RFC 9883: An Attribute for Statement of Possession of a Private Key

R. Housley

Proposed Standard

Abstract

This document specifies an attribute for a statement of possession of a private key by a certificate subject. As part of X.509 certificate enrollment, a Certification Authority (CA) typically demands proof that the subject possesses the private key that corresponds to the to-be-certified public key. In some cases, a CA might accept a signed statement from the certificate subject. For example, when a certificate subject needs separate certificates for signature and key establishment, a statement that can be validated with the previously issued signature certificate for the same subject might be adequate for subsequent issuance of the key establishment certificate.¶

Status of This Memo

This is an Internet Standards Track document.¶

This document is a product of the Internet Engineering Task Force (IETF). It represents the consensus of the IETF community. It has received public review and has been approved for publication by the Internet Engineering Steering Group (IESG). Further information on Internet Standards is available in Section 2 of RFC 7841.¶

Information about the current status of this document, any errata, and how to provide feedback on it may be obtained at https://www.rfc-editor.org/info/rfc9883.¶

Copyright Notice

This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Revised BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Revised BSD License.¶

1. Introduction

This document specifies an attribute for a statement of possession of a private key by a certificate subject. X.509 certificate [RFC5280] enrollment often depends on PKCS#10 [RFC2986] or the Certificate Request Message Format (CRMF) [RFC4211]. As part of enrollment, a Certification Authority (CA) typically demands proof that the subject possesses the private key that corresponds to the to-be-certified public key. Alternatively, a CA may accept a signed statement from the certificate subject claiming knowledge of that private key. When a certificate subject needs separate certificates for signature and key establishment, a signed statement that can be validated with the previously issued signature certificate for the same subject might be adequate for subsequent issuance of the key establishment certificate.¶

For example, a subject may need a signature certificate that contains an ML-DSA (Module-Lattice-Based Digital Signature Algorithm) public key and a key establishment certificate that contains an ML-KEM (Module-Lattice-Based Key-Encapsulation Mechanism) public key. For another example, a subject may need a signature certificate that contains an ECDSA (Elliptic Curve Digital Signature Algorithm) public key and a key establishment certificate that contains an ECDH (Elliptic Curve Diffie-Hellman) public key.¶

A statement of possession may be used in lieu of the usual proof-of-possession mechanisms. The statement is simply a signed assertion that the requestor of a key establishment certificate has possession of the key establishment private key and that statement is signed using a signature private key that was previously shown to be in the possession of the same certificate subject. If allowed by the Certificate Policy [RFC3647], the CA is permitted to accept this statement in lieu of proof that the requestor has possession of the private key, such as [RFC6955].¶

Note that [RFC6955] offers some algorithms that provide proof of possession for Diffie-Hellman private keys; however, these algorithms are not suitable for use with PKCS#10 [RFC2986]. In addition, the algorithms in [RFC6955] do not support key encapsulation mechanism algorithms, such as ML-KEM. The attribute specified in this document, on the other hand, is suitable for use with both PKCS#10 and the CRMF [RFC4211].¶

1.1. ASN.1

The attribute defined in this document is generated using ASN.1 [X680], using the Distinguished Encoding Rules (DER) [X690].¶

1.2. 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.¶

2. Overview

When using the attribute defined in this document to make a statement about the possession of the key establishment private key, the process to obtain two certificates with PKCS#10 is as follows:¶

The subject generates the signature key pair.¶
The subject composes a PKCS#10 Certificate Signing Request (CSR) in the usual manner. It includes a signature that is produced with the private key from step 1.¶
The subject sends the CSR to the CA, and it gets back a signature certificate. The signature certificate includes a key usage of digitalSignature, nonRepudiation, or both (see Section 4.2.1.3 of [RFC5280]).¶
The subject generates the key establishment key pair.¶
The subject composes a PKCS#10 CSR containing the key establishment public key. The CSR attributes include the attribute specified in Section 3 of this document. The subject name matches the one from step 3. The CSR includes a signature that is produced with the private key from step 1.¶
The subject sends the CSR to the CA, and it gets back a key establishment certificate. The key establishment certificate includes a key usage of keyEncipherment or keyAgreement (see Section 4.2.1.3 of [RFC5280]).¶

In general, the issuer of the key establishment certificate will be the same as the issuer of the signature certificate. If the issuers of the two certificates will be different, then the certificate policy of the issuer of the key establishment certificate MUST explain the procedure that is used to verify the subject and subject alternative names.¶

3. Attribute for Statement of Possession of a Private Key

The attribute for statement of possession of a private key is included in a certificate request to make the following statement:¶

The subject of the signature certificate that is used to validate the signature on this certificate request states, without providing proof, that it has possession of the private key that corresponds to the public key in the certificate request.¶

The CA MUST perform certification path validation for the signature certificate as specified in Section 6 of [RFC5280]. If the certification path is not valid, then the CA MUST reject the request for the key establishment certificate.¶

The CA MUST validate the signature on the certificate request using the public key from the signature certificate. If the signature is not valid, then the CA MUST reject the certificate request.¶

The subject in the signature certificate SHOULD be the same as the subject name in the certificate request. If they are different, the certificate policy MUST describe how the CA can determine that the two subject names identify the same entity. If the CA is unable to determine that the two subject names identify the same entity, then the CA MUST reject the certificate request.¶

If subject alternative names are present in the certificate request, they SHOULD match subject alternative names in the signature certificate. If they are different, the certificate policy MUST describe how the CA can determine that the two subject alternative names identify the same entity. If the CA is unable to determine that each of subject alternative names identifies the same entity as is named in the signature certificate, then the CA MUST reject the certificate request.¶

When the CA rejects a certificate request for any of the reasons listed above, the CA should provide information to the requestor about the reason for the rejection to aid with diagnostic efforts. Likewise, the CA should log the rejection events.¶

The attribute for statement of possession of a private key has the following structure:¶

   id-at-statementOfPossession OBJECT IDENTIFIER ::=
     { 1 3 6 1 4 1 22112 2 1 }

   privateKeyPossessionStatement ATTRIBUTE ::= {
     TYPE PrivateKeyPossessionStatement
     IDENTIFIED BY id-at-statementOfPossession }

   PrivateKeyPossessionStatement ::= SEQUENCE {
     signer  IssuerAndSerialNumber,
     cert    Certificate OPTIONAL }

The components of the PrivateKeyStatement SEQUENCE have the following semantics:¶

signer:: The issuer name and certificate serial number of the signature certificate.¶
cert:: The signature certificate. If the issuer of the key establishment certificate will be the same as the issuer of the signature certificate, then this component MAY be omitted. When the signature certificate is omitted, the signer is assuming that the CA has a mechanism to obtain all valid certificates that it issued.¶

4. Conventions for PKCS#10

This section specifies the conventions for using the attribute for statement of possession of a private key with PKCS#10 [RFC2986] when requesting a key establishment certificate.¶

The PKCS#10 CertificationRequest always has three components, as follows:¶

certificationRequestInfo:: The subject name SHOULD be the same as the subject name in the signature certificate, the subjectPKInfo MUST contain the public key for the key establishment algorithm, and the attributes MUST include privateKeyPossessionStatement attribute as specified in Section 3 of this document.¶
signatureAlgorithm:: The signature algorithm MUST be one that can be validated with the public key in the signature certificate.¶
signature:: The signature over certificationRequestInfo MUST validate with the public key in the signature certificate, and certification path validation for the signature certificate MUST be successful as specified in Section 6 of [RFC5280].¶

5. Conventions for CRMF

This section specifies the conventions for using the attribute for statement of possession of a private key with the CRMF [RFC4211] when requesting a key establishment certificate.¶

The following ASN.1 types are defined for use with CRMF. They have exactly the same semantics and syntax as the attribute discussed above, but they offer a similar naming convention to the Registration Controls in [RFC4211].¶

  regCtrl-privateKeyPossessionStatement ATTRIBUTE ::=
    privateKeyPossessionStatement

  id-regCtrl-statementOfPossession OBJECT IDENTIFIER ::=
    id-at-statementOfPossession

The CRMF CertificationRequest always has three components, as follows:¶

certReq:: The certTemplate MUST include the subject and the publicKey components. The same subject name SHOULD match the subject name in the signature certificate, and publicKey MUST contain the public key for the key establishment algorithm.¶
popo:: The ProofOfPossession MUST use the signature CHOICE, the poposkInput MUST be present, POPOSigningKeyInput.authInfo MUST use the sender CHOICE, the sender SHOULD be set to the subject name that appears in the signature certificate, the publicKey MUST contain a copy of the public key from the certTemplate, the algorithmIdentifier MUST identify a signature algorithm that can be validated with the public key in the signature certificate, the signature over the poposkInput MUST validate with the public key in the signature certificate, and certification path validation for the signature certificate MUST be successful as specified in Section 6 of [RFC5280].¶
regInfo:: The attributes MUST include the privateKeyPossessionStatement attribute as specified in Section 3 of this document.¶

6. Security Considerations

The privateKeyPossessionStatement attribute MUST NOT be used to obtain a signature certificate. Performing proof of possession of the signature private key is easily accomplished by signing the certificate request.¶

The subject is signing the privateKeyPossessionStatement attribute to tell the CA that it has possession of the key establishment private key. This is being done instead of providing technical proof of possession. If the subject has lost control of the signature private key, then the signed privateKeyPossessionStatement attribute could be generated by some other party. Timely revocation of the compromised signature certificate is the only protection against such loss of control.¶

If the CA revokes a compromised signature certificate, then the CA SHOULD also revoke all key establishment certificates that were obtained with privateKeyPossessionStatement attributes signed by that compromised signature certificate.¶

The signature key pair and the key establishment key pair are expected to have roughly the same security strength. To ensure that the signature on the statement is not the weakest part of the certificate enrollment, the signature key pair SHOULD be at least as strong as the key establishment key pair.¶

If a CA allows a subject in the key establishment certificate to be different than the subject name in the signature certificate, then certificate policy MUST describe how to determine that the two subject names identify the same entity. Likewise, if a CA allows subject alternative names in the key establishment certificate that are not present in the signature certificate, then certificate policy MUST describe how to determine that the subject alternative names identify the same entity as is named in the signature certificate.¶

7. IANA Considerations

For the ASN.1 Module in Appendix A of this document, IANA has assigned an object identifier (OID) for the module identifier (118) with a Description of "id-mod-private-key-possession-stmt-2025" in the "SMI Security for PKIX Module Identifier" registry (1.3.6.1.5.5.7.0).¶

8. References

8.1. 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/info/rfc2119>.
[RFC2986]: Nystrom, M. and B. Kaliski, "PKCS #10: Certification Request Syntax Specification Version 1.7", RFC 2986, DOI 10.17487/RFC2986, November 2000, <https://www.rfc-editor.org/info/rfc2986>.
[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/info/rfc4211>.
[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/info/rfc5280>.
[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/info/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/info/rfc6268>.
[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/info/rfc8174>.
[X680]: 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>.
[X690]: 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>.

8.2. Informative References

[RFC3647]: Chokhani, S., Ford, W., Sabett, R., Merrill, C., and S. Wu, "Internet X.509 Public Key Infrastructure Certificate Policy and Certification Practices Framework", RFC 3647, DOI 10.17487/RFC3647, November 2003, <https://www.rfc-editor.org/info/rfc3647>.
[RFC6955]: Schaad, J. and H. Prafullchandra, "Diffie-Hellman Proof-of-Possession Algorithms", RFC 6955, DOI 10.17487/RFC6955, May 2013, <https://www.rfc-editor.org/info/rfc6955>.

Appendix A. ASN.1 Module

This ASN.1 Module uses the conventions established by [RFC5912] and [RFC6268].¶

<CODE BEGINS>
PrivateKeyPossessionStatement-2025
  { iso(1) identified-organization(3) dod(6) internet(1)
    security(5) mechanisms(5) pkix(7) id-mod(0)
    id-mod-private-key-possession-stmt-2025(118) }

DEFINITIONS IMPLICIT TAGS ::= BEGIN

EXPORTS ALL;

IMPORTS
  ATTRIBUTE
  FROM PKIX-CommonTypes-2009 -- in [RFC5912]
    { iso(1) identified-organization(3) dod(6) internet(1)
      security(5) mechanisms(5) pkix(7) id-mod(0)
      id-mod-pkixCommon-02(57) }

  Certificate
  FROM PKIX1Explicit-2009 -- in [RFC5912]
    { iso(1) identified-organization(3) dod(6) internet(1)
      security(5) mechanisms(5) pkix(7) id-mod(0)
      id-mod-pkix1-explicit-02(51) }

  IssuerAndSerialNumber
  FROM CryptographicMessageSyntax-2010 -- [RFC6268]
    { iso(1) member-body(2) us(840) rsadsi(113549)
       pkcs(1) pkcs-9(9) smime(16) modules(0)
       id-mod-cms-2009(58) } ;

--
-- Private Key Possession Statement Attribute
--

id-at-statementOfPossession OBJECT IDENTIFIER ::=
  { 1 3 6 1 4 1 22112 2 1 }

privateKeyPossessionStatement ATTRIBUTE ::= {
  TYPE PrivateKeyPossessionStatement
  IDENTIFIED BY id-at-statementOfPossession }

PrivateKeyPossessionStatement ::= SEQUENCE {
  signer  IssuerAndSerialNumber,
  cert    Certificate OPTIONAL }

--
-- Registration Control Support
--

RegControlSet ATTRIBUTE ::=
  { regCtrl-privateKeyPossessionStatement, ... }

regCtrl-privateKeyPossessionStatement ATTRIBUTE ::=
  privateKeyPossessionStatement

id-regCtrl-statementOfPossession OBJECT IDENTIFIER ::=
  id-at-statementOfPossession

END
<CODE ENDS>

Appendix B. Example Use of the privateKeyPossessionStatement Attribute

In this example, the self-signed certificate for the CA is as follows:¶

Alice generates her ECDSA signature key pair. Then, Alice composes a PKCS#10 Certificate Signing Request (CSR) in the usual manner as specified in [RFC2986]. The CSR includes a signature that is produced with her ECDSA private key. The CSR is as follows:¶

The CA issues a signature certificate to Alice:¶

Alice generates her ECDH key establishment key pair. Then, Alice composes a PKCS#10 CSR. The CSR attributes include the privateKeyPossessionStatement attribute, which points to her ECDSA signature certificate. The CSR includes her ECDH public key and a signature that is produced with her ECDSA private key. The CSR is as follows:¶

The CSR decodes to the following:¶

   0 1073: SEQUENCE {
   4  952:  SEQUENCE {
   8    1:   INTEGER 0
  11   60:   SEQUENCE {
  13   11:    SET {
  15    9:     SEQUENCE {
  17    3:      OBJECT IDENTIFIER countryName (2 5 4 6)
  22    2:      PrintableString 'US'
         :       }
         :      }
  26   11:    SET {
  28    9:     SEQUENCE {
  30    3:      OBJECT IDENTIFIER stateOrProvinceName (2 5 4 8)
  35    2:      PrintableString 'VA'
         :       }
         :      }
  39   16:    SET {
  41   14:     SEQUENCE {
  43    3:      OBJECT IDENTIFIER localityName (2 5 4 7)
  48    7:      PrintableString 'Herndon'
         :       }
         :      }
  57   14:    SET {
  59   12:     SEQUENCE {
  61    3:      OBJECT IDENTIFIER commonName (2 5 4 3)
  66    5:      PrintableString 'Alice'
         :       }
         :      }
         :     }
  73  116:   SEQUENCE {
  75   14:    SEQUENCE {
  77    5:     OBJECT IDENTIFIER ECDH (1 3 132 1 12)
  84    5:     OBJECT IDENTIFIER secp384r1 (1 3 132 0 34)
         :      }
  91   98:    BIT STRING
         :     04 01 47 24 13 1F E7 2A D6 CE 45 F7 8B 85 A8 57
         :     BB 97 52 EA 19 D1 02 F1 39 BE 7B 95 58 04 27 CA
         :     00 2F 0C 27 24 90 32 3D 46 8B 11 04 5C BF B5 5A
         :     3B 60 DB 75 EF 9C 9A 2E 08 3A 31 4A 90 C2 48 CA
         :     9F DE 4B E9 E7 E9 DA 33 7E EE C5 AD D9 62 00 FA
         :     0C F6 37 99 EE 44 66 FC 99 3E F4 91 25 31 65 FC
         :     16
         :     }
 191  765:   [0] {
 195  103:    SEQUENCE {
 197    9:     OBJECT IDENTIFIER
         :      extensionRequest (1 2 840 113549 1 9 14)
 208   90:     SET {
 210   88:      SEQUENCE {
 212   12:       SEQUENCE {
 214    3:        OBJECT IDENTIFIER
         :         basicConstraints (2 5 29 19)
 219    1:        BOOLEAN TRUE
 222    2:        OCTET STRING, encapsulates {
 224    0:         SEQUENCE {}
         :          }
         :         }
 226   11:       SEQUENCE {
 228    3:        OBJECT IDENTIFIER keyUsage (2 5 29 15)
 233    4:        OCTET STRING, encapsulates {
 235    2:         BIT STRING 3 unused bits
         :          '10000'B (bit 4)
         :          }
         :         }
 239   34:       SEQUENCE {
 241    3:        OBJECT IDENTIFIER subjectAltName (2 5 29 17)
 246   27:        OCTET STRING, encapsulates {
 248   25:         SEQUENCE {
 250   23:          [1] 'alice@email.example.com'
         :           }
         :          }
         :         }
 275   23:       SEQUENCE {
 277    3:        OBJECT IDENTIFIER
         :         certificatePolicies (2 5 29 32)
 282   16:        OCTET STRING, encapsulates {
 284   14:         SEQUENCE {
 286   12:          SEQUENCE {
 288   10:           OBJECT IDENTIFIER
         :            testCertPolicy (2 16 840 1 101 3 2 1 48 48)
         :            }
         :           }
         :          }
         :         }
         :        }
         :       }
         :      }
 300  656:    SEQUENCE {
 304   10:     OBJECT IDENTIFIER
         :      statementOfPossession (1 3 6 1 4 1 22112 2 1)
 316  640:     SET {
 320  636:      SEQUENCE {
 324   79:       SEQUENCE {
 326   55:        SEQUENCE {
 328   11:         SET {
 330    9:          SEQUENCE {
 332    3:           OBJECT IDENTIFIER countryName (2 5 4 6)
 337    2:           PrintableString 'US'
         :            }
         :           }
 341   19:         SET {
 343   17:          SEQUENCE {
 345    3:           OBJECT IDENTIFIER
         :            organizationName (2 5 4 10)
 350   10:           PrintableString 'Example CA'
         :            }
         :           }
 362   19:         SET {
 364   17:          SEQUENCE {
 366    3:           OBJECT IDENTIFIER commonName (2 5 4 3)
 371   10:           PrintableString 'ca.example'
         :            }
         :           }
         :          }
 383   20:        INTEGER
         :      7F 74 A3 FC 03 6C E2 14 78 5C 59 61 4E 6F 8D F2
         :      4C 47 A8 79
         :         }
 405  551:       SEQUENCE {
 409  430:        SEQUENCE {
 413    3:         [0] {
 415    1:          INTEGER 2
         :           }
 418   20:         INTEGER
         :      7F 74 A3 FC 03 6C E2 14 78 5C 59 61 4E 6F 8D F2
         :      4C 47 A8 79
 440   10:         SEQUENCE {
 442    8:          OBJECT IDENTIFIER
         :           ecdsaWithSHA384 (1 2 840 10045 4 3 3)
         :           }
 452   55:         SEQUENCE {
 454   11:          SET {
 456    9:           SEQUENCE {
 458    3:            OBJECT IDENTIFIER
         :             countryName (2 5 4 6)
 463    2:            PrintableString 'US'
         :             }
         :            }
 467   19:          SET {
 469   17:           SEQUENCE {
 471    3:            OBJECT IDENTIFIER
         :             organizationName (2 5 4 10)
 476   10:            PrintableString 'Example CA'
         :             }
         :            }
 488   19:          SET {
 490   17:           SEQUENCE {
 492    3:            OBJECT IDENTIFIER
         :             commonName (2 5 4 3)
 497   10:            PrintableString 'ca.example'
         :             }
         :            }
         :           }
 509   30:         SEQUENCE {
 511   13:          UTCTime 09/01/2025 17:03:48 GMT
 526   13:          UTCTime 09/01/2026 17:03:48 GMT
         :           }
 541   60:         SEQUENCE {
 543   11:          SET {
 545    9:           SEQUENCE {
 547    3:            OBJECT IDENTIFIER
         :             countryName (2 5 4 6)
 552    2:            PrintableString 'US'
         :             }
         :            }
 556   11:          SET {
 558    9:           SEQUENCE {
 560    3:            OBJECT IDENTIFIER
         :             stateOrProvinceName (2 5 4 8)
 565    2:            PrintableString 'VA'
         :             }
         :            }
 569   16:          SET {
 571   14:           SEQUENCE {
 573    3:            OBJECT IDENTIFIER
         :             localityName (2 5 4 7)
 578    7:            PrintableString 'Herndon'
         :             }
         :            }
 587   14:          SET {
 589   12:           SEQUENCE {
 591    3:            OBJECT IDENTIFIER
         :             commonName (2 5 4 3)
 596    5:            PrintableString 'Alice'
         :             }
         :            }
         :           }
 603  118:         SEQUENCE {
 605   16:          SEQUENCE {
 607    7:           OBJECT IDENTIFIER
         :            ecPublicKey (1 2 840 10045 2 1)
 616    5:           OBJECT IDENTIFIER
         :            secp384r1 (1 3 132 0 34)
         :            }
 623   98:          BIT STRING
         :      04 80 1C FB A9 57 37 53 08 33 FF 36 41 E5 8D 6F
         :      9E 47 D3 3A FE 95 58 16 55 E1 74 6D FE 23 CF 10
         :      9B E4 C0 A3 55 A3 34 78 51 2F 72 35 CC 57 9A 78
         :      93 3A A2 25 31 C2 D1 5D 89 02 8A 98 31 7F C3 30
         :      52 1C C1 9E F1 3F DB 90 77 D7 A9 E8 A6 7E 45 7B
         :      AD DB 5D 4B F3 E5 B5 40 8D 50 25 20 CD C4 03 51
         :      B1
         :           }
 723  118:         [3] {
 725  116:          SEQUENCE {
 727   12:           SEQUENCE {
 729    3:            OBJECT IDENTIFIER
         :             basicConstraints (2 5 29 19)
 734    1:            BOOLEAN TRUE
 737    2:            OCTET STRING, encapsulates {
 739    0:             SEQUENCE {}
         :              }
         :             }
 741   11:           SEQUENCE {
 743    3:            OBJECT IDENTIFIER
         :             keyUsage (2 5 29 15)
 748    4:            OCTET STRING, encapsulates {
 750    2:             BIT STRING 7 unused bits
         :              '1'B (bit 0)
         :              }
         :             }
 754   29:           SEQUENCE {
 756    3:            OBJECT IDENTIFIER
         :             subjectKeyIdentifier (2 5 29 14)
 761   22:            OCTET STRING, encapsulates {
 763   20:             OCTET STRING
         :      23 1D 00 D1 FE ED 0B 39 10 11 98 18 CC 7D CD 70
         :      CD 8B D3 92
         :              }
         :             }
 785   31:           SEQUENCE {
 787    3:            OBJECT IDENTIFIER
         :             authorityKeyIdentifier (2 5 29 35)
 792   24:            OCTET STRING, encapsulates {
 794   22:             SEQUENCE {
 796   20:              [0]
         :      3E 98 BC B2 EF DC 34 1B BE 71 92 D2 A3 FA 6D BC
         :      F2 66 40 AA
         :               }
         :              }
         :             }
 818   23:           SEQUENCE {
 820    3:            OBJECT IDENTIFIER
         :             certificatePolicies (2 5 29 32)
 825   16:            OCTET STRING, encapsulates {
 827   14:             SEQUENCE {
 829   12:              SEQUENCE {
 831   10:               OBJECT IDENTIFIER
         :                testCertPolicy (2 16 840 1 101 3 2 1 48 48)
         :                }
         :               }
         :              }
         :             }
         :            }
         :           }
         :          }
 843   10:        SEQUENCE {
 845    8:         OBJECT IDENTIFIER
         :          ecdsaWithSHA384 (1 2 840 10045 4 3 3)
         :          }
 855  103:        BIT STRING, encapsulates {
 858  100:         SEQUENCE {
 860   48:          INTEGER
         :      6B BF 53 2A 5D EC 16 95 9D 48 C1 DF A5 2D 5F D9
         :      B9 66 63 E2 EF CC B9 D5 10 3C 5A 16 CE BF 42 90
         :      56 B7 18 B6 3E 2A 39 D8 8C 54 A0 5C A1 57 1E C8
 910   48:          INTEGER
         :      44 9E 94 F7 5D 38 F0 D0 1B DE 78 9C 1D CA C6 15
         :      FD 54 62 B8 5B 0E 5C AD 2B 8B 42 6B 91 C1 C4 3F
         :      EA 02 0C B8 FD E5 33 03 93 59 C1 56 8B 2B BF 2E
         :           }
         :          }
         :         }
         :        }
         :       }
         :      }
         :     }
         :    }
 960   10:  SEQUENCE {
 962    8:   OBJECT IDENTIFIER ecdsaWithSHA384 (1 2 840 10045 4 3 3)
         :    }
 972  103:  BIT STRING, encapsulates {
 975  100:   SEQUENCE {
 977   47:    INTEGER
         :     64 CD 1C F5 0B 59 C0 92 D8 3A 99 08 28 90 79 2C
         :     31 D8 93 CB 30 8D 78 56 2F 7B ED BC F2 AC 89 AA
         :     E6 9D 07 DC 17 A5 E9 F0 12 F0 19 D0 D3 45 8D
1026   49:    INTEGER
         :     00 84 70 C0 95 C6 D1 B8 78 6A 75 6E A6 3A 00 DD
         :     E6 45 84 18 6A A0 8B 12 2E BC 41 1C 7D 56 E7 34
         :     21 32 10 4E 27 D2 64 3D F4 F1 D4 46 75 E8 1F 0A
         :     85
         :     }
         :    }
         :   }

The CA issues a key establishment certificate to Alice:¶

Acknowledgements

Thanks to Sean Turner, Joe Mandel, Mike StJohns, Mike Ounsworth, John Gray, Carl Wallace, Corey Bonnell, Hani Ezzadeen, Deb Cooley, Mohamed Boucadair, and Bron Gondwana for their constructive comments.¶

Author's Address

Russ Housley

Vigil Security, LLC

Herndon, VA

United States of America

Email: housley@vigilsec.com

RFC 9883: An Attribute for Statement of Possession of a Private Key

Proposed Standard

In this section

RFC 9883: An Attribute for Statement of Possession of a Private Key