Internet Engineering Task Force (IETF)                        M. Thomson
Request for Comments: 8291                                       Mozilla
Category: Standards Track                                  November 2017
ISSN: 2070-1721

Message Encryption for Web Push




This document describes a message encryption scheme for the Web Push protocol. This scheme provides confidentiality and integrity for messages sent from an application server to a user agent.


Status of This Memo


This is an Internet Standards Track document.

これはInternet Standards Trackドキュメントです。

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.

このドキュメントは、IETF(Internet Engineering Task Force)の製品です。これは、IETFコミュニティのコンセンサスを表しています。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)による公開が承認されました。インターネット標準の詳細については、RFC 7841のセクション2をご覧ください。

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) 2017 IETF Trust and the persons identified as the document authors. All rights reserved.

Copyright(c)2017 IETF Trustおよびドキュメントの作成者として識別された人物。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.

この文書は、BCP 78およびIETF文書に関するIETFトラストの法的規定(の対象であり、この文書の発行日に有効です。これらのドキュメントは、このドキュメントに関するあなた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 Legal Provisionsのセクション4.eに記載されているSimplified BSD Licenseのテキストが含まれている必要があり、Simplified BSD Licenseに記載されているように保証なしで提供されます。

Table of Contents


   1. Introduction ....................................................2
      1.1. Notational Conventions .....................................3
   2. Push Message Encryption Overview ................................3
      2.1. Key and Secret Distribution ................................4
   3. Push Message Encryption .........................................4
      3.1. Diffie-Hellman Key Agreement ...............................5
      3.2. Push Message Authentication ................................5
      3.3. Combining Shared and Authentication Secrets ................5
      3.4. Encryption Summary .........................................6
   4. Restrictions on Use of "aes128gcm" Content Coding ...............7
   5. Push Message Encryption Example .................................8
   6. IANA Considerations .............................................8
   7. Security Considerations .........................................8
   8. References .....................................................10
      8.1. Normative References ......................................10
      8.2. Informative References ....................................11
   Appendix A.  Intermediate Values for Encryption ...................12
   Author's Address ..................................................13
1. Introduction
1. はじめに

The Web Push protocol [RFC8030] is an intermediated protocol by necessity. Messages from an application server are delivered to a user agent (UA) via a push service, as shown in Figure 1.


    +-------+           +--------------+       +-------------+
    |  UA   |           | Push Service |       | Application |
    +-------+           +--------------+       +-------------+
        |                      |                      |
        |        Setup         |                      |
        |<====================>|                      |
        |           Provide Subscription              |
        |                      |                      |
        :                      :                      :
        |                      |     Push Message     |
        |    Push Message      |<---------------------|
        |<---------------------|                      |
        |                      |                      |

Figure 1


This document describes how messages sent using this protocol can be secured against inspection, modification, and forgery by a push service.


Web Push messages are the payload of an HTTP message [RFC7230]. These messages are encrypted using an encrypted content encoding [RFC8188]. This document describes how this content encoding is applied and describes a recommended key management scheme.


Multiple users of Web Push at the same user agent often share a central agent that aggregates push functionality. This agent can enforce the use of this encryption scheme by applications that use push messaging. An agent that only delivers messages that are properly encrypted strongly encourages the end-to-end protection of messages.


A web browser that implements the Push API [API] can enforce the use of encryption by forwarding only those messages that were properly encrypted.

Push API [API]を実装するWebブラウザは、適切に暗号化されたメッセージのみを転送することにより、暗号化の使用を強制できます。

1.1. Notational Conventions
1.1. 表記規則

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.


This document uses the terminology from [RFC8030], primarily "user agent", "push service", and "application server".


2. Push Message Encryption Overview
2. プッシュメッセージ暗号化の概要

Encrypting a push message uses Elliptic Curve Diffie-Hellman (ECDH) [ECDH] on the P-256 curve [FIPS186] to establish a shared secret (see Section 3.1) and a symmetric secret for authentication (see Section 3.2).


A user agent generates an ECDH key pair and authentication secret that it associates with each subscription it creates. The ECDH public key and the authentication secret are sent to the application server with other details of the push subscription.

ユーザーエージェントは、作成する各サブスクリプションに関連付けるECDHキーペアと認証シークレットを生成します。 ECDH公開鍵と認証シークレットは、プッシュサブスクリプションの他の詳細とともにアプリケーションサーバーに送信されます。

When sending a message, an application server generates an ECDH key pair and a random salt. The ECDH public key is encoded into the "keyid" parameter of the encrypted content coding header, and the salt is encoded into the "salt" parameter of that same header (see Section 2.1 of [RFC8188]). The ECDH key pair can be discarded after encrypting the message.

メッセージを送信するとき、アプリケーションサーバーはECDHキーペアとランダムソルトを生成します。 ECDH公開鍵は暗号化されたコンテンツコーディングヘッダーの「keyid」パラメーターにエンコードされ、saltは同じヘッダーの「salt」パラメーターにエンコードされます([RFC8188]のセクション2.1を参照)。 ECDHキーペアは、メッセージの暗号化後に破棄できます。

The content of the push message is encrypted or decrypted using a content encryption key and nonce. These values are derived by taking the "keyid" and "salt" as input to the process described in Section 3.


2.1. Key and Secret Distribution
2.1. 鍵と秘密の配布

The application using the subscription distributes the subscription public key and authentication secret to an authorized application server. This could be sent along with other subscription information that is provided by the user agent, such as the push subscription URI.


An application MUST use an authenticated, confidentiality-protected communications medium for this purpose. In addition to the reasons described in [RFC8030], this use ensures that the authentication secret is not revealed to unauthorized entities, which would allow those entities to generate push messages that will be accepted by the user agent.

アプリケーションは、この目的のために、認証され、機密性が保護された通信メディアを使用する必要があります。 [RFC8030]で説明されている理由に加えて、この使用により、認証シークレットが許可されていないエンティティに明らかにされないため、これらのエンティティはユーザーエージェントによって受け入れられるプッシュメッセージを生成できます。

Most applications that use push messaging have a preexisting relationship with an application server that can be used for distribution of subscription data. An authenticated communication mechanism that provides adequate confidentiality and integrity protection, such as HTTPS [RFC2818], is sufficient.

プッシュメッセージングを使用するほとんどのアプリケーションには、サブスクリプションデータの配布に使用できるアプリケーションサーバーとの既存の関係があります。 HTTPS [RFC2818]などの適切な機密性と整合性保護を提供する認証された通信メカニズムで十分です。

3. Push Message Encryption
3. プッシュメッセージの暗号化

Push message encryption happens in four phases:


o A shared secret is derived using ECDH [ECDH] (see Section 3.1 of this document).

o 共有秘密はECDH [ECDH]を使用して導出されます(このドキュメントのセクション3.1を参照)。

o The shared secret is then combined with the authentication secret to produce the input keying material (IKM) used in [RFC8188] (see Section 3.3 of this document).

o 共有シークレットは認証シークレットと組み合わされて、[RFC8188]で使用される入力キーイングマテリアル(IKM)を生成します(このドキュメントのセクション3.3を参照)。

o A content encryption key and nonce are derived using the process in [RFC8188].

o コンテンツ暗号化キーとノンスは、[RFC8188]のプロセスを使用して導出されます。

o Encryption or decryption follows according to [RFC8188].

o 暗号化または復号化は、[RFC8188]に従って行われます。

The key derivation process is summarized in Section 3.4. Restrictions on the use of the encrypted content coding are described in Section 4.


3.1. Diffie-Hellman Key Agreement
3.1. Diffie-Hellman鍵合意

For each new subscription that the user agent generates for an application, it also generates a P-256 [FIPS186] key pair for use in ECDH [ECDH].

ユーザーエージェントがアプリケーションに対して生成する新しいサブスクリプションごとに、ECDH [ECDH]で使用するためのP-256 [FIPS186]キーペアも生成します。

When sending a push message, the application server also generates a new ECDH key pair on the same P-256 curve.


The ECDH public key for the application server is included as the "keyid" parameter in the encrypted content coding header (see Section 2.1 of [RFC8188]).


An application server combines its ECDH private key with the public key provided by the user agent using the process described in [ECDH]; on receipt of the push message, a user agent combines its private key with the public key provided by the application server in the "keyid" parameter in the same way. These operations produce the same value for the ECDH shared secret.


3.2. Push Message Authentication
3.2. プッシュメッセージ認証

To ensure that push messages are correctly authenticated, a symmetric authentication secret is added to the information generated by a user agent. The authentication secret is mixed into the key derivation process described in Section 3.3.


A user agent MUST generate and provide a hard-to-guess sequence of 16 octets that is used for authentication of push messages. This SHOULD be generated by a cryptographically strong random number generator [RFC4086].


3.3. Combining Shared and Authentication Secrets
3.3. 共有シークレットと認証シークレットを組み合わせる

The shared secret produced by ECDH is combined with the authentication secret using the HMAC-based key derivation function (HKDF) [RFC5869]. This produces the input keying material used by [RFC8188].


The HKDF function uses the SHA-256 hash algorithm [FIPS180-4] with the following inputs:


salt: the authentication secret


IKM: the shared secret derived using ECDH info: the concatenation of the ASCII-encoded string "WebPush: info" (this string is not NUL-terminated), a zero octet, the user agent ECDH public key, and the application server ECDH public key, (both ECDH public keys are in the uncompressed point form defined in [X9.62]. That is:


key_info = "WebPush: info" || 0x00 || ua_public || as_public

key_info = "WebPush:info" || 0x00 || ua_public || as_public

L: 32 octets (i.e., the output is the length of the underlying SHA-256 HMAC function output)

L:32オクテット(つまり、出力は、基になるSHA-256 HMAC関数出力の長さです)

3.4. Encryption Summary
3.4. 暗号化の概要

This results in a final content encryption key and nonce generation using the following sequence, which is shown here in pseudocode with HKDF expanded into separate discrete steps using HMAC with SHA-256:


      -- For a user agent:
      ecdh_secret = ECDH(ua_private, as_public)
      auth_secret = random(16)
      salt = <from content coding header>
      -- For an application server:
      ecdh_secret = ECDH(as_private, ua_public)
      auth_secret = <from user agent>
      salt = random(16)

-- For both:

- 両方のための:

      ## Use HKDF to combine the ECDH and authentication secrets
      # HKDF-Extract(salt=auth_secret, IKM=ecdh_secret)
      PRK_key = HMAC-SHA-256(auth_secret, ecdh_secret)
      # HKDF-Expand(PRK_key, key_info, L_key=32)
      key_info = "WebPush: info" || 0x00 || ua_public || as_public
      IKM = HMAC-SHA-256(PRK_key, key_info || 0x01)
      ## HKDF calculations from RFC 8188
      # HKDF-Extract(salt, IKM)
      PRK = HMAC-SHA-256(salt, IKM)
      # HKDF-Expand(PRK, cek_info, L_cek=16)
      cek_info = "Content-Encoding: aes128gcm" || 0x00
      CEK = HMAC-SHA-256(PRK, cek_info || 0x01)[0..15]
      # HKDF-Expand(PRK, nonce_info, L_nonce=12)
      nonce_info = "Content-Encoding: nonce" || 0x00
      NONCE = HMAC-SHA-256(PRK, nonce_info || 0x01)[0..11]

Note that this omits the exclusive-OR of the final nonce with the record sequence number, since push messages contain only a single record (see Section 4) and the sequence number of the first record is zero.


4. Restrictions on Use of "aes128gcm" Content Coding
4. 「aes128gcm」コンテンツコーディングの使用に関する制限

An application server MUST encrypt a push message with a single record. This allows for a minimal receiver implementation that handles a single record. An application server MUST set the "rs" parameter in the "aes128gcm" content coding header to a size that is greater than the sum of the lengths of the plaintext, the padding delimiter (1 octet), any padding, and the authentication tag (16 octets).

アプリケーションサーバーは、単一のレコードでプッシュメッセージを暗号化する必要があります。これにより、単一のレコードを処理する最小限のレシーバー実装が可能になります。アプリケーションサーバーは、「aes128gcm」コンテンツコーディングヘッダーの「rs」パラメーターを、平文の長さ、パディング区切り文字(1オクテット)、パディング、および認証タグ( 16オクテット)。

A push message MUST include the application server ECDH public key in the "keyid" parameter of the encrypted content coding header. The uncompressed point form defined in [X9.62] (that is, a 65-octet sequence that starts with a 0x04 octet) forms the entirety of the "keyid". Note that this means that the "keyid" parameter will not be valid UTF-8 as recommended in [RFC8188].

プッシュメッセージは、暗号化されたコンテンツコーディングヘッダーの「keyid」パラメーターにアプリケーションサーバーECDH公開鍵を含める必要があります。 [X9.62]で定義された非圧縮ポイント形式(つまり、0x04オクテットで始まる65オクテットシーケンス)が「キーID」全体を形成します。これは、[RFC8188]で推奨されているように、「keyid」パラメータが有効なUTF-8ではないことに注意してください。

A push service is not required to support more than 4096 octets of payload body (see Section 7.2 of [RFC8030]). Absent header (86 octets), padding (minimum 1 octet), and expansion for AEAD_AES_128_GCM (16 octets), this equates to, at most, 3993 octets of plaintext.


An application server MUST NOT use other content encodings for push messages. In particular, content encodings that compress could result in leaking of push message contents. The Content-Encoding header field therefore has exactly one value, which is "aes128gcm". Multiple "aes128gcm" values are not permitted.

アプリケーションサーバーは、プッシュメッセージに他のコンテンツエンコーディングを使用してはなりません(MUST NOT)。特に、圧縮するコンテンツエンコーディングにより、プッシュメッセージのコンテンツが漏洩する可能性があります。したがって、Content-Encodingヘッダーフィールドには、「aes128gcm」という1つの値しかありません。複数の「aes128gcm」値は許可されていません。

A user agent is not required to support multiple records. A user agent MAY ignore the "rs" parameter. If a record size is unchecked, decryption will fail with high probability for all valid cases. The padding delimiter octet MUST be checked; values other than 0x02 MUST cause the message to be discarded.

ユーザーエージェントは、複数のレコードをサポートする必要はありません。ユーザーエージェントは、「rs」パラメーターを無視してもよい(MAY)。レコードサイズがチェックされていない場合、すべての有効なケースで高い確率で復号化が失敗します。パディング区切り文字のオク​​テットをチェックする必要があります。 0x02以外の値では、メッセージが破棄される必要があります。

5. Push Message Encryption Example
5. プッシュメッセージ暗号化の例

The following example shows a push message being sent to a push service.


   POST /push/JzLQ3raZJfFBR0aqvOMsLrt54w4rJUsV HTTP/1.1
   TTL: 10
   Content-Length: 145
   Content-Encoding: aes128gcm

DGv6ra1nlYgDCS1FRnbzlwAAEABBBP4z9KsN6nGRTbVYI_c7VJSPQTBtkgcy27ml mlMoZIIgDll6e3vCYLocInmYWAmS6TlzAC8wEqKK6PBru3jl7A_yl95bQpu6cVPT pK4Mqgkf1CXztLVBSt2Ks3oZwbuwXPXLWyouBWLVWGNWQexSgSxsj_Qulcy4a-fN

DGv6ra1nlYgDCS1FRnbzlwAAEABBBP4z9KsN6nGRTbVYI_c7VJSPQTBtkgcy27ml mlMoZIIgDll6e3vCYLocInmYWAmS6TlzAC8wEqKK6PBru3jl7A_yl95bQpu6cVPT pK4Mqgkf1CXztLVBSt2Ks3oZwbuwXPXLWyouBWLVWGNWQexSgSxsj_Qulcy4a-FN

This example shows the ASCII-encoded string, "When I grow up, I want to be a watermelon". The content body is shown here with line wrapping and URL-safe base64url [RFC4648] encoding to meet presentation constraints.

この例は、ASCIIでエンコードされた文字列「大人になったらスイカになりたい」を示しています。コンテンツの本文は、表示の制約を満たすために、行の折り返しとURLセーフのbase64url [RFC4648]エンコーディングでここに示されています。

The keys used are shown below using the uncompressed form [X9.62] encoded using base64url.


      Authentication Secret: BTBZMqHH6r4Tts7J_aSIgg
         private key: q1dXpw3UpT5VOmu_cf_v6ih07Aems3njxI-JWgLcM94
         public key: BCVxsr7N_eNgVRqvHtD0zTZsEc6-VV-JvLexhqUzORcx
         private key: yfWPiYE-n46HLnH0KqZOF1fJJU3MYrct3AELtAQ-oRw
         public key: BP4z9KsN6nGRTbVYI_c7VJSPQTBtkgcy27mlmlMoZIIg

Intermediate values for this example are included in Appendix A.


6. IANA Considerations
6. IANAに関する考慮事項

This document does not require any IANA actions.


7. Security Considerations
7. セキュリティに関する考慮事項

The privacy and security considerations of [RFC8030] all apply to the use of this mechanism.


The Security Considerations section of [RFC8188] describes the limitations of the content encoding. In particular, no HTTP header fields are protected by the content encoding scheme. A user agent MUST consider HTTP header fields to have come from the push service.


Though header fields might be necessary for processing an HTTP response correctly, they are not needed for correct operation of the protocol. An application on the user agent that uses information from header fields to alter their processing of a push message is exposed to a risk of attack by the push service.


The timing and length of communication cannot be hidden from the push service. While an outside observer might see individual messages intermixed with each other, the push service will see which application server is talking to which user agent and the subscription that is used. Additionally, the length of messages could be revealed unless the padding provided by the content encoding scheme is used to obscure length.


The user agent and application MUST verify that the public key they receive is on the P-256 curve. Failure to validate a public key can allow an attacker to extract a private key. The appropriate validation procedures are defined in Section 4.3.7 of [X9.62] and, alternatively, in Section of [KEYAGREEMENT]. This process consists of three steps:


1. Verify that Y is not the point at infinity (O),

1. Yが無限遠点(O)ではないことを確認します。

2. Verify that for Y = (x, y), both integers are in the correct interval,

2. Y =(x、y)の場合、両方の整数が正しい間隔にあることを確認します。

3. Ensure that (x, y) is a correct solution to the elliptic curve equation.

3. (x、y)が楕円曲線方程式の正しい解であることを確認してください。

For these curves, implementers do not need to verify membership in the correct subgroup.


In the event that this encryption scheme would need to be replaced, a new content coding scheme could be defined. In order to manage progressive deployment of the new scheme, the user agent can expose information on the content coding schemes that it supports. The "supportedContentEncodings" parameter of the Push API [API] is an example of how this might be done.

この暗号化スキームを置き換える必要がある場合は、新しいコンテンツコーディングスキームを定義できます。新しいスキームの漸進的な展開を管理するために、ユーザーエージェントは、サポートするコンテンツコーディングスキームに関する情報を公開できます。プッシュAPI [API]の "supportedContentEncodings"パラメータは、これを行う方法の例です。

8. References
8. 参考文献
8.1. Normative References
8.1. 引用文献

[ECDH] SECG, "SEC 1: Elliptic Curve Cryptography", Version 2.0, May 2009, <>.

[ECDH] SECG、「SEC 1:Elliptic Curve Cryptography」、バージョン2.0、2009年5月、<>。

[FIPS180-4] National Institute of Standards and Technology (NIST), "Secure Hash Standard (SHS)", FIPS PUB 180-4, DOI 10.6028/NIST.FIPS.180-4, August 2015.

[FIPS180-4]米国国立標準技術研究所(NIST)、「Secure Hash Standard(SHS)」、FIPS PUB 180-4、DOI 10.6028 / NIST.FIPS.180-4、2015年8月。

[FIPS186] National Institute of Standards and Technology (NIST), "Digital Signature Standard (DSS)", FIPS PUB 186-4, DOI 10.6028/NIST.FIPS.186-4, July 2013.

[FIPS186]米国国立標準技術研究所(NIST)、「デジタル署名標準(DSS)」、FIPS PUB 186-4、DOI 10.6028 / NIST.FIPS.186-4、2013年7月。

[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。、「要件レベルを示すためにRFCで使用するキーワード」、BCP 14、RFC 2119、DOI 10.17487 / RFC2119、1997年3月、< rfc2119>。

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

[RFC4086] Eastlake 3rd、D.、Schiller、J.、and S. Crocker、 "Randomness Requirements for Security"、BCP 106、RFC 4086、DOI 10.17487 / RFC4086、June 2005、<https://www.rfc-editor .org / info / rfc4086>。

[RFC5869] Krawczyk, H. and P. Eronen, "HMAC-based Extract-and-Expand Key Derivation Function (HKDF)", RFC 5869, DOI 10.17487/RFC5869, May 2010, <>.

[RFC5869] Krawczyk、H。およびP. Eronen、「HMACベースの抽出および拡張キー導出関数(HKDF)」、RFC 5869、DOI 10.17487 / RFC5869、2010年5月、<https://www.rfc-editor .org / info / rfc5869>。

[RFC8030] Thomson, M., Damaggio, E., and B. Raymor, Ed., "Generic Event Delivery Using HTTP Push", RFC 8030, DOI 10.17487/RFC8030, December 2016, <>.

[RFC8030] Thomson、M.、Damaggio、E。、およびB. Raymor、編、「HTTPプッシュを使用した一般的なイベント配信」、RFC 8030、DOI 10.17487 / RFC8030、2016年12月、<https://www.rfc->。

[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と小文字のあいまいさ」、BCP 14、RFC 8174、DOI 10.17487 / RFC8174、2017年5月、< rfc8174>。

[RFC8188] Thomson, M., "Encrypted Content-Encoding for HTTP", RFC 8188, DOI 10.17487/RFC8188, June 2017, <>.

[RFC8188] Thomson、M。、「HTTPの暗号化されたコンテンツエンコーディング」、RFC 8188、DOI 10.17487 / RFC8188、2017年6月、<>。

[X9.62] ANSI, "Public Key Cryptography for the Financial Services Industry: the Elliptic Curve Digital Signature Algorithm (ECDSA)", ANSI X9.62, 2005.

[X9.62] ANSI、「金融サービス業界の公開鍵暗号化:楕円曲線デジタル署名アルゴリズム(ECDSA)」、ANSI X9.62、2005年。

8.2. Informative References
8.2. 参考引用

[API] Beverloo, P., Thomson, M., van Ouwerkerk, M., Sullivan, B., and E. Fullea, "Push API", October 2017, <>.

[API] Beverloo、P.、Thomson、M.、van Ouwerkerk、M.、Sullivan、B。、およびE. Fullea、「Push API」、2017年10月、< push-api />。

[KEYAGREEMENT] Barker, E., Chen, L., Roginsky, A., and M. Smid, "Recommendation for Pair-Wise Key Establishment Schemes Using Discrete Logarithm Cryptography", NIST Special Publication 800-56A, Revision 2, DOI 10.6028/NIST.SP.800-56Ar2, May 2013.

[KEYAGREEMENT] Barker、E.、Chen、L.、Roginsky、A。、およびM. Smid、「離散対数暗号化を使用したペアワイズキー確立スキームの推奨」、NIST Special Publication 800-56A、Revision 2、DOI 10.6028 /NIST.SP.800-56Ar2、2013年5月。

[RFC2818] Rescorla, E., "HTTP Over TLS", RFC 2818, DOI 10.17487/RFC2818, May 2000, <>.

[RFC2818] Rescorla、E。、「HTTP Over TLS」、RFC 2818、DOI 10.17487 / RFC2818、2000年5月、<>。

[RFC4648] Josefsson, S., "The Base16, Base32, and Base64 Data Encodings", RFC 4648, DOI 10.17487/RFC4648, October 2006, <>.

[RFC4648] Josefsson、S。、「The Base16、Base32、およびBase64データエンコーディング」、RFC 4648、DOI 10.17487 / RFC4648、2006年10月、<>。

[RFC7230] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer Protocol (HTTP/1.1): Message Syntax and Routing", RFC 7230, DOI 10.17487/RFC7230, June 2014, <>.

[RFC7230]フィールディング、R。、エド。およびJ. Reschke編、「Hypertext Transfer Protocol(HTTP / 1.1):Message Syntax and Routing」、RFC 7230、DOI 10.17487 / RFC7230、2014年6月、< rfc7230>。

Appendix A. Intermediate Values for Encryption

The intermediate values calculated for the example in Section 5 are shown here. The base64url values in these examples include whitespace that can be removed.


The following are inputs to the calculation:


   Plaintext:  V2hlbiBJIGdyb3cgdXAsIEkgd2FudCB0byBiZSBhIHdhdGVybWVsb24
   Application server public key (as_public):

Application server private key (as_private): yfWPiYE-n46HLnH0KqZOF1fJJU3MYrct3AELtAQ-oRw


   User agent public key (ua_public):  BCVxsr7N_eNgVRqvHtD0zTZsEc6-VV-
      JvLexhqUzORcx aOzi6-AYWXvTBHm4bjyPjs7Vd8pZGH6SRpkNtoIAiw4

User agent private key (ua_private): q1dXpw3UpT5VOmu_cf_v6ih07Aems3njxI-JWgLcM94


Salt: DGv6ra1nlYgDCS1FRnbzlw


Authentication secret (auth_secret): BTBZMqHH6r4Tts7J_aSIgg


Note that knowledge of just one of the private keys is necessary. The application server randomly generates the salt value, whereas salt is input to the receiver.


This produces the following intermediate values:


   Shared ECDH secret (ecdh_secret):
   Pseudorandom key (PRK) for key combining (PRK_key):

Info for key combining (key_info): V2ViUHVzaDogaW5mbwAEJXGyvs3942BVG q8e0PTNNmwR zr5VX4m8t7GGpTM5FzFo7OLr4BhZe9MEebhuPI-OztV3 ylkYfpJGmQ22ggCLDgT-M_SrDepxkU21WCP3O1SUj0Ew bZIHMtu5pZpTKGSCIA5Zent7wmC6HCJ5mFgJkuk5cwAv MBKiiujwa7t45ewP

(key_info)を組み合わせたキーの情報:V2ViUHVzaDogaW5mbwAEJXGyvs3942BVG q8e0PTNNmwR zr5VX4m8t7GGpTM5FzFo7OLr4BhZe9MEebhuPI-OztV3 ylkYfpJGmQ22ggCLDgT-M_SrDepxkU21WCP3O1SUj0Ew bZIHMtu5pZpTKGSCIA5Zent7wmC6HCJ5mFgJkuk5cwAv MBKiiujwa7t45ewP

   Input keying material for content encryption key derivation (IKM):
   PRK for content encryption (PRK):
   Info for content encryption key derivation (cek_info):

Content encryption key (CEK): oIhVW04MRdy2XN9CiKLxTg


   Info for content encryption nonce derivation (nonce_info):

Nonce (NONCE): 4h_95klXJ5E_qnoN


The salt, record size of 4096, and application server public key produce an 86-octet header of:


DGv6ra1nlYgDCS1FRnbzlwAAEABBBP4z 9KsN6nGRTbVYI_c7VJSPQTBtkgcy27ml mlMoZIIgDll6e3vCYLocInmYWAmS6Tlz AC8wEqKK6PBru3jl7A8

DGv6ra1nlYgDCS1FRnbzlwAAEABBBP4z 9KsN6nGRTbVYI_c7VJSPQTBtkgcy27ml mlMoZIIgDll6e3vCYLocInmYWAmS6Tlz AC8wEqKK6PBru3jl7A8

The push message plaintext has the padding delimiter octet (0x02) appended to produce:


V2hlbiBJIGdyb3cgdXAsIEkgd2FudCB0 byBiZSBhIHdhdGVybWVsb24C

V2hlbiBJIGdyb3cgdXAsIEkgd2FudCB0 byBiZSBhIHdhdGVybWVsb24C

The plaintext is then encrypted with AES-GCM, which emits ciphertext of:


8pfeW0KbunFT06SuDKoJH9Ql87S1QUrd irN6GcG7sFz1y1sqLgVi1VhjVkHsUoEs bI_0LpXMuGvnzQ

8pfeW0KbunFT06SuDKoJH9Ql87S1QUrd irN6GcG7sFz1y1sqLgVi1VhjVkHsUoEs bI_0LpXMuGvnzQ

The header and ciphertext are concatenated and produce the result shown in Section 5.


Author's Address


Martin Thomson Mozilla