LAMPS Working Group M. Richardson, Ed.
Internet-Draft Sandelman Software Works
Updates: 7030 (if approved) O. Friel
Intended status: Standards Track Cisco
Expires: 4 September 2025 D. von Oheimb
Siemens
D. Harkins
The Industrial Lounge
3 March 2025
Clarification and enhancement of RFC7030 CSR Attributes definition
draft-ietf-lamps-rfc7030-csrattrs-18
Abstract
This document updates RFC7030 (EST) and clarifies how the CSR
Attributes Response can be used by an EST server to specify both CSR
attribute OIDs and also CSR attribute values, in particular X.509
extension values, that the server expects the client to include in
subsequent CSR request.
The Enrollment over Secure Transport (EST, RFC7030) is ambiguous in
its specification of the CSR Attributes Response. This has resulted
in implementation challenges and implementor confusion. As a result
of some of the implementation challenges, it came to light that the
particular way of that RFC7030 (EST) says to use the CSR attributes
was not universally agreed upon.
This document therefore also provides a new straightforward approach:
using a template for CSR contents that may be partially filled in by
the server. This also allows an EST server to specify a subject
Distinguished Name (DN).
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
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Internet-Drafts are draft documents valid for a maximum of six months
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time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
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This Internet-Draft will expire on 4 September 2025.
Copyright Notice
Copyright (c) 2025 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 (https://trustee.ietf.org/
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Please review these documents carefully, as they describe your rights
and restrictions with respect to this document. Code Components
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provided without warranty as described in the Revised BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. CSR Attributes Handling . . . . . . . . . . . . . . . . . . . 4
3.1. Extensions to RFC 7030 section 2.6 . . . . . . . . . . . 4
3.2. Extensions to RFC 7030 section 4.5.2 . . . . . . . . . . 4
3.3. Use of CSR templates . . . . . . . . . . . . . . . . . . 5
4. Co-existence with existing implementations . . . . . . . . . 9
5. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . 10
5.1. RFC8994/ACP subjectAltName with specific otherName . . . 10
5.1.1. Base64 encoded example . . . . . . . . . . . . . . . 10
5.1.2. ASN.1 DUMP output . . . . . . . . . . . . . . . . . . 10
5.2. RFC7030 original example . . . . . . . . . . . . . . . . 11
5.2.1. Base64 encoded example . . . . . . . . . . . . . . . 11
5.2.2. ASN.1 DUMP output . . . . . . . . . . . . . . . . . . 12
5.3. Requires a specific extension . . . . . . . . . . . . . . 13
5.3.1. Base64 encoded example . . . . . . . . . . . . . . . 13
5.3.2. ASN.1 DUMP output . . . . . . . . . . . . . . . . . . 13
5.4. Require a public key of a specific size . . . . . . . . . 14
5.4.1. Base64 encoded example . . . . . . . . . . . . . . . 14
5.4.2. ASN.1 DUMP output . . . . . . . . . . . . . . . . . . 14
5.5. Require a public key of a specific curve . . . . . . . . 15
5.5.1. Base64 encoded example . . . . . . . . . . . . . . . 15
5.5.2. ASN.1 DUMP output . . . . . . . . . . . . . . . . . . 15
5.6. Require a specific extension . . . . . . . . . . . . . . 16
5.6.1. Base64 encoded example . . . . . . . . . . . . . . . 16
5.6.2. ASN.1 DUMP output . . . . . . . . . . . . . . . . . . 17
6. Security Considerations . . . . . . . . . . . . . . . . . . . 18
6.1. Identity and Privacy Considerations . . . . . . . . . . . 18
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 18
8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 18
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9. References . . . . . . . . . . . . . . . . . . . . . . . . . 18
9.1. Normative References . . . . . . . . . . . . . . . . . . 19
9.2. Informative References . . . . . . . . . . . . . . . . . 19
Appendix A. ASN.1 Module . . . . . . . . . . . . . . . . . . . . 21
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 23
1. Introduction
This document updates RFC7030 (EST) and clarifies how the CSR
Attributes Response can be used by an EST server to specify both CSR
attribute OIDs and also CSR attribute values, in particular X.509
extension values, that the server expects the client to include in
subsequent CSR request.
Enrollment over Secure Transport [RFC7030] (EST) has been used in a
wide variety of applications. In particular, [RFC8994] and [RFC8995]
describe a way to use it in order to build out an autonomic control
plane (ACP) [RFC8368].
The ACP requires that each node be given a very specific
subjectAltName. In the ACP specification, the solution was for the
EST server to use section 2.6 of [RFC7030] to convey to the EST
client the actual subjectAltName that will end up in its certificate.
As a result of some implementation challenges, it came to light that
this particular way of using the CSR attributes was not universally
agreed upon, and it was suggested that it went contrary to section
2.6.
Section 2.6 says that the CSR attributes "can provide additional
descriptive information that the EST server cannot access itself".
This is extended to describe how the EST server can provide values
that it demands to use.
After significant discussion, it has been determined that Section 4.5
of [RFC7030] specification is sufficiently difficult to read and
ambiguous to interpret that clarification is needed.
This document motivates the different use cases, and provides
additional worked out examples.
Also, section 4.5.2 is extended to clarify the use of the existing
ASN.1 syntax [X.680][X.690]. This covers all uses and is fully
backward compatible with existing use.
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2. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in
BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
3. CSR Attributes Handling
3.1. Extensions to RFC 7030 section 2.6
Replace the second paragraph with the following text:
These attributes can provide additional descriptive information that
the EST server cannot access itself, such as the Media Access Control
(MAC) address of an interface of the EST client. The EST server can
also provide concrete values that it tells the client to include in
the CSR, such as a specific X.509 Subject Alternative Name extension.
Moreover, these attributes can indicate the type of the included
public key or which crypto algorithms to use for the self-signature,
such as a specific elliptic curve or a specific hash function that
the client is expected to use when generating the CSR.
3.2. Extensions to RFC 7030 section 4.5.2
The ASN.1 syntax for CSR Attributes as defined in EST [RFC7030],
Section 4.5.2 is as follows:
CsrAttrs ::= SEQUENCE SIZE (0..MAX) OF AttrOrOID
AttrOrOID ::= CHOICE (oid OBJECT IDENTIFIER, attribute Attribute }
Attribute { ATTRIBUTE:IOSet } ::= SEQUENCE {
type ATTRIBUTE.&id({IOSet}),
values SET SIZE(1..MAX) OF ATTRIBUTE.&Type({IOSet}{@type}) }
This remains unchanged, such that bits-on-the-wire compatibility is
maintained.
Key parts that were unclear were which OID to use in the 'type' field
and that the 'values' field can contain an entire sequence of X.509
extensions.
The OID to use for such attributes in the 'type' field MUST be id-
ExtensionReq, which has the value 1.2.840.113549.1.9.14. Note that
is the same as pkcs-9-at-extensionRequest defined in PKCS#9
[RFC2985]. There MUST be only one such attribute.
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The 'values' field of this attribute MUST contain a set with exactly
one element, and this element MUST be of type Extensions, as per
Section 4.1 of [RFC5280]:
Extensions ::= SEQUENCE SIZE (1..MAX) OF Extension
Extension ::= SEQUENCE {
extnID OBJECT IDENTIFIER,
critical BOOLEAN DEFAULT FALSE,
extnValue OCTET STRING
-- contains the DER encoding of an ASN.1 value
-- corresponding to the extension type identified
-- by extnID
}
An Extension comprises the OID of the specific X.509 extension
(extnID), optionally the 'critical' bit, and the extension value
(extnValue).
An Extensions structure, which is a sequence of elements of type
Extension, MUST NOT include more than one element with a particular
extnID.
With this understanding, the needs of [RFC8994] and [RFC8995] are
satisfied with no change to the bits on the wire.
3.3. Use of CSR templates
Alternatively to the unstructured inclusion of CSR attributes
specified in [RFC7030], Section 4.5.2 with its limitations and
ambiguities, Appendix B of [RFC8295] describes an approach using a
CSR template. An entire CSR object is returned with various fields
filled out, and other fields waiting to be filled in. In that
approach, a pKCS7PDU attribute includes a Full PKI Data content type
[RFC5272] and that in turn includes a CSR or CRMF formatted request
(for details see [RFC6268] Sections 5 or 9, respectively).
One drawback to that approach, particularly for the CSR, is that some
useless fields have to be included; specifically, the 'signature'
field on the CSR is faked with an empty bit string.
A similar method has been defined in CMP Updates [RFC9480] and the
Lightweight CMP profile [RFC9483], Section 4.3.3, using a CSR
template as defined for CRMF [RFC4211]. Like the approach mentioned
before, this method does not properly deal with absent RDNs (encoding
them as empty strings), absent 'subjectPublicKey' fields (encoding
them as empty BIT STRING), and absent X.509 extension values
(encoding them as empty OCTET STRING), which may cause issues with
strict ASN.1 parsing and decoding.
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We avoid these drawbacks as follows.
This specification defines a new Certificate Request Information
Template attribute for CsrAttrs (as given in Section 3.2) that is
essentially a partially filled in PKCS#10 CSR minus the signature
wrapper:
CertificationRequestInfoTemplate ::= SEQUENCE {
version INTEGER { v1(0) } (v1, ... ),
subject NameTemplate OPTIONAL,
subjectPKInfo [0] SubjectPublicKeyInfoTemplate
{{ PKInfoAlgorithms }} OPTIONAL,
attributes [1] Attributes{{ CRIAttributes }}
}
Appendix A contains all detail.
The CertificationRequestInfoTemplate closely resembles the
CertificationRequestInfo from [RFC5912], Section 5:
CertificationRequestInfo ::= SEQUENCE {
version INTEGER { v1(0) } (v1,...),
subject Name,
subjectPKInfo SubjectPublicKeyInfo{{ PKInfoAlgorithms }},
attributes [0] Attributes{{ CRIAttributes }}
}
with the following differences.
* The 'subject' field has been made OPTIONAL. It MUST be present if
the server places any requirements on the RDNs of the subject
name; otherwise it MUST be absent.
* RelativeDistinguishedNames (RDNs) in the 'subject' fields are
allowed to have no value, which has been achieved by adding
OPTIONAL to the 'value' field of SingleAttributeTemplate. If the
client is expected to provide an RDN of a certain type such as
commonName, the respective RDN MUST be present in the 'subject'
field; otherwise it MUST be absent. If the RDN value is present,
this means that the client is required to use the given value for
the RDN, otherwise the client is expected to fill in the value.
SingleAttributeTemplate {ATTRIBUTE:AttrSet} ::= SEQUENCE {
type ATTRIBUTE.&id({AttrSet}),
value ATTRIBUTE.&Type({AttrSet}{@type}) OPTIONAL
}
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* The 'subjectPKInfo' field has been made OPTIONAL. The field MUST
be absent if the server places no requirements on the key.
Otherwise it MUST be present, and the 'algorithm' field specifies
the type of the key pair the client is expected to use.
* The 'subjectPublicKey' field contained in
SubjectPublicKeyInfoTemplate has been made OPTIONAL because
usually it is not needed. In case the server requires use of an
RSA key and needs to specify its size, the field MUST be present
and contain a dummy public key value of the desired RSA modulus
length. Otherwise, the subjectPublicKey MUST be absent.
SubjectPublicKeyInfoTemplate{PUBLIC-KEY:IOSet} ::= SEQUENCE {
algorithm AlgorithmIdentifier{PUBLIC-KEY, {IOSet}},
subjectPublicKey BIT STRING OPTIONAL
}
* A new OID id-aa-extensionReqTemplate and the related
ExtensionTemplate structure is defined where the 'extnValue' field
has been made OPTIONAL. This is only needed to enable specifying
partial extensions with values to be filled in by the client;
otherwise the id-ExtensionReq OID and the respective value of type
ExtensionReq MUST be used.
For each extension of type Extension or ExtensionTemplate provided by
the server, the client is expected to include an extension of the
type given by the extnID. If the 'critical' field is present, the
client is expected to use the given value. If the 'extnValue' is
present (which is always the case when type Extension is used), the
client is required to use the given extension value. Otherwise it is
expected to fill in the extension value.
If the 'subjectAltName' extension contains the 'directoryName' choice
containing the NULL-DN (i.e., an empty sequence of RDNs) or the
'iPAddress' choice with an empty OCTET STRING, this means that the
client is expected to fill in the respective GeneralName value.
ExtensionTemplate {EXTENSION:ExtensionSet} ::= SEQUENCE {
extnID EXTENSION.&id({ExtensionSet}),
critical BOOLEAN DEFAULT FALSE,
extnValue OCTET STRING (CONTAINING
EXTENSION.&ExtnType({ExtensionSet}{@extnID})) OPTIONAL
-- contains the DER encoding of the ASN.1 value
-- corresponding to the extension type identified
-- by extnID when present
}
The 'version' field of the CertificationRequestInfoTemplate MUST
contain v1 (0).
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The 'attributes' field MUST NOT contain multiple id-aa-
extensionReqTemplate attributes and MUST NOT contain both id-
ExtensionReq and id-aa-extensionReqTemplate attributes.
The 'values' field of an id-aa-extensionReqTemplate attribute MUST
contain a set with exactly one element, and this element MUST be of
type ExtensionTemplate.
Suppose the server requires that the CSR will contain:
* the 'subject' field with a common name to be filled in by the EE
and two organizational unit names with given values "myDept" and
"myGroup",
* the 'publicKey' field contains an Elliptic Curve Cryptography
(ECC) key on curve secp256r1,
* the 'subjectAltName' extension with DNS name "www.myServer.com"
and an empty IP address to be filled in,
* the 'keyUsage' extension marked critical with the value
digitalSignature and keyAgreement, and
* the 'extKeyUsage' extension with value to be filled in by the EE.
Then the CertificationRequestInfo structure constructed by the server
will be as follows:
SEQUENCE {
INTEGER 0
SEQUENCE {
SET {
SEQUENCE {
OBJECT IDENTIFIER commonName (2 5 4 3)
}
}
SET {
SEQUENCE {
OBJECT IDENTIFIER organizationalUnitName (2 5 4 11)
UTF8String "myDept"
}
}
SET {
SEQUENCE {
OBJECT IDENTIFIER organizationalUnitName (2 5 4 11)
UTF8String "myGroup"
}
}
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}
[0] {
SEQUENCE {
OBJECT IDENTIFIER ecPublicKey (1 2 840 10045 2 1)
OBJECT IDENTIFIER secp256r1 (1 2 840 10045 3 1 7)
}
}
[1] {
SEQUENCE {
OBJECT IDENTIFIER id-extensionReqTemplate
(1 2 840 113549 1 9 TBD3)
SET {
SEQUENCE {
SEQUENCE {
OBJECT IDENTIFIER subjectAltName (2 5 29 17)
OCTET STRING, encapsulates {
SEQUENCE {
[2] "www.myServer.com"
[7] ""
}
}
}
SEQUENCE {
OBJECT IDENTIFIER keyUsage (2 5 29 15)
BOOLEAN TRUE
OCTET STRING, encapsulates {
BIT STRING 3 unused bits
"10001"B
}
}
SEQUENCE {
OBJECT IDENTIFIER extKeyUsage (2 5 29 37)
}
}
}
}
}
}
4. Co-existence with existing implementations
Legacy servers MAY continue to use the [RFC7030]-style unstructured
list of attribute/value pairs, and MAY also include the template
style described in {#csrtemplate}. Clients which understand both MUST
use the template only, and ignore all other CSRattrs elements. Older
clients will ignore the new CertificationRequestInfoTemplate element.
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5. Examples
Each example has a high-level (English) explanation of what is
expected. Some mapping back to the Attribute and Extension
definitions above are included. The base64 DER encoding is then
shown. The output of "dumpasn1" [dumpasn1] is then provided to
detail what the contents are.
5.1. RFC8994/ACP subjectAltName with specific otherName
A single subjectAltName extension is specified in a single [RFC7030]
CsrAttrs Extension attribute. This is what might be created by an
[RFC8995] Registrar that is asking for [RFC8994] AcpNodeName format
otherNames.
5.1.1. Base64 encoded example
The Base64:
MGQwYgYJKoZIhvcNAQkOMVUwUwYDVR0RAQH/BEmgRzBFBggr
BgEFBQcICgw5cmZjODk5NCtmZDczOWZjMjNjMzQ0MDExMjIz
MzQ0NTUwMDAwMDAwMCtAYWNwLmV4YW1wbGUuY29t
5.1.2. ASN.1 DUMP output
There is a single subjectAltName Extension with an Attribute with
Extension type.
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<30 64>
0 100: SEQUENCE {
<30 62>
2 98: SEQUENCE {
<06 09>
4 9: OBJECT IDENTIFIER extensionRequest (1 2 840 113549 1 9 14)
: (PKCS #9 via CRMF)
<31 55>
15 85: SET {
<30 53>
17 83: SEQUENCE {
<06 03>
19 3: OBJECT IDENTIFIER subjectAltName (2 5 29 17)
: (X.509 extension)
<01 01>
24 1: BOOLEAN TRUE
<04 49>
27 73: OCTET STRING
: A0 47 30 45 06 08 2B 06 .G0E..+.
: 01 05 05 07 08 0A 0C 39 .......9
: 72 66 63 38 39 39 34 2B rfc8994+
: 66 64 37 33 39 66 63 32 fd739fc2
: 33 63 33 34 34 30 31 31 3c344011
: 32 32 33 33 34 34 35 35 22334455
: 30 30 30 30 30 30 30 30 00000000
: 2B 40 61 63 70 2E 65 78 +@acp.ex
: 61 6D 70 6C 65 2E 63 6F ample.co
: 6D m
: }
: }
: }
: }
5.2. RFC7030 original example
In this example, taken from [RFC7030], Section 4.5.2, a few different
attributes are included. The original example is NOT CORRECT. It
was not aligned with the definition of the Extension Request
attribute as specified in Section 5.4.2 of [RFC2985]. This example
uses one item in the SET OF attribute values, but it does not
Extension Request attribute because the MAC Address is not a X.509v3
certificate extension.
5.2.1. Base64 encoded example
The Base64:
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MDIGCSqGSIb3DQEJBzASBgcqhkjOPQIBMQcGBSuBBAAiBgcr
BgEBAQEWBggqhkjOPQQDAw==
5.2.2. ASN.1 DUMP output
The CsrAttrs structure contains:
1. The challengePassword attribute is included to indicate that the
CSR should include this value.
2. An ecPublicKey OID is provided with the value secp384r1 to
indicate what kind of public key should be submitted.
3. An extensionRequest attribute with a requirement to include the
subjectDirectoryAttributes extension. The macAddress attribute
is required in that extension, with the OID 1.3.6.1.1.1.1.22, but
without a value. This indicates that the CSR should include a
subjectDirectoryAttributes extension, and the value for this
extension is is required to include the macAddress.
4. The ecdsaWithSHA384 OID is included to indicate what kind of hash
is expected to be used for the self-signature in the PKCS#10 CSR.
<30 32>
0 50: SEQUENCE {
<06 09>
2 9: OBJECT IDENTIFIER challengePassword (1 2 840 113549 1 9 7)
: (PKCS #9)
<30 12>
13 18: SEQUENCE {
<06 07>
15 7: OBJECT IDENTIFIER ecPublicKey (1 2 840 10045 2 1)
: (ANSI X9.62 public key type)
<31 07>
24 7: SET {
<06 05>
26 5: OBJECT IDENTIFIER secp384r1 (1 3 132 0 34)
: (SECG (Certicom) named elliptic curve)
: }
: }
<06 07>
33 7: OBJECT IDENTIFIER '1 3 6 1 1 1 1 22'
<06 08>
42 8: OBJECT IDENTIFIER ecdsaWithSHA384 (1 2 840 10045 4 3 3)
: (ANSI X9.62 ECDSA algorithm with SHA384)
: }
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5.3. Requires a specific extension
In this example, the CSR is required to have an Elliptic Curve key,
to include a serial number as part of the subject name, to include
both the friendly name and favorite drink attributes, and to use
SHA-512 as the hash algorithm within the signature.
5.3.1. Base64 encoded example
The Base64:
MEUGCSqGSIb3DQEJBzASBgcqhkjOPQIBMQcGBSuBBAAjBgkq
hkiG9w0BCRQGCgmSJomT8ixkAQUGA1UEBQYIKoZIzj0EAwQ=
5.3.2. ASN.1 DUMP output
The CsrAttrs structure contains:
1. The challengePassword attribute is included to indicate that the
CSR should include this value.
2. An ecPublicKey OID is provided with the value secp521r1 to
indicate what kind of public key should be submitted.
3. The friendly name attributes are required in the CSR.
4. The favorite drink attributes are required in the CSR.
5. A serialNumber OID to indicate that the CSR should include a
serial number as part of subject name.
6. The ecdsaWithSHA512 OID is included to indicate the SHA-512 hash
is expected to be used for the self-signature in the PKCS#10 CSR.
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<30 45>
0 69: SEQUENCE {
<06 09>
2 9: OBJECT IDENTIFIER challengePassword (1 2 840 113549 1 9 7)
: (PKCS #9)
<30 12>
13 18: SEQUENCE {
<06 07>
15 7: OBJECT IDENTIFIER ecPublicKey (1 2 840 10045 2 1)
: (ANSI X9.62 public key type)
<31 07>
24 7: SET {
<06 05>
26 5: OBJECT IDENTIFIER secp521r1 (1 3 132 0 35)
: (SECG (Certicom) named elliptic curve)
: }
: }
<06 09>
33 9: OBJECT IDENTIFIER friendlyName (for PKCS #12) (1 2 840 113549 1 9 20)
: (PKCS #9 via PKCS #12)
<06 0A>
44 10: OBJECT IDENTIFIER '0 9 2342 19200300 100 1 5'
<06 03>
56 3: OBJECT IDENTIFIER serialNumber (2 5 4 5)
: (X.520 DN component)
<06 08>
61 8: OBJECT IDENTIFIER ecdsaWithSHA512 (1 2 840 10045 4 3 4)
: (ANSI X9.62 ECDSA algorithm with SHA512)
: }
5.4. Require a public key of a specific size
The CSR requires a public key of a specific size
5.4.1. Base64 encoded example
The Base64:
MCkGCSqGSIb3DQEJBzARBgkqhkiG9w0BAQExBAICEAAGCSqG
SIb3DQEBCw==
5.4.2. ASN.1 DUMP output
Provide a CSR with an RSA key that's 4096 bits and use SHA256 as the
hash algorithm within the signature.
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<30 29>
0 41: SEQUENCE {
<06 09>
2 9: OBJECT IDENTIFIER challengePassword (1 2 840 113549 1 9 7)
: (PKCS #9)
<30 11>
13 17: SEQUENCE {
<06 09>
15 9: OBJECT IDENTIFIER rsaEncryption (1 2 840 113549 1 1 1)
: (PKCS #1)
<31 04>
26 4: SET {
<02 02>
28 2: INTEGER 4096
: }
: }
<06 09>
32 9: OBJECT IDENTIFIER sha256WithRSAEncryption
(1 2 840 113549 1 1 11)
: (PKCS #1)
: }
5.5. Require a public key of a specific curve
The CSR requires a public key with a specific curve
5.5.1. Base64 encoded example
The Base64:
MD0GCSqGSIb3DQEJBzASBgcqhkjOPQIBMQcGBSuBBAAiMBIGCSqGSIb3DQEJDjEF
BgNVBAUGCCqGSM49BAMD
5.5.2. ASN.1 DUMP output
Provide a CSR with an ECC key from p384, include your serial number,
and use SHA384 as the hash algorithm within the signature.
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<30 3D>
0 61: SEQUENCE {
<06 09>
2 9: OBJECT IDENTIFIER challengePassword (1 2 840 113549 1 9 7)
: (PKCS #9)
<30 12>
13 18: SEQUENCE {
<06 07>
15 7: OBJECT IDENTIFIER ecPublicKey (1 2 840 10045 2 1)
: (ANSI X9.62 public key type)
<31 07>
24 7: SET {
<06 05>
26 5: OBJECT IDENTIFIER secp384r1 (1 3 132 0 34)
: (SECG (Certicom) named elliptic curve)
: }
: }
<30 12>
33 18: SEQUENCE {
<06 09>
35 9: OBJECT IDENTIFIER extensionRequest (1 2 840 113549 1 9 14)
: (PKCS #9 via CRMF)
<31 05>
46 5: SET {
<06 03>
48 3: OBJECT IDENTIFIER serialNumber (2 5 4 5)
: (X.520 DN component)
: }
: }
<06 08>
53 8: OBJECT IDENTIFIER ecdsaWithSHA384 (1 2 840 10045 4 3 3)
: (ANSI X9.62 ECDSA algorithm with SHA384)
: }
5.6. Require a specific extension
The CSR is required to have an EC key, to include a serial number, a
friendly name, favorite drink [favoritedrink] [OID
0.9.2342.19200300.100.1.5], and use SHA512 as the hash algorithm
within the signature.
5.6.1. Base64 encoded example
The Base64:
MFQGCSqGSIb3DQEJBzASBgcqhkjOPQIBMQcGBSuBBAAjMCkG
CSqGSIb3DQEJDjEcBgNVBAUGCSqGSIb3DQEJFAYKCZImiZPy
LGQBBQYIKoZIzj0EAwQ=
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5.6.2. ASN.1 DUMP output
Provide a CSR with an EC key from sha521, include your serial number,
friendly name, and favorite drink, and hash it with SHA512
<30 54>
0 84: SEQUENCE {
<06 09>
2 9: OBJECT IDENTIFIER challengePassword (1 2 840 113549 1 9 7)
: (PKCS #9)
<30 12>
13 18: SEQUENCE {
<06 07>
15 7: OBJECT IDENTIFIER ecPublicKey (1 2 840 10045 2 1)
: (ANSI X9.62 public key type)
<31 07>
24 7: SET {
<06 05>
26 5: OBJECT IDENTIFIER secp521r1 (1 3 132 0 35)
: (SECG (Certicom) named elliptic curve)
: }
: }
<30 29>
33 41: SEQUENCE {
<06 09>
35 9: OBJECT IDENTIFIER extensionRequest (1 2 840 113549 1 9 14)
: (PKCS #9 via CRMF)
<31 1C>
46 28: SET {
<06 03>
48 3: OBJECT IDENTIFIER serialNumber (2 5 4 5)
: (X.520 DN component)
<06 09>
53 9: OBJECT IDENTIFIER
: friendlyName (for PKCS #12) (1 2 840 113549 1 9 20)
: (PKCS #9 via PKCS #12)
<06 0A>
64 10: OBJECT IDENTIFIER '0 9 2342 19200300 100 1 5'
: }
: }
<06 08>
76 8: OBJECT IDENTIFIER ecdsaWithSHA512 (1 2 840 10045 4 3 4)
: (ANSI X9.62 ECDSA algorithm with SHA512)
: }
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6. Security Considerations
The security considerations from EST [RFC7030] section 6 are
unchanged.
6.1. Identity and Privacy Considerations
An EST server may use this mechanism to instruct the EST client about
the identities it should include in the CSR it sends as part of
enrollment. The client may only be aware of its IDevID Subject,
which includes a manufacturer serial number. The EST server can use
this mechanism to tell the client to include a specific fully
qualified domain name in the CSR in order to complete domain
ownership proofs required by the CA. Additionally, the EST server
may deem the manufacturer serial number in an IDevID as personally
identifiable information, and may want to specify a new random opaque
identifier that the pledge should use in its CSR. This may be
desirable if the CA and EST server have different operators.
7. IANA Considerations
IANA is asked to allocate two new Object Identifiers:
* One (TBD1) from the SMI Security for S/MIME Module Identifier
(1.2.840.113549.1.9.16.0) registry for the ASN.1 module: id-mod-
critemplate; see Appendix A
* One (TBD2) from the SMI Security for S/MIME Attributes
(1.2.840.113549.1.9.16.2) registry for the Certification Request
Information Template (csrinfo) attribute; see Appendix A
* One (TBD3) SMI Security for S/MIME Attributes
(1.2.840.113549.1.9.16.2) registry for the extension request
template (extensionReqTemplate) attribute; see Appendix A
8. Acknowledgments
Corey Bonnell crafted example02 using a different tool, and this
helped debug other running code.
Carl Wallace provided major parts of the
CertificationRequestInfoTemplate syntax declaration.
Russ Housley did many reviews of the ASN.1 and suggested many fixes.
Deb Cooley did the usual Area Director Review.
9. References
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9.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/rfc/rfc2119>.
[RFC5911] Hoffman, P. and J. Schaad, "New ASN.1 Modules for
Cryptographic Message Syntax (CMS) and S/MIME", RFC 5911,
DOI 10.17487/RFC5911, June 2010,
<https://www.rfc-editor.org/rfc/rfc5911>.
[RFC5912] Hoffman, P. and J. Schaad, "New ASN.1 Modules for the
Public Key Infrastructure Using X.509 (PKIX)", RFC 5912,
DOI 10.17487/RFC5912, June 2010,
<https://www.rfc-editor.org/rfc/rfc5912>.
[RFC6268] Schaad, J. and S. Turner, "Additional New ASN.1 Modules
for the Cryptographic Message Syntax (CMS) and the Public
Key Infrastructure Using X.509 (PKIX)", RFC 6268,
DOI 10.17487/RFC6268, July 2011,
<https://www.rfc-editor.org/rfc/rfc6268>.
[RFC7030] Pritikin, M., Ed., Yee, P., Ed., and D. Harkins, Ed.,
"Enrollment over Secure Transport", RFC 7030,
DOI 10.17487/RFC7030, October 2013,
<https://www.rfc-editor.org/rfc/rfc7030>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/rfc/rfc8174>.
[X.680] ITU-T, "Information technology -- Abstract Syntax Notation
One (ASN.1): Specification of basic notation", ITU-T
Recommendation X.680, ISO/IEC 8824-1:2021, February 2021,
<https://www.itu.int/rec/T-REC-X.680>.
9.2. Informative References
[dumpasn1] Gutmann, P., "Dump ASN", n.d.,
<https://www.cs.auckland.ac.nz/~pgut001/dumpasn1.c>.
[favoritedrink]
"Favorite Drink: arbitrary OID", n.d.,
<https://oid-base.com/get/0.9.2342.19200300.100.1.5>.
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[RFC2985] Nystrom, M. and B. Kaliski, "PKCS #9: Selected Object
Classes and Attribute Types Version 2.0", RFC 2985,
DOI 10.17487/RFC2985, November 2000,
<https://www.rfc-editor.org/rfc/rfc2985>.
[RFC4211] Schaad, J., "Internet X.509 Public Key Infrastructure
Certificate Request Message Format (CRMF)", RFC 4211,
DOI 10.17487/RFC4211, September 2005,
<https://www.rfc-editor.org/rfc/rfc4211>.
[RFC5272] Schaad, J. and M. Myers, "Certificate Management over CMS
(CMC)", RFC 5272, DOI 10.17487/RFC5272, June 2008,
<https://www.rfc-editor.org/rfc/rfc5272>.
[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, DOI 10.17487/RFC5280, May 2008,
<https://www.rfc-editor.org/rfc/rfc5280>.
[RFC8295] Turner, S., "EST (Enrollment over Secure Transport)
Extensions", RFC 8295, DOI 10.17487/RFC8295, January 2018,
<https://www.rfc-editor.org/rfc/rfc8295>.
[RFC8368] Eckert, T., Ed. and M. Behringer, "Using an Autonomic
Control Plane for Stable Connectivity of Network
Operations, Administration, and Maintenance (OAM)",
RFC 8368, DOI 10.17487/RFC8368, May 2018,
<https://www.rfc-editor.org/rfc/rfc8368>.
[RFC8994] Eckert, T., Ed., Behringer, M., Ed., and S. Bjarnason, "An
Autonomic Control Plane (ACP)", RFC 8994,
DOI 10.17487/RFC8994, May 2021,
<https://www.rfc-editor.org/rfc/rfc8994>.
[RFC8995] Pritikin, M., Richardson, M., Eckert, T., Behringer, M.,
and K. Watsen, "Bootstrapping Remote Secure Key
Infrastructure (BRSKI)", RFC 8995, DOI 10.17487/RFC8995,
May 2021, <https://www.rfc-editor.org/rfc/rfc8995>.
[RFC9480] Brockhaus, H., von Oheimb, D., and J. Gray, "Certificate
Management Protocol (CMP) Updates", RFC 9480,
DOI 10.17487/RFC9480, November 2023,
<https://www.rfc-editor.org/rfc/rfc9480>.
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[RFC9483] Brockhaus, H., von Oheimb, D., and S. Fries, "Lightweight
Certificate Management Protocol (CMP) Profile", RFC 9483,
DOI 10.17487/RFC9483, November 2023,
<https://www.rfc-editor.org/rfc/rfc9483>.
[X.690] ITU-T, "Information technology -- ASN.1 encoding rules:
Specification of Basic Encoding Rules (BER), Canonical
Encoding Rules (CER) and Distinguished Encoding Rules
(DER)", ITU-T Recommendation X.690, ISO/IEC 8825-1:2021,
February 2021, <https://www.itu.int/rec/T-REC-X.690>.
Appendix A. ASN.1 Module
| RFC EDITOR: Please replace TBD1, TBD2, and TBD3 with the value
| assigned by IANA during the publication of this document.
This appendix provides an ASN.1 module [X.680] for the Certification
Request Information Template attribute, and it follows the
conventions established in [RFC5911], [RFC5912], and [RFC6268].
CRITemplateModule
{ iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1)
pkcs-9(9) smime(16) modules(0) id-mod-critemplate(TBD1) }
DEFINITIONS IMPLICIT TAGS ::=
BEGIN
IMPORTS -- from [RFC5912]
SupportedAttributes
FROM PKIX1Explicit-2009
{ iso(1) identified-organization(3) dod(6) internet(1) security(5)
mechanisms(5) pkix(7) id-mod(0) id-mod-pkix1-explicit-02(51)}
ATTRIBUTE, EXTENSION
FROM PKIX-CommonTypes-2009
{ iso(1) identified-organization(3) dod(6) internet(1) security(5)
mechanisms(5) pkix(7) id-mod(0) id-mod-pkixCommon-02(57) }
PUBLIC-KEY, AlgorithmIdentifier{}
FROM AlgorithmInformation-2009
{ iso(1) identified-organization(3) dod(6) internet(1) security(5)
mechanisms(5) pkix(7) id-mod(0)
id-mod-algorithmInformation-02(58)}
CertExtensions
FROM PKIX1Implicit-2009
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{ iso(1) identified-organization(3) dod(6) internet(1) security(5)
mechanisms(5) pkix(7) id-mod(0) id-mod-pkix1-implicit-02(59)}
Attributes{}, CRIAttributes, PKInfoAlgorithms
FROM PKCS-10
{ iso(1) identified-organization(3) dod(6) internet(1)
security(5) mechanisms(5) pkix(7)
id-mod(0) id-mod-pkcs10-2009(69) }
;
aa-certificationRequestInfoTemplate ATTRIBUTE ::=
{ TYPE CertificationRequestInfoTemplate IDENTIFIED BY
id-aa-certificationRequestInfoTemplate }
id-aa-certificationRequestInfoTemplate OBJECT IDENTIFIER ::=
{ iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs9(9)
smime(16) aa(2) csrinfo(TBD2) }
-- like CertificationRequestInfo but OPTIONAL subject, subjectPKInfo
CertificationRequestInfoTemplate ::= SEQUENCE {
version INTEGER { v1(0) } (v1, ... ),
subject NameTemplate OPTIONAL,
subjectPKInfo [0] SubjectPublicKeyInfoTemplate
{{ PKInfoAlgorithms }} OPTIONAL,
attributes [1] Attributes{{ CRIAttributes }}
}
-- like Name, but with OPTIONAL RDN values
NameTemplate ::= CHOICE { -- only one possibility for now --
rdnSequence RDNSequenceTemplate }
RDNSequenceTemplate ::= SEQUENCE OF RelativeDistinguishedNameTemplate
RelativeDistinguishedNameTemplate ::= SET SIZE (1 .. MAX)
OF SingleAttributeTemplate { {SupportedAttributes} }
-- like Attributes, but with OPTIONAL value
SingleAttributeTemplates{ATTRIBUTE:AttrSet} ::= SEQUENCE OF
SingleAttributeTemplates{ {AttrSet} }
-- like SingleAttribute, but with OPTIONAL value
SingleAttributeTemplate{ATTRIBUTE:AttrSet} ::= SEQUENCE {
type ATTRIBUTE.&id({AttrSet}),
value ATTRIBUTE.&Type({AttrSet}{@type}) OPTIONAL
}
-- like SubjectPublicKeyInfo, but with OPTIONAL subjectPublicKey
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SubjectPublicKeyInfoTemplate{PUBLIC-KEY:IOSet} ::= SEQUENCE {
algorithm AlgorithmIdentifier{PUBLIC-KEY, {IOSet}},
subjectPublicKey BIT STRING OPTIONAL
}
id-aa-extensionReqTemplate OBJECT IDENTIFIER ::=
{ iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs9(9)
smime(16) aa(2) extnReqTemplate(TBD3) }
-- like extensionRequest, but with OPTIONAL Extension extnValues
-- original definition was in PKCS#9 RFC 2985 section 5.4.2
at-extensionReqTemplate ATTRIBUTE ::= {
TYPE ExtensionReqTemplate IDENTIFIED BY id-aa-extensionReqTemplate }
ExtensionReqTemplate ::= ExtensionTemplates{{CertExtensions}}
-- like Extensions, but with OPTIONAL extnValue
ExtensionTemplates{EXTENSION:ExtensionSet} ::=
SEQUENCE SIZE (1..MAX) OF ExtensionTemplate{{ExtensionSet}}
-- like Extension, but with OPTIONAL extnValue
ExtensionTemplate{EXTENSION:ExtensionSet} ::= SEQUENCE {
extnID EXTENSION.&id({ExtensionSet}),
critical BOOLEAN
-- (EXTENSION.&Critical({ExtensionSet}{@extnID}))
DEFAULT FALSE,
extnValue OCTET STRING (CONTAINING
EXTENSION.&ExtnType({ExtensionSet}{@extnID})) OPTIONAL
-- contains the DER encoding of the ASN.1 value
-- corresponding to the extension type identified
-- by extnID when present
}
END
Authors' Addresses
Michael Richardson (editor)
Sandelman Software Works
Email: mcr+ietf@sandelman.ca
Owen Friel
Cisco
Email: ofriel@cisco.com
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Dr. David von Oheimb
Siemens
Email: dev@ddvo.net
Dan Harkins
The Industrial Lounge
Email: dharkins@lounge.org
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