. References
7.1. Normative References
[RFC1321] Rivest, R., "The MD5 Message-Digest Algorithm", RFC 1321,
April 1992.
[RFC2046] Freed, N. and N. Borenstein, "Multipurpose Internet Mail
Extensions (MIME) Part Two: Media Types", RFC 2046,
November 1996.
Pritikin, et al. Expires April 25, 2013 [Page 32]
Internet-Draft EST October 2012
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2314] Kaliski, B., "PKCS #10: Certification Request Syntax
Version 1.5", RFC 2314, March 1998.
[RFC2585] Housley, R. and P. Hoffman, "Internet X.509 Public Key
Infrastructure Operational Protocols: FTP and HTTP",
RFC 2585, May 1999.
[RFC2616] Fielding, R., Gettys, J., Mogul, J., Frystyk, H.,
Masinter, L., Leach, P., and T. Berners-Lee, "Hypertext
Transfer Protocol -- HTTP/1.1", RFC 2616, June 1999.
[RFC2617] Franks, J., Hallam-Baker, P., Hostetler, J., Lawrence, S.,
Leach, P., Luotonen, A., and L. Stewart, "HTTP
Authentication: Basic and Digest Access Authentication",
RFC 2617, June 1999.
[RFC2818] Rescorla, E., "HTTP Over TLS", RFC 2818, May 2000.
[RFC2985] Nystrom, M. and B. Kaliski, "PKCS #9: Selected Object
Classes and Attribute Types Version 2.0", RFC 2985,
November 2000.
[RFC2986] Nystrom, M. and B. Kaliski, "PKCS #10: Certification
Request Syntax Specification Version 1.7", RFC 2986,
November 2000.
[RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
Resource Identifier (URI): Generic Syntax", STD 66,
RFC 3986, January 2005.
[RFC4086] Eastlake, D., Schiller, J., and S. Crocker, "Randomness
Requirements for Security", BCP 106, RFC 4086, June 2005.
[RFC4210] Adams, C., Farrell, S., Kause, T., and T. Mononen,
"Internet X.509 Public Key Infrastructure Certificate
Management Protocol (CMP)", RFC 4210, September 2005.
[RFC4288] Freed, N. and J. Klensin, "Media Type Specifications and
Registration Procedures", BCP 13, RFC 4288, December 2005.
[RFC4346] Dierks, T. and E. Rescorla, "The Transport Layer Security
(TLS) Protocol Version 1.1", RFC 4346, April 2006.
[RFC4648] Josefsson, S., "The Base16, Base32, and Base64 Data
Encodings", RFC 4648, October 2006.
Pritikin, et al. Expires April 25, 2013 [Page 33]
Internet-Draft EST October 2012
[RFC4945] Korver, B., "The Internet IP Security PKI Profile of
IKEv1/ISAKMP, IKEv2, and PKIX", RFC 4945, August 2007.
[RFC5077] Salowey, J., Zhou, H., Eronen, P., and H. Tschofenig,
"Transport Layer Security (TLS) Session Resumption without
Server-Side State", RFC 5077, January 2008.
[RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security
(TLS) Protocol Version 1.2", RFC 5246, August 2008.
[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.
[RFC5274] Schaad, J. and M. Myers, "Certificate Management Messages
over CMS (CMC): Compliance Requirements", RFC 5274,
June 2008.
[RFC5280] Cooper, D., Santesson, S., Farrell, S., Boeyen, S.,
Housley, R., and W. Polk, "Internet X.509 Public Key
Infrastructure Certificate and Certificate Revocation List
(CRL) Profile", RFC 5280, May 2008.
[RFC5652] Housley, R., "Cryptographic Message Syntax (CMS)", STD 70,
RFC 5652, September 2009.
[RFC5746] Rescorla, E., Ray, M., Dispensa, S., and N. Oskov,
"Transport Layer Security (TLS) Renegotiation Indication
Extension", RFC 5746, February 2010.
[RFC5929] Altman, J., Williams, N., and L. Zhu, "Channel Bindings
for TLS", RFC 5929, July 2010.
[RFC5958] Turner, S., "Asymmetric Key Packages", RFC 5958,
August 2010.
[RFC5967] Turner, S., "The application/pkcs10 Media Type", RFC 5967,
August 2010.
[RFC6125] Saint-Andre, P. and J. Hodges, "Representation and
Verification of Domain-Based Application Service Identity
within Internet Public Key Infrastructure Using X.509
(PKIX) Certificates in the Context of Transport Layer
Security (TLS)", RFC 6125, March 2011.
[RFC6402] Schaad, J., "Certificate Management over CMS (CMC)
Pritikin, et al. Expires April 25, 2013 [Page 34]
Internet-Draft EST October 2012
Updates", RFC 6402, November 2011.
[SHS] National Institute of Standards and Technology, "Federal
Information Processing Standard Publication 180-4: Secure
Hash Standard (SHS)", March 2012, <http://csrc.nist.gov/
publications/fips/fips180-4/fips-180-4.pdf>.
[X.680] ITU-T Recommendation, "ITU-T Recommendation X.680 Abstract
Syntax Notation One (ASN.1): Specification of basic
notation", November 2008,
<http://www.itu.int/rec/T-REC-X.680-200811-I/en>.
[X.690] ITU-T Recommendation, "ITU-T Recommendation X.690 ASN.1
encoding rules: Specification of Basic Encoding Rules
(BER), Canonical Encoding Rules (CER) and Distinguished
Encoding Rules (DER)", November 2008,
<http://www.itu.int/rec/T-REC-X.690-200811-I/en>.
7.2. Informative References
[IDevID] IEEE Std, "IEEE 802.1AR Secure Device Identifier",
December 2009, <http://standards.ieee.org/findstds/
standard/802.1AR-2009.html>.
[RFC2397] Masinter, L., "The "data" URL scheme", RFC 2397,
August 1998.
[RFC2925] White, K., "Definitions of Managed Objects for Remote
Ping, Traceroute, and Lookup Operations", RFC 2925,
September 2000.
[RFC6403] Zieglar, L., Turner, S., and M. Peck, "Suite B Profile of
Certificate Management over CMS", RFC 6403, November 2011.
[SP-800-57-Part-1]
National Institute of Standards and Technology,
"Recommendation for Key Management - Part 1: General
(Revision 3)", July 2012, <http://csrc.nist.gov/
publications/nistpubs/800-57/
sp800-57_part1_rev3_general.pdf>.
[X.520] ITU-T Recommendation, "ITU-T Recommendation X.520 The
Directory: Selected attribute types", November 2008,
<http://www.itu.int/rec/T-REC-X.520-200811-I/en>.
Pritikin, et al. Expires April 25, 2013 [Page 35]
Internet-Draft EST October 2012
Appendix A. Operational Scenario Example Messages
(informative)
This section expands on the Operational Scenario Overviews by
providing detailed examples of the messages at each TLS layer.
A.1. Obtaining CA Certificates
The following is an example of a valid /CACerts exchange.
During the initial TLS handshake the client can ignore the optional
server generated "certificate request" and can instead proceed with
the HTTP GET request:
GET /CACerts HTTP/1.1
User-Agent: curl/7.24.0 (i686-pc-linux-gnu) libcurl/7.24.0 OpenS
SL/0.9.8b zlib/1.2.3 libidn/0.6.5
Host: 127.0.0.1:8085
Accept: */*
In response the server provides the current CA certificate:
<= Recv header, 38 bytes (0x26)
Content-Type: application/pkcs7-mime
== Info: no chunk, no close, no size. Assume close to signal end
<= Recv header, 2 bytes (0x2)
<= Recv data, 1111 bytes (0x457)
-----BEGIN PKCS7-----.MIIDEQYJKoZIhvcNAQcCoIIDAjCCAv4CAQExADALBg
kqhkiG9w0BBwGgggLkMIIC.4DCCAcigAwIBAgIJAOjxMZcXhE5wMA0GCSqGSIb3D
QEBBQUAMBcxFTATBgNVBAMT.DGVzdEV4YW1wbGVDQTAeFw0xMjA3MDQxODM5Mjda
Fw0xMzA3MDQxODM5MjdaMBcx.FTATBgNVBAMTDGVzdEV4YW1wbGVDQTCCASIwDQY
JKoZIhvcNAQEBBQADggEPADCC.AQoCggEBALQ7SjZSt6qrnBzUnBNj9z4oxYkvMA
Vh0OIOVRkNhz/2kDGsds0ne7cw.W33kYlxPba4psdLMixCT/O8ZQMpgA+QFKtwb9
VPE8EFUgGzxSYHQHjhJsbg0BVaN.Ya38vjKMjvosuSXUHwkvU57SInSkMr3/aNtS
T8qFfeC6Vuf/G/GLHGuHQKAy/DSo.206MjaMNmWYRVQQVErGookRA4GBF/YE+G/C
SlTsCQNE0KyBFz8JWIkgYY2gYkxb7.wWMvvhaU/Esp+2DG92v9Dhs2MRgrR+WPs7
Y6CYOLD5Mr5lEdkHg27IxkSAoRrI6D.fnVVEQGCj7QrrsUgfXFVYv6cCWFfhMcCA
wEAAaMvMC0wDAYDVR0TBAUwAwEB/zAd.BgNVHQ4EFgQUhH9KxW5TsjkgL7kg2kxJ
yy5tD/MwDQYJKoZIhvcNAQEFBQADggEB.AD+vydZo292XFb2vXojdKD57Gv4tKVm
hvXRdVInntzkY/0AyFCfHJ4BwndgtMh4t.rvBD8+8dL+W3jfPjcSCcUQ/JEnFuMn
b5+kivLeqOnUshETasFPBz2Xq4C1sHDno9.CWOcsjPPw08Tn4dSrzDBSq1NdXB2z
9NOpaVnbpb01qQGhXSOaEvcbZcDuGiW7Di3.gV++remokuPph/s6XoZffzc7ZVzf
Job6tS4RwNz01sutPybXiRWivOz7+QeCOT87.nTGlkQH/+RImUyJ2jefjAW/GDFT
Pzek6cZnabAtsg32n0Pv0j0/1RTNSdYGxPIVA.2f9fhMqMz+vm3w4CFNkGZnOhAD
EA.-----END PKCS7-----.
Pritikin, et al. Expires April 25, 2013 [Page 36]
Internet-Draft EST October 2012
A.2. Previously Installed Signature Certificate
The following is an example of a valid /simpleEnroll exchange.
During this exchange the EST client uses an existing certificate
issued by a trusted 3rd party PKI to obtain an initial certificate
from the EST server.
During the initial TLS handshake the server generated "certificate
request" includes both the distinguished name of the CA the EST
server provides services for ("estExampleCA") and it includes the
distinguished name of a trusted 3rd party CA ("estEXTERNALCA"):
0d 00 00 3d 03 01 02 40 00 37 00 1a 30 18 31 16 ...=...@.7..0.1.
30 14 06 03 55 04 03 13 0d 65 73 74 45 58 54 45 0...U....estEXTE
52 4e 41 4c 43 41 00 19 30 17 31 15 30 13 06 03 RNALCA..0.1.0...
55 04 03 13 0c 65 73 74 45 78 61 6d 70 6c 65 43 U....estExampleC
41 A
Which decodes as:
Acceptable client certificate CA names
/CN=estEXTERNALCA
/CN=estExampleCA
The EST client provides a certificate issued by "estEXTERNALCA" in
the certificate response and the TLS handshake proceeds to
completion. The EST server accepts the EST client certificate for
authentication and accepts the EST client's POSTed certificate
request:
Pritikin, et al. Expires April 25, 2013 [Page 37]
Internet-Draft EST October 2012
POST /simpleEnroll HTTP/1.1
User-Agent: curl/7.24.0 (i686-pc-linux-gnu) libcurl/7.24.0 OpenS
SL/0.9.8b zlib/1.2.3 libidn/0.6.5
Host: 127.0.0.1:8085
Accept: */*
Content-Type: application/pkcs10
Content-Length: 952
=> Send data, 952 bytes (0x3b8)
-----BEGIN CERTIFICATE REQUEST-----.MIIChjCCAW4CAQAwQTElMCMGA1UE
AxMccmVxIGJ5IGNsaWVudCBpbiBkZW1vIHN0.ZXAgNjEYMBYGA1UEBRMPUElEOld
pZGdldCBTTjo2MIIBIjANBgkqhkiG9w0BAQEF.AAOCAQ8AMIIBCgKCAQEAwhYyI+
aYezyx+kW0GVUbMKLf2BUd8BgGykkIJYxms6SH.Bv5S4ktcpYbEpR9iCmp96vK6a
Ar57ArZtMmi0Y6eLX4c+njJnYhUeTivnfyfMM5d.hNVwyzKbJagm5f+RLTMfp0y0
ykqrfZ1hFhcNrRzF6mJeaORTHBehMdu8RXcbmy5R.s+vjnUC4Fe3/oLHtXePyYv1
qqlkk0XDrw/+lx0y4Px5tiyb84iPnQOXjG2tuStM+.iEvfpNAnwU0+3GDjl3sjx0
+gTKvblp6Diw9NSaqIAKupcgWsA0JlyYkgPiJnXFKL.vy6rXoOyx3wAbGKLrKCxT
l+RH3oNXf3UCH70aD758QIDAQABoAAwDQYJKoZIhvcN.AQEFBQADggEBADwpafWU
BsOJ2g2oyHQ7Ksw6MwvimjhB7GhjweCcceTSLInUMk10.4E0TfNqaWcoQengMVZr
IcbOb+sa69BWNB/WYIULfEtJIV23/g3n/y3JltMNw/q+R.200t0bNAViijHQHmlF
6dt93tkRrTzXnhV70Ijnff08G7P9HfnXQH4Eiv3zOB6Pak.JoL7QlWQ+w5vHpPo6
WGH5n2iE+Ql76F0HykGeqaR402+ae0WlGLHEvcN9wiFQVKh.KUHteU10SEPijlqf
QW+hciLleX2CwuZY5MqKb4qqyDTs4HSQCBCl8jR2cXsGDuN4.PcMPp+9A1/UPuGD
jhwPt/K3y6aV8zUEh8Ws=.-----END CERTIFICATE REQUEST-----.
The EST server uses the trusted 3rd party CA issued certificate to
perform additional authorization and issues a certificate to the
client:
Pritikin, et al. Expires April 25, 2013 [Page 38]
Internet-Draft EST October 2012
<= Recv header, 38 bytes (0x26)
Content-Type: application/pkcs7-mime
== Info: no chunk, no close, no size. Assume close to signal end
<= Recv header, 2 bytes (0x2)
<= Recv data, 1200 bytes (0x4b0)
-----BEGIN PKCS7-----.MIIDUQYJKoZIhvcNAQcCoIIDQjCCAz4CAQExADALBg
kqhkiG9w0BBwGgggMkMIID.IDCCAgigAwIBAgIBBjANBgkqhkiG9w0BAQUFADAXM
RUwEwYDVQQDEwxlc3RFeGFt.cGxlQ0EwHhcNMTIwNzA0MTgzOTM3WhcNMTMwNzA0
MTgzOTM3WjBBMSUwIwYDVQQD.ExxyZXEgYnkgY2xpZW50IGluIGRlbW8gc3RlcCA
2MRgwFgYDVQQFEw9QSUQ6V2lk.Z2V0IFNOOjYwggEiMA0GCSqGSIb3DQEBAQUAA4
IBDwAwggEKAoIBAQDCFjIj5ph7.PLH6RbQZVRswot/YFR3wGAbKSQgljGazpIcG/
lLiS1ylhsSlH2IKan3q8rpoCvns.Ctm0yaLRjp4tfhz6eMmdiFR5OK+d/J8wzl2E
1XDLMpslqCbl/5EtMx+nTLTKSqt9.nWEWFw2tHMXqYl5o5FMcF6Ex27xFdxubLlG
z6+OdQLgV7f+gse1d4/Ji/WqqWSTR.cOvD/6XHTLg/Hm2LJvziI+dA5eMba25K0z
6IS9+k0CfBTT7cYOOXeyPHT6BMq9uW.noOLD01JqogAq6lyBawDQmXJiSA+ImdcU
ou/Lqteg7LHfABsYousoLFOX5Efeg1d./dQIfvRoPvnxAgMBAAGjTTBLMAkGA1Ud
EwQCMAAwHQYDVR0OBBYEFJv4oLLeNxNK.OMmQDDujyNR+zaVPMB8GA1UdIwQYMBa
AFIR/SsVuU7I5IC+5INpMScsubQ/zMA0G.CSqGSIb3DQEBBQUAA4IBAQCMdomfdR
9vi4VUYdF+eym7F8qVUG/1jtjfaxmrzKeZ.7LQ1F758RtwG9CDu2GPHNPjjeM+DJ
RQZN999eLs3Qd/DIJCNimaqdDqmkeBFC5hq.LZOxbKhSmhlR7YKjIZuyI299rOaI
W54ULyz8k0zw6R1/0lMJTsDFGJM+9yDeaARE.n3vtKnUDGHsVU3fYpDENaqUunoU
MZfuEdejfHhU7lVbJI1oSJbnRwBFkPr/RQ3/5.FymcrBD9RpAM5MsQIn0BONil/o
JM+LjOJqyZLbBxz6P3w/OiJGYJNfFT8YudLfjZ.LDX8A8FFcReapNELC4QxE4OrA
hN3sQUT2O7ndIsit4kJoQAxAA==.-----END PKCS7-----.
A.3. Username/Password Distributed Out-of-Band
The following is an example of a valid /simpleEnroll exchange.
During this exchange the EST client uses an out-of-band distributed
username/password to authenticate itself to the EST server.
During the initial TLS handshake the client can ignore the optional
server generated "certificate request" and can instead proceed with
the HTTP POST request:
Pritikin, et al. Expires April 25, 2013 [Page 39]
Internet-Draft EST October 2012
POST /simpleEnroll HTTP/1.1
User-Agent: curl/7.24.0 (i686-pc-linux-gnu) libcurl/7.24.0 OpenS
SL/0.9.8b zlib/1.2.3 libidn/0.6.5
Host: 127.0.0.1:8085
Accept: */*
Content-Type: application/pkcs10
Content-Length: 952
=> Send data, 952 bytes (0x3b8)
-----BEGIN CERTIFICATE REQUEST-----.MIIChjCCAW4CAQAwQTElMCMGA1UE
AxMccmVxIGJ5IGNsaWVudCBpbiBkZW1vIHN0.ZXAgMjEYMBYGA1UEBRMPUElEOld
pZGdldCBTTjoyMIIBIjANBgkqhkiG9w0BAQEF.AAOCAQ8AMIIBCgKCAQEAz9lXz9
MowulOx0W5v1k7GKlsNy7mAgmkz/wZDImBDXez.QZCb8lrO8iTD3tI0NH2xpkY3b
uqFjdtQTzCmANLyNWtR1sC5GjN/EM1JSCrO/zZM.ig835RXJTP878N/jNW7EzSxb
/zK5OzKJoRbZ4HgZm4NDapMfMcB4jqBdPxoPAqeR.+KTkv1+9m1vvsdKIs5Hm4Sp
O2WolHPw5BCXdu5zleb6ACih7Zpd2cpHFz6ZHC0G1.Of+F//0BzkFSqWsmUomyJy
WCfLCuX9grs1CNlLxw0gcMprdTxLxjc18z03ZmBCq0.qq5/mUK/tv9R2k8+WuP3a
kzTUIkeHtcp6FVFl3D+TwIDAQABoAAwDQYJKoZIhvcN.AQEFBQADggEBAJH7Etuy
B/oQgQeals08mD2U31FfQ/uYqjNxzZpZJSzVLGMASv9a.pNzaWdfqPdIs+ZZ+gAQ
QkVcXjdbqY3pAf/EeWk+KnuAUjOIPKu3ZBPVbWbXu/Ie7.F1ekQ7TLkFNkHSxHRu
2/bPIByBLRVfWNVXd3wPq+QxqMqgIjBGaTJM5kuHndYFGj.Xdf4rlGRPyOOwG/Xf
QrKBB3tzpbJCy+cwOUAJFPOTO+86RUjf9Wh+yoM182vlg8O.FyEaaA/PMpl3aEcT
BlRZmPx4e7FLwGIhbgE7/6K0nF99xdGd7JYPHasbcWszxD0Z.oPYm+44g0gOnhlj
OWpRiKXcnngSSutRILaw=.-----END CERTIFICATE REQUEST-----.
== Info: upload completely sent off: 952 out of 952 bytes
== Info: HTTP 1.1 or later with persistent connection, pipelining
supported
The EST server accepts this request but since a client certificate
was not provided for authentication/authorization the EST server
responds with the WWW-authenticate header:
<= Recv header, 27 bytes (0x1b)
HTTP/1.1 401 Unauthorized
<= Recv header, 75 bytes (0x4b)
WWW-Authenticate: Digest qop="auth", realm="estrealm", nonce="13
41427174"
The EST client repeats the request, this time including the requested
Authorization header:
Pritikin, et al. Expires April 25, 2013 [Page 40]
Internet-Draft EST October 2012
== Info: SSL connection using AES256-SHA
== Info: Server certificate:
== Info: subject: CN=127.0.0.1
== Info: start date: 2012-07-04 18:39:27 GMT
== Info: expire date: 2013-07-04 18:39:27 GMT
== Info: common name: 127.0.0.1 (matched)
== Info: issuer: CN=estExampleCA
== Info: SSL certificate verify ok.
== Info: Server auth using Digest with user 'estuser'
=> Send header, 416 bytes (0x1a0)
POST /simpleEnroll HTTP/1.1
Authorization: Digest username="estuser", realm="estrealm", nonc
e="1341427174", uri="/simpleEnroll", cnonce="ODc0OTk2", nc=00000
001, qop="auth", response="48a2b671ccb6596adfef039e134b7d5d"
User-Agent: curl/7.24.0 (i686-pc-linux-gnu) libcurl/7.24.0 OpenS
SL/0.9.8b zlib/1.2.3 libidn/0.6.5
Host: 127.0.0.1:8085
Accept: */*
Content-Type: application/pkcs10
Content-Length: 952
=> Send data, 952 bytes (0x3b8)
-----BEGIN CERTIFICATE REQUEST-----.MIIChjCCAW4CAQAwQTElMCMGA1UE
AxMccmVxIGJ5IGNsaWVudCBpbiBkZW1vIHN0.ZXAgMjEYMBYGA1UEBRMPUElEOld
pZGdldCBTTjoyMIIBIjANBgkqhkiG9w0BAQEF.AAOCAQ8AMIIBCgKCAQEAz9lXz9
MowulOx0W5v1k7GKlsNy7mAgmkz/wZDImBDXez.QZCb8lrO8iTD3tI0NH2xpkY3b
uqFjdtQTzCmANLyNWtR1sC5GjN/EM1JSCrO/zZM.ig835RXJTP878N/jNW7EzSxb
/zK5OzKJoRbZ4HgZm4NDapMfMcB4jqBdPxoPAqeR.+KTkv1+9m1vvsdKIs5Hm4Sp
O2WolHPw5BCXdu5zleb6ACih7Zpd2cpHFz6ZHC0G1.Of+F//0BzkFSqWsmUomyJy
WCfLCuX9grs1CNlLxw0gcMprdTxLxjc18z03ZmBCq0.qq5/mUK/tv9R2k8+WuP3a
kzTUIkeHtcp6FVFl3D+TwIDAQABoAAwDQYJKoZIhvcN.AQEFBQADggEBAJH7Etuy
B/oQgQeals08mD2U31FfQ/uYqjNxzZpZJSzVLGMASv9a.pNzaWdfqPdIs+ZZ+gAQ
QkVcXjdbqY3pAf/EeWk+KnuAUjOIPKu3ZBPVbWbXu/Ie7.F1ekQ7TLkFNkHSxHRu
2/bPIByBLRVfWNVXd3wPq+QxqMqgIjBGaTJM5kuHndYFGj.Xdf4rlGRPyOOwG/Xf
QrKBB3tzpbJCy+cwOUAJFPOTO+86RUjf9Wh+yoM182vlg8O.FyEaaA/PMpl3aEcT
BlRZmPx4e7FLwGIhbgE7/6K0nF99xdGd7JYPHasbcWszxD0Z.oPYm+44g0gOnhlj
OWpRiKXcnngSSutRILaw=.-----END CERTIFICATE REQUEST-----.
The ESTserver uses the username/password to perform authentication/
authorization and responds with the issued certificate:
Pritikin, et al. Expires April 25, 2013 [Page 41]
Internet-Draft EST October 2012
<= Recv header, 38 bytes (0x26)
0000: Content-Type: application/pkcs7-mime
== Info: no chunk, no close, no size. Assume close to signal end
<= Recv header, 2 bytes (0x2)
<= Recv data, 1200 bytes (0x4b0)
-----BEGIN PKCS7-----.MIIDUQYJKoZIhvcNAQcCoIIDQjCCAz4CAQExADALBg
kqhkiG9w0BBwGgggMkMIID.IDCCAgigAwIBAgIBAjANBgkqhkiG9w0BAQUFADAXM
RUwEwYDVQQDEwxlc3RFeGFt.cGxlQ0EwHhcNMTIwNzA0MTgzOTM0WhcNMTMwNzA0
MTgzOTM0WjBBMSUwIwYDVQQD.ExxyZXEgYnkgY2xpZW50IGluIGRlbW8gc3RlcCA
yMRgwFgYDVQQFEw9QSUQ6V2lk.Z2V0IFNOOjIwggEiMA0GCSqGSIb3DQEBAQUAA4
IBDwAwggEKAoIBAQDP2VfP0yjC.6U7HRbm/WTsYqWw3LuYCCaTP/BkMiYENd7NBk
JvyWs7yJMPe0jQ0fbGmRjdu6oWN.21BPMKYA0vI1a1HWwLkaM38QzUlIKs7/NkyK
DzflFclM/zvw3+M1bsTNLFv/Mrk7.MomhFtngeBmbg0Nqkx8xwHiOoF0/Gg8Cp5H
4pOS/X72bW++x0oizkebhKk7ZaiUc./DkEJd27nOV5voAKKHtml3ZykcXPpkcLQb
U5/4X//QHOQVKpayZSibInJYJ8sK5f.2CuzUI2UvHDSBwymt1PEvGNzXzPTdmYEK
rSqrn+ZQr+2/1HaTz5a4/dqTNNQiR4e.1ynoVUWXcP5PAgMBAAGjTTBLMAkGA1Ud
EwQCMAAwHQYDVR0OBBYEFChDQpKEfG9c.e4JaMf8438tb2XOIMB8GA1UdIwQYMBa
AFIR/SsVuU7I5IC+5INpMScsubQ/zMA0G.CSqGSIb3DQEBBQUAA4IBAQAn42mIVG
piaY4yqFD0F8KyUhKsdNnyKeeISQxP//lp.quIieJzdWSc7bhWZNldSzNswCod8B
4eJToQejLSNb8JBDC849z0tcuyHgN6N/p8z.IwI+hAlfXS9q02OECyFes4Jmzc7r
erE5jtOdGsEDBIscw/A+Kv86wv6BKbagMslQ.51AJyPsL6iBhm7LPFrErJgH2kWN
jDKFH9CcVFjXvgriMrLPFeqQWOpj/2XF+4m+c.f9QP5tSjieHJR1hnYk2tlodfE7
iV4pJ07Mmf3yBf753VSUVybqWiMCd0Lm7oghSX.E2GAxrsU1N+N1odn+gJ2wmxTu
AC2aHt9VPRViov4RRTvoQAxAA==.-----END PKCS7-----.
A.4. Re-Enrollment
The following is an example of a valid /simpleReEnroll exchange.
During this exchange the EST client authenticates itself using an
existing certificate issued by the CA the EST server provides
services for.
Initially this exchange is identical to enrollment using an
externally issued certificate for client authentication since the
server is not yet aware of the client's intention. As in that
example the EST server the server generated "certificate request"
includes both the distinguished name of the CA the EST server
provides services for ("estExampleCA") and it includes the
distinguished name of a trusted 3rd party CA ("estEXTERNALCA").
Pritikin, et al. Expires April 25, 2013 [Page 42]
Internet-Draft EST October 2012
0d 00 00 3d 03 01 02 40 00 37 00 1a 30 18 31 16 ...=...@.7..0.1.
30 14 06 03 55 04 03 13 0d 65 73 74 45 58 54 45 0...U....estEXTE
52 4e 41 4c 43 41 00 19 30 17 31 15 30 13 06 03 RNALCA..0.1.0...
55 04 03 13 0c 65 73 74 45 78 61 6d 70 6c 65 43 U....estExampleC
41 A
In text format this is:
Acceptable client certificate CA names
/CN=estEXTERNALCA
/CN=estExampleCA
The EST client provides a certificate issued by "estExampleCA" in the
certificate response and the TLS handshake proceeds to completion.
The EST server accepts the EST client certificate for authentication
and accepts the EST client's POSTed certificate request.
The rest of the protocol traffic is effectively identical to a normal
enrollment.
A.5. Server Key Generation
The following is an example of a valid /serverKeyGen exchange.
During this exchange the EST client authenticates itself using an
existing certificate issued by the CA the EST server provides
services for.
The initial TLS handshake is identical to the enrollment example
handshake. The HTTP POSTed message is:
Pritikin, et al. Expires April 25, 2013 [Page 43]
Internet-Draft EST October 2012
POST /serverKeyGen HTTP/1.1
User-Agent: curl/7.24.0 (i686-pc-linux-gnu) libcurl/7.24.0 OpenS
SL/0.9.8b zlib/1.2.3 libidn/0.6.5
Host: 127.0.0.1:8085
Accept: */*
Content-Type: application/pkcs10
Content-Length: 968
=> Send data, 968 bytes (0x3c8)
-----BEGIN CERTIFICATE REQUEST-----.MIICkzCCAXsCAQAwTjEyMDAGA1UE
AxMpc2VydmVyS2V5R2VuIHJlcSBieSBjbGll.bnQgaW4gZGVtbyBzdGVwIDUxGDA
WBgNVBAUTD1BJRDpXaWRnZXQgU046NTCCASIw.DQYJKoZIhvcNAQEBBQADggEPAD
CCAQoCggEBAMnlUlq0ag/fDAVhLgrXEAD6WtZw.Y2rVGev5saWirer2n0OzghB59
uJByxPo0DYBYqZRuoRF0FTL1ZZTMaZxivge0ecA.ZcoR46jwSBoceMT1jkwFyAER
t9Q2EwdnJLIPo/Ib2PLJNb4Jo8NNKmxtg55BgIVi.vkIB+rMtLeYRUVL0RUaBAqX
FmtXRDceVFIEY24iUQw6vESGJKpArht592aT8lyaP.24bZovuG19dd5xtTX3j37K
x49SlkUvLSpD6ZavIFAZn7Yv19LBKHvRIemybUo294.QeLb/VYP1O+EAthV/igiX
1DHqlUZCZp5SdyUXUwZPatFboNwEVR0R3MJwVECAwEA.AaAAMA0GCSqGSIb3DQEB
BQUAA4IBAQAqhHezK5/tvbXleHO/aTBVYO9l414NM+WA.wJcnS2UaJYScPBqlYK/
gij+dqAtFE+5ukAj56t7HnooI4EFo9r8jqCHewx7iLZYh.JDxo4hWOsAvHV+Iziy
jkhJNdHBIqGM7Gd5f/2VJLEPQPmwNOL5P+2O4eQC/QeEYc.bAmfhOS8b/ZH09/9T
PeaeQpjspjOui/100OuLE8KvU3FM0sXMYt1Va0A0jxzl+5k.EiEJo+ltXsQwdP0H
csoTNBN+j3K18omJQS0e91X8v0xkMWYhUtonXD0YZ6SO/B9c.AE6GTADHA/xpSvA
cqlWa+FHxjwEMXdmViHvMUywo31fDZ/TUvCPX.-----END CERTIFICATE REQUE
ST-----.
After processing the request the EST server response is:
<= Recv header, 17 bytes (0x11)
HTTP/1.1 200 OK
<= Recv header, 16 bytes (0x10)
Status: 200 OK
<= Recv header, 67 bytes (0x43)
Content-Type: multipart/mixed ; boundary=estServerExampleBoundar
y
== Info: no chunk, no close, no size. Assume close to signal end
<= Recv header, 2 bytes (0x2)
<= Recv data, 3234 bytes (0xca2)
This is the preamble. It is to be ignored, though it.is a handy
place for estServer to include an explanatory note.including con
tact or support information..--estServerExampleBoundary.Content-
Type=application/pkcs8..-----BEGIN PRIVATE KEY-----.MIIEvQIBADAN
BgkqhkiG9w0BAQEFAASCBKcwggSjAgEAAoIBAQC0781l7tri0yii.Mb9ZZYch8ze
izXrjMPF/Rxoz2C9IU2THCrhPGXGQMne/zivce0m8/BMkkUc+DsSM.tzxn4l+9tI
sVDkAe4FyzN0hLd/zawgj6kUoCi3mxZnb2rWaRYAmM5w41ImDV3blv.aMUKDSJhV
bQ+z/G1W1TRx3iWi5CMHYb+1pJXPTJz/GuWr/b/+Efqwz2ZlwGcj4Dx.Igbx9vG0
mftIIxM4TUX28KBbaLgJbalsiuOx3C2bEyaSPerdzqgvXFHGGAhg1FU8.DQiQEki
nn66GPMtm1SNgitxFxWouFqpsax5MWn/i52TfEaF2PNThOuzKtilweJhk.g0gMIQ
Pritikin, et al. Expires April 25, 2013 [Page 44]
Internet-Draft EST October 2012
TXAgMBAAECggEANlrz8XNX/lxBELixK0H83o4aYKYqDKZfZkUN8hU33xpu.Y/0sc
VbLbu46WzysoIfJFyUC+zFJnbMCCOPjGbI/4NWkEqc9TAlKz+wDo+hf5bf0.ypFr
EmikHk8R3fkpnvKi69ldw0iYnqcFVhq7VtGrSmJcy6Hckwbk7EBoUZGL0wtp.xlO
6XlhksAvn8+75qoWzsNhi7S/L0IVCVLbUaV3hodTHlH5M4daFbqyRWD7UiPKt.Q3
hdw1rpyVZg8ZbBFp0Ej4f9GdRaq88SIKMKCDu3t9ibn/v1kEte+PxhuwyW+d0o.h
kKSEW0yLKCzQm5tujsPq0UVzPBkLJACUnFAi+a4AQKBgQDu6VLH2eYoTjPPTyAv.
vOJnNWP7oMzyJ4/eFqdE9m+2Ajm/0qaMY95ftZ+GpEKggvC6Z5DFevEmgH4Sg2+G
.gFd93diyRPScVbNE8SmpXxLPU2UoykVmICuQZzLDNE18B3buxAm2GJ219NEnZOe
c.jPMOV/IcG1aLzTqQssL3zo/0gQKBgQDB4Olpg3EBggtJ/+dlkLHUw8c7Pe3UyL
kS.VxVsyQwioYt8xMeCWuPvPNFcOjcW53KN/YSpCVjpttKGsPtLibMlKYKgasEqg
cvl.Vb5OFtA/jNAP3mdAgCzBn6IF1NhVQe2dclo5puZ0gO38HDWq7EtqSi9Q0JSM
g3YC.QNcOORptVwKBgQCHrCafaYWDhA11/+g2U9x6Yd56ifF43rCbnV+2EQCVaqQ
i49xC.w4AH+Bs0mdlgT5unL6MOEmgZxkRR/SP7TKzixHYHnpMOqLhaQV24Wk5TQH
ek92D7.wu8aXRB9vBj4g0CuDNO6/jWpm/KenXXN+Fka3ySVg4zdbVmBzJJdqYckg
QKBgFXS.zSBzGgwz1/F7AaDZK49m1wPnhyeBb0OqHwbX/LI71rZ1mWef+nSF9Juh
/Y77B5/J.UPdO9vgGgS00nRk0LIRP2s5OU5IQgQTVLvf8a1UmbVgI+KX511Yi5yM
ztEwRcjEX.VM9ejXeXN0I57pvqG/xCOK3Kl2eYLh4TO9/E8WjjAoGAA1mqUV4Hnf
4yvF1rydMp.fpvoWekiiRE33iEbYZNATYhsl7uxwn760pqVifkq2DSrZeYm4+lw9
jwWMtUoPzpg.CJYMoGl846nhiZrbbJ5b5twoLV6GRmkk/CfOxPXNzCtSoQA86HHq
7rRdhXSau/bY.EXc91tnhLjFzZxdBgrd+f4k=.-----END PRIVATE KEY-----.
--estServerExampleBoundary.Content-Type: application/pkcs7-mime.
.-----BEGIN PKCS7-----.MIIDPAYJKoZIhvcNAQcCoIIDLTCCAykCAQExADALB
gkqhkiG9w0BBwGgggMPMIID.CzCCAfOgAwIBAgIBBTANBgkqhkiG9w0BAQUFADAX
MRUwEwYDVQQDEwxlc3RFeGFt.cGxlQ0EwHhcNMTIwNzA0MTgzOTM2WhcNMTMwNzA
0MTgzOTM2WjAsMSowKAYDVQQD.EyFzZXJ2ZXJzaWRlIGtleSBnZW5lcmF0ZWQgcm
VzcG9uc2UwggEiMA0GCSqGSIb3.DQEBAQUAA4IBDwAwggEKAoIBAQC0781l7tri0
yiiMb9ZZYch8zeizXrjMPF/Rxoz.2C9IU2THCrhPGXGQMne/zivce0m8/BMkkUc+
DsSMtzxn4l+9tIsVDkAe4FyzN0hL.d/zawgj6kUoCi3mxZnb2rWaRYAmM5w41ImD
V3blvaMUKDSJhVbQ+z/G1W1TRx3iW.i5CMHYb+1pJXPTJz/GuWr/b/+Efqwz2Zlw
Gcj4DxIgbx9vG0mftIIxM4TUX28KBb.aLgJbalsiuOx3C2bEyaSPerdzqgvXFHGG
Ahg1FU8DQiQEkinn66GPMtm1SNgitxF.xWouFqpsax5MWn/i52TfEaF2PNThOuzK
tilweJhkg0gMIQTXAgMBAAGjTTBLMAkG.A1UdEwQCMAAwHQYDVR0OBBYEFLylcQN
0D5xTfRdayv+0GDULR2+EMB8GA1UdIwQY.MBaAFIR/SsVuU7I5IC+5INpMScsubQ
/zMA0GCSqGSIb3DQEBBQUAA4IBAQButIeM.DB9PkwlGGe7zqvUWVD8y99zowwV6A
rAOXWX+JO0bihgMtZaUfvPCX/LhZVEKDAki.W5orjAEvIu10b6l38ZzX2oyJgkYy
Mmbb14lzTsRyjiqFw9j1PXxwgZvhwcaCF4b7.eDUUBQIeZg3AnkQrEwnHR5oVIN5
8qo0P7PSKC3Vl3H6DlQh3y7w87nN12923/wk0.v/bS3lv7lDX3HdmbQD1r2KPtBs
JGF4jMdstT7FTx32ZFKObycbK7WJ4LHytNJDci.4iXf+B0S3D6Zbf1cXj80/W+jC
GvU0+4SV3cgEXFE5VQvXd8x40W4h0dTSkQCDPOS.nPj4Dl/PsLqX3lDboQAxAA==
.-----END PKCS7-----.--estServerExampleBoundary--.This is the ep
ilogue. It is also to be ignored..
In text format this is:
HTTP/1.1 200 OK
Status: 200 OK
Content-Type: multipart/mixed ; boundary=estServerExampleBoundary
Pritikin, et al. Expires April 25, 2013 [Page 45]
Internet-Draft EST October 2012
This is the preamble. It is to be ignored, though it
is a handy place for estServer to include an explanatory note
including contact or support information.
--estServerExampleBoundary
Content-Type=application/pkcs8
-----BEGIN PRIVATE KEY-----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-----END PRIVATE KEY-----
--estServerExampleBoundary
Content-Type: application/pkcs7-mime
-----BEGIN PKCS7-----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, et al. Expires April 25, 2013 [Page 46]
Internet-Draft EST October 2012
A1UdEwQCMAAwHQYDVR0OBBYEFLylcQN0D5xTfRdayv+0GDULR2+EMB8GA1UdIwQY
MBaAFIR/SsVuU7I5IC+5INpMScsubQ/zMA0GCSqGSIb3DQEBBQUAA4IBAQButIeM
DB9PkwlGGe7zqvUWVD8y99zowwV6ArAOXWX+JO0bihgMtZaUfvPCX/LhZVEKDAki
W5orjAEvIu10b6l38ZzX2oyJgkYyMmbb14lzTsRyjiqFw9j1PXxwgZvhwcaCF4b7
eDUUBQIeZg3AnkQrEwnHR5oVIN58qo0P7PSKC3Vl3H6DlQh3y7w87nN12923/wk0
v/bS3lv7lDX3HdmbQD1r2KPtBsJGF4jMdstT7FTx32ZFKObycbK7WJ4LHytNJDci
4iXf+B0S3D6Zbf1cXj80/W+jCGvU0+4SV3cgEXFE5VQvXd8x40W4h0dTSkQCDPOS
nPj4Dl/PsLqX3lDboQAxAA==
-----END PKCS7-----
--estServerExampleBoundary--
This is the epilogue. It is also to be ignored.
A.6. CSR Attributes
The following is an example of a valid /CSRAttrs exchange. During
this exchange the EST client authenticates itself using an existing
certificate issued by the CA the EST server provides services for.
The initial TLS handshake is identical to the enrollment example
handshake. The HTTP GET request:
GET /CSRAttrs HTTP/1.1
User-Agent: curl/7.22.0 (i686-pc-linux-gnu) libcurl/7.22.0 OpenS
SL/1.0.1 zlib/1.2.3.4 libidn/1.23 librtmp/2.3
Host: 127.0.0.1:8085
Accept: */*
In response the server provides suggested attributes that are
appropriate for the authenticated client:
<= Recv header, 36 bytes (0x24)
Content-Type: application/csrattrs
== Info: no chunk, no close, no size. Assume close to signal end
<= Recv header, 2 bytes (0x2)
<= Recv data, 33 bytes (0x21)
0000: MBQGBysGAQEBARYGCSqGSIb3DQEJBw==.
Authors' Addresses
Max Pritikin (editor)
Cisco Systems, Inc.
510 McCarthy Drive
Milpitas, CA 95035
USA
Email: pritikin@cisco.com
Pritikin, et al. Expires April 25, 2013 [Page 47]
Internet-Draft EST October 2012
Peter E. Yee (editor)
AKAYLA, Inc.
7150 Moorland Drive
Clarksville, MD 21029
USA
Email: peter@akayla.com
Dan Harkins (editor)
Aruba Networks
1322 Crossman Avenue
Sunnyvale, CA 94089-1113
USA
Email: dharkins@arubanetworks.com
Pritikin, et al. Expires April 25, 2013 [Page 48]
