Internet-Draft CSRAttrs March 2025
Richardson, et al. Expires 4 September 2025 [Page]
Workgroup:
LAMPS Working Group
Internet-Draft:
draft-ietf-lamps-rfc7030-csrattrs-18
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

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 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 4 September 2025.

▲

Table of Contents

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.

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.

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.

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
  }

  • 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).

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"
        }
      }
    }
  [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.

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.

    <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:

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)
       :   }

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.

    <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.

    <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.

    <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=

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)
       :   }

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. 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

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, , <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, , <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>.
[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>.

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>.
[RFC2985]
Nystrom, M. and B. Kaliski, "PKCS #9: Selected Object Classes and Attribute Types Version 2.0", RFC 2985, DOI 10.17487/RFC2985, , <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, , <https://www.rfc-editor.org/rfc/rfc4211>.
[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>.
[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>.
[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>.
[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>.
[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>.

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