JSON Web Encryption (JWE)
draft-ietf-jose-json-web-encryption-26

Abstract

JSON Web Encryption (JWE) represents encrypted content using JavaScript Object Notation (JSON) based data structures. Cryptographic algorithms and identifiers for use with this specification are described in the separate JSON Web Algorithms (JWA) specification and IANA registries defined by that specification. Related digital signature and MAC capabilities are described in the separate JSON Web Signature (JWS) specification.

Status of this Memo

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Copyright (c) 2014 IETF Trust and the persons identified as the document authors. All rights reserved.

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Table of Contents

1.  Introduction
    1.1.  Notational Conventions
2.  Terminology
3.  JSON Web Encryption (JWE) Overview
    3.1.  Example JWE
4.  JWE Header
    4.1.  Registered Header Parameter Names
        4.1.1.  "alg" (Algorithm) Header Parameter
        4.1.2.  "enc" (Encryption Algorithm) Header Parameter
        4.1.3.  "zip" (Compression Algorithm) Header Parameter
        4.1.4.  "jku" (JWK Set URL) Header Parameter
        4.1.5.  "jwk" (JSON Web Key) Header Parameter
        4.1.6.  "kid" (Key ID) Header Parameter
        4.1.7.  "x5u" (X.509 URL) Header Parameter
        4.1.8.  "x5c" (X.509 Certificate Chain) Header Parameter
        4.1.9.  "x5t" (X.509 Certificate SHA-1 Thumbprint) Header Parameter
        4.1.10.  "typ" (Type) Header Parameter
        4.1.11.  "cty" (Content Type) Header Parameter
        4.1.12.  "crit" (Critical) Header Parameter
    4.2.  Public Header Parameter Names
    4.3.  Private Header Parameter Names
5.  Producing and Consuming JWEs
    5.1.  Message Encryption
    5.2.  Message Decryption
    5.3.  String Comparison Rules
6.  Key Identification
7.  Serializations
    7.1.  JWE Compact Serialization
    7.2.  JWE JSON Serialization
8.  TLS Requirements
9.  Distinguishing between JWS and JWE Objects
10.  IANA Considerations
    10.1.  JSON Web Signature and Encryption Header Parameters Registration
        10.1.1.  Registry Contents
11.  Security Considerations
12.  References
    12.1.  Normative References
    12.2.  Informative References
Appendix A.  JWE Examples
    A.1.  Example JWE using RSAES OAEP and AES GCM
        A.1.1.  JWE Header
        A.1.2.  Content Encryption Key (CEK)
        A.1.3.  Key Encryption
        A.1.4.  Initialization Vector
        A.1.5.  Additional Authenticated Data
        A.1.6.  Content Encryption
        A.1.7.  Complete Representation
        A.1.8.  Validation
    A.2.  Example JWE using RSAES-PKCS1-V1_5 and AES_128_CBC_HMAC_SHA_256
        A.2.1.  JWE Header
        A.2.2.  Content Encryption Key (CEK)
        A.2.3.  Key Encryption
        A.2.4.  Initialization Vector
        A.2.5.  Additional Authenticated Data
        A.2.6.  Content Encryption
        A.2.7.  Complete Representation
        A.2.8.  Validation
    A.3.  Example JWE using AES Key Wrap and AES_128_CBC_HMAC_SHA_256
        A.3.1.  JWE Header
        A.3.2.  Content Encryption Key (CEK)
        A.3.3.  Key Encryption
        A.3.4.  Initialization Vector
        A.3.5.  Additional Authenticated Data
        A.3.6.  Content Encryption
        A.3.7.  Complete Representation
        A.3.8.  Validation
    A.4.  Example JWE using JWE JSON Serialization
        A.4.1.  JWE Per-Recipient Unprotected Headers
        A.4.2.  JWE Protected Header
        A.4.3.  JWE Unprotected Header
        A.4.4.  Complete JWE Header Values
        A.4.5.  Additional Authenticated Data
        A.4.6.  Content Encryption
        A.4.7.  Complete JWE JSON Serialization Representation
Appendix B.  Example AES_128_CBC_HMAC_SHA_256 Computation
    B.1.  Extract MAC_KEY and ENC_KEY from Key
    B.2.  Encrypt Plaintext to Create Ciphertext
    B.3.  64 Bit Big Endian Representation of AAD Length
    B.4.  Initialization Vector Value
    B.5.  Create Input to HMAC Computation
    B.6.  Compute HMAC Value
    B.7.  Truncate HMAC Value to Create Authentication Tag
Appendix C.  Acknowledgements
Appendix D.  Document History
§  Authors' Addresses

1.  Introduction

JSON Web Encryption (JWE) represents encrypted content using JavaScript Object Notation (JSON) [RFC7159] (Bray, T., “The JavaScript Object Notation (JSON) Data Interchange Format,” March 2014.) based data structures. The JWE cryptographic mechanisms encrypt and provide integrity protection for an arbitrary sequence of octets.

Two closely related serializations for JWE objects are defined. The JWE Compact Serialization is a compact, URL-safe representation intended for space constrained environments such as HTTP Authorization headers and URI query parameters. The JWE JSON Serialization represents JWE objects as JSON objects and enables the same content to be encrypted to multiple parties. Both share the same cryptographic underpinnings.

Cryptographic algorithms and identifiers for use with this specification are described in the separate JSON Web Algorithms (JWA) [JWA] (Jones, M., “JSON Web Algorithms (JWA),” April 2014.) specification and IANA registries defined by that specification. Related digital signature and MAC capabilities are described in the separate JSON Web Signature (JWS) [JWS] (Jones, M., Bradley, J., and N. Sakimura, “JSON Web Signature (JWS),” April 2014.) specification.

Names defined by this specification are short because a core goal is for the resulting representations to be compact.

1.1.  Notational Conventions

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 Key words for use in RFCs to Indicate Requirement Levels [RFC2119] (Bradner, S., “Key words for use in RFCs to Indicate Requirement Levels,” March 1997.). If these words are used without being spelled in uppercase then they are to be interpreted with their normal natural language meanings.

BASE64URL(OCTETS) denotes the base64url encoding of OCTETS, per Section 2 (Terminology).

UTF8(STRING) denotes the octets of the UTF-8 [RFC3629] (Yergeau, F., “UTF-8, a transformation format of ISO 10646,” November 2003.) representation of STRING.

ASCII(STRING) denotes the octets of the ASCII [USASCII] (American National Standards Institute, “Coded Character Set -- 7-bit American Standard Code for Information Interchange,” 1986.) representation of STRING.

The concatenation of two values A and B is denoted as A || B.

2.  Terminology

These terms defined by the JSON Web Signature (JWS) [JWS] (Jones, M., Bradley, J., and N. Sakimura, “JSON Web Signature (JWS),” April 2014.) specification are incorporated into this specification: "JSON Web Signature (JWS)", "Base64url Encoding", "Collision-Resistant Name", and "StringOrURI".

These terms are defined for use by this specification:

JSON Web Encryption (JWE)

A data structure representing an encrypted and integrity protected message.

Authenticated Encryption with Associated Data (AEAD)

An AEAD algorithm is one that encrypts the Plaintext, allows Additional Authenticated Data to be specified, and provides an integrated content integrity check over the Ciphertext and Additional Authenticated Data. AEAD algorithms accept two inputs, the Plaintext and the Additional Authenticated Data value, and produce two outputs, the Ciphertext and the Authentication Tag value. AES Galois/Counter Mode (GCM) is one such algorithm.

Plaintext

The sequence of octets to be encrypted -- a.k.a., the message. The plaintext can contain an arbitrary sequence of octets.

Ciphertext

An encrypted representation of the Plaintext.

Additional Authenticated Data (AAD)

An input to an AEAD operation that is integrity protected but not encrypted.

Authentication Tag

An output of an AEAD operation that ensures the integrity of the Ciphertext and the Additional Authenticated Data. Note that some algorithms may not use an Authentication Tag, in which case this value is the empty octet sequence.

Content Encryption Key (CEK)

A symmetric key for the AEAD algorithm used to encrypt the Plaintext for the recipient to produce the Ciphertext and the Authentication Tag.

JWE Header

JSON object containing the parameters describing the cryptographic operations and parameters employed. The JWE Header members are the union of the members of the JWE Protected Header, the JWE Shared Unprotected Header, and the JWE Per-Recipient Unprotected Header. The members of the JWE Header are Header Parameters.

JWE Encrypted Key

Encrypted Content Encryption Key (CEK) value. Note that for some algorithms, the JWE Encrypted Key value is specified as being the empty octet sequence.

JWE Initialization Vector

Initialization Vector value used when encrypting the plaintext. Note that some algorithms may not use an Initialization Vector, in which case this value is the empty octet sequence.

JWE AAD

Additional value to be integrity protected by the authenticated encryption operation. This can only be present when using the JWE JSON Serialization. (Note that this can also be achieved when using either serialization by including the AAD value as an integrity protected Header Parameter value, but at the cost of the value being double base64url encoded.)

JWE Ciphertext

Ciphertext value resulting from authenticated encryption of the plaintext with additional authenticated data.

JWE Authentication Tag

Authentication Tag value resulting from authenticated encryption of the plaintext with additional authenticated data.

Header Parameter

A name/value pair that is member of the JWE Header.

JWE Protected Header

JSON object that contains the JWE Header Parameters that are integrity protected by the authenticated encryption operation. These parameters apply to all recipients of the JWE. For the JWE Compact Serialization, this comprises the entire JWE Header. For the JWE JSON Serialization, this is one component of the JWE Header.

JWE Shared Unprotected Header

JSON object that contains the JWE Header Parameters that apply to all recipients of the JWE that are not integrity protected. This can only be present when using the JWE JSON Serialization.

JWE Per-Recipient Unprotected Header

JSON object that contains JWE Header Parameters that apply to a single recipient of the JWE. These Header Parameter values are not integrity protected. This can only be present when using the JWE JSON Serialization.

JWE Compact Serialization

A representation of the JWE as a compact, URL-safe string.

JWE JSON Serialization

A representation of the JWE as a JSON object. The JWE JSON Serialization enables the same content to be encrypted to multiple parties. This representation is neither optimized for compactness nor URL-safe.

Key Management Mode

A method of determining the Content Encryption Key (CEK) value to use. Each algorithm used for determining the CEK value uses a specific Key Management Mode. Key Management Modes employed by this specification are Key Encryption, Key Wrapping, Direct Key Agreement, Key Agreement with Key Wrapping, and Direct Encryption.

Key Encryption

A Key Management Mode in which the Content Encryption Key (CEK) value is encrypted to the intended recipient using an asymmetric encryption algorithm.

Key Wrapping

A Key Management Mode in which the Content Encryption Key (CEK) value is encrypted to the intended recipient using a symmetric key wrapping algorithm.

Direct Key Agreement

A Key Management Mode in which a key agreement algorithm is used to agree upon the Content Encryption Key (CEK) value.

Key Agreement with Key Wrapping

A Key Management Mode in which a key agreement algorithm is used to agree upon a symmetric key used to encrypt the Content Encryption Key (CEK) value to the intended recipient using a symmetric key wrapping algorithm.

Direct Encryption

A Key Management Mode in which the Content Encryption Key (CEK) value used is the secret symmetric key value shared between the parties.

3.  JSON Web Encryption (JWE) Overview

JWE represents encrypted content using JSON data structures and base64url encoding. A JWE represents these logical values:

JWE Header

JSON object containing the parameters describing the cryptographic operations and parameters employed. The JWE Header members are the union of the members of the JWE Protected Header, the JWE Shared Unprotected Header, and the JWE Per-Recipient Unprotected Header, as described below.

JWE Encrypted Key

Encrypted Content Encryption Key (CEK) value.

JWE Initialization Vector

Initialization Vector value used when encrypting the plaintext.

JWE AAD

Additional value to be integrity protected by the authenticated encryption operation.

JWE Ciphertext

Ciphertext value resulting from authenticated encryption of the plaintext with additional authenticated data.

JWE Authentication Tag

Authentication Tag value resulting from authenticated encryption of the plaintext with additional authenticated data.

The JWE Header represents the combination of these logical values:

JWE Protected Header

JSON object that contains the JWE Header Parameters that are integrity protected by the authenticated encryption operation. These parameters apply to all recipients of the JWE.

JWE Shared Unprotected Header

JSON object that contains the JWE Header Parameters that apply to all recipients of the JWE that are not integrity protected.

JWE Per-Recipient Unprotected Header

JSON object that contains JWE Header Parameters that apply to a single recipient of the JWE. These Header Parameter values are not integrity protected.

This document defines two serializations for JWE objects: a compact, URL-safe serialization called the JWE Compact Serialization and a JSON serialization called the JWE JSON Serialization. In both serializations, the JWE Protected Header, JWE Encrypted Key, JWE Initialization Vector, JWE Ciphertext, and JWE Authentication Tag are base64url encoded for transmission, since JSON lacks a way to directly represent octet sequences. When present, the JWE AAD is also base64url encoded for transmission.

In the JWE Compact Serialization, no JWE Shared Unprotected Header or JWE Per-Recipient Unprotected Header are used. In this case, the JWE Header and the JWE Protected Header are the same.

In the JWE Compact Serialization, a JWE object is represented as the combination of these five string values,

BASE64URL(UTF8(JWE Protected Header)),

BASE64URL(JWE Encrypted Key),

BASE64URL(JWE Initialization Vector),

BASE64URL(JWE Ciphertext), and

BASE64URL(JWE Authentication Tag),

concatenated in that order, with the five strings being separated by four period ('.') characters.

In the JWE JSON Serialization, one or more of the JWE Protected Header, JWE Shared Unprotected Header, and JWE Per-Recipient Unprotected Header MUST be present. In this case, the members of the JWE Header are the combination of the members of the JWE Protected Header, JWE Shared Unprotected Header, and JWE Per-Recipient Unprotected Header values that are present.

In the JWE JSON Serialization, a JWE object is represented as the combination of these eight values,

BASE64URL(UTF8(JWE Protected Header)),

JWE Shared Unprotected Header,

JWE Per-Recipient Unprotected Header,

BASE64URL(JWE Encrypted Key),

BASE64URL(JWE Initialization Vector),

BASE64URL(JWE Ciphertext),

BASE64URL(JWE Authentication Tag), and

BASE64URL(JWE AAD),

with the six base64url encoding result strings and the two unprotected JSON object values being represented as members within a JSON object. The inclusion of some of these values is OPTIONAL. The JWE JSON Serialization can also encrypt the plaintext to multiple recipients. See Section 7.2 (JWE JSON Serialization) for more information about the JWE JSON Serialization.

JWE utilizes authenticated encryption to ensure the confidentiality and integrity of the Plaintext and the integrity of the JWE Protected Header and the JWE AAD.

3.1.  Example JWE

This example encrypts the plaintext "The true sign of intelligence is not knowledge but imagination." to the recipient using RSAES OAEP for key encryption and AES GCM for content encryption.

The following example JWE Protected Header declares that:

• the Content Encryption Key is encrypted to the recipient using the RSAES OAEP algorithm to produce the JWE Encrypted Key and
• the Plaintext is encrypted using the AES GCM algorithm with a 256 bit key to produce the Ciphertext.

  {"alg":"RSA-OAEP","enc":"A256GCM"}

Encoding this JWE Protected Header as BASE64URL(UTF8(JWE Protected Header)) gives this value:

  eyJhbGciOiJSU0EtT0FFUCIsImVuYyI6IkEyNTZHQ00ifQ

The remaining steps to finish creating this JWE are:

• Generate a random Content Encryption Key (CEK).
• Encrypt the CEK with the recipient's public key using the RSAES OAEP algorithm to produce the JWE Encrypted Key.
• Base64url encode the JWE Encrypted Key.
• Generate a random JWE Initialization Vector.
• Base64url encode the JWE Initialization Vector.
• Let the Additional Authenticated Data encryption parameter be ASCII(BASE64URL(UTF8(JWE Protected Header))).
• Encrypt the Plaintext with AES GCM using the CEK as the encryption key, the JWE Initialization Vector, and the Additional Authenticated Data value, requesting a 128 bit Authentication Tag output.
• Base64url encode the Ciphertext.
• Base64url encode the Authentication Tag.
• Assemble the final representation: The Compact Serialization of this result is the string BASE64URL(UTF8(JWE Protected Header)) || '.' || BASE64URL(JWE Encrypted Key) || '.' || BASE64URL(JWE Initialization Vector) || '.' || BASE64URL(JWE Ciphertext) || '.' || BASE64URL(JWE Authentication Tag).

The final result in this example (with line breaks for display purposes only) is:

  eyJhbGciOiJSU0EtT0FFUCIsImVuYyI6IkEyNTZHQ00ifQ.
  OKOawDo13gRp2ojaHV7LFpZcgV7T6DVZKTyKOMTYUmKoTCVJRgckCL9kiMT03JGe
  ipsEdY3mx_etLbbWSrFr05kLzcSr4qKAq7YN7e9jwQRb23nfa6c9d-StnImGyFDb
  Sv04uVuxIp5Zms1gNxKKK2Da14B8S4rzVRltdYwam_lDp5XnZAYpQdb76FdIKLaV
  mqgfwX7XWRxv2322i-vDxRfqNzo_tETKzpVLzfiwQyeyPGLBIO56YJ7eObdv0je8
  1860ppamavo35UgoRdbYaBcoh9QcfylQr66oc6vFWXRcZ_ZT2LawVCWTIy3brGPi
  6UklfCpIMfIjf7iGdXKHzg.
  48V1_ALb6US04U3b.
  5eym8TW_c8SuK0ltJ3rpYIzOeDQz7TALvtu6UG9oMo4vpzs9tX_EFShS8iB7j6ji
  SdiwkIr3ajwQzaBtQD_A.
  XFBoMYUZodetZdvTiFvSkQ

See Appendix A.1 (Example JWE using RSAES OAEP and AES GCM) for the complete details of computing this JWE. See other parts of Appendix A (JWE Examples) for additional examples.

4.  JWE Header

The members of the JSON object(s) representing the JWE Header describe the encryption applied to the Plaintext and optionally additional properties of the JWE. The Header Parameter names within the JWE Header MUST be unique; recipients MUST either reject JWEs with duplicate Header Parameter names or use a JSON parser that returns only the lexically last duplicate member name, as specified in Section 15.12 (The JSON Object) of ECMAScript 5.1 [ECMAScript] (Ecma International, “ECMAScript Language Specification, 5.1 Edition,” June 2011.).

Implementations are required to understand the specific Header Parameters defined by this specification that are designated as "MUST be understood" and process them in the manner defined in this specification. All other Header Parameters defined by this specification that are not so designated MUST be ignored when not understood. Unless listed as a critical Header Parameter, per Section 4.1.12 ("crit" (Critical) Header Parameter), all Header Parameters not defined by this specification MUST be ignored when not understood.

There are three classes of Header Parameter names: Registered Header Parameter names, Public Header Parameter names, and Private Header Parameter names.

4.1.  Registered Header Parameter Names

The following Header Parameter names are registered in the IANA JSON Web Signature and Encryption Header Parameters registry defined in [JWS] (Jones, M., Bradley, J., and N. Sakimura, “JSON Web Signature (JWS),” April 2014.), with meanings as defined below.

As indicated by the common registry, JWSs and JWEs share a common Header Parameter space; when a parameter is used by both specifications, its usage must be compatible between the specifications.

4.1.1.  "alg" (Algorithm) Header Parameter

This parameter has the same meaning, syntax, and processing rules as the alg Header Parameter defined in Section 4.1.1 of [JWS] (Jones, M., Bradley, J., and N. Sakimura, “JSON Web Signature (JWS),” April 2014.), except that the Header Parameter identifies the cryptographic algorithm used to encrypt or determine the value of the Content Encryption Key (CEK). The encrypted content is not usable if the alg value does not represent a supported algorithm, or if the recipient does not have a key that can be used with that algorithm.

A list of defined alg values for this use can be found in the IANA JSON Web Signature and Encryption Algorithms registry defined in [JWA] (Jones, M., “JSON Web Algorithms (JWA),” April 2014.); the initial contents of this registry are the values defined in Section 4.1 of the JSON Web Algorithms (JWA) [JWA] (Jones, M., “JSON Web Algorithms (JWA),” April 2014.) specification.

4.1.2.  "enc" (Encryption Algorithm) Header Parameter

The enc (encryption algorithm) Header Parameter identifies the content encryption algorithm used to encrypt the Plaintext to produce the Ciphertext. This algorithm MUST be an AEAD algorithm with a specified key length. The recipient MUST reject the JWE if the enc value does not represent a supported algorithm. enc values should either be registered in the IANA JSON Web Signature and Encryption Algorithms registry defined in [JWA] (Jones, M., “JSON Web Algorithms (JWA),” April 2014.) or be a value that contains a Collision-Resistant Name. The enc value is a case-sensitive string containing a StringOrURI value. This Header Parameter MUST be present and MUST be understood and processed by implementations.

A list of defined enc values for this use can be found in the IANA JSON Web Signature and Encryption Algorithms registry defined in [JWA] (Jones, M., “JSON Web Algorithms (JWA),” April 2014.); the initial contents of this registry are the values defined in Section 5.1 of the JSON Web Algorithms (JWA) [JWA] (Jones, M., “JSON Web Algorithms (JWA),” April 2014.) specification.

4.1.3.  "zip" (Compression Algorithm) Header Parameter

The zip (compression algorithm) applied to the Plaintext before encryption, if any. The zip value defined by this specification is:

• DEF - Compression with the DEFLATE [RFC1951] (Deutsch, P., “DEFLATE Compressed Data Format Specification version 1.3,” May 1996.) algorithm

Other values MAY be used. Compression algorithm values can be registered in the IANA JSON Web Encryption Compression Algorithm registry defined in [JWA] (Jones, M., “JSON Web Algorithms (JWA),” April 2014.). The zip value is a case-sensitive string. If no zip parameter is present, no compression is applied to the Plaintext before encryption. This Header Parameter MUST be integrity protected, and therefore MUST occur only within the JWE Protected Header, when used. Use of this Header Parameter is OPTIONAL. This Header Parameter MUST be understood and processed by implementations.

4.1.4.  "jku" (JWK Set URL) Header Parameter

This parameter has the same meaning, syntax, and processing rules as the jku Header Parameter defined in Section 4.1.2 of [JWS] (Jones, M., Bradley, J., and N. Sakimura, “JSON Web Signature (JWS),” April 2014.), except that the JWK Set resource contains the public key to which the JWE was encrypted; this can be used to determine the private key needed to decrypt the JWE.

4.1.5.  "jwk" (JSON Web Key) Header Parameter

This parameter has the same meaning, syntax, and processing rules as the jwk Header Parameter defined in Section 4.1.3 of [JWS] (Jones, M., Bradley, J., and N. Sakimura, “JSON Web Signature (JWS),” April 2014.), except that the key is the public key to which the JWE was encrypted; this can be used to determine the private key needed to decrypt the JWE.

4.1.6.  "kid" (Key ID) Header Parameter

This parameter has the same meaning, syntax, and processing rules as the kid Header Parameter defined in Section 4.1.4 of [JWS] (Jones, M., Bradley, J., and N. Sakimura, “JSON Web Signature (JWS),” April 2014.), except that the key hint references the public key to which the JWE was encrypted; this can be used to determine the private key needed to decrypt the JWE. This parameter allows originators to explicitly signal a change of key to JWE recipients.

4.1.7.  "x5u" (X.509 URL) Header Parameter

This parameter has the same meaning, syntax, and processing rules as the x5u Header Parameter defined in Section 4.1.5 of [JWS] (Jones, M., Bradley, J., and N. Sakimura, “JSON Web Signature (JWS),” April 2014.), except that the X.509 public key certificate or certificate chain [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,” May 2008.) contains the public key to which the JWE was encrypted; this can be used to determine the private key needed to decrypt the JWE.

4.1.8.  "x5c" (X.509 Certificate Chain) Header Parameter

This parameter has the same meaning, syntax, and processing rules as the x5c Header Parameter defined in Section 4.1.6 of [JWS] (Jones, M., Bradley, J., and N. Sakimura, “JSON Web Signature (JWS),” April 2014.), except that the X.509 public key certificate or certificate chain [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,” May 2008.) contains the public key to which the JWE was encrypted; this can be used to determine the private key needed to decrypt the JWE.

See Appendix B of [JWS] (Jones, M., Bradley, J., and N. Sakimura, “JSON Web Signature (JWS),” April 2014.) for an example x5c value.

4.1.9.  "x5t" (X.509 Certificate SHA-1 Thumbprint) Header Parameter

This parameter has the same meaning, syntax, and processing rules as the x5t Header Parameter defined in Section 4.1.7 of [JWS] (Jones, M., Bradley, J., and N. Sakimura, “JSON Web Signature (JWS),” April 2014.), except that certificate referenced by the thumbprint contains the public key to which the JWE was encrypted; this can be used to determine the private key needed to decrypt the JWE.

4.1.10.  "typ" (Type) Header Parameter

This parameter has the same meaning, syntax, and processing rules as the typ Header Parameter defined in Section 4.1.8 of [JWS] (Jones, M., Bradley, J., and N. Sakimura, “JSON Web Signature (JWS),” April 2014.), except that the type is of this complete JWE object.

4.1.11.  "cty" (Content Type) Header Parameter

This parameter has the same meaning, syntax, and processing rules as the cty Header Parameter defined in Section 4.1.9 of [JWS] (Jones, M., Bradley, J., and N. Sakimura, “JSON Web Signature (JWS),” April 2014.), except that the type is of the secured content (the plaintext).

4.1.12.  "crit" (Critical) Header Parameter

This parameter has the same meaning, syntax, and processing rules as the crit Header Parameter defined in Section 4.1.10 of [JWS] (Jones, M., Bradley, J., and N. Sakimura, “JSON Web Signature (JWS),” April 2014.), except that JWE Header Parameters are being referred to, rather than JWS Header Parameters.

4.2.  Public Header Parameter Names

Additional Header Parameter names can be defined by those using JWEs. However, in order to prevent collisions, any new Header Parameter name should either be registered in the IANA JSON Web Signature and Encryption Header Parameters registry defined in [JWS] (Jones, M., Bradley, J., and N. Sakimura, “JSON Web Signature (JWS),” April 2014.) or be a Public Name: a value that contains a Collision-Resistant Name. In each case, the definer of the name or value needs to take reasonable precautions to make sure they are in control of the part of the namespace they use to define the Header Parameter name.

New Header Parameters should be introduced sparingly, as they can result in non-interoperable JWEs.

4.3.  Private Header Parameter Names

A producer and consumer of a JWE may agree to use Header Parameter names that are Private Names: names that are not Registered Header Parameter names Section 4.1 (Registered Header Parameter Names) or Public Header Parameter names Section 4.2 (Public Header Parameter Names). Unlike Public Header Parameter names, Private Header Parameter names are subject to collision and should be used with caution.

5.  Producing and Consuming JWEs

5.1.  Message Encryption

The message encryption process is as follows. The order of the steps is not significant in cases where there are no dependencies between the inputs and outputs of the steps.

1. Determine the Key Management Mode employed by the algorithm used to determine the Content Encryption Key (CEK) value. (This is the algorithm recorded in the alg (algorithm) Header Parameter of the resulting JWE.)
2. When Key Wrapping, Key Encryption, or Key Agreement with Key Wrapping are employed, generate a random Content Encryption Key (CEK) value. See RFC 4086 (Eastlake, D., Schiller, J., and S. Crocker, “Randomness Requirements for Security,” June 2005.) [RFC4086] for considerations on generating random values. The CEK MUST have a length equal to that required for the content encryption algorithm.
3. When Direct Key Agreement or Key Agreement with Key Wrapping are employed, use the key agreement algorithm to compute the value of the agreed upon key. When Direct Key Agreement is employed, let the Content Encryption Key (CEK) be the agreed upon key. When Key Agreement with Key Wrapping is employed, the agreed upon key will be used to wrap the CEK.
4. When Key Wrapping, Key Encryption, or Key Agreement with Key Wrapping are employed, encrypt the CEK to the recipient and let the result be the JWE Encrypted Key.
5. When Direct Key Agreement or Direct Encryption are employed, let the JWE Encrypted Key be the empty octet sequence.
6. When Direct Encryption is employed, let the Content Encryption Key (CEK) be the shared symmetric key.
7. Compute the encoded key value BASE64URL(JWE Encrypted Key).
8. If the JWE JSON Serialization is being used, repeat this process (steps 1-7) for each recipient.
9. Generate a random JWE Initialization Vector of the correct size for the content encryption algorithm (if required for the algorithm); otherwise, let the JWE Initialization Vector be the empty octet sequence.
10. Compute the encoded initialization vector value BASE64URL(JWE Initialization Vector).
11. If a zip parameter was included, compress the Plaintext using the specified compression algorithm.
12. Serialize the (compressed) Plaintext into an octet sequence M.
13. Create the JSON object(s) containing the desired set of Header Parameters, which together comprise the JWE Header: the JWE Protected Header, and if the JWE JSON Serialization is being used, the JWE Shared Unprotected Header and the JWE Per-Recipient Unprotected Header.
14. Compute the Encoded Protected Header value BASE64URL(UTF8(JWE Protected Header)). If the JWE Protected Header is not present (which can only happen when using the JWE JSON Serialization and no protected member is present), let this value be the empty string.
15. Let the Additional Authenticated Data encryption parameter be ASCII(Encoded Protected Header). However if a JWE AAD value is present (which can only be the case when using the JWE JSON Serialization), instead let the Additional Authenticated Data encryption parameter be ASCII(Encoded Protected Header || '.' || BASE64URL(JWE AAD)).
16. Encrypt M using the CEK, the JWE Initialization Vector, and the Additional Authenticated Data value using the specified content encryption algorithm to create the JWE Ciphertext value and the JWE Authentication Tag (which is the Authentication Tag output from the encryption operation).
17. Compute the encoded ciphertext value BASE64URL(JWE Ciphertext).
18. Compute the encoded authentication tag value BASE64URL(JWE Authentication Tag).
19. The five encoded values are used in both the JWE Compact Serialization and the JWE JSON Serialization representations.
20. If a JWE AAD value is present, compute the encoded AAD value BASE64URL(JWE AAD).
21. Create the desired serialized output. The Compact Serialization of this result is the string BASE64URL(UTF8(JWE Protected Header)) || '.' || BASE64URL(JWE Encrypted Key) || '.' || BASE64URL(JWE Initialization Vector) || '.' || BASE64URL(JWE Ciphertext) || '.' || BASE64URL(JWE Authentication Tag). The JWE JSON Serialization is described in Section 7.2 (JWE JSON Serialization).

5.2.  Message Decryption

The message decryption process is the reverse of the encryption process. The order of the steps is not significant in cases where there are no dependencies between the inputs and outputs of the steps. If any of these steps fails, the encrypted content cannot be validated.

It is an application decision which recipients' encrypted content must successfully validate for the JWE to be accepted. In some cases, encrypted content for all recipients must successfully validate or the JWE will be rejected. In other cases, only the encrypted content for a single recipient needs to be successfully validated. However, in all cases, the encrypted content for at least one recipient MUST successfully validate or the JWE MUST be rejected.

1. Parse the JWE representation to extract the serialized values for the components of the JWE -- when using the JWE Compact Serialization, the base64url encoded representations of the JWE Protected Header, the JWE Encrypted Key, the JWE Initialization Vector, the JWE Ciphertext, and the JWE Authentication Tag, and when using the JWE JSON Serialization, also the base64url encoded representation of the JWE AAD and the unencoded JWE Shared Unprotected Header and JWE Per-Recipient Unprotected Header values. When using the JWE Compact Serialization, the JWE Protected Header, the JWE Encrypted Key, the JWE Initialization Vector, the JWE Ciphertext, and the JWE Authentication Tag are represented as base64url encoded values in that order, separated by four period ('.') characters. The JWE JSON Serialization is described in Section 7.2 (JWE JSON Serialization).
2. The encoded representations of the JWE Protected Header, the JWE Encrypted Key, the JWE Initialization Vector, the JWE Ciphertext, the JWE Authentication Tag, and the JWE AAD MUST be successfully base64url decoded following the restriction that no padding characters have been used.
3. The octet sequence resulting from decoding the encoded JWE Protected Header MUST be a UTF-8 encoded representation of a completely valid JSON object conforming to [RFC7159] (Bray, T., “The JavaScript Object Notation (JSON) Data Interchange Format,” March 2014.), which is the JWE Protected Header.
4. If using the JWE Compact Serialization, let the JWE Header be the JWE Protected Header; otherwise, when using the JWE JSON Serialization, let the JWE Header be the union of the members of the JWE Protected Header, the JWE Shared Unprotected Header and the corresponding JWE Per-Recipient Unprotected Header, all of which must be completely valid JSON objects.
5. The resulting JWE Header MUST NOT contain duplicate Header Parameter names. When using the JWE JSON Serialization, this restriction includes that the same Header Parameter name also MUST NOT occur in distinct JSON object values that together comprise the JWE Header.
6. Verify that the implementation understands and can process all fields that it is required to support, whether required by this specification, by the algorithms being used, or by the crit Header Parameter value, and that the values of those parameters are also understood and supported.
7. Determine the Key Management Mode employed by the algorithm specified by the alg (algorithm) Header Parameter.
8. Verify that the JWE uses a key known to the recipient.
9. When Direct Key Agreement or Key Agreement with Key Wrapping are employed, use the key agreement algorithm to compute the value of the agreed upon key. When Direct Key Agreement is employed, let the Content Encryption Key (CEK) be the agreed upon key. When Key Agreement with Key Wrapping is employed, the agreed upon key will be used to decrypt the JWE Encrypted Key.
10. When Key Wrapping, Key Encryption, or Key Agreement with Key Wrapping are employed, decrypt the JWE Encrypted Key to produce the Content Encryption Key (CEK). The CEK MUST have a length equal to that required for the content encryption algorithm. Note that when there are multiple recipients, each recipient will only be able decrypt any JWE Encrypted Key values that were encrypted to a key in that recipient's possession. It is therefore normal to only be able to decrypt one of the per-recipient JWE Encrypted Key values to obtain the CEK value. To mitigate the attacks described in RFC 3218 (Rescorla, E., “Preventing the Million Message Attack on Cryptographic Message Syntax,” January 2002.) [RFC3218], the recipient MUST NOT distinguish between format, padding, and length errors of encrypted keys. It is strongly recommended, in the event of receiving an improperly formatted key, that the receiver substitute a randomly generated CEK and proceed to the next step, to mitigate timing attacks.
11. When Direct Key Agreement or Direct Encryption are employed, verify that the JWE Encrypted Key value is empty octet sequence.
12. When Direct Encryption is employed, let the Content Encryption Key (CEK) be the shared symmetric key.
13. If the JWE JSON Serialization is being used, repeat this process (steps 4-12) for each recipient contained in the representation until the CEK value has been determined.
14. Compute the Encoded Protected Header value BASE64URL(UTF8(JWE Protected Header)). If the JWE Protected Header is not present (which can only happen when using the JWE JSON Serialization and no protected member is present), let this value be the empty string.
15. Let the Additional Authenticated Data encryption parameter be ASCII(Encoded Protected Header). However if a JWE AAD value is present (which can only be the case when using the JWE JSON Serialization), instead let the Additional Authenticated Data encryption parameter be ASCII(Encoded Protected Header || '.' || BASE64URL(JWE AAD)).
16. Decrypt the JWE Ciphertext using the CEK, the JWE Initialization Vector, the Additional Authenticated Data value, and the JWE Authentication Tag (which is the Authentication Tag input to the calculation) using the specified content encryption algorithm, returning the decrypted plaintext and validating the JWE Authentication Tag in the manner specified for the algorithm, rejecting the input without emitting any decrypted output if the JWE Authentication Tag is incorrect.
17. If a zip parameter was included, uncompress the decrypted plaintext using the specified compression algorithm.
18. If all the previous steps succeeded, output the resulting Plaintext.

5.3.  String Comparison Rules

The string comparison rules for this specification are the same as those defined in Section 5.3 of [JWS] (Jones, M., Bradley, J., and N. Sakimura, “JSON Web Signature (JWS),” April 2014.).

6.  Key Identification

The key identification methods for this specification are the same as those defined in Section 6 of [JWS] (Jones, M., Bradley, J., and N. Sakimura, “JSON Web Signature (JWS),” April 2014.), except that the key being identified is the public key to which the JWE was encrypted.

7.  Serializations

JWE objects use one of two serializations, the JWE Compact Serialization or the JWE JSON Serialization. Applications using this specification need to specify what serialization and serialization features are used for that application. For instance, applications might specify that only the JWE JSON Serialization is used, that only JWE JSON Serialization support for a single recipient is used, or that support for multiple recipients is used. JWE implementations only need to implement the features needed for the applications they are designed to support.

7.1.  JWE Compact Serialization

The JWE Compact Serialization represents encrypted content as a compact URL-safe string. This string is BASE64URL(UTF8(JWE Protected Header)) || '.' || BASE64URL(JWE Encrypted Key) || '.' || BASE64URL(JWE Initialization Vector) || '.' || BASE64URL(JWE Ciphertext) || '.' || BASE64URL(JWE Authentication Tag). Only one recipient is supported by the JWE Compact Serialization and it provides no syntax to represent JWE Shared Unprotected Header, JWE Per-Recipient Unprotected Header, or JWE AAD values.

7.2.  JWE JSON Serialization

The JWE JSON Serialization represents encrypted content as a JSON object. Content using the JWE JSON Serialization can be encrypted to more than one recipient. This representation is neither optimized for compactness nor URL-safe.

The following members are defined for use in top-level JSON objects used for the JWE JSON Serialization:

protected

The protected member MUST be present and contain the value BASE64URL(UTF8(JWE Protected Header)) when the JWE Protected Header value is non-empty; otherwise, it MUST be absent. These Header Parameter values are integrity protected.

unprotected

The unprotected member MUST be present and contain the value JWE Shared Unprotected Header when the JWE Shared Unprotected Header value is non-empty; otherwise, it MUST be absent. This value is represented as an unencoded JSON object, rather than as a string. These Header Parameter values are not integrity protected.

iv

The iv member MUST be present and contain the value BASE64URL(JWE Initialization Vector) when the JWE Initialization Vector value is non-empty; otherwise, it MUST be absent.

aad

The aad member MUST be present and contain the value BASE64URL(JWE AAD)) when the JWE AAD value is non-empty; otherwise, it MUST be absent. A JWE AAD value can be included to supply a base64url encoded value to be integrity protected but not encrypted.

ciphertext

The ciphertext member MUST be present and contain the value BASE64URL(JWE Ciphertext).

tag

The tag member MUST be present and contain the value BASE64URL(JWE Authentication Tag) when the JWE Authentication Tag value is non-empty; otherwise, it MUST be absent.

recipients

The recipients member value MUST be an array of JSON objects. Each object contains information specific to a single recipient. This member MUST be present, even if the array elements contain only the empty JSON object {} (which can happen when all Header Parameter values are shared between all recipients and when no encrypted key is used, such as when doing Direct Encryption).

The following members are defined for use in the JSON objects that are elements of the recipients array:

header

The header member MUST be present and contain the value JWE Per-Recipient Unprotected Header when the JWE Per-Recipient Unprotected Header value is non-empty; otherwise, it MUST be absent. This value is represented as an unencoded JSON object, rather than as a string. These Header Parameter values are not integrity protected.

encrypted_key

The encrypted_key member MUST be present and contain the value BASE64URL(JWE Encrypted Key) when the JWE Encrypted Key value is non-empty; otherwise, it MUST be absent.

At least one of the header, protected, and unprotected members MUST be present so that alg and enc Header Parameter values are conveyed for each recipient computation.

Additional members can be present in both the JSON objects defined above; if not understood by implementations encountering them, they MUST be ignored.

Some Header Parameters, including the alg parameter, can be shared among all recipient computations. Header Parameters in the JWE Protected Header and JWE Shared Unprotected Header values are shared among all recipients.

The Header Parameter values used when creating or validating per-recipient Ciphertext and Authentication Tag values are the union of the three sets of Header Parameter values that may be present: (1) the JWE Protected Header represented in the protected member, (2) the JWE Shared Unprotected Header represented in the unprotected member, and (3) the JWE Per-Recipient Unprotected Header represented in the header member of the recipient's array element. The union of these sets of Header Parameters comprises the JWE Header. The Header Parameter names in the three locations MUST be disjoint.

Each JWE Encrypted Key value is computed using the parameters of the corresponding JWE Header value in the same manner as for the JWE Compact Serialization. This has the desirable property that each JWE Encrypted Key value in the recipients array is identical to the value that would have been computed for the same parameter in the JWE Compact Serialization. Likewise, the JWE Ciphertext and JWE Authentication Tag values match those produced for the JWE Compact Serialization, provided that the JWE Protected Header value (which represents the integrity-protected Header Parameter values) matches that used in the JWE Compact Serialization.

All recipients use the same JWE Protected Header, JWE Initialization Vector, JWE Ciphertext, and JWE Authentication Tag values, when present, resulting in potentially significant space savings if the message is large. Therefore, all Header Parameters that specify the treatment of the Plaintext value MUST be the same for all recipients. This primarily means that the enc (encryption algorithm) Header Parameter value in the JWE Header for each recipient and any parameters of that algorithm MUST be the same.

In summary, the syntax of a JWE using the JWE JSON Serialization is as follows:

  {"protected":"<integrity-protected shared header contents>",
   "unprotected":<non-integrity-protected shared header contents>,
   "recipients":[
    {"header":<per-recipient unprotected header 1 contents>,
     "encrypted_key":"<encrypted key 1 contents>"},
    ...
    {"header":<per-recipient unprotected header N contents>,
     "encrypted_key":"<encrypted key N contents>"}],
   "aad":"<additional authenticated data contents>",
   "iv":"<initialization vector contents>",
   "ciphertext":"<ciphertext contents>",
   "tag":"<authentication tag contents>"
  }

See Appendix A.4 (Example JWE using JWE JSON Serialization) for an example of computing a JWE using the JWE JSON Serialization.

8.  TLS Requirements

The TLS requirements for this specification are the same as those defined in Section 8 of [JWS] (Jones, M., Bradley, J., and N. Sakimura, “JSON Web Signature (JWS),” April 2014.).

9.  Distinguishing between JWS and JWE Objects

There are several ways of distinguishing whether an object is a JWS or JWE object. All these methods will yield the same result for all legal input values; they may yield different results for malformed inputs.

• If the object is using the JWS Compact Serialization or the JWE Compact Serialization, the number of base64url encoded segments separated by period ('.') characters differs for JWSs and JWEs. JWSs have three segments separated by two period ('.') characters. JWEs have five segments separated by four period ('.') characters.
• If the object is using the JWS JSON Serialization or the JWE JSON Serialization, the members used will be different. JWSs have a signatures member and JWEs do not. JWEs have a recipients member and JWSs do not.
• A JWS Header can be distinguished from a JWE header by examining the alg (algorithm) Header Parameter value. If the value represents a digital signature or MAC algorithm, or is the value none, it is for a JWS; if it represents a Key Encryption, Key Wrapping, Direct Key Agreement, Key Agreement with Key Wrapping, or Direct Encryption algorithm, it is for a JWE. (Extracting the alg value to examine is straightforward when using the JWS Compact Serialization or the JWE Compact Serialization and may be more difficult when using the JWS JSON Serialization or the JWE JSON Serialization.)
• A JWS Header can also be distinguished from a JWE header by determining whether an enc (encryption algorithm) member exists. If the enc member exists, it is a JWE; otherwise, it is a JWS.

10.  IANA Considerations

10.1.  JSON Web Signature and Encryption Header Parameters Registration

This specification registers the Header Parameter names defined in Section 4.1 (Registered Header Parameter Names) in the IANA JSON Web Signature and Encryption Header Parameters registry defined in [JWS] (Jones, M., Bradley, J., and N. Sakimura, “JSON Web Signature (JWS),” April 2014.).

10.1.1.  Registry Contents

• Header Parameter Name: alg
• Header Parameter Description: Algorithm
• Header Parameter Usage Location(s): JWE
• Change Controller: IESG
• Specification Document(s): Section 4.1.1 ("alg" (Algorithm) Header Parameter) of [[ this document ]]

• Header Parameter Name: enc
• Header Parameter Description: Encryption Algorithm
• Header Parameter Usage Location(s): JWE
• Change Controller: IESG
• Specification Document(s): Section 4.1.2 ("enc" (Encryption Algorithm) Header Parameter) of [[ this document ]]

• Header Parameter Name: zip
• Header Parameter Description: Compression Algorithm
• Header Parameter Usage Location(s): JWE
• Change Controller: IESG
• Specification Document(s): Section 4.1.3 ("zip" (Compression Algorithm) Header Parameter) of [[ this document ]]

• Header Parameter Name: jku
• Header Parameter Description: JWK Set URL
• Header Parameter Usage Location(s): JWE
• Change Controller: IESG
• Specification Document(s): Section 4.1.4 ("jku" (JWK Set URL) Header Parameter) of [[ this document ]]

• Header Parameter Name: jwk
• Header Parameter Description: JSON Web Key
• Header Parameter Usage Location(s): JWE
• Change Controller: IESG
• Specification document(s): Section 4.1.5 ("jwk" (JSON Web Key) Header Parameter) of [[ this document ]]

• Header Parameter Name: kid
• Header Parameter Description: Key ID
• Header Parameter Usage Location(s): JWE
• Change Controller: IESG
• Specification Document(s): Section 4.1.6 ("kid" (Key ID) Header Parameter) of [[ this document ]]

• Header Parameter Name: x5u
• Header Parameter Description: X.509 URL
• Header Parameter Usage Location(s): JWE
• Change Controller: IESG
• Specification Document(s): Section 4.1.7 ("x5u" (X.509 URL) Header Parameter) of [[ this document ]]

• Header Parameter Name: x5c
• Header Parameter Description: X.509 Certificate Chain
• Header Parameter Usage Location(s): JWE
• Change Controller: IESG
• Specification Document(s): Section 4.1.8 ("x5c" (X.509 Certificate Chain) Header Parameter) of [[ this document ]]

• Header Parameter Name: x5t
• Header Parameter Description: X.509 Certificate SHA-1 Thumbprint
• Header Parameter Usage Location(s): JWE
• Change Controller: IESG
• Specification Document(s): Section 4.1.9 ("x5t" (X.509 Certificate SHA-1 Thumbprint) Header Parameter) of [[ this document ]]

• Header Parameter Name: typ
• Header Parameter Description: Type
• Header Parameter Usage Location(s): JWE
• Change Controller: IESG
• Specification Document(s): Section 4.1.10 ("typ" (Type) Header Parameter) of [[ this document ]]

• Header Parameter Name: cty
• Header Parameter Description: Content Type
• Header Parameter Usage Location(s): JWE
• Change Controller: IESG
• Specification Document(s): Section 4.1.11 ("cty" (Content Type) Header Parameter) of [[ this document ]]

• Header Parameter Name: crit
• Header Parameter Description: Critical
• Header Parameter Usage Location(s): JWE
• Change Controller: IESG
• Specification Document(s): Section 4.1.12 ("crit" (Critical) Header Parameter) of [[ this document ]]

11.  Security Considerations

All of the security issues faced by any cryptographic application must be faced by a JWS/JWE/JWK agent. Among these issues are protecting the user's private and symmetric keys, preventing various attacks, and helping the user avoid mistakes such as inadvertently encrypting a message for the wrong recipient. The entire list of security considerations is beyond the scope of this document.

All the security considerations in the JWS specification also apply to this specification. Likewise, all the security considerations in XML Encryption 1.1 (Eastlake, D., Reagle, J., Hirsch, F., and T. Roessler, “XML Encryption Syntax and Processing Version 1.1,” April 2013.) [W3C.REC‑xmlenc‑core1‑20130411] also apply, other than those that are XML specific.

When decrypting, particular care must be taken not to allow the JWE recipient to be used as an oracle for decrypting messages. RFC 3218 (Rescorla, E., “Preventing the Million Message Attack on Cryptographic Message Syntax,” January 2002.) [RFC3218] should be consulted for specific countermeasures to attacks on RSAES-PKCS1-V1_5. An attacker might modify the contents of the alg parameter from RSA-OAEP to RSA1_5 in order to generate a formatting error that can be detected and used to recover the CEK even if RSAES OAEP was used to encrypt the CEK. It is therefore particularly important to report all formatting errors to the CEK, Additional Authenticated Data, or ciphertext as a single error when the encrypted content is rejected.

Additionally, this type of attack can be prevented by the use of "key tainting". This method restricts the use of a key to a limited set of algorithms -- usually one. This means, for instance, that if the key is marked as being for RSA-OAEP only, any attempt to decrypt a message using the RSA1_5 algorithm with that key would fail immediately due to invalid use of the key.

12.  References

12.1. Normative References

12.2. Informative References

Appendix A.  JWE Examples

This section provides examples of JWE computations.

A.1.  Example JWE using RSAES OAEP and AES GCM

This example encrypts the plaintext "The true sign of intelligence is not knowledge but imagination." to the recipient using RSAES OAEP for key encryption and AES GCM for content encryption. The representation of this plaintext (using JSON array notation) is:

[84, 104, 101, 32, 116, 114, 117, 101, 32, 115, 105, 103, 110, 32, 111, 102, 32, 105, 110, 116, 101, 108, 108, 105, 103, 101, 110, 99, 101, 32, 105, 115, 32, 110, 111, 116, 32, 107, 110, 111, 119, 108, 101, 100, 103, 101, 32, 98, 117, 116, 32, 105, 109, 97, 103, 105, 110, 97, 116, 105, 111, 110, 46]

A.1.1.  JWE Header

The following example JWE Protected Header declares that:

• the Content Encryption Key is encrypted to the recipient using the RSAES OAEP algorithm to produce the JWE Encrypted Key and
• the Plaintext is encrypted using the AES GCM algorithm with a 256 bit key to produce the Ciphertext.

  {"alg":"RSA-OAEP","enc":"A256GCM"}

Encoding this JWE Protected Header as BASE64URL(UTF8(JWE Protected Header)) gives this value:

  eyJhbGciOiJSU0EtT0FFUCIsImVuYyI6IkEyNTZHQ00ifQ

A.1.2.  Content Encryption Key (CEK)

Generate a 256 bit random Content Encryption Key (CEK). In this example, the value (using JSON array notation) is:

[177, 161, 244, 128, 84, 143, 225, 115, 63, 180, 3, 255, 107, 154, 212, 246, 138, 7, 110, 91, 112, 46, 34, 105, 47, 130, 203, 46, 122, 234, 64, 252]

A.1.3.  Key Encryption

Encrypt the CEK with the recipient's public key using the RSAES OAEP algorithm to produce the JWE Encrypted Key. This example uses the RSA key represented in JSON Web Key [JWK] (Jones, M., “JSON Web Key (JWK),” April 2014.) format below (with line breaks for display purposes only):

  {"kty":"RSA",
   "n":"oahUIoWw0K0usKNuOR6H4wkf4oBUXHTxRvgb48E-BVvxkeDNjbC4he8rUW
        cJoZmds2h7M70imEVhRU5djINXtqllXI4DFqcI1DgjT9LewND8MW2Krf3S
        psk_ZkoFnilakGygTwpZ3uesH-PFABNIUYpOiN15dsQRkgr0vEhxN92i2a
        sbOenSZeyaxziK72UwxrrKoExv6kc5twXTq4h-QChLOln0_mtUZwfsRaMS
        tPs6mS6XrgxnxbWhojf663tuEQueGC-FCMfra36C9knDFGzKsNa7LZK2dj
        YgyD3JR_MB_4NUJW_TqOQtwHYbxevoJArm-L5StowjzGy-_bq6Gw",
   "e":"AQAB",
   "d":"kLdtIj6GbDks_ApCSTYQtelcNttlKiOyPzMrXHeI-yk1F7-kpDxY4-WY5N
        WV5KntaEeXS1j82E375xxhWMHXyvjYecPT9fpwR_M9gV8n9Hrh2anTpTD9
        3Dt62ypW3yDsJzBnTnrYu1iwWRgBKrEYY46qAZIrA2xAwnm2X7uGR1hghk
        qDp0Vqj3kbSCz1XyfCs6_LehBwtxHIyh8Ripy40p24moOAbgxVw3rxT_vl
        t3UVe4WO3JkJOzlpUf-KTVI2Ptgm-dARxTEtE-id-4OJr0h-K-VFs3VSnd
        VTIznSxfyrj8ILL6MG_Uv8YAu7VILSB3lOW085-4qE3DzgrTjgyQ"
  }

The resulting JWE Encrypted Key value is:

[56, 163, 154, 192, 58, 53, 222, 4, 105, 218, 136, 218, 29, 94, 203, 22, 150, 92, 129, 94, 211, 232, 53, 89, 41, 60, 138, 56, 196, 216, 82, 98, 168, 76, 37, 73, 70, 7, 36, 8, 191, 100, 136, 196, 244, 220, 145, 158, 138, 155, 4, 117, 141, 230, 199, 247, 173, 45, 182, 214, 74, 177, 107, 211, 153, 11, 205, 196, 171, 226, 162, 128, 171, 182, 13, 237, 239, 99, 193, 4, 91, 219, 121, 223, 107, 167, 61, 119, 228, 173, 156, 137, 134, 200, 80, 219, 74, 253, 56, 185, 91, 177, 34, 158, 89, 154, 205, 96, 55, 18, 138, 43, 96, 218, 215, 128, 124, 75, 138, 243, 85, 25, 109, 117, 140, 26, 155, 249, 67, 167, 149, 231, 100, 6, 41, 65, 214, 251, 232, 87, 72, 40, 182, 149, 154, 168, 31, 193, 126, 215, 89, 28, 111, 219, 125, 182, 139, 235, 195, 197, 23, 234, 55, 58, 63, 180, 68, 202, 206, 149, 75, 205, 248, 176, 67, 39, 178, 60, 98, 193, 32, 238, 122, 96, 158, 222, 57, 183, 111, 210, 55, 188, 215, 206, 180, 166, 150, 166, 106, 250, 55, 229, 72, 40, 69, 214, 216, 104, 23, 40, 135, 212, 28, 127, 41, 80, 175, 174, 168, 115, 171, 197, 89, 116, 92, 103, 246, 83, 216, 182, 176, 84, 37, 147, 35, 45, 219, 172, 99, 226, 233, 73, 37, 124, 42, 72, 49, 242, 35, 127, 184, 134, 117, 114, 135, 206]

Encoding this JWE Encrypted Key as BASE64URL(JWE Encrypted Key) gives this value (with line breaks for display purposes only):

  OKOawDo13gRp2ojaHV7LFpZcgV7T6DVZKTyKOMTYUmKoTCVJRgckCL9kiMT03JGe
  ipsEdY3mx_etLbbWSrFr05kLzcSr4qKAq7YN7e9jwQRb23nfa6c9d-StnImGyFDb
  Sv04uVuxIp5Zms1gNxKKK2Da14B8S4rzVRltdYwam_lDp5XnZAYpQdb76FdIKLaV
  mqgfwX7XWRxv2322i-vDxRfqNzo_tETKzpVLzfiwQyeyPGLBIO56YJ7eObdv0je8
  1860ppamavo35UgoRdbYaBcoh9QcfylQr66oc6vFWXRcZ_ZT2LawVCWTIy3brGPi
  6UklfCpIMfIjf7iGdXKHzg

A.1.4.  Initialization Vector

Generate a random 96 bit JWE Initialization Vector. In this example, the value is:

[227, 197, 117, 252, 2, 219, 233, 68, 180, 225, 77, 219]

Encoding this JWE Initialization Vector as BASE64URL(JWE Initialization Vector) gives this value:

  48V1_ALb6US04U3b

A.1.5.  Additional Authenticated Data

Let the Additional Authenticated Data encryption parameter be ASCII(BASE64URL(UTF8(JWE Protected Header))). This value is:

[101, 121, 74, 104, 98, 71, 99, 105, 79, 105, 74, 83, 85, 48, 69, 116, 84, 48, 70, 70, 85, 67, 73, 115, 73, 109, 86, 117, 89, 121, 73, 54, 73, 107, 69, 121, 78, 84, 90, 72, 81, 48, 48, 105, 102, 81]

A.1.6.  Content Encryption

Encrypt the Plaintext with AES GCM using the CEK as the encryption key, the JWE Initialization Vector, and the Additional Authenticated Data value above, requesting a 128 bit Authentication Tag output. The resulting Ciphertext is:

[229, 236, 166, 241, 53, 191, 115, 196, 174, 43, 73, 109, 39, 122, 233, 96, 140, 206, 120, 52, 51, 237, 48, 11, 190, 219, 186, 80, 111, 104, 50, 142, 47, 167, 59, 61, 181, 127, 196, 21, 40, 82, 242, 32, 123, 143, 168, 226, 73, 216, 176, 144, 138, 247, 106, 60, 16, 205, 160, 109, 64, 63, 192]

The resulting Authentication Tag value is:

[92, 80, 104, 49, 133, 25, 161, 215, 173, 101, 219, 211, 136, 91, 210, 145]

Encoding this JWE Ciphertext as BASE64URL(JWE Ciphertext) gives this value (with line breaks for display purposes only):

  5eym8TW_c8SuK0ltJ3rpYIzOeDQz7TALvtu6UG9oMo4vpzs9tX_EFShS8iB7j6ji
  SdiwkIr3ajwQzaBtQD_A

Encoding this JWE Authentication Tag as BASE64URL(JWE Authentication Tag) gives this value:

  XFBoMYUZodetZdvTiFvSkQ

A.1.7.  Complete Representation

Assemble the final representation: The Compact Serialization of this result is the string BASE64URL(UTF8(JWE Protected Header)) || '.' || BASE64URL(JWE Encrypted Key) || '.' || BASE64URL(JWE Initialization Vector) || '.' || BASE64URL(JWE Ciphertext) || '.' || BASE64URL(JWE Authentication Tag).

The final result in this example (with line breaks for display purposes only) is:

  eyJhbGciOiJSU0EtT0FFUCIsImVuYyI6IkEyNTZHQ00ifQ.
  OKOawDo13gRp2ojaHV7LFpZcgV7T6DVZKTyKOMTYUmKoTCVJRgckCL9kiMT03JGe
  ipsEdY3mx_etLbbWSrFr05kLzcSr4qKAq7YN7e9jwQRb23nfa6c9d-StnImGyFDb
  Sv04uVuxIp5Zms1gNxKKK2Da14B8S4rzVRltdYwam_lDp5XnZAYpQdb76FdIKLaV
  mqgfwX7XWRxv2322i-vDxRfqNzo_tETKzpVLzfiwQyeyPGLBIO56YJ7eObdv0je8
  1860ppamavo35UgoRdbYaBcoh9QcfylQr66oc6vFWXRcZ_ZT2LawVCWTIy3brGPi
  6UklfCpIMfIjf7iGdXKHzg.
  48V1_ALb6US04U3b.
  5eym8TW_c8SuK0ltJ3rpYIzOeDQz7TALvtu6UG9oMo4vpzs9tX_EFShS8iB7j6ji
  SdiwkIr3ajwQzaBtQD_A.
  XFBoMYUZodetZdvTiFvSkQ

A.1.8.  Validation

This example illustrates the process of creating a JWE with RSAES OAEP for key encryption and AES GCM for content encryption. These results can be used to validate JWE decryption implementations for these algorithms. Note that since the RSAES OAEP computation includes random values, the encryption results above will not be completely reproducible. However, since the AES GCM computation is deterministic, the JWE Encrypted Ciphertext values will be the same for all encryptions performed using these inputs.

A.2.  Example JWE using RSAES-PKCS1-V1_5 and AES_128_CBC_HMAC_SHA_256

This example encrypts the plaintext "Live long and prosper." to the recipient using RSAES-PKCS1-V1_5 for key encryption and AES_128_CBC_HMAC_SHA_256 for content encryption. The representation of this plaintext (using JSON array notation) is:

[76, 105, 118, 101, 32, 108, 111, 110, 103, 32, 97, 110, 100, 32, 112, 114, 111, 115, 112, 101, 114, 46]

A.2.1.  JWE Header

The following example JWE Protected Header declares that:

• the Content Encryption Key is encrypted to the recipient using the RSAES-PKCS1-V1_5 algorithm to produce the JWE Encrypted Key and
• the Plaintext is encrypted using the AES_128_CBC_HMAC_SHA_256 algorithm to produce the Ciphertext.

  {"alg":"RSA1_5","enc":"A128CBC-HS256"}

Encoding this JWE Protected Header as BASE64URL(UTF8(JWE Protected Header)) gives this value:

  eyJhbGciOiJSU0ExXzUiLCJlbmMiOiJBMTI4Q0JDLUhTMjU2In0

A.2.2.  Content Encryption Key (CEK)

Generate a 256 bit random Content Encryption Key (CEK). In this example, the key value is:

[4, 211, 31, 197, 84, 157, 252, 254, 11, 100, 157, 250, 63, 170, 106, 206, 107, 124, 212, 45, 111, 107, 9, 219, 200, 177, 0, 240, 143, 156, 44, 207]

A.2.3.  Key Encryption

Encrypt the CEK with the recipient's public key using the RSAES-PKCS1-V1_5 algorithm to produce the JWE Encrypted Key. This example uses the RSA key represented in JSON Web Key [JWK] (Jones, M., “JSON Web Key (JWK),” April 2014.) format below (with line breaks for display purposes only):

  {"kty":"RSA",
   "n":"sXchDaQebHnPiGvyDOAT4saGEUetSyo9MKLOoWFsueri23bOdgWp4Dy1Wl
        UzewbgBHod5pcM9H95GQRV3JDXboIRROSBigeC5yjU1hGzHHyXss8UDpre
        cbAYxknTcQkhslANGRUZmdTOQ5qTRsLAt6BTYuyvVRdhS8exSZEy_c4gs_
        7svlJJQ4H9_NxsiIoLwAEk7-Q3UXERGYw_75IDrGA84-lA_-Ct4eTlXHBI
        Y2EaV7t7LjJaynVJCpkv4LKjTTAumiGUIuQhrNhZLuF_RJLqHpM2kgWFLU
        7-VTdL1VbC2tejvcI2BlMkEpk1BzBZI0KQB0GaDWFLN-aEAw3vRw",
   "e":"AQAB",
   "d":"VFCWOqXr8nvZNyaaJLXdnNPXZKRaWCjkU5Q2egQQpTBMwhprMzWzpR8Sxq
        1OPThh_J6MUD8Z35wky9b8eEO0pwNS8xlh1lOFRRBoNqDIKVOku0aZb-ry
        nq8cxjDTLZQ6Fz7jSjR1Klop-YKaUHc9GsEofQqYruPhzSA-QgajZGPbE_
        0ZaVDJHfyd7UUBUKunFMScbflYAAOYJqVIVwaYR5zWEEceUjNnTNo_CVSj
        -VvXLO5VZfCUAVLgW4dpf1SrtZjSt34YLsRarSb127reG_DUwg9Ch-Kyvj
        T1SkHgUWRVGcyly7uvVGRSDwsXypdrNinPA4jlhoNdizK2zF2CWQ"
  }

The resulting JWE Encrypted Key value is:

[80, 104, 72, 58, 11, 130, 236, 139, 132, 189, 255, 205, 61, 86, 151, 176, 99, 40, 44, 233, 176, 189, 205, 70, 202, 169, 72, 40, 226, 181, 156, 223, 120, 156, 115, 232, 150, 209, 145, 133, 104, 112, 237, 156, 116, 250, 65, 102, 212, 210, 103, 240, 177, 61, 93, 40, 71, 231, 223, 226, 240, 157, 15, 31, 150, 89, 200, 215, 198, 203, 108, 70, 117, 66, 212, 238, 193, 205, 23, 161, 169, 218, 243, 203, 128, 214, 127, 253, 215, 139, 43, 17, 135, 103, 179, 220, 28, 2, 212, 206, 131, 158, 128, 66, 62, 240, 78, 186, 141, 125, 132, 227, 60, 137, 43, 31, 152, 199, 54, 72, 34, 212, 115, 11, 152, 101, 70, 42, 219, 233, 142, 66, 151, 250, 126, 146, 141, 216, 190, 73, 50, 177, 146, 5, 52, 247, 28, 197, 21, 59, 170, 247, 181, 89, 131, 241, 169, 182, 246, 99, 15, 36, 102, 166, 182, 172, 197, 136, 230, 120, 60, 58, 219, 243, 149, 94, 222, 150, 154, 194, 110, 227, 225, 112, 39, 89, 233, 112, 207, 211, 241, 124, 174, 69, 221, 179, 107, 196, 225, 127, 167, 112, 226, 12, 242, 16, 24, 28, 120, 182, 244, 213, 244, 153, 194, 162, 69, 160, 244, 248, 63, 165, 141, 4, 207, 249, 193, 79, 131, 0, 169, 233, 127, 167, 101, 151, 125, 56, 112, 111, 248, 29, 232, 90, 29, 147, 110, 169, 146, 114, 165, 204, 71, 136, 41, 252]

Encoding this JWE Encrypted Key as BASE64URL(JWE Encrypted Key) gives this value (with line breaks for display purposes only):

  UGhIOguC7IuEvf_NPVaXsGMoLOmwvc1GyqlIKOK1nN94nHPoltGRhWhw7Zx0-kFm
  1NJn8LE9XShH59_i8J0PH5ZZyNfGy2xGdULU7sHNF6Gp2vPLgNZ__deLKxGHZ7Pc
  HALUzoOegEI-8E66jX2E4zyJKx-YxzZIItRzC5hlRirb6Y5Cl_p-ko3YvkkysZIF
  NPccxRU7qve1WYPxqbb2Yw8kZqa2rMWI5ng8OtvzlV7elprCbuPhcCdZ6XDP0_F8
  rkXds2vE4X-ncOIM8hAYHHi29NX0mcKiRaD0-D-ljQTP-cFPgwCp6X-nZZd9OHBv
  -B3oWh2TbqmScqXMR4gp_A

A.2.4.  Initialization Vector

Generate a random 128 bit JWE Initialization Vector. In this example, the value is:

[3, 22, 60, 12, 43, 67, 104, 105, 108, 108, 105, 99, 111, 116, 104, 101]

Encoding this JWE Initialization Vector as BASE64URL(JWE Initialization Vector) gives this value:

  AxY8DCtDaGlsbGljb3RoZQ

A.2.5.  Additional Authenticated Data

Let the Additional Authenticated Data encryption parameter be ASCII(BASE64URL(UTF8(JWE Protected Header))). This value is:

[101, 121, 74, 104, 98, 71, 99, 105, 79, 105, 74, 83, 85, 48, 69, 120, 88, 122, 85, 105, 76, 67, 74, 108, 98, 109, 77, 105, 79, 105, 74, 66, 77, 84, 73, 52, 81, 48, 74, 68, 76, 85, 104, 84, 77, 106, 85, 50, 73, 110, 48]

A.2.6.  Content Encryption

Encrypt the Plaintext with AES_128_CBC_HMAC_SHA_256 using the CEK as the encryption key, the JWE Initialization Vector, and the Additional Authenticated Data value above. The steps for doing this using the values from Appendix A.3 (Example JWE using AES Key Wrap and AES_128_CBC_HMAC_SHA_256) are detailed in Appendix B (Example AES_128_CBC_HMAC_SHA_256 Computation). The resulting Ciphertext is:

[40, 57, 83, 181, 119, 33, 133, 148, 198, 185, 243, 24, 152, 230, 6, 75, 129, 223, 127, 19, 210, 82, 183, 230, 168, 33, 215, 104, 143, 112, 56, 102]

The resulting Authentication Tag value is:

[246, 17, 244, 190, 4, 95, 98, 3, 231, 0, 115, 157, 242, 203, 100, 191]

Encoding this JWE Ciphertext as BASE64URL(JWE Ciphertext) gives this value:

  KDlTtXchhZTGufMYmOYGS4HffxPSUrfmqCHXaI9wOGY

Encoding this JWE Authentication Tag as BASE64URL(JWE Authentication Tag) gives this value:

  9hH0vgRfYgPnAHOd8stkvw

A.2.7.  Complete Representation

Assemble the final representation: The Compact Serialization of this result is the string BASE64URL(UTF8(JWE Protected Header)) || '.' || BASE64URL(JWE Encrypted Key) || '.' || BASE64URL(JWE Initialization Vector) || '.' || BASE64URL(JWE Ciphertext) || '.' || BASE64URL(JWE Authentication Tag).

The final result in this example (with line breaks for display purposes only) is:

  eyJhbGciOiJSU0ExXzUiLCJlbmMiOiJBMTI4Q0JDLUhTMjU2In0.
  UGhIOguC7IuEvf_NPVaXsGMoLOmwvc1GyqlIKOK1nN94nHPoltGRhWhw7Zx0-kFm
  1NJn8LE9XShH59_i8J0PH5ZZyNfGy2xGdULU7sHNF6Gp2vPLgNZ__deLKxGHZ7Pc
  HALUzoOegEI-8E66jX2E4zyJKx-YxzZIItRzC5hlRirb6Y5Cl_p-ko3YvkkysZIF
  NPccxRU7qve1WYPxqbb2Yw8kZqa2rMWI5ng8OtvzlV7elprCbuPhcCdZ6XDP0_F8
  rkXds2vE4X-ncOIM8hAYHHi29NX0mcKiRaD0-D-ljQTP-cFPgwCp6X-nZZd9OHBv
  -B3oWh2TbqmScqXMR4gp_A.
  AxY8DCtDaGlsbGljb3RoZQ.
  KDlTtXchhZTGufMYmOYGS4HffxPSUrfmqCHXaI9wOGY.
  9hH0vgRfYgPnAHOd8stkvw

A.2.8.  Validation

This example illustrates the process of creating a JWE with RSAES-PKCS1-V1_5 for key encryption and AES_CBC_HMAC_SHA2 for content encryption. These results can be used to validate JWE decryption implementations for these algorithms. Note that since the RSAES-PKCS1-V1_5 computation includes random values, the encryption results above will not be completely reproducible. However, since the AES CBC computation is deterministic, the JWE Encrypted Ciphertext values will be the same for all encryptions performed using these inputs.

A.3.  Example JWE using AES Key Wrap and AES_128_CBC_HMAC_SHA_256

This example encrypts the plaintext "Live long and prosper." to the recipient using AES Key Wrap for key encryption and AES_128_CBC_HMAC_SHA_256 for content encryption. The representation of this plaintext (using JSON array notation) is:

[76, 105, 118, 101, 32, 108, 111, 110, 103, 32, 97, 110, 100, 32, 112, 114, 111, 115, 112, 101, 114, 46]

A.3.1.  JWE Header

The following example JWE Protected Header declares that:

• the Content Encryption Key is encrypted to the recipient using the AES Key Wrap algorithm with a 128 bit key to produce the JWE Encrypted Key and
• the Plaintext is encrypted using the AES_128_CBC_HMAC_SHA_256 algorithm to produce the Ciphertext.

  {"alg":"A128KW","enc":"A128CBC-HS256"}

Encoding this JWE Protected Header as BASE64URL(UTF8(JWE Protected Header)) gives this value:

  eyJhbGciOiJBMTI4S1ciLCJlbmMiOiJBMTI4Q0JDLUhTMjU2In0

A.3.2.  Content Encryption Key (CEK)

Generate a 256 bit random Content Encryption Key (CEK). In this example, the value is:

[4, 211, 31, 197, 84, 157, 252, 254, 11, 100, 157, 250, 63, 170, 106, 206, 107, 124, 212, 45, 111, 107, 9, 219, 200, 177, 0, 240, 143, 156, 44, 207]

A.3.3.  Key Encryption

Encrypt the CEK with the shared symmetric key using the AES Key Wrap algorithm to produce the JWE Encrypted Key. This example uses the symmetric key represented in JSON Web Key [JWK] (Jones, M., “JSON Web Key (JWK),” April 2014.) format below:

  {"kty":"oct",
   "k":"GawgguFyGrWKav7AX4VKUg"
  }

The resulting JWE Encrypted Key value is:

[232, 160, 123, 211, 183, 76, 245, 132, 200, 128, 123, 75, 190, 216, 22, 67, 201, 138, 193, 186, 9, 91, 122, 31, 246, 90, 28, 139, 57, 3, 76, 124, 193, 11, 98, 37, 173, 61, 104, 57]

Encoding this JWE Encrypted Key as BASE64URL(JWE Encrypted Key) gives this value:

  6KB707dM9YTIgHtLvtgWQ8mKwboJW3of9locizkDTHzBC2IlrT1oOQ

A.3.4.  Initialization Vector

Generate a random 128 bit JWE Initialization Vector. In this example, the value is:

[3, 22, 60, 12, 43, 67, 104, 105, 108, 108, 105, 99, 111, 116, 104, 101]

Encoding this JWE Initialization Vector as BASE64URL(JWE Initialization Vector) gives this value:

  AxY8DCtDaGlsbGljb3RoZQ

A.3.5.  Additional Authenticated Data

Let the Additional Authenticated Data encryption parameter be ASCII(BASE64URL(UTF8(JWE Protected Header))). This value is:

[101, 121, 74, 104, 98, 71, 99, 105, 79, 105, 74, 66, 77, 84, 73, 52, 83, 49, 99, 105, 76, 67, 74, 108, 98, 109, 77, 105, 79, 105, 74, 66, 77, 84, 73, 52, 81, 48, 74, 68, 76, 85, 104, 84, 77, 106, 85, 50, 73, 110, 48]

A.3.6.  Content Encryption

Encrypt the Plaintext with AES_128_CBC_HMAC_SHA_256 using the CEK as the encryption key, the JWE Initialization Vector, and the Additional Authenticated Data value above. The steps for doing this using the values from this example are detailed in Appendix B (Example AES_128_CBC_HMAC_SHA_256 Computation). The resulting Ciphertext is:

[40, 57, 83, 181, 119, 33, 133, 148, 198, 185, 243, 24, 152, 230, 6, 75, 129, 223, 127, 19, 210, 82, 183, 230, 168, 33, 215, 104, 143, 112, 56, 102]

The resulting Authentication Tag value is:

[83, 73, 191, 98, 104, 205, 211, 128, 201, 189, 199, 133, 32, 38, 194, 85]

Encoding this JWE Ciphertext as BASE64URL(JWE Ciphertext) gives this value:

  KDlTtXchhZTGufMYmOYGS4HffxPSUrfmqCHXaI9wOGY

Encoding this JWE Authentication Tag as BASE64URL(JWE Authentication Tag) gives this value:

  U0m_YmjN04DJvceFICbCVQ

A.3.7.  Complete Representation

Assemble the final representation: The Compact Serialization of this result is the string BASE64URL(UTF8(JWE Protected Header)) || '.' || BASE64URL(JWE Encrypted Key) || '.' || BASE64URL(JWE Initialization Vector) || '.' || BASE64URL(JWE Ciphertext) || '.' || BASE64URL(JWE Authentication Tag).

The final result in this example (with line breaks for display purposes only) is:

  eyJhbGciOiJBMTI4S1ciLCJlbmMiOiJBMTI4Q0JDLUhTMjU2In0.
  6KB707dM9YTIgHtLvtgWQ8mKwboJW3of9locizkDTHzBC2IlrT1oOQ.
  AxY8DCtDaGlsbGljb3RoZQ.
  KDlTtXchhZTGufMYmOYGS4HffxPSUrfmqCHXaI9wOGY.
  U0m_YmjN04DJvceFICbCVQ

A.3.8.  Validation

This example illustrates the process of creating a JWE with AES Key Wrap for key encryption and AES GCM for content encryption. These results can be used to validate JWE decryption implementations for these algorithms. Also, since both the AES Key Wrap and AES GCM computations are deterministic, the resulting JWE value will be the same for all encryptions performed using these inputs. Since the computation is reproducible, these results can also be used to validate JWE encryption implementations for these algorithms.

A.4.  Example JWE using JWE JSON Serialization

This section contains an example using the JWE JSON Serialization. This example demonstrates the capability for encrypting the same plaintext to multiple recipients.

Two recipients are present in this example. The algorithm and key used for the first recipient are the same as that used in Appendix A.2 (Example JWE using RSAES-PKCS1-V1_5 and AES_128_CBC_HMAC_SHA_256). The algorithm and key used for the second recipient are the same as that used in Appendix A.3 (Example JWE using AES Key Wrap and AES_128_CBC_HMAC_SHA_256). The resulting JWE Encrypted Key values are therefore the same; those computations are not repeated here.

The Plaintext, the Content Encryption Key (CEK), Initialization Vector, and JWE Protected Header are shared by all recipients (which must be the case, since the Ciphertext and Authentication Tag are also shared).

A.4.1.  JWE Per-Recipient Unprotected Headers

The first recipient uses the RSAES-PKCS1-V1_5 algorithm to encrypt the Content Encryption Key (CEK). The second uses AES Key Wrap to encrypt the CEK. Key ID values are supplied for both keys. The two per-recipient header values used to represent these algorithms and Key IDs are:

  {"alg":"RSA1_5","kid":"2011-04-29"}

and

  {"alg":"A128KW","kid":"7"}

A.4.2.  JWE Protected Header

The Plaintext is encrypted using the AES_128_CBC_HMAC_SHA_256 algorithm to produce the common JWE Ciphertext and JWE Authentication Tag values. The JWE Protected Header value representing this is:

  {"enc":"A128CBC-HS256"}

Encoding this JWE Protected Header as BASE64URL(UTF8(JWE Protected Header)) gives this value:

  eyJlbmMiOiJBMTI4Q0JDLUhTMjU2In0

A.4.3.  JWE Unprotected Header

This JWE uses the jku Header Parameter to reference a JWK Set. This is represented in the following JWE Unprotected Header value as:

  {"jku":"https://server.example.com/keys.jwks"}

A.4.4.  Complete JWE Header Values

Combining the per-recipient, protected, and unprotected header values supplied, the JWE Header values used for the first and second recipient respectively are:

  {"alg":"RSA1_5",
   "kid":"2011-04-29",
   "enc":"A128CBC-HS256",
   "jku":"https://server.example.com/keys.jwks"}

and

  {"alg":"A128KW",
   "kid":"7",
   "enc":"A128CBC-HS256",
   "jku":"https://server.example.com/keys.jwks"}

A.4.5.  Additional Authenticated Data

Let the Additional Authenticated Data encryption parameter be ASCII(BASE64URL(UTF8(JWE Protected Header))). This value is:

[101, 121, 74, 108, 98, 109, 77, 105, 79, 105, 74, 66, 77, 84, 73, 52, 81, 48, 74, 68, 76, 85, 104, 84, 77, 106, 85, 50, 73, 110, 48]

A.4.6.  Content Encryption

Encrypt the Plaintext with AES_128_CBC_HMAC_SHA_256 using the CEK as the encryption key, the JWE Initialization Vector, and the Additional Authenticated Data value above. The steps for doing this using the values from Appendix A.3 (Example JWE using AES Key Wrap and AES_128_CBC_HMAC_SHA_256) are detailed in Appendix B (Example AES_128_CBC_HMAC_SHA_256 Computation). The resulting Ciphertext is:

[40, 57, 83, 181, 119, 33, 133, 148, 198, 185, 243, 24, 152, 230, 6, 75, 129, 223, 127, 19, 210, 82, 183, 230, 168, 33, 215, 104, 143, 112, 56, 102]

The resulting Authentication Tag value is:

[51, 63, 149, 60, 252, 148, 225, 25, 92, 185, 139, 245, 35, 2, 47, 207]

Encoding this JWE Ciphertext as BASE64URL(JWE Ciphertext) gives this value:

  KDlTtXchhZTGufMYmOYGS4HffxPSUrfmqCHXaI9wOGY

Encoding this JWE Authentication Tag as BASE64URL(JWE Authentication Tag) gives this value:

  Mz-VPPyU4RlcuYv1IwIvzw

A.4.7.  Complete JWE JSON Serialization Representation

The complete JSON Web Encryption JSON Serialization for these values is as follows (with line breaks for display purposes only):

  {"protected":
    "eyJlbmMiOiJBMTI4Q0JDLUhTMjU2In0",
   "unprotected":
    {"jku":"https://server.example.com/keys.jwks"},
   "recipients":[
    {"header":
      {"alg":"RSA1_5","kid":"2011-04-29"},
     "encrypted_key":
      "UGhIOguC7IuEvf_NPVaXsGMoLOmwvc1GyqlIKOK1nN94nHPoltGRhWhw7Zx0-
       kFm1NJn8LE9XShH59_i8J0PH5ZZyNfGy2xGdULU7sHNF6Gp2vPLgNZ__deLKx
       GHZ7PcHALUzoOegEI-8E66jX2E4zyJKx-YxzZIItRzC5hlRirb6Y5Cl_p-ko3
       YvkkysZIFNPccxRU7qve1WYPxqbb2Yw8kZqa2rMWI5ng8OtvzlV7elprCbuPh
       cCdZ6XDP0_F8rkXds2vE4X-ncOIM8hAYHHi29NX0mcKiRaD0-D-ljQTP-cFPg
       wCp6X-nZZd9OHBv-B3oWh2TbqmScqXMR4gp_A"},
    {"header":
      {"alg":"A128KW","kid":"7"},
     "encrypted_key":
      "6KB707dM9YTIgHtLvtgWQ8mKwboJW3of9locizkDTHzBC2IlrT1oOQ"}],
   "iv":
    "AxY8DCtDaGlsbGljb3RoZQ",
   "ciphertext":
    "KDlTtXchhZTGufMYmOYGS4HffxPSUrfmqCHXaI9wOGY",
   "tag":
    "Mz-VPPyU4RlcuYv1IwIvzw"
  }

Appendix B.  Example AES_128_CBC_HMAC_SHA_256 Computation

This example shows the steps in the AES_128_CBC_HMAC_SHA_256 authenticated encryption computation using the values from the example in Appendix A.3 (Example JWE using AES Key Wrap and AES_128_CBC_HMAC_SHA_256). As described where this algorithm is defined in Sections 5.2 and 5.2.3 of JWA, the AES_CBC_HMAC_SHA2 family of algorithms are implemented using Advanced Encryption Standard (AES) in Cipher Block Chaining (CBC) mode with PKCS #5 padding to perform the encryption and an HMAC SHA-2 function to perform the integrity calculation - in this case, HMAC SHA-256.

B.1.  Extract MAC_KEY and ENC_KEY from Key

The 256 bit AES_128_CBC_HMAC_SHA_256 key K used in this example (using JSON array notation) is:

[4, 211, 31, 197, 84, 157, 252, 254, 11, 100, 157, 250, 63, 170, 106, 206, 107, 124, 212, 45, 111, 107, 9, 219, 200, 177, 0, 240, 143, 156, 44, 207]

Use the first 128 bits of this key as the HMAC SHA-256 key MAC_KEY, which is:

[4, 211, 31, 197, 84, 157, 252, 254, 11, 100, 157, 250, 63, 170, 106, 206]

Use the last 128 bits of this key as the AES CBC key ENC_KEY, which is:

[107, 124, 212, 45, 111, 107, 9, 219, 200, 177, 0, 240, 143, 156, 44, 207]

Note that the MAC key comes before the encryption key in the input key K; this is in the opposite order of the algorithm names in the identifiers "AES_128_CBC_HMAC_SHA_256" and A128CBC-HS256.

B.2.  Encrypt Plaintext to Create Ciphertext

Encrypt the Plaintext with AES in Cipher Block Chaining (CBC) mode using PKCS #5 padding using the ENC_KEY above. The Plaintext in this example is:

[76, 105, 118, 101, 32, 108, 111, 110, 103, 32, 97, 110, 100, 32, 112, 114, 111, 115, 112, 101, 114, 46]

The encryption result is as follows, which is the Ciphertext output:

[40, 57, 83, 181, 119, 33, 133, 148, 198, 185, 243, 24, 152, 230, 6, 75, 129, 223, 127, 19, 210, 82, 183, 230, 168, 33, 215, 104, 143, 112, 56, 102]

B.3.  64 Bit Big Endian Representation of AAD Length

The Additional Authenticated Data (AAD) in this example is:

[101, 121, 74, 104, 98, 71, 99, 105, 79, 105, 74, 66, 77, 84, 73, 52, 83, 49, 99, 105, 76, 67, 74, 108, 98, 109, 77, 105, 79, 105, 74, 66, 77, 84, 73, 52, 81, 48, 74, 68, 76, 85, 104, 84, 77, 106, 85, 50, 73, 110, 48]

This AAD is 51 bytes long, which is 408 bits long. The octet string AL, which is the number of bits in AAD expressed as a big endian 64 bit unsigned integer is:

[0, 0, 0, 0, 0, 0, 1, 152]

B.4.  Initialization Vector Value

The Initialization Vector value used in this example is:

[3, 22, 60, 12, 43, 67, 104, 105, 108, 108, 105, 99, 111, 116, 104, 101]

B.5.  Create Input to HMAC Computation

Concatenate the AAD, the Initialization Vector, the Ciphertext, and the AL value. The result of this concatenation is:

[101, 121, 74, 104, 98, 71, 99, 105, 79, 105, 74, 66, 77, 84, 73, 52, 83, 49, 99, 105, 76, 67, 74, 108, 98, 109, 77, 105, 79, 105, 74, 66, 77, 84, 73, 52, 81, 48, 74, 68, 76, 85, 104, 84, 77, 106, 85, 50, 73, 110, 48, 3, 22, 60, 12, 43, 67, 104, 105, 108, 108, 105, 99, 111, 116, 104, 101, 40, 57, 83, 181, 119, 33, 133, 148, 198, 185, 243, 24, 152, 230, 6, 75, 129, 223, 127, 19, 210, 82, 183, 230, 168, 33, 215, 104, 143, 112, 56, 102, 0, 0, 0, 0, 0, 0, 1, 152]

B.6.  Compute HMAC Value

Compute the HMAC SHA-256 of the concatenated value above. This result M is:

[83, 73, 191, 98, 104, 205, 211, 128, 201, 189, 199, 133, 32, 38, 194, 85, 9, 84, 229, 201, 219, 135, 44, 252, 145, 102, 179, 140, 105, 86, 229, 116]

B.7.  Truncate HMAC Value to Create Authentication Tag

Use the first half (128 bits) of the HMAC output M as the Authentication Tag output T. This truncated value is:

[83, 73, 191, 98, 104, 205, 211, 128, 201, 189, 199, 133, 32, 38, 194, 85]

Appendix C.  Acknowledgements

Solutions for encrypting JSON content were also explored by JSON Simple Encryption (Bradley, J. and N. Sakimura (editor), “JSON Simple Encryption,” September 2010.) [JSE] and JavaScript Message Security Format (Rescorla, E. and J. Hildebrand, “JavaScript Message Security Format,” March 2011.) [I‑D.rescorla‑jsms], both of which significantly influenced this draft. This draft attempts to explicitly reuse as many of the relevant concepts from XML Encryption 1.1 (Eastlake, D., Reagle, J., Hirsch, F., and T. Roessler, “XML Encryption Syntax and Processing Version 1.1,” April 2013.) [W3C.REC‑xmlenc‑core1‑20130411] and RFC 5652 (Housley, R., “Cryptographic Message Syntax (CMS),” September 2009.) [RFC5652] as possible, while utilizing simple, compact JSON-based data structures.

Special thanks are due to John Bradley, Eric Rescorla, and Nat Sakimura for the discussions that helped inform the content of this specification, to Eric Rescorla and Joe Hildebrand for allowing the reuse of text from [I‑D.rescorla‑jsms] (Rescorla, E. and J. Hildebrand, “JavaScript Message Security Format,” March 2011.) in this document, and to Eric Rescorla for co-authoring many drafts of this specification.

Thanks to Axel Nennker, Emmanuel Raviart, Brian Campbell, and Edmund Jay for validating the examples in this specification.

This specification is the work of the JOSE Working Group, which includes dozens of active and dedicated participants. In particular, the following individuals contributed ideas, feedback, and wording that influenced this specification:

Richard Barnes, John Bradley, Brian Campbell, Breno de Medeiros, Dick Hardt, Jeff Hodges, Edmund Jay, James Manger, Matt Miller, Tony Nadalin, Hideki Nara, Axel Nennker, Emmanuel Raviart, Eric Rescorla, Nat Sakimura, Jim Schaad, Hannes Tschofenig, and Sean Turner.

Jim Schaad and Karen O'Donoghue chaired the JOSE working group and Sean Turner, Stephen Farrell, and Kathleen Moriarty served as Security area directors during the creation of this specification.

Appendix D.  Document History

[[ to be removed by the RFC Editor before publication as an RFC ]]

-26

• Noted that octet sequences are depicted using JSON array notation.
• Updated references, including to W3C specifications.

-25

• Corrected two external section number references that had changed.
• Corrected a typo in an algorithm name in the prose of an example.

-24

• Corrected complete JSON Serialization example.
• Replaced uses of the term "associated data" wherever it was used to refer to a data value with "additional authenticated data", since both terms were being used as synonyms, causing confusion.
• Updated the JSON reference to RFC 7159.
• Thanked Eric Rescorla for helping to author of most of the drafts of this specification and removed him from the current author list.

-23

• Corrected a use of the word "payload" to "plaintext".

-22

• Corrected RFC 2119 terminology usage.
• Replaced references to draft-ietf-json-rfc4627bis with RFC 7158.

-21

• Changed some references from being normative to informative, addressing issue #90.
• Applied review comments to the JSON Serialization section, addressing issue #178.

-20

• Made terminology definitions more consistent, addressing issue #165.
• Restructured the JSON Serialization section to call out the parameters used in hanging lists, addressing issue #178.
• Replaced references to RFC 4627 with draft-ietf-json-rfc4627bis, addressing issue #90.

-19

• Reordered the key selection parameters.

-18

• Updated the mandatory-to-implement (MTI) language to say that applications using this specification need to specify what serialization and serialization features are used for that application, addressing issue #176.
• Changes to address editorial and minor issues #89, #135, #165, #174, #175, #177, #179, and #180.
• Used Header Parameter Description registry field.

-17

• Refined the typ and cty definitions to always be MIME Media Types, with the omission of "application/" prefixes recommended for brevity, addressing issue #50.
• Updated the mandatory-to-implement (MTI) language to say that general-purpose implementations must implement the single recipient case for both serializations whereas special-purpose implementations can implement just one serialization if that meets the needs of the use cases the implementation is designed for, addressing issue #176.
• Explicitly named all the logical components of a JWE and defined the processing rules and serializations in terms of those components, addressing issues #60, #61, and #62.
• Replaced verbose repetitive phases such as "base64url encode the octets of the UTF-8 representation of X" with mathematical notation such as "BASE64URL(UTF8(X))".
• Header Parameters and processing rules occurring in both JWS and JWE are now referenced in JWS by JWE, rather than duplicated, addressing issue #57.
• Terms used in multiple documents are now defined in one place and incorporated by reference. Some lightly used or obvious terms were also removed. This addresses issue #58.

-16

• Changes to address editorial and minor issues #163, #168, #169, #170, #172, and #173.

-15

• Clarified that it is an application decision which recipients' encrypted content must successfully validate for the JWE to be accepted, addressing issue #35.
• Changes to address editorial issues #34, #164, and #169.

-14

• Clarified that the protected, unprotected, header, iv, tag, and encrypted_key parameters are to be omitted in the JWE JSON Serialization when their values would be empty. Stated that the recipients array must always be present.

-13

• Added an aad (Additional Authenticated Data) member for the JWE JSON Serialization, enabling Additional Authenticated Data to be supplied that is not double base64url encoded, addressing issue #29.

-12

• Clarified that the typ and cty header parameters are used in an application-specific manner and have no effect upon the JWE processing.
• Replaced the MIME types application/jwe+json and application/jwe with application/jose+json and application/jose.
• Stated that recipients MUST either reject JWEs with duplicate Header Parameter Names or use a JSON parser that returns only the lexically last duplicate member name.
• Moved the epk, apu, and apv Header Parameter definitions to be with the algorithm descriptions that use them.
• Added a Serializations section with parallel treatment of the JWE Compact Serialization and the JWE JSON Serialization and also moved the former Implementation Considerations content there.
• Restored use of the term "AEAD".
• Changed terminology from "block encryption" to "content encryption".

-11

• Added Key Identification section.
• Removed the Encrypted Key value from the AAD computation since it is already effectively integrity protected by the encryption process. The AAD value now only contains the representation of the JWE Encrypted Header.
• For the JWE JSON Serialization, enable Header Parameter values to be specified in any of three parameters: the protected member that is integrity protected and shared among all recipients, the unprotected member that is not integrity protected and shared among all recipients, and the header member that is not integrity protected and specific to a particular recipient. (This does not affect the JWE Compact Serialization, in which all Header Parameter values are in a single integrity protected JWE Header value.)
• Shortened the names authentication_tag to tag and initialization_vector to iv in the JWE JSON Serialization, addressing issue #20.
• Removed apv (agreement PartyVInfo) since it is no longer used.
• Removed suggested compact serialization for multiple recipients.
• Changed the MIME type name application/jwe-js to application/jwe+json, addressing issue #22.
• Tightened the description of the crit (critical) header parameter.

-10

• Changed the JWE processing rules for multiple recipients so that a single AAD value contains the header parameters and encrypted key values for all the recipients, enabling AES GCM to be safely used for multiple recipients.
• Added an appendix suggesting a possible compact serialization for JWEs with multiple recipients.

-09

• Added JWE JSON Serialization, as specified by draft-jones-jose-jwe-json-serialization-04.
• Registered application/jwe-js MIME type and JWE-JS typ header parameter value.
• Defined that the default action for header parameters that are not understood is to ignore them unless specifically designated as "MUST be understood" or included in the new crit (critical) header parameter list. This addressed issue #6.
• Corrected x5c description. This addressed issue #12.
• Changed from using the term "byte" to "octet" when referring to 8 bit values.
• Added Key Management Mode definitions to terminology section and used the defined terms to provide clearer key management instructions. This addressed issue #5.
• Added text about preventing the recipient from behaving as an oracle during decryption, especially when using RSAES-PKCS1-V1_5.
• Changed from using the term "Integrity Value" to "Authentication Tag".
• Changed member name from integrity_value to authentication_tag in the JWE JSON Serialization.
• Removed Initialization Vector from the AAD value since it is already integrity protected by all of the authenticated encryption algorithms specified in the JWA specification.
• Replaced A128CBC+HS256 and A256CBC+HS512 with A128CBC-HS256 and A256CBC-HS512. The new algorithms perform the same cryptographic computations as [I‑D.mcgrew‑aead‑aes‑cbc‑hmac‑sha2] (McGrew, D., Foley, J., and K. Paterson, “Authenticated Encryption with AES-CBC and HMAC-SHA,” February 2014.), but with the Initialization Vector and Authentication Tag values remaining separate from the Ciphertext value in the output representation. Also deleted the header parameters epu (encryption PartyUInfo) and epv (encryption PartyVInfo), since they are no longer used.

-08

• Replaced uses of the term "AEAD" with "Authenticated Encryption", since the term AEAD in the RFC 5116 sense implied the use of a particular data representation, rather than just referring to the class of algorithms that perform authenticated encryption with associated data.
• Applied editorial improvements suggested by Jeff Hodges and Hannes Tschofenig. Many of these simplified the terminology used.
• Clarified statements of the form "This header parameter is OPTIONAL" to "Use of this header parameter is OPTIONAL".
• Added a Header Parameter Usage Location(s) field to the IANA JSON Web Signature and Encryption Header Parameters registry.
• Added seriesInfo information to Internet Draft references.

-07

• Added a data length prefix to PartyUInfo and PartyVInfo values.
• Updated values for example AES CBC calculations.
• Made several local editorial changes to clean up loose ends left over from to the decision to only support block encryption methods providing integrity. One of these changes was to explicitly state that the enc (encryption method) algorithm must be an Authenticated Encryption algorithm with a specified key length.

-06

• Removed the int and kdf parameters and defined the new composite Authenticated Encryption algorithms A128CBC+HS256 and A256CBC+HS512 to replace the former uses of AES CBC, which required the use of separate integrity and key derivation functions.
• Included additional values in the Concat KDF calculation -- the desired output size and the algorithm value, and optionally PartyUInfo and PartyVInfo values. Added the optional header parameters apu (agreement PartyUInfo), apv (agreement PartyVInfo), epu (encryption PartyUInfo), and epv (encryption PartyVInfo). Updated the KDF examples accordingly.
• Promoted Initialization Vector from being a header parameter to being a top-level JWE element. This saves approximately 16 bytes in the compact serialization, which is a significant savings for some use cases. Promoting the Initialization Vector out of the header also avoids repeating this shared value in the JSON serialization.
• Changed x5c (X.509 Certificate Chain) representation from being a single string to being an array of strings, each containing a single base64 encoded DER certificate value, representing elements of the certificate chain.
• Added an AES Key Wrap example.
• Reordered the encryption steps so CMK creation is first, when required.
• Correct statements in examples about which algorithms produce reproducible results.

-05

• Support both direct encryption using a shared or agreed upon symmetric key, and the use of a shared or agreed upon symmetric key to key wrap the CMK.
• Added statement that "StringOrURI values are compared as case-sensitive strings with no transformations or canonicalizations applied".
• Updated open issues.
• Indented artwork elements to better distinguish them from the body text.

-04

• Refer to the registries as the primary sources of defined values and then secondarily reference the sections defining the initial contents of the registries.
• Normatively reference XML Encryption 1.1 for its security considerations.
• Reference draft-jones-jose-jwe-json-serialization instead of draft-jones-json-web-encryption-json-serialization.
• Described additional open issues.
• Applied editorial suggestions.

-03

• Added the kdf (key derivation function) header parameter to provide crypto agility for key derivation. The default KDF remains the Concat KDF with the SHA-256 digest function.
• Reordered encryption steps so that the Encoded JWE Header is always created before it is needed as an input to the Authenticated Encryption "additional authenticated data" parameter.
• Added the cty (content type) header parameter for declaring type information about the secured content, as opposed to the typ (type) header parameter, which declares type information about this object.
• Moved description of how to determine whether a header is for a JWS or a JWE from the JWT spec to the JWE spec.
• Added complete encryption examples for both Authenticated Encryption and non-Authenticated Encryption algorithms.
• Added complete key derivation examples.
• Added "Collision Resistant Namespace" to the terminology section.
• Reference ITU.X690.1994 for DER encoding.
• Added Registry Contents sections to populate registry values.
• Numerous editorial improvements.

-02

• When using Authenticated Encryption algorithms (such as AES GCM), use the "additional authenticated data" parameter to provide integrity for the header, encrypted key, and ciphertext and use the resulting "authentication tag" value as the JWE Authentication Tag.
• Defined KDF output key sizes.
• Generalized text to allow key agreement to be employed as an alternative to key wrapping or key encryption.
• Changed compression algorithm from gzip to DEFLATE.
• Clarified that it is an error when a kid value is included and no matching key is found.
• Clarified that JWEs with duplicate Header Parameter Names MUST be rejected.
• Clarified the relationship between typ header parameter values and MIME types.
• Registered application/jwe MIME type and "JWE" typ header parameter value.
• Simplified JWK terminology to get replace the "JWK Key Object" and "JWK Container Object" terms with simply "JSON Web Key (JWK)" and "JSON Web Key Set (JWK Set)" and to eliminate potential confusion between single keys and sets of keys. As part of this change, the Header Parameter Name for a public key value was changed from jpk (JSON Public Key) to jwk (JSON Web Key).
• Added suggestion on defining additional header parameters such as x5t#S256 in the future for certificate thumbprints using hash algorithms other than SHA-1.
• Specify RFC 2818 server identity validation, rather than RFC 6125 (paralleling the same decision in the OAuth specs).
• Generalized language to refer to Message Authentication Codes (MACs) rather than Hash-based Message Authentication Codes (HMACs) unless in a context specific to HMAC algorithms.
• Reformatted to give each header parameter its own section heading.

-01

• Added an integrity check for non-Authenticated Encryption algorithms.
• Added jpk and x5c header parameters for including JWK public keys and X.509 certificate chains directly in the header.
• Clarified that this specification is defining the JWE Compact Serialization. Referenced the new JWE-JS spec, which defines the JWE JSON Serialization.
• Added text "New header parameters should be introduced sparingly since an implementation that does not understand a parameter MUST reject the JWE".
• Clarified that the order of the encryption and decryption steps is not significant in cases where there are no dependencies between the inputs and outputs of the steps.
• Made other editorial improvements suggested by JOSE working group participants.

-00

• Created the initial IETF draft based upon draft-jones-json-web-encryption-02 with no normative changes.
• Changed terminology to no longer call both digital signatures and HMACs "signatures".

Authors' Addresses