Internet Engineering Task Force (IETF)                     M. Sahni, Ed.
Request for Comments: 8954                            Palo Alto Networks
Updates: 6960                                              November 2020
Category: Standards Track
ISSN: 2070-1721

Online Certificate Status Protocol (OCSP) Nonce Extension

オンライン証明書ステータスプロトコル(OCSP)Nonce Extension



This document specifies the updated format of the Nonce extension in the Online Certificate Status Protocol (OCSP) request and response messages. OCSP is used to check the status of a certificate, and the Nonce extension is used to cryptographically bind an OCSP response message to a particular OCSP request message. This document updates RFC 6960.

このドキュメントでは、オンライン証明書ステータスプロトコル(OCSP)要求および応答メッセージのNonce拡張機能の更新形式を指定します。OCSPは証明書の状態を確認するために使用され、Nonce拡張はOCSP応答メッセージを特定のOCSP要求メッセージに暗号化的にバインドするために使用されます。この文書はRFC 6960を更新します。

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.

この文書は、インターネットエンジニアリングタスクフォース(IETF)の製品です。IETFコミュニティのコンセンサスを表します。それは公開レビューを受け、インターネットエンジニアリングステアリンググループ(IESG)による出版の承認を受けました。インターネット規格に関する詳細情報は、RFC 7841のセクション2で利用できます。

Information about the current status of this document, any errata, and how to provide feedback on it may be obtained at


Copyright Notice


Copyright (c) 2020 IETF Trust and the persons identified as the document authors. All rights reserved.

Copyright(C)2020 IETFの信頼と文書著者として識別された人。全著作権所有。

This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents ( 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 Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License.

このドキュメントは、このドキュメントの発行日に有効なBCP 78およびIETFドキュメントに関連するIETFトラストの法的規定(の対象となります。 これらのドキュメントは、このドキュメントに関するお客様の権利と制限について説明しているため、注意深く確認してください。 このドキュメントから抽出されたコードコンポーネントには、Trust LegalProvisionsのセクション4.eで説明されているSimplifiedBSD Licenseテキストが含まれている必要があり、Simplified BSDLicenseで説明されているように保証なしで提供されます。

Table of Contents


   1.  Introduction
     1.1.  Terminology
   2.  OCSP Extensions
     2.1.  Nonce Extension
   3.  Security Considerations
     3.1.  Replay Attack
     3.2.  Nonce Collision
   4.  IANA Considerations
   5.  Changes to Appendix B of RFC 6960
     5.1.  Changes to Appendix B.1 OCSP in ASN.1 - 1998 Syntax
     5.2.  Changes to Appendix B.2 OCSP in ASN.1 - 2008 Syntax
   6.  References
     6.1.  Normative References
     6.2.  Informative References
   Author's Address
1. Introduction
1. はじめに

This document updates the usage and format of the Nonce extension in OCSP request and response messages. This extension was previously defined in Section 4.4.1 of [RFC6960]. [RFC6960] does not mention any minimum or maximum length of the nonce in the Nonce extension. Lacking limits on the length of the nonce in the Nonce extension, OCSP responders that follow [RFC6960] may be vulnerable to various attacks, like Denial-of-Service attacks [RFC4732] or chosen-prefix attacks (to get a desired signature), and possible evasions using the Nonce extension data. This document specifies a lower limit of 1 and an upper limit of 32 for the length of the nonce in the Nonce extension. This document updates [RFC6960].


1.1. Terminology
1.1. 用語

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.

この文書のキーワード "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", および "OPTIONAL" はBCP 14 [RFC2119] [RFC8174]で説明されているように、すべて大文字の場合にのみ解釈されます。

2. OCSP Extensions
2. OCSPエクステンション

The message formats for OCSP requests and responses are defined in [RFC6960]. [RFC6960] also defines the standard extensions for OCSP messages based on the extension model employed in X.509 version 3 certificates (see [RFC5280]). This document only specifies the new format for the Nonce extension and does not change the specifications of any of the other standard extensions defined in [RFC6960].

OCSP要求および応答のメッセージフォーマットは[RFC6960]で定義されています。[RFC6960] X.509バージョン3証明書で採用されている拡張モデルに基づくOCSPメッセージの標準拡張機能を定義します([RFC5280]参照)。この文書は、Nonce拡張機能の新しいフォーマットを指定し、[RFC6960]で定義されている他の標準拡張の仕様を変更しません。

2.1. Nonce Extension
2.1. Nonce Extension

This section replaces the entirety of Section 4.4.1 of [RFC6960], which describes the OCSP Nonce extension.

このセクションは[RFC6960]のセクション4.4.1の全体を置き換えます。[RFC6960]。これはOCSP Nonce拡張機能を説明します。

The nonce cryptographically binds a request and a response to prevent replay attacks. The nonce is included as one of the requestExtensions in requests; in responses, it would be included as one of the responseExtensions. In both the request and the response, the nonce will be identified by the object identifier id-pkix-ocsp-nonce, while the extnValue is the value of the nonce. If the Nonce extension is present, then the length of the nonce MUST be at least 1 octet and can be up to 32 octets.

NONCE暗号化でリクエストとレスポンスをバインドして、リプレイ攻撃を防ぐ。nonceはリクエスト内のrequestExtensionsの1つとして含まれています。回答では、それはResponseExtensionsの1つとして含まれます。要求と応答の両方で、NONCEはオブジェクト識別子ID-PKIX-OCSP - NONCEによって識別され、EXTNVALUEはNONCEの値です。Nonce拡張機能が存在する場合、Nonceの長さは少なくとも1オクテットでなければならず、最大32オクテットである可能性があります。

A server MUST reject any OCSP request that has a nonce in the Nonce extension with a length of either 0 octets or more than 32 octets with the malformedRequest OCSPResponseStatus, as described in Section 4.2.1 of [RFC6960].

[RFC6960]のセクション4.2.1のセクション4.2.1で説明されているように、0オクテットまたは32 OCTSESTATUSSESTATUSを使用して、Nonce拡張機能にNONCEを持つOCSP要求を拒否しなければなりません。

The value of the nonce MUST be generated using a cryptographically strong pseudorandom number generator (see [RFC4086]). The minimum nonce length of 1 octet is defined to provide backward compatibility with older clients that follow [RFC6960]. Newer OCSP clients that support this document MUST use a length of 32 octets for the nonce in the Nonce extension. OCSP responders MUST accept lengths of at least 16 octets and MAY choose to ignore the Nonce extension for requests where the length of the nonce is less than 16 octets.


      id-pkix-ocsp           OBJECT IDENTIFIER ::= { id-ad-ocsp }
      id-pkix-ocsp-nonce     OBJECT IDENTIFIER ::= { id-pkix-ocsp 2 }
      Nonce ::= OCTET STRING(SIZE(1..32))
3. Security Considerations
3. セキュリティに関する考慮事項

The security considerations of OCSP, in general, are described in [RFC6960]. During the interval in which the previous OCSP response for a certificate is not expired but the responder has a changed status for that certificate, a copy of that OCSP response can be used to indicate that the status of the certificate is still valid. Including a client's nonce value in the OCSP response makes sure that the response is the latest response from the server and not an old copy.


3.1. Replay Attack
3.1. リプレイ攻撃

The Nonce extension is used to avoid replay attacks. Since the OCSP responder may choose not to send the Nonce extension in the OCSP response even if the client has sent the Nonce extension in the request [RFC5019], an on-path attacker can intercept the OCSP request and respond with an earlier response from the server without the Nonce extension. This can be mitigated by configuring the server to use a short time interval between the thisUpdate and nextUpdate fields in the OCSP response.


3.2. Nonce Collision
3.2. 無衝突

If the value of the nonce used by a client in the OCSP request is predictable, then an attacker may prefetch responses with the predicted nonce and can replay them, thus defeating the purpose of using the nonce. Therefore, the value of the Nonce extension in the OCSP request MUST contain cryptographically strong randomness and MUST be freshly generated at the time of the creation of the OCSP request. Also, if the length of the nonce is too small (e.g., 1 octet), then an on-path attacker can prefetch responses with all the possible values of the nonce and replay a matching nonce.


4. IANA Considerations
4. IANAの考慮事項

This document has no IANA actions.


5. Changes to Appendix B of RFC 6960
5. RFC 6960の付録Bへの変更

This section updates the ASN.1 definitions of the OCSP Nonce extension in Appendices B.1 and B.2 of [RFC6960]. Appendix B.1 defines OCSP using ASN.1 - 1998 Syntax; Appendix B.2 defines OCSP using ASN.1 - 2008 Syntax.

このセクションでは、[RFC6960]の付録B.1とB.2のOCSP Nonce拡張機能のASN.1定義を更新します。付録B.1は、ASN.1 - 1998の構文を使用してOCSPを定義します。付録B.2は、ASN.1 - 2008構文を使用してOCSPを定義します。

5.1. Changes to Appendix B.1 OCSP in ASN.1 - 1998 Syntax
5.1. ASN.1 - 1998構文の付録B.1 OCSPへの変更

OLD Syntax:


The definition of OCSP Nonce extension is not provided in Appendix B.1 of [RFC6960] for the ASN.1 - 1998 Syntax.

ASN.1 - 1998の構文のための[RFC6960]の付録B.1には、OCSP Nonce拡張の定義は提供されていません。

NEW Syntax:


       Nonce ::= OCTET STRING(SIZE(1..32))
5.2. Changes to Appendix B.2 OCSP in ASN.1 - 2008 Syntax
5.2. 付録B.2 ASN.1 - 2008の構文でのOCSPへの変更

OLD Syntax:


           BY id-pkix-ocsp-nonce }

NEW Syntax:


       re-ocsp-nonce EXTENSION ::= { SYNTAX OCTET STRING(SIZE(1..32))
           IDENTIFIED BY id-pkix-ocsp-nonce }
6. References
6. 参考文献
6.1. Normative References
6.1. 引用文献

[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, <>.

[RFC2119] BRADNER、S、「RFCSで使用するためのキーワード」、BCP 14、RFC 2119、DOI 10.17487 / RFC2119、1997年3月、<>。

[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, <>.

[RFC5280] Cooper、D.、Santesson、S.、Farrell、S.、Boeyen、S.、Housley、R.、およびW.Polk、 "Internet X.509公開鍵インフラストラクチャ証明書および証明書失効リスト(CRL)プロファイル「、RFC 5280、DOI 10.17487 / RFC5280、2008年5月、<>。

[RFC6960] Santesson, S., Myers, M., Ankney, R., Malpani, A., Galperin, S., and C. Adams, "X.509 Internet Public Key Infrastructure Online Certificate Status Protocol - OCSP", RFC 6960, DOI 10.17487/RFC6960, June 2013, <>.

[RFC6960] Santesson、S、Myers、M.、Ankney、R.、Malpani、A.、Galparin、S、およびC. ADAMS、「X.509インターネット公開鍵インフラストラクチャオンライン証明書ステータスプロトコル - OCSP」、RFC6960、DOI 10.17487 / RFC6960、2013年6月、<>。

[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, <>.

[RFC8174] Leiba、B、「RFC 2119キーワードの大文字の曖昧さ」、BCP 14、RFC 8174、DOI 10.17487 / RFC8174、2017年5月、<>。

6.2. Informative References
6.2. 参考引用

[RFC4086] Eastlake 3rd, D., Schiller, J., and S. Crocker, "Randomness Requirements for Security", BCP 106, RFC 4086, DOI 10.17487/RFC4086, June 2005, <>.

[RFC4086]イーストレイク3RD、D.、Schiller、J.、S. Crocker、「セキュリティのためのランダム性要件」、BCP 106、RFC 4086、DOI 10.17487 / RFC4086、2005年6月、<https://www.rfc-編集者.org / info / rfc4086>。

[RFC4732] Handley, M., Ed., Rescorla, E., Ed., and IAB, "Internet Denial-of-Service Considerations", RFC 4732, DOI 10.17487/RFC4732, December 2006, <>.

[RFC4732]ハンドリー、M.、ED。、RESCORLA、E.、ED。、およびIAB、「インターネット拒否サービス考慮事項」、RFC 4732、DOI 10.17487 / RFC4732、2006年12月、<https:// www。>。

[RFC5019] Deacon, A. and R. Hurst, "The Lightweight Online Certificate Status Protocol (OCSP) Profile for High-Volume Environments", RFC 5019, DOI 10.17487/RFC5019, September 2007, <>.

[RFC5019] Deacon、A.およびR. Hurst、「高音量環境のための軽量のオンライン証明書ステータスプロトコル(OCSP)プロファイル」、RFC 5019、DOI 10.17487 / RFC5019、2007年9月、<https:///>。

Author's Address


Mohit Sahni (editor) Palo Alto Networks 3000 Tannery Way Santa Clara, CA 95054 United States of America

Mohit Sahni(編集)Palo Alto Networks 3000 Tannery Way Santa Clara、CA 95054アメリカ