Internet-Draft CSRAttrs September 2024
Richardson, et al. Expires 10 March 2025 [Page]
Workgroup:
LAMPS Working Group
Internet-Draft:
draft-ietf-lamps-rfc7030-csrattrs-12
Updates:
7030 (if approved)
Published:
Intended Status:
Standards Track
Expires:
Authors:
M. Richardson, Ed.
Sandelman Software Works
O. Friel
Cisco
D. von Oheimb
Siemens
D. Harkins
The Industrial Lounge

Clarification and enhancement of RFC7030 CSR Attributes definition

Abstract

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.

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.

Moreover, it provides new convenient and straightforward approach: using a template for CSR contents that may be partially filled in by the server. This also allows specifying 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 working documents as Internet-Drafts. The list of current Internet-Drafts is at https://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 10 March 2025.

▲

Table of Contents

1. Introduction

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.

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 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 extensionRequest, which has the numerical value 1.2.840.113549.1.9.14. There MUST be only one such Attribute.

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 particiular 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

[RFC8295], Appendix B describes a mechanism that avoids the piecemeal inclusion of attributes that [RFC7030] documented. Instead, an entire CSR object is returned with various fields filled out, and other fields waiting to be filled in, in a pKCS7PDU attribute. In that approach, the pKCS7PDU attribute includes a Full PKI Data content type [RFC5272] and that in turn includes a CSR or CRMF formatted request; see [RFC6268] Sections 5 and 9, respectively.

The 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. We avoid this drawback as follows.

This specification defines the Certificate Request Information Template attribute for CsrAttrs, see Section 3.2, that is essentially a partially filled in PKCS#10 CSR minus the signature wrapper as follows:

  CertificationRequestInfoTemplate ::= SEQUENCE {
      version           INTEGER { v1(0) } (v1, ... ),
      subject           NameTemplate OPTIONAL,
      subjectPKInfo [0] SubjectPublicKeyInfoTemplate
                                {{ PKInfoAlgorithms }} OPTIONAL,
      attributes       [1] Attributes{{ CRIAttributes }}
  }

Appendix A contains all detail.

Note that 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 is made OPTIONAL to cover the case the server does not provide any requrements on the subject name and its RDNs.

  • RelativeDistinguishedNames (RDNs) in the subject fields are allowed to be empty, which is achieved by adding OPTIONAL to the value field of AttributeTypeAndValueTemplate. This means that the client is required to provide an RDN of the given type and fill in its value.

  AttributeTypeAndValueTemplate {ATTRIBUTE:AttrSet} ::= SEQUENCE {
      type      ATTRIBUTE.&id({AttrSet}),
      value     ATTRIBUTE.&Type({AttrSet}{@type}) OPTIONAL
  }

  • The subjectPKInfo field is made OPTIONAL, such that the server can leave it out in case there are no requirements on the key.
    Otherwise the server specifies the algorithm of the key, i.e., the key type, in the algorithm field. The subjectPublicKey field contained in SubjectPublicKeyInfoTemplate is made OPTIONAL because usually it is left out, but in case the server needs to specify the size of an RSA key, the field is used to provide a dummy public key value of the desired RSA modulus length.

  SubjectPublicKeyInfoTemplate {PUBLIC-KEY: IOSet} ::= SEQUENCE {
      algorithm        AlgorithmIdentifier {PUBLIC-KEY, {IOSet}},
      subjectPublicKey BIT STRING OPTIONAL
  }

  • A new OID pkcs-9-at-extensionRequestTemplate and the related ExtensionTemplate structure is defind where the extnValue field is optional. If the field is absent this means that the client is required to provide an X.509 extension with the given extnID and potentially the critical flag and fill in its value.

  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
  }

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]. That method does not properly deal with empty RDNs (encoding them as empty strings), absent subjectPublicKey fields (encoding them as empty BIT STRING), and empty X.509v3 extension values (encoding them as empty OCTET STRING), which may cause issues with strict ASN.1 parsing and decoding.

The version code MUST be v1 (0).

If the subjectPKInfo field is present, it indicates the type of the key pair the client is expected to use, where the subjectPublicKey MUST NOT be given except if the algorithm indicates RSA.

The attributes field MUST NOT contain multiple extensionRequestTemplate attributes and MUST NOT contain both extensionRequest and extensionRequestTemplate attributes.

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 fields with given values "myDept" and "myGroup",

  • the publicKey field contains an Elliptic Curve Cryptography (ECC) key on curve secp256r1,

  • the subjectAltName X.509 extension with DNS name "www.myServer.com" and an IP address to be filled in,

  • the keyUsage extension marked critical with the value digitalSignature and keyAgreement, and

  • the extKeyUsage extension with values 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"
         }
       }
     }
  SEQUENCE {
    SEQUENCE {
      OBJECT IDENTIFIER ecPublicKey (1 2 840 10045 2 1)
      OBJECT IDENTIFIER secp256r1 (1 2 840 10045 3 1 7)
      }
    }
  [0] {
    SEQUENCE {
      OBJECT IDENTIFIER extensionRequest (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 piecemeal 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 CertificateRequestInfoTemplate element.

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" 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 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.

    <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], a few different attributes are included.

5.2.1. Base64 encoded example

The Base64:

MEEGCSqGSIb3DQEJBzASBgcqhkjOPQIBMQcGBSuBBAAiMBYG
CSqGSIb3DQEJDjEJBgcrBgEBAQEWBggqhkjOPQQDAw==

5.2.2. ASN.1 DUMP output

  1. The challengePassword attribute is included to indicate that the CSR should include this value.

  2. An ecPublicKey attribute is provided with the value secp384r1 to indicate what kind of key should be submitted.

  3. An extensionRequest container with an OID 1.3.6.1.1.1.1.22 (macAddress), but without a value, to indicate that the CSR should include an X.509v3 extension with this value.

  4. The ecdsaWithSHA384 OID is included to indicate what kind of hash is expected to be used for the self-signature of the PCKS#10 CSR structure.

    <30 41>
  0  65: 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 16>
 33  22:   SEQUENCE {
    <06 09>
 35   9:     OBJECT IDENTIFIER extensionRequest (1 2 840 113549 1 9 14)
       :       (PKCS #9 via CRMF)
    <31 09>
 46   9:     SET {
    <06 07>
 48   7:       OBJECT IDENTIFIER '1 3 6 1 1 1 1 22'
       :       }
       :     }
    <06 08>
 57   8:   OBJECT IDENTIFIER ecdsaWithSHA384 (1 2 840 10045 4 3 3)
       :     (ANSI X9.62 ECDSA algorithm with SHA384)
       :   }

5.3. EST server requires a specific subjectAltName extension

This example is the same as the previous one except that instead of the OID for a macAddress, a subjectAltName is specified as the only Extension element.

5.3.1. Base64 encoded example

The Base64:

MGYGCSqGSIb3DQEJBzASBgcqhkjOPQIBMQcGBSuBBAAiMDsG
CSqGSIb3DQEJDjEuMCwGA1UdEQEB/wQioCAwHgYIKwYBBQUH
CAoMEnBvdGF0b0BleGFtcGxlLmNvbQYIKoZIzj0EAwM=

5.3.2. ASN.1 DUMP output

  1. The challengePassword attribute is included to indicate that the CSR should include this value.

  2. An ecPublicKey attribute is provided with the value secp384r1 to indicate what kind of key should be submitted.

  3. An extensionRequest container with a subjectAltName value containing the name potato@example.com

  4. The ecdsaWithSHA384 OID is included to indicate what kind of hash is expected to be used for the self-signature of the PCKS#10 CSR structure.

    <30 66>
  0 102: 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 3B>
 33  59:   SEQUENCE {
    <06 09>
 35   9:     OBJECT IDENTIFIER extensionRequest (1 2 840 113549 1 9 14)
       :       (PKCS #9 via CRMF)
    <31 2E>
 46  46:     SET {
    <30 2C>
 48  44:       SEQUENCE {
    <06 03>
 50   3:         OBJECT IDENTIFIER subjectAltName (2 5 29 17)
       :           (X.509 extension)
    <01 01>
 55   1:         BOOLEAN TRUE
    <04 22>
 58  34:         OCTET STRING
       :           A0 20 30 1E 06 08 2B 06    . 0...+.
       :           01 05 05 07 08 0A 0C 12    ........
       :           70 6F 74 61 74 6F 40 65    potato@e
       :           78 61 6D 70 6C 65 2E 63    xample.c
       :           6F 6D                      om
       :         }
       :       }
       :     }
    <06 08>
 94   8:   OBJECT IDENTIFIER ecdsaWithSHA384 (1 2 840 10045 4 3 3)
       :     (ANSI X9.62 ECDSA algorithm with SHA384)
       :   }

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

  1. Provide a CSR with an RSA key that's 4096 bits and sign it with sha256

    <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 sign it with sha384.

    <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, and be signed with SHA512.

5.6.1. Base64 encoded example

The Base64:

MFQGCSqGSIb3DQEJBzASBgcqhkjOPQIBMQcGBSuBBAAjMCkG
CSqGSIb3DQEJDjEcBgNVBAUGCSqGSIb3DQEJFAYKCZImiZPy
LGQBBQYIKoZIzj0EAwQ=

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 sign 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)
       :   }

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:

8. Acknowledgements

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.

9. Changelog

10. References

10.1. Normative References

[RFC2119]
Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, , <https://www.rfc-editor.org/rfc/rfc2119>.
[RFC5272]
Schaad, J. and M. Myers, "Certificate Management over CMS (CMC)", RFC 5272, DOI 10.17487/RFC5272, , <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, , <https://www.rfc-editor.org/rfc/rfc5280>.
[RFC5911]
Hoffman, P. and J. Schaad, "New ASN.1 Modules for Cryptographic Message Syntax (CMS) and S/MIME", RFC 5911, DOI 10.17487/RFC5911, , <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, , <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, , <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, , <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, , <https://www.rfc-editor.org/rfc/rfc8174>.
[RFC8994]
Eckert, T., Ed., Behringer, M., Ed., and S. Bjarnason, "An Autonomic Control Plane (ACP)", RFC 8994, DOI 10.17487/RFC8994, , <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, , <https://www.rfc-editor.org/rfc/rfc8995>.
[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, , <https://www.itu.int/rec/T-REC-X.680>.
[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, , <https://www.itu.int/rec/T-REC-X.690>.

10.2. Informative References

[RFC4211]
Schaad, J., "Internet X.509 Public Key Infrastructure Certificate Request Message Format (CRMF)", RFC 4211, DOI 10.17487/RFC4211, , <https://www.rfc-editor.org/rfc/rfc4211>.
[RFC8295]
Turner, S., "EST (Enrollment over Secure Transport) Extensions", RFC 8295, DOI 10.17487/RFC8295, , <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, , <https://www.rfc-editor.org/rfc/rfc8368>.
[RFC9480]
Brockhaus, H., von Oheimb, D., and J. Gray, "Certificate Management Protocol (CMP) Updates", RFC 9480, DOI 10.17487/RFC9480, , <https://www.rfc-editor.org/rfc/rfc9480>.
[RFC9483]
Brockhaus, H., von Oheimb, D., and S. Fries, "Lightweight Certificate Management Protocol (CMP) Profile", RFC 9483, DOI 10.17487/RFC9483, , <https://www.rfc-editor.org/rfc/rfc9483>.

Appendix A. ASN.1 Module

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

ATTRIBUTE -- [RFC5911]
 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) }

CertificationRequestInfo -- [RFC5912]
  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) }

CertificationRequestInfoTemplate ::= SEQUENCE {
    version           INTEGER { v1(0) } (v1, ... ),
    subject           NameTemplate OPTIONAL,
    subjectPKInfo [0] SubjectPublicKeyInfoTemplate
                              {{ PKInfoAlgorithms }} OPTIONAL,
    attributes       [1] Attributes{{ CRIAttributes }}
}

NameTemplate ::= CHOICE { -- only one possibility for now --
    rdnSequence  RDNSequenceTemplate }

RDNSequenceTemplate ::= SEQUENCE OF RelativeDistinguishedNameTemplate

RelativeDistinguishedNameTemplate  ::=
    SET SIZE (1 .. MAX) OF AttributeTypeAndValueTemplate {
                           {SupportedAttributes} }

AttributeTypeAndValueTemplate {ATTRIBUTE:AttrSet} ::= SEQUENCE {
    type      ATTRIBUTE.&id({AttrSet}),
    value     ATTRIBUTE.&Type({AttrSet}{@type}) OPTIONAL
}

SubjectPublicKeyInfoTemplate {PUBLIC-KEY: IOSet} ::= SEQUENCE {
    algorithm        AlgorithmIdentifier {PUBLIC-KEY, {IOSet}},
    subjectPublicKey BIT STRING OPTIONAL
}

pkcs-9-at-extensionRequestTemplate OBJECT IDENTIFIER ::=
    {pkcs-9 TBD3}

extensionRequestTemplate ATTRIBUTE ::= {
        WITH SYNTAX ExtensionRequestTemplate
        SINGLE VALUE TRUE
        ID pkcs-9-at-extensionRequestTemplate
}

ExtensionRequestTemplate ::= ExtensionTemplates

ExtensionTemplates  ::=  SEQUENCE SIZE (1..MAX) OF ExtensionTemplate

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
Owen Friel
Cisco
Dr. David von Oheimb
Siemens
Dan Harkins
The Industrial Lounge