JOSE Working Group M. Jones
Internet-Draft Microsoft
Intended status: Standards Track E. Rescorla
Expires: June 30, 2013 RTFM
J. Hildebrand
Cisco
December 27, 2012
JSON Web Encryption (JWE)
draft-ietf-jose-json-web-encryption-08
Abstract
JSON Web Encryption (JWE) is a means of representing encrypted
content using JavaScript Object Notation (JSON) data structures.
Cryptographic algorithms and identifiers for use with this
specification are described in the separate JSON Web Algorithms (JWA)
specification. Related digital signature and MAC capabilities are
described in the separate JSON Web Signature (JWS) specification.
Status of this Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
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Internet-Drafts are draft documents valid for a maximum of six months
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time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on June 30, 2013.
Copyright Notice
Copyright (c) 2012 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
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to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.1. Notational Conventions . . . . . . . . . . . . . . . . . . 5
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5
3. JSON Web Encryption (JWE) Overview . . . . . . . . . . . . . . 7
3.1. Example JWE using RSAES OAEP and AES GCM . . . . . . . . . 8
3.2. Example JWE using RSAES-PKCS1-V1_5 and AES CBC . . . . . . 9
4. JWE Header . . . . . . . . . . . . . . . . . . . . . . . . . . 11
4.1. Reserved Header Parameter Names . . . . . . . . . . . . . 12
4.1.1. "alg" (Algorithm) Header Parameter . . . . . . . . . . 12
4.1.2. "enc" (Encryption Method) Header Parameter . . . . . . 12
4.1.3. "epk" (Ephemeral Public Key) Header Parameter . . . . 13
4.1.4. "zip" (Compression Algorithm) Header Parameter . . . . 13
4.1.5. "jku" (JWK Set URL) Header Parameter . . . . . . . . . 13
4.1.6. "jwk" (JSON Web Key) Header Parameter . . . . . . . . 13
4.1.7. "x5u" (X.509 URL) Header Parameter . . . . . . . . . . 13
4.1.8. "x5t" (X.509 Certificate Thumbprint) Header
Parameter . . . . . . . . . . . . . . . . . . . . . . 14
4.1.9. "x5c" (X.509 Certificate Chain) Header Parameter . . . 14
4.1.10. "kid" (Key ID) Header Parameter . . . . . . . . . . . 15
4.1.11. "typ" (Type) Header Parameter . . . . . . . . . . . . 15
4.1.12. "cty" (Content Type) Header Parameter . . . . . . . . 15
4.1.13. "apu" (Agreement PartyUInfo) Header Parameter . . . . 15
4.1.14. "apv" (Agreement PartyVInfo) Header Parameter . . . . 15
4.1.15. "epu" (Encryption PartyUInfo) Header Parameter . . . . 16
4.1.16. "epv" (Encryption PartyVInfo) Header Parameter . . . . 16
4.2. Public Header Parameter Names . . . . . . . . . . . . . . 16
4.3. Private Header Parameter Names . . . . . . . . . . . . . . 16
5. Producing and Consuming JWEs . . . . . . . . . . . . . . . . . 16
5.1. Message Encryption . . . . . . . . . . . . . . . . . . . . 16
5.2. Message Decryption . . . . . . . . . . . . . . . . . . . . 18
5.3. String Comparison Rules . . . . . . . . . . . . . . . . . 19
6. Encrypting JWEs with Cryptographic Algorithms . . . . . . . . 20
6.1. CMK Encryption . . . . . . . . . . . . . . . . . . . . . . 20
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 20
7.1. Registration of JWE Header Parameter Names . . . . . . . . 20
7.1.1. Registry Contents . . . . . . . . . . . . . . . . . . 21
7.2. JSON Web Signature and Encryption Type Values
Registration . . . . . . . . . . . . . . . . . . . . . . . 22
7.2.1. Registry Contents . . . . . . . . . . . . . . . . . . 22
7.3. Media Type Registration . . . . . . . . . . . . . . . . . 23
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7.3.1. Registry Contents . . . . . . . . . . . . . . . . . . 23
8. Security Considerations . . . . . . . . . . . . . . . . . . . 23
9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 24
9.1. Normative References . . . . . . . . . . . . . . . . . . . 24
9.2. Informative References . . . . . . . . . . . . . . . . . . 25
Appendix A. JWE Examples . . . . . . . . . . . . . . . . . . . . 25
A.1. Example JWE using RSAES OAEP and AES GCM . . . . . . . . . 26
A.1.1. JWE Header . . . . . . . . . . . . . . . . . . . . . . 26
A.1.2. Encoded JWE Header . . . . . . . . . . . . . . . . . . 26
A.1.3. Content Master Key (CMK) . . . . . . . . . . . . . . . 26
A.1.4. Key Encryption . . . . . . . . . . . . . . . . . . . . 26
A.1.5. Encoded JWE Encrypted Key . . . . . . . . . . . . . . 29
A.1.6. Initialization Vector . . . . . . . . . . . . . . . . 29
A.1.7. "Additional Authenticated Data" Parameter . . . . . . 29
A.1.8. Plaintext Encryption . . . . . . . . . . . . . . . . . 30
A.1.9. Encoded JWE Ciphertext . . . . . . . . . . . . . . . . 30
A.1.10. Encoded JWE Integrity Value . . . . . . . . . . . . . 31
A.1.11. Complete Representation . . . . . . . . . . . . . . . 31
A.1.12. Validation . . . . . . . . . . . . . . . . . . . . . . 31
A.2. Example JWE using RSAES-PKCS1-V1_5 and AES CBC . . . . . . 31
A.2.1. JWE Header . . . . . . . . . . . . . . . . . . . . . . 32
A.2.2. Encoded JWE Header . . . . . . . . . . . . . . . . . . 32
A.2.3. Content Master Key (CMK) . . . . . . . . . . . . . . . 32
A.2.4. Key Encryption . . . . . . . . . . . . . . . . . . . . 32
A.2.5. Encoded JWE Encrypted Key . . . . . . . . . . . . . . 35
A.2.6. Key Derivation . . . . . . . . . . . . . . . . . . . . 35
A.2.7. Initialization Vector . . . . . . . . . . . . . . . . 35
A.2.8. Plaintext Encryption . . . . . . . . . . . . . . . . . 35
A.2.9. Encoded JWE Ciphertext . . . . . . . . . . . . . . . . 36
A.2.10. Secured Input Value . . . . . . . . . . . . . . . . . 36
A.2.11. JWE Integrity Value . . . . . . . . . . . . . . . . . 37
A.2.12. Encoded JWE Integrity Value . . . . . . . . . . . . . 37
A.2.13. Complete Representation . . . . . . . . . . . . . . . 37
A.2.14. Validation . . . . . . . . . . . . . . . . . . . . . . 38
A.3. Example JWE using AES Key Wrap and AES GCM . . . . . . . . 38
A.3.1. JWE Header . . . . . . . . . . . . . . . . . . . . . . 38
A.3.2. Encoded JWE Header . . . . . . . . . . . . . . . . . . 39
A.3.3. Content Master Key (CMK) . . . . . . . . . . . . . . . 39
A.3.4. Key Encryption . . . . . . . . . . . . . . . . . . . . 39
A.3.5. Encoded JWE Encrypted Key . . . . . . . . . . . . . . 39
A.3.6. Initialization Vector . . . . . . . . . . . . . . . . 39
A.3.7. "Additional Authenticated Data" Parameter . . . . . . 40
A.3.8. Plaintext Encryption . . . . . . . . . . . . . . . . . 40
A.3.9. Encoded JWE Ciphertext . . . . . . . . . . . . . . . . 40
A.3.10. Encoded JWE Integrity Value . . . . . . . . . . . . . 41
A.3.11. Complete Representation . . . . . . . . . . . . . . . 41
A.3.12. Validation . . . . . . . . . . . . . . . . . . . . . . 41
A.4. Example Key Derivation for "enc" value "A128CBC+HS256" . . 41
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A.4.1. CEK Generation . . . . . . . . . . . . . . . . . . . . 42
A.4.2. CIK Generation . . . . . . . . . . . . . . . . . . . . 43
A.5. Example Key Derivation for "enc" value "A256CBC+HS512" . . 44
A.5.1. CEK Generation . . . . . . . . . . . . . . . . . . . . 44
A.5.2. CIK Generation . . . . . . . . . . . . . . . . . . . . 45
Appendix B. Acknowledgements . . . . . . . . . . . . . . . . . . 46
Appendix C. Open Issues . . . . . . . . . . . . . . . . . . . . . 47
Appendix D. Document History . . . . . . . . . . . . . . . . . . 47
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 51
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1. Introduction
JSON Web Encryption (JWE) is a compact encryption format intended for
space constrained environments such as HTTP Authorization headers and
URI query parameters. It represents this content using JavaScript
Object Notation (JSON) [RFC4627] based data structures. The JWE
cryptographic mechanisms encrypt and provide integrity protection for
arbitrary sequences of bytes.
Cryptographic algorithms and identifiers for use with this
specification are described in the separate JSON Web Algorithms (JWA)
[JWA] specification. Related digital signature and MAC capabilities
are described in the separate JSON Web Signature (JWS) [JWS]
specification.
1.1. Notational Conventions
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD 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].
2. Terminology
JSON Web Encryption (JWE) A data structure representing an encrypted
message. The structure consists of five parts: the JWE Header,
the JWE Encrypted Key, the JWE Initialization Vector, the JWE
Ciphertext, and the JWE Integrity Value.
Plaintext The bytes to be encrypted -- a.k.a., the message. The
plaintext can contain an arbitrary sequence of bytes.
Ciphertext An encrypted representation of the Plaintext.
Content Encryption Key (CEK) A symmetric key used to encrypt the
Plaintext for the recipient to produce the Ciphertext.
Content Integrity Key (CIK) A key used with a MAC function to ensure
the integrity of the Ciphertext and the parameters used to create
it.
Content Master Key (CMK) A key from which the CEK and CIK are
derived. When key wrapping or key encryption are employed, the
CMK is randomly generated and encrypted to the recipient as the
JWE Encrypted Key. When direct encryption with a shared symmetric
key is employed, the CMK is the shared key. When key agreement
without key wrapping is employed, the CMK is the result of the key
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agreement algorithm.
JSON Text Object A UTF-8 encoded text string representing a JSON
object; the syntax of JSON objects is defined in Section 2.2 of
[RFC4627].
JWE Header A JSON Text Object that describes the encryption
operations applied to create the JWE Encrypted Key, the JWE
Ciphertext, and the JWE Integrity Value.
JWE Encrypted Key When key wrapping or key encryption are employed,
the Content Master Key (CMK) is encrypted with the intended
recipient's key and the resulting encrypted content is recorded as
a byte array, which is referred to as the JWE Encrypted Key.
Otherwise, when direct encryption with a shared or agreed upon
symmetric key is employed, the JWE Encrypted Key is the empty byte
array.
JWE Initialization Vector A byte array containing the Initialization
Vector used when encrypting the Plaintext.
JWE Ciphertext A byte array containing the Ciphertext.
JWE Integrity Value A byte array containing a MAC value that ensures
the integrity of the Ciphertext and the parameters used to create
it.
Base64url Encoding The URL- and filename-safe Base64 encoding
described in RFC 4648 [RFC4648], Section 5, with the (non URL-
safe) '=' padding characters omitted, as permitted by Section 3.2.
(See Appendix C of [JWS] for notes on implementing base64url
encoding without padding.)
Encoded JWE Header Base64url encoding of the JWE Header.
Encoded JWE Encrypted Key Base64url encoding of the JWE Encrypted
Key.
Encoded JWE Initialization Vector Base64url encoding of the JWE
Initialization Vector.
Encoded JWE Ciphertext Base64url encoding of the JWE Ciphertext.
Encoded JWE Integrity Value Base64url encoding of the JWE Integrity
Value.
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Header Parameter Name The name of a member of the JWE Header.
Header Parameter Value The value of a member of the JWE Header.
JWE Compact Serialization A representation of the JWE as the
concatenation of the Encoded JWE Header, the Encoded JWE Encrypted
Key, the Encoded JWE Initialization Vector, the Encoded JWE
Ciphertext, and the Encoded JWE Integrity Value in that order,
with the five strings being separated by four period ('.')
characters.
Authenticated Encryption An Authenticated Encryption algorithm is
one that provides an integrated content integrity check.
Authenticated Encryption 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.
Collision Resistant Namespace A namespace that allows names to be
allocated in a manner such that they are highly unlikely to
collide with other names. For instance, collision resistance can
be achieved through administrative delegation of portions of the
namespace or through use of collision-resistant name allocation
functions. Examples of Collision Resistant Namespaces include:
Domain Names, Object Identifiers (OIDs) as defined in the ITU-T
X.660 and X.670 Recommendation series, and Universally Unique
IDentifiers (UUIDs) [RFC4122]. When using an administratively
delegated namespace, the definer of a name needs to take
reasonable precautions to ensure they are in control of the
portion of the namespace they use to define the name.
StringOrURI A JSON string value, with the additional requirement
that while arbitrary string values MAY be used, any value
containing a ":" character MUST be a URI [RFC3986]. StringOrURI
values are compared as case-sensitive strings with no
transformations or canonicalizations applied.
3. JSON Web Encryption (JWE) Overview
JWE represents encrypted content using JSON data structures and
base64url encoding. The representation consists of five parts: the
JWE Header, the JWE Encrypted Key, the JWE Initialization Vector, the
JWE Ciphertext, and the JWE Integrity Value. In the Compact
Serialization, the five parts are base64url-encoded for transmission,
and represented as the concatenation of the encoded strings in that
order, with the five strings being separated by four period ('.')
characters. (A JSON Serialization for this information is defined in
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the separate JSON Web Encryption JSON Serialization (JWE-JS) [JWE-JS]
specification.)
JWE utilizes encryption to ensure the confidentiality of the
Plaintext. JWE adds a content integrity check if not provided by the
underlying encryption algorithm.
3.1. Example JWE using RSAES OAEP and AES GCM
This example encrypts the plaintext "Live long and prosper." to the
recipient using RSAES OAEP and AES GCM. The AES GCM algorithm has an
integrated integrity check.
The following example JWE Header declares that:
o the Content Master Key is encrypted to the recipient using the
RSAES OAEP algorithm to produce the JWE Encrypted Key and
o the Plaintext is encrypted using the AES GCM algorithm with a 256
bit key to produce the Ciphertext.
{"alg":"RSA-OAEP","enc":"A256GCM"}
Base64url encoding the bytes of the UTF-8 representation of the JWE
Header yields this Encoded JWE Header value:
eyJhbGciOiJSU0EtT0FFUCIsImVuYyI6IkEyNTZHQ00ifQ
The remaining steps to finish creating this JWE are:
o Generate a random Content Master Key (CMK)
o Encrypt the CMK with the recipient's public key using the RSAES
OAEP algorithm to produce the JWE Encrypted Key
o Base64url encode the JWE Encrypted Key to produce the Encoded JWE
Encrypted Key
o Generate a random JWE Initialization Vector
o Base64url encode the JWE Initialization Vector to produce the
Encoded JWE Initialization Vector
o Concatenate the Encoded JWE Header value, a period character
('.'), the Encoded JWE Encrypted Key, a second period character
('.'), and the Encoded JWE Initialization Vector to create the
"additional authenticated data" parameter for the AES GCM
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algorithm
o Encrypt the Plaintext with AES GCM, using the CMK as the
encryption key, the JWE Initialization Vector, and the "additional
authenticated data" value above, requesting a 128 bit
"authentication tag" output
o Base64url encode the resulting Ciphertext to create the Encoded
JWE Ciphertext
o Base64url encode the resulting "authentication tag" to create the
Encoded JWE Integrity Value
o Assemble the final representation: The Compact Serialization of
this result is the concatenation of the Encoded JWE Header, the
Encoded JWE Encrypted Key, the Encoded JWE Initialization Vector,
the Encoded JWE Ciphertext, and the Encoded JWE Integrity Value in
that order, with the five strings being separated by four period
('.') characters.
The final result in this example (with line breaks for display
purposes only) is:
eyJhbGciOiJSU0EtT0FFUCIsImVuYyI6IkEyNTZHQ00ifQ.
M2XxpbORKezKSzzQL_95-GjiudRBTqn_omS8z9xgoRb7L0Jw5UsEbxmtyHn2T71m
rZLkjg4Mp8gbhYoltPkEOHvAopz25-vZ8C2e1cOaAo5WPcbSIuFcB4DjBOM3t0UA
O6JHkWLuAEYoe58lcxIQneyKdaYSLbV9cKqoUoFQpvKWYRHZbfszIyfsa18rmgTj
zrtLDTPnc09DSJE24aQ8w3i8RXEDthW9T1J6LsTH_vwHdwUgkI-tC2PNeGrnM-dN
SfzF3Y7-lwcGy0FsdXkPXytvDV7y4pZeeUiQ-0VdibIN2AjjfW60nfrPuOjepMFG
6BBBbR37pHcyzext9epOAQ.
48V1_ALb6US04U3b.
_e21tGGhac_peEFkLXr2dMPUZiUkrw.
7V5ZDko0v_mf2PAc4JMiUg
See Appendix A.1 for the complete details of computing this JWE.
3.2. Example JWE using RSAES-PKCS1-V1_5 and AES CBC
This example encrypts the plaintext "No matter where you go, there
you are." to the recipient using RSAES-PKCS1-V1_5 and AES CBC. AES
CBC does not have an integrated integrity check, so a separate
integrity check calculation is performed using HMAC SHA-256, with
separate encryption and integrity keys being derived from a master
key using the Concat KDF with the SHA-256 digest function.
The following example JWE Header (with line breaks for display
purposes only) declares that:
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o the Content Master Key is encrypted to the recipient using the
RSAES-PKCS1-V1_5 algorithm to produce the JWE Encrypted Key and
o the Plaintext is encrypted using the AES CBC algorithm with a 128
bit key to produce the Ciphertext, with the integrity of the
Ciphertext and the parameters used to create it being secured
using the HMAC SHA-256 algorithm.
{"alg":"RSA1_5","enc":"A128CBC+HS256"}
Base64url encoding the bytes of the UTF-8 representation of the JWE
Header yields this Encoded JWE Header value:
eyJhbGciOiJSU0ExXzUiLCJlbmMiOiJBMTI4Q0JDK0hTMjU2In0
The remaining steps to finish creating this JWE are like the previous
example, but with an additional step to compute the separate
integrity value:
o Generate a random Content Master Key (CMK)
o Encrypt the CMK with the recipient's public key using the RSAES-
PKCS1-V1_5 algorithm to produce the JWE Encrypted Key
o Base64url encode the JWE Encrypted Key to produce the Encoded JWE
Encrypted Key
o Generate a random JWE Initialization Vector
o Base64url encode the JWE Initialization Vector to produce the
Encoded JWE Initialization Vector
o Use the Concat key derivation function to derive Content
Encryption Key (CEK) and Content Integrity Key (CIK) values from
the CMK
o Encrypt the Plaintext with AES CBC using the CEK and JWE
Initialization Vector to produce the Ciphertext
o Base64url encode the resulting Ciphertext to create the Encoded
JWE Ciphertext
o Concatenate the Encoded JWE Header value, a period character
('.'), the Encoded JWE Encrypted Key, a second period character
('.'), the Encoded JWE Initialization Vector, a third period ('.')
character, and the Encoded JWE Ciphertext to create the value to
integrity protect
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o Compute the HMAC SHA-256 of this value using the CIK to create the
JWE Integrity Value
o Base64url encode the resulting JWE Integrity Value to create the
Encoded JWE Integrity Value
o Assemble the final representation: The Compact Serialization of
this result is the concatenation of the Encoded JWE Header, the
Encoded JWE Encrypted Key, the Encoded JWE Initialization Vector,
the Encoded JWE Ciphertext, and the Encoded JWE Integrity Value in
that order, with the five strings being separated by four period
('.') characters.
The final result in this example (with line breaks for display
purposes only) is:
eyJhbGciOiJSU0ExXzUiLCJlbmMiOiJBMTI4Q0JDK0hTMjU2In0.
O6AqXqgVlJJ4c4lp5sXZd7bpGHAw6ARkHUeXQxD1cAW4-X1x0qtj_AN0mukqEOl4
Y6UOwJXIJY9-G1ELK-RQWrKH_StR-AM9H7GpKmSEji8QYOcMOjr-u9H1Lt_pBEie
G802SxWz0rbFTXRcj4BWLxcpCtjUZ31AP-sc-L_eCZ5UNl0aSRNqFskuPkzRsFZR
DJqSSJeVOyJ7pZCQ83fli19Vgi_3R7XMUqluQuuc7ZHOWixi47jXlBTlWRZ5iFxa
S8G6J8wUrd4BKggAw3qX5XoIfXQVlQZE0Vmkq_zQSIo5LnFKyowooRcdsEuNh9B9
Mkyt0ZQElG-jGdtHWjZSOA.
AxY8DCtDaGlsbGljb3RoZQ.
1eBWFgcrz40wC88cgv8rPgu3EfmC1p4zT0kIxxfSF2zDJcQ-iEHk1jQM95xAdr5Z.
RBGhYzE8_cZLHjJqqHuLhzbgWgL_wV3LDSUrcbkOiIA
See Appendix A.2 for the complete details of computing this JWE.
4. JWE Header
The members of the JSON object represented by the JWE Header describe
the encryption applied to the Plaintext and optionally additional
properties of the JWE. The Header Parameter Names within this object
MUST be unique; JWEs with duplicate Header Parameter Names MUST be
rejected. Implementations MUST understand the entire contents of the
header; otherwise, the JWE MUST be rejected.
There are two ways of distinguishing whether a header is a JWS Header
or a JWE Header. The first is by examining the "alg" (algorithm)
header value. If the value represents a digital signature or MAC
algorithm, or is the value "none", it is for a JWS; if it represents
an encryption or key agreement algorithm, it is for a JWE. A second
method is determining whether an "enc" (encryption method) member
exists. If the "enc" member exists, it is a JWE; otherwise, it is a
JWS. Both methods will yield the same result for all legal input
values.
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There are three classes of Header Parameter Names: Reserved Header
Parameter Names, Public Header Parameter Names, and Private Header
Parameter Names.
4.1. Reserved Header Parameter Names
The following Header Parameter Names are reserved with meanings as
defined below. All the names are short because a core goal of JWE is
for the representations to be compact.
Additional reserved Header Parameter Names MAY be defined via the
IANA JSON Web Signature and Encryption Header Parameters registry
[JWS]. 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
The "alg" (algorithm) header parameter identifies the cryptographic
algorithm used to encrypt or determine the value of the Content
Master Key (CMK). The algorithm specified by the "alg" value MUST be
supported by the implementation and there MUST be a key for use with
that algorithm associated with the intended recipient or the JWE MUST
be rejected. "alg" values SHOULD either be registered in the IANA
JSON Web Signature and Encryption Algorithms registry [JWA] or be a
value that contains a Collision Resistant Namespace. The "alg" value
is a case sensitive string containing a StringOrURI value. Use of
this header parameter is REQUIRED.
A list of defined "alg" values can be found in the IANA JSON Web
Signature and Encryption Algorithms registry [JWA]; the initial
contents of this registry are the values defined in Section 4.1 of
the JSON Web Algorithms (JWA) [JWA] specification.
4.1.2. "enc" (Encryption Method) Header Parameter
The "enc" (encryption method) header parameter identifies the block
encryption algorithm used to encrypt the Plaintext to produce the
Ciphertext. This algorithm MUST be an Authenticated Encryption
algorithm with a specified key length. The algorithm specified by
the "enc" value MUST be supported by the implementation or the JWE
MUST be rejected. "enc" values SHOULD either be registered in the
IANA JSON Web Signature and Encryption Algorithms registry [JWA] or
be a value that contains a Collision Resistant Namespace. The "enc"
value is a case sensitive string containing a StringOrURI value. Use
of this header parameter is REQUIRED.
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A list of defined "enc" values can be found in the IANA JSON Web
Signature and Encryption Algorithms registry [JWA]; the initial
contents of this registry are the values defined in Section 4.2 of
the JSON Web Algorithms (JWA) [JWA] specification.
4.1.3. "epk" (Ephemeral Public Key) Header Parameter
The "epk" (ephemeral public key) value created by the originator for
the use in key agreement algorithms. This key is represented as a
JSON Web Key [JWK] value. Use of this header parameter is OPTIONAL,
although its use is REQUIRED with some "alg" algorithms.
4.1.4. "zip" (Compression Algorithm) Header Parameter
The "zip" (compression algorithm) applied to the Plaintext before
encryption, if any. If present, the value of the "zip" header
parameter MUST be the case sensitive string "DEF". Compression is
performed with the DEFLATE [RFC1951] algorithm. If no "zip"
parameter is present, no compression is applied to the Plaintext
before encryption. Use of this header parameter is OPTIONAL.
4.1.5. "jku" (JWK Set URL) Header Parameter
The "jku" (JWK Set URL) header parameter is a URI [RFC3986] that
refers to a resource for a set of JSON-encoded public keys, one of
which corresponds to the key used to encrypt the JWE; this can be
used to determine the private key needed to decrypt the JWE. The
keys MUST be encoded as a JSON Web Key Set (JWK Set) [JWK]. The
protocol used to acquire the resource MUST provide integrity
protection; an HTTP GET request to retrieve the certificate MUST use
TLS [RFC2818] [RFC5246]; the identity of the server MUST be
validated, as per Section 3.1 of HTTP Over TLS [RFC2818]. Use of
this header parameter is OPTIONAL.
4.1.6. "jwk" (JSON Web Key) Header Parameter
The "jwk" (JSON Web Key) header parameter is a public key that
corresponds to the key used to encrypt the JWE; this can be used to
determine the private key needed to decrypt the JWE. This key is
represented as a JSON Web Key [JWK]. Use of this header parameter is
OPTIONAL.
4.1.7. "x5u" (X.509 URL) Header Parameter
The "x5u" (X.509 URL) header parameter is a URI [RFC3986] that refers
to a resource for the X.509 public key certificate or certificate
chain [RFC5280] corresponding to the key used to encrypt the JWE;
this can be used to determine the private key needed to decrypt the
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JWE. The identified resource MUST provide a representation of the
certificate or certificate chain that conforms to RFC 5280 [RFC5280]
in PEM encoded form [RFC1421]. The certificate containing the public
key of the entity that encrypted the JWE MUST be the first
certificate. This MAY be followed by additional certificates, with
each subsequent certificate being the one used to certify the
previous one. The protocol used to acquire the resource MUST provide
integrity protection; an HTTP GET request to retrieve the certificate
MUST use TLS [RFC2818] [RFC5246]; the identity of the server MUST be
validated, as per Section 3.1 of HTTP Over TLS [RFC2818]. Use of
this header parameter is OPTIONAL.
4.1.8. "x5t" (X.509 Certificate Thumbprint) Header Parameter
The "x5t" (X.509 Certificate Thumbprint) header parameter provides a
base64url encoded SHA-1 thumbprint (a.k.a. digest) of the DER
encoding of the X.509 certificate [RFC5280] corresponding to the key
used to encrypt the JWE; this can be used to determine the private
key needed to decrypt the JWE. Use of this header parameter is
OPTIONAL.
If, in the future, certificate thumbprints need to be computed using
hash functions other than SHA-1, it is suggested that additional
related header parameters be defined for that purpose. For example,
it is suggested that a new "x5t#S256" (X.509 Certificate Thumbprint
using SHA-256) header parameter could be defined by registering it in
the IANA JSON Web Signature and Encryption Header Parameters registry
[JWS].
4.1.9. "x5c" (X.509 Certificate Chain) Header Parameter
The "x5c" (X.509 Certificate Chain) header parameter contains the
X.509 public key certificate or certificate chain [RFC5280]
corresponding to the key used to encrypt the JWE; this can be used to
determine the private key needed to decrypt the JWE. The certificate
or certificate chain is represented as an array of certificate value
strings. Each string is a base64 encoded ([RFC4648] Section 4 -- not
base64url encoded) DER [ITU.X690.1994] PKIX certificate value. The
certificate containing the public key of the entity that encrypted
the JWE MUST be the first certificate. This MAY be followed by
additional certificates, with each subsequent certificate being the
one used to certify the previous one. The recipient MUST verify the
certificate chain according to [RFC5280] and reject the JWE if any
validation failure occurs. Use of this header parameter is OPTIONAL.
See Appendix B of [JWS] for an example "x5c" value.
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4.1.10. "kid" (Key ID) Header Parameter
The "kid" (key ID) header parameter is a hint indicating which key
was used to encrypt the JWE; 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 recipients.
Should the recipient be unable to locate a key corresponding to the
"kid" value, they SHOULD treat that condition as an error. The
interpretation of the "kid" value is unspecified. Its value MUST be
a string. Use of this header parameter is OPTIONAL.
When used with a JWK, the "kid" value MAY be used to match a JWK
"kid" parameter value.
4.1.11. "typ" (Type) Header Parameter
The "typ" (type) header parameter is used to declare the type of this
object. The type value "JWE" MAY be used to indicate that this
object is a JWE. The "typ" value is a case sensitive string. Use of
this header parameter is OPTIONAL.
MIME Media Type [RFC2046] values MAY be used as "typ" values.
"typ" values SHOULD either be registered in the IANA JSON Web
Signature and Encryption Type Values registry [JWS] or be a value
that contains a Collision Resistant Namespace.
4.1.12. "cty" (Content Type) Header Parameter
The "cty" (content type) header parameter is used to declare the type
of the encrypted content (the Plaintext). The "cty" value is a case
sensitive string. Use of this header parameter is OPTIONAL.
The values used for the "cty" header parameter come from the same
value space as the "typ" header parameter, with the same rules
applying.
4.1.13. "apu" (Agreement PartyUInfo) Header Parameter
The "apu" (agreement PartyUInfo) value for key agreement algorithms
using it (such as "ECDH-ES"), represented as a base64url encoded
string. Use of this header parameter is OPTIONAL.
4.1.14. "apv" (Agreement PartyVInfo) Header Parameter
The "apv" (agreement PartyVInfo) value for key agreement algorithms
using it (such as "ECDH-ES"), represented as a base64url encoded
string. Use of this header parameter is OPTIONAL.
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4.1.15. "epu" (Encryption PartyUInfo) Header Parameter
The "epu" (encryption PartyUInfo) value for plaintext encryption
algorithms using it (such as "A128CBC+HS256"), represented as a
base64url encoded string. Use of this header parameter is OPTIONAL.
4.1.16. "epv" (Encryption PartyVInfo) Header Parameter
The "epv" (encryption PartyVInfo) value for plaintext encryption
algorithms using it (such as "A128CBC+HS256"), represented as a
base64url encoded string. Use of this header parameter is OPTIONAL.
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 [JWS] or be a Public Name: a
value that contains a Collision Resistant Namespace. 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 Reserved Names
Section 4.1 or Public Names Section 4.2. Unlike Public Names,
Private 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. When key wrapping, key encryption, or key agreement with key
wrapping are employed, generate a random Content Master Key
(CMK). See RFC 4086 [RFC4086] for considerations on generating
random values. The CMK MUST have a length equal to that
required for the block encryption algorithm.
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2. When key agreement is employed, use the key agreement algorithm
to compute the value of the agreed upon key. When key agreement
without key wrapping is employed, let the Content Master Key
(CMK) be the agreed upon key. When key agreement with key
wrapping is employed, the agreed upon key will be used to wrap
the CMK.
3. When key wrapping, key encryption, or key agreement with key
wrapping are employed, encrypt the CMK for the recipient (see
Section 6.1) and let the result be the JWE Encrypted Key.
Otherwise, when direct encryption with a shared or agreed upon
symmetric key is employed, let the JWE Encrypted Key be the
empty byte array.
4. When direct encryption with a shared symmetric key is employed,
let the Content Master Key (CMK) be the shared key.
5. Base64url encode the JWE Encrypted Key to create the Encoded JWE
Encrypted Key.
6. Generate a random JWE Initialization Vector of the correct size
for the block encryption algorithm (if required for the
algorithm); otherwise, let the JWE Initialization Vector be the
empty byte string.
7. Base64url encode the JWE Initialization Vector to create the
Encoded JWE Initialization Vector.
8. Compress the Plaintext if a "zip" parameter was included.
9. Serialize the (compressed) Plaintext into a byte sequence M.
10. Create a JWE Header containing the encryption parameters used.
Note that white space is explicitly allowed in the
representation and no canonicalization need be performed before
encoding.
11. Base64url encode the bytes of the UTF-8 representation of the
JWE Header to create the Encoded JWE Header.
12. Let the "additional authenticated data" value be the bytes of
the ASCII representation of the concatenation of the Encoded JWE
Header, a period ('.') character, the Encoded JWE Encrypted Key,
a second period character ('.'), and the Encoded JWE
Initialization Vector.
13. Encrypt M using the CMK, the JWE Initialization Vector, and the
"additional authenticated data" value using the specified block
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encryption algorithm to create the JWE Ciphertext value and the
JWE Integrity Value (which is the "authentication tag" output
from the calculation).
14. Base64url encode the JWE Ciphertext to create the Encoded JWE
Ciphertext.
15. Base64url encode the JWE Integrity Value to create the Encoded
JWE Integrity Value.
16. The five encoded parts, taken together, are the result.
17. The Compact Serialization of this result is the concatenation of
the Encoded JWE Header, the Encoded JWE Encrypted Key, the
Encoded JWE Initialization Vector, the Encoded JWE Ciphertext,
and the Encoded JWE Integrity Value in that order, with the five
strings being separated by four period ('.') characters.
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 JWE MUST be rejected.
1. Determine the Encoded JWE Header, the Encoded JWE Encrypted Key,
the Encoded JWE Initialization Vector, the Encoded JWE
Ciphertext, and the Encoded JWE Integrity Value values contained
in the JWE. When using the Compact Serialization, these five
values are represented in that order, separated by four period
('.') characters.
2. The Encoded JWE Header, the Encoded JWE Encrypted Key, the
Encoded JWE Initialization Vector, the Encoded JWE Ciphertext,
and the Encoded JWE Integrity Value MUST be successfully
base64url decoded following the restriction that no padding
characters have been used.
3. The resulting JWE Header MUST be completely valid JSON syntax
conforming to RFC 4627 [RFC4627].
4. The resulting JWE Header MUST be validated to only include
parameters and values whose syntax and semantics are both
understood and supported.
5. Verify that the JWE uses a key known to the recipient.
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6. When key agreement is employed, use the key agreement algorithm
to compute the value of the agreed upon key. When key agreement
without key wrapping is employed, let the Content Master Key
(CMK) 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.
7. When key wrapping, key encryption, or key agreement with key
wrapping are employed, decrypt the JWE Encrypted Key to produce
the Content Master Key (CMK). The CMK MUST have a length equal
to that required for the block encryption algorithm.
8. When direct encryption with a shared symmetric key is employed,
let the Content Master Key (CMK) be the shared key.
9. Let the "additional authenticated data" value be the bytes of
the ASCII representation of the concatenation of the Encoded JWE
Header, a period ('.') character, the Encoded JWE Encrypted Key,
a second period character ('.'), and the Encoded JWE
Initialization Vector.
10. Decrypt the JWE Ciphertext using the CMK, the JWE Initialization
Vector, the "additional authenticated data" value, and the JWE
Integrity Value (which is the "authentication tag" input to the
calculation) using the specified block encryption algorithm,
returning the decrypted plaintext and verifying the JWE
Integrity Value in the manner specified for the algorithm,
rejecting the input without emitting any decrypted output if the
JWE Integrity Value is incorrect.
11. Uncompress the decrypted plaintext if a "zip" parameter was
included.
12. Output the resulting Plaintext.
5.3. String Comparison Rules
Processing a JWE inevitably requires comparing known strings to
values in JSON objects. For example, in checking what the encryption
method is, the Unicode string encoding "enc" will be checked against
the member names in the JWE Header to see if there is a matching
Header Parameter Name.
Comparisons between JSON strings and other Unicode strings MUST be
performed by comparing Unicode code points without normalization as
specified in the String Comparison Rules in Section 5.3 of [JWS].
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6. Encrypting JWEs with Cryptographic Algorithms
JWE uses cryptographic algorithms to encrypt the Plaintext and the
Content Encryption Key (CMK) and to provide integrity protection for
the JWE Header, JWE Encrypted Key, and JWE Ciphertext. The JSON Web
Algorithms (JWA) [JWA] specification specifies a set of cryptographic
algorithms and identifiers to be used with this specification and
defines registries for additional such algorithms. Specifically,
Section 4.1 specifies a set of "alg" (algorithm) header parameter
values and Section 4.2 specifies a set of "enc" (encryption method)
header parameter values intended for use this specification. It also
describes the semantics and operations that are specific to these
algorithms.
Public keys employed for encryption can be identified using the
Header Parameter methods described in Section 4.1 or can be
distributed using methods that are outside the scope of this
specification.
6.1. CMK Encryption
JWE supports three forms of Content Master Key (CMK) encryption:
o Asymmetric encryption under the recipient's public key.
o Symmetric encryption under a key shared between the sender and
receiver.
o Symmetric encryption under a key agreed upon between the sender
and receiver.
See the algorithms registered for "enc" usage in the IANA JSON Web
Signature and Encryption Algorithms registry [JWA] and Section 4.1 of
the JSON Web Algorithms (JWA) [JWA] specification for lists of
encryption algorithms that can be used for CMK encryption.
7. IANA Considerations
7.1. Registration of JWE Header Parameter Names
This specification registers the Header Parameter Names defined in
Section 4.1 in the IANA JSON Web Signature and Encryption Header
Parameters registry [JWS].
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7.1.1. Registry Contents
o Header Parameter Name: "alg"
o Header Parameter Usage Location(s): JWE
o Change Controller: IETF
o Specification Document(s): Section 4.1.1 of [[ this document ]]
o Header Parameter Name: "enc"
o Header Parameter Usage Location(s): JWE
o Change Controller: IETF
o Specification Document(s): Section 4.1.2 of [[ this document ]]
o Header Parameter Name: "epk"
o Header Parameter Usage Location(s): JWE
o Change Controller: IETF
o Specification Document(s): Section 4.1.3 of [[ this document ]]
o Header Parameter Name: "zip"
o Header Parameter Usage Location(s): JWE
o Change Controller: IETF
o Specification Document(s): Section 4.1.4 of [[ this document ]]
o Header Parameter Name: "jku"
o Header Parameter Usage Location(s): JWE
o Change Controller: IETF
o Specification Document(s): Section 4.1.5 of [[ this document ]]
o Header Parameter Name: "jwk"
o Header Parameter Usage Location(s): JWE
o Change Controller: IETF
o Specification document(s): Section 4.1.6 of [[ this document ]]
o Header Parameter Name: "x5u"
o Header Parameter Usage Location(s): JWE
o Change Controller: IETF
o Specification Document(s): Section 4.1.7 of [[ this document ]]
o Header Parameter Name: "x5t"
o Header Parameter Usage Location(s): JWE
o Change Controller: IETF
o Specification Document(s): Section 4.1.8 of [[ this document ]]
o Header Parameter Name: "x5c"
o Header Parameter Usage Location(s): JWE
o Change Controller: IETF
o Specification Document(s): Section 4.1.9 of [[ this document ]]
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o Header Parameter Name: "kid"
o Header Parameter Usage Location(s): JWE
o Change Controller: IETF
o Specification Document(s): Section 4.1.10 of [[ this document ]]
o Header Parameter Name: "typ"
o Header Parameter Usage Location(s): JWE
o Change Controller: IETF
o Specification Document(s): Section 4.1.11 of [[ this document ]]
o Header Parameter Name: "cty"
o Header Parameter Usage Location(s): JWE
o Change Controller: IETF
o Specification Document(s): Section 4.1.12 of [[ this document ]]
o Header Parameter Name: "apu"
o Header Parameter Usage Location(s): JWE
o Change Controller: IETF
o Specification Document(s): Section 4.1.13 of [[ this document ]]
o Header Parameter Name: "apv"
o Header Parameter Usage Location(s): JWE
o Change Controller: IETF
o Specification Document(s): Section 4.1.14 of [[ this document ]]
o Header Parameter Name: "epu"
o Header Parameter Usage Location(s): JWE
o Change Controller: IETF
o Specification Document(s): Section 4.1.15 of [[ this document ]]
o Header Parameter Name: "epv"
o Header Parameter Usage Location(s): JWE
o Change Controller: IETF
o Specification Document(s): Section 4.1.16 of [[ this document ]]
7.2. JSON Web Signature and Encryption Type Values Registration
7.2.1. Registry Contents
This specification registers the "JWE" type value in the IANA JSON
Web Signature and Encryption Type Values registry [JWS]:
o "typ" Header Parameter Value: "JWE"
o Abbreviation for MIME Type: application/jwe
o Change Controller: IETF
o Specification Document(s): Section 4.1.11 of [[ this document ]]
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7.3. Media Type Registration
7.3.1. Registry Contents
This specification registers the "application/jwe" Media Type
[RFC2046] in the MIME Media Type registry [RFC4288] to indicate that
the content is a JWE using the Compact Serialization.
o Type Name: application
o Subtype Name: jwe
o Required Parameters: n/a
o Optional Parameters: n/a
o Encoding considerations: JWE values are encoded as a series of
base64url encoded values (some of which may be the empty string)
separated by period ('.') characters
o Security Considerations: See the Security Considerations section
of this document
o Interoperability Considerations: n/a
o Published Specification: [[ this document ]]
o Applications that use this media type: OpenID Connect and other
applications using encrypted JWTs
o Additional Information: Magic number(s): n/a, File extension(s):
n/a, Macintosh file type code(s): n/a
o Person & email address to contact for further information: Michael
B. Jones, mbj@microsoft.com
o Intended Usage: COMMON
o Restrictions on Usage: none
o Author: Michael B. Jones, mbj@microsoft.com
o Change Controller: IETF
8. 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 [W3C.CR-xmlenc-core1-20120313] also apply to JWE,
other than those that are XML specific.
9. References
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9.1. Normative References
[ITU.X690.1994]
International Telecommunications Union, "Information
Technology - ASN.1 encoding rules: Specification of Basic
Encoding Rules (BER), Canonical Encoding Rules (CER) and
Distinguished Encoding Rules (DER)", ITU-T Recommendation
X.690, 1994.
[JWA] Jones, M., "JSON Web Algorithms (JWA)",
draft-ietf-jose-json-web-algorithms (work in progress),
December 2012.
[JWK] Jones, M., "JSON Web Key (JWK)",
draft-ietf-jose-json-web-key (work in progress),
December 2012.
[JWS] Jones, M., Bradley, J., and N. Sakimura, "JSON Web
Signature (JWS)", draft-ietf-jose-json-web-signature (work
in progress), December 2012.
[RFC1421] Linn, J., "Privacy Enhancement for Internet Electronic
Mail: Part I: Message Encryption and Authentication
Procedures", RFC 1421, February 1993.
[RFC1951] Deutsch, P., "DEFLATE Compressed Data Format Specification
version 1.3", RFC 1951, May 1996.
[RFC2046] Freed, N. and N. Borenstein, "Multipurpose Internet Mail
Extensions (MIME) Part Two: Media Types", RFC 2046,
November 1996.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2818] Rescorla, E., "HTTP Over TLS", RFC 2818, May 2000.
[RFC3629] Yergeau, F., "UTF-8, a transformation format of ISO
10646", STD 63, RFC 3629, November 2003.
[RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
Resource Identifier (URI): Generic Syntax", STD 66,
RFC 3986, January 2005.
[RFC4086] Eastlake, D., Schiller, J., and S. Crocker, "Randomness
Requirements for Security", BCP 106, RFC 4086, June 2005.
[RFC4288] Freed, N. and J. Klensin, "Media Type Specifications and
Jones, et al. Expires June 30, 2013 [Page 24]
Internet-Draft JWE December 2012
Registration Procedures", BCP 13, RFC 4288, December 2005.
[RFC4627] Crockford, D., "The application/json Media Type for
JavaScript Object Notation (JSON)", RFC 4627, July 2006.
[RFC4648] Josefsson, S., "The Base16, Base32, and Base64 Data
Encodings", RFC 4648, October 2006.
[RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security
(TLS) Protocol Version 1.2", RFC 5246, August 2008.
[RFC5280] Cooper, D., Santesson, S., Farrell, S., Boeyen, S.,
Housley, R., and W. Polk, "Internet X.509 Public Key
Infrastructure Certificate and Certificate Revocation List
(CRL) Profile", RFC 5280, May 2008.
[W3C.CR-xmlenc-core1-20120313]
Eastlake, D., Reagle, J., Roessler, T., and F. Hirsch,
"XML Encryption Syntax and Processing Version 1.1", World
Wide Web Consortium CR CR-xmlenc-core1-20120313,
March 2012,
<http://www.w3.org/TR/2012/CR-xmlenc-core1-20120313>.
9.2. Informative References
[I-D.rescorla-jsms]
Rescorla, E. and J. Hildebrand, "JavaScript Message
Security Format", draft-rescorla-jsms-00 (work in
progress), March 2011.
[JSE] Bradley, J. and N. Sakimura (editor), "JSON Simple
Encryption", September 2010.
[JWE-JS] Jones, M., "JSON Web Encryption JSON Serialization
(JWE-JS)", draft-jones-jose-jwe-json-serialization (work
in progress), December 2012.
[RFC4122] Leach, P., Mealling, M., and R. Salz, "A Universally
Unique IDentifier (UUID) URN Namespace", RFC 4122,
July 2005.
[RFC5652] Housley, R., "Cryptographic Message Syntax (CMS)", STD 70,
RFC 5652, September 2009.
Appendix A. JWE Examples
This section provides examples of JWE computations.
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A.1. Example JWE using RSAES OAEP and AES GCM
This example encrypts the plaintext "Live long and prosper." to the
recipient using RSAES OAEP and AES GCM. The AES GCM algorithm has an
integrated integrity check. The representation of this plaintext is:
[76, 105, 118, 101, 32, 108, 111, 110, 103, 32, 97, 110, 100, 32,
112, 114, 111, 115, 112, 101, 114, 46]
A.1.1. JWE Header
The following example JWE Header declares that:
o the Content Master Key is encrypted to the recipient using the
RSAES OAEP algorithm to produce the JWE Encrypted Key and
o the Plaintext is encrypted using the AES GCM algorithm with a 256
bit key to produce the Ciphertext.
{"alg":"RSA-OAEP","enc":"A256GCM"}
A.1.2. Encoded JWE Header
Base64url encoding the bytes of the UTF-8 representation of the JWE
Header yields this Encoded JWE Header value:
eyJhbGciOiJSU0EtT0FFUCIsImVuYyI6IkEyNTZHQ00ifQ
A.1.3. Content Master Key (CMK)
Generate a 256 bit random Content Master Key (CMK). In this example,
the value 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.1.4. Key Encryption
Encrypt the CMK with the recipient's public key using the RSAES OAEP
algorithm to produce the JWE Encrypted Key. In this example, the RSA
key parameters are:
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+-----------+-------------------------------------------------------+
| Parameter | Value |
| Name | |
+-----------+-------------------------------------------------------+
| Modulus | [161, 168, 84, 34, 133, 176, 208, 173, 46, 176, 163, |
| | 110, 57, 30, 135, 227, 9, 31, 226, 128, 84, 92, 116, |
| | 241, 70, 248, 27, 227, 193, 62, 5, 91, 241, 145, 224, |
| | 205, 141, 176, 184, 133, 239, 43, 81, 103, 9, 161, |
| | 153, 157, 179, 104, 123, 51, 189, 34, 152, 69, 97, |
| | 69, 78, 93, 140, 131, 87, 182, 169, 101, 92, 142, 3, |
| | 22, 167, 8, 212, 56, 35, 79, 210, 222, 192, 208, 252, |
| | 49, 109, 138, 173, 253, 210, 166, 201, 63, 102, 74, |
| | 5, 158, 41, 90, 144, 108, 160, 79, 10, 89, 222, 231, |
| | 172, 31, 227, 197, 0, 19, 72, 81, 138, 78, 136, 221, |
| | 121, 118, 196, 17, 146, 10, 244, 188, 72, 113, 55, |
| | 221, 162, 217, 171, 27, 57, 233, 210, 101, 236, 154, |
| | 199, 56, 138, 239, 101, 48, 198, 186, 202, 160, 76, |
| | 111, 234, 71, 57, 183, 5, 211, 171, 136, 126, 64, 40, |
| | 75, 58, 89, 244, 254, 107, 84, 103, 7, 236, 69, 163, |
| | 18, 180, 251, 58, 153, 46, 151, 174, 12, 103, 197, |
| | 181, 161, 162, 55, 250, 235, 123, 110, 17, 11, 158, |
| | 24, 47, 133, 8, 199, 235, 107, 126, 130, 246, 73, |
| | 195, 20, 108, 202, 176, 214, 187, 45, 146, 182, 118, |
| | 54, 32, 200, 61, 201, 71, 243, 1, 255, 131, 84, 37, |
| | 111, 211, 168, 228, 45, 192, 118, 27, 197, 235, 232, |
| | 36, 10, 230, 248, 190, 82, 182, 140, 35, 204, 108, |
| | 190, 253, 186, 186, 27] |
| Exponent | [1, 0, 1] |
Jones, et al. Expires June 30, 2013 [Page 27]
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| Private | [144, 183, 109, 34, 62, 134, 108, 57, 44, 252, 10, |
| Exponent | 66, 73, 54, 16, 181, 233, 92, 54, 219, 101, 42, 35, |
| | 178, 63, 51, 43, 92, 119, 136, 251, 41, 53, 23, 191, |
| | 164, 164, 60, 88, 227, 229, 152, 228, 213, 149, 228, |
| | 169, 237, 104, 71, 151, 75, 88, 252, 216, 77, 251, |
| | 231, 28, 97, 88, 193, 215, 202, 248, 216, 121, 195, |
| | 211, 245, 250, 112, 71, 243, 61, 129, 95, 39, 244, |
| | 122, 225, 217, 169, 211, 165, 48, 253, 220, 59, 122, |
| | 219, 42, 86, 223, 32, 236, 39, 48, 103, 78, 122, 216, |
| | 187, 88, 176, 89, 24, 1, 42, 177, 24, 99, 142, 170, |
| | 1, 146, 43, 3, 108, 64, 194, 121, 182, 95, 187, 134, |
| | 71, 88, 96, 134, 74, 131, 167, 69, 106, 143, 121, 27, |
| | 72, 44, 245, 95, 39, 194, 179, 175, 203, 122, 16, |
| | 112, 183, 17, 200, 202, 31, 17, 138, 156, 184, 210, |
| | 157, 184, 154, 131, 128, 110, 12, 85, 195, 122, 241, |
| | 79, 251, 229, 183, 117, 21, 123, 133, 142, 220, 153, |
| | 9, 59, 57, 105, 81, 255, 138, 77, 82, 54, 62, 216, |
| | 38, 249, 208, 17, 197, 49, 45, 19, 232, 157, 251, |
| | 131, 137, 175, 72, 126, 43, 229, 69, 179, 117, 82, |
| | 157, 213, 83, 35, 57, 210, 197, 252, 171, 143, 194, |
| | 11, 47, 163, 6, 253, 75, 252, 96, 11, 187, 84, 130, |
| | 210, 7, 121, 78, 91, 79, 57, 251, 138, 132, 220, 60, |
| | 224, 173, 56, 224, 201] |
+-----------+-------------------------------------------------------+
The resulting JWE Encrypted Key value is:
[51, 101, 241, 165, 179, 145, 41, 236, 202, 75, 60, 208, 47, 255,
121, 248, 104, 226, 185, 212, 65, 78, 169, 255, 162, 100, 188, 207,
220, 96, 161, 22, 251, 47, 66, 112, 229, 75, 4, 111, 25, 173, 200,
121, 246, 79, 189, 102, 173, 146, 228, 142, 14, 12, 167, 200, 27,
133, 138, 37, 180, 249, 4, 56, 123, 192, 162, 156, 246, 231, 235,
217, 240, 45, 158, 213, 195, 154, 2, 142, 86, 61, 198, 210, 34, 225,
92, 7, 128, 227, 4, 227, 55, 183, 69, 0, 59, 162, 71, 145, 98, 238,
0, 70, 40, 123, 159, 37, 115, 18, 16, 157, 236, 138, 117, 166, 18,
45, 181, 125, 112, 170, 168, 82, 129, 80, 166, 242, 150, 97, 17, 217,
109, 251, 51, 35, 39, 236, 107, 95, 43, 154, 4, 227, 206, 187, 75,
13, 51, 231, 115, 79, 67, 72, 145, 54, 225, 164, 60, 195, 120, 188,
69, 113, 3, 182, 21, 189, 79, 82, 122, 46, 196, 199, 254, 252, 7,
119, 5, 32, 144, 143, 173, 11, 99, 205, 120, 106, 231, 51, 231, 77,
73, 252, 197, 221, 142, 254, 151, 7, 6, 203, 65, 108, 117, 121, 15,
95, 43, 111, 13, 94, 242, 226, 150, 94, 121, 72, 144, 251, 69, 93,
137, 178, 13, 216, 8, 227, 125, 110, 180, 157, 250, 207, 184, 232,
222, 164, 193, 70, 232, 16, 65, 109, 29, 251, 164, 119, 50, 205, 236,
109, 245, 234, 78, 1]
Jones, et al. Expires June 30, 2013 [Page 28]
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A.1.5. Encoded JWE Encrypted Key
Base64url encode the JWE Encrypted Key to produce the Encoded JWE
Encrypted Key. This result (with line breaks for display purposes
only) is:
M2XxpbORKezKSzzQL_95-GjiudRBTqn_omS8z9xgoRb7L0Jw5UsEbxmtyHn2T71m
rZLkjg4Mp8gbhYoltPkEOHvAopz25-vZ8C2e1cOaAo5WPcbSIuFcB4DjBOM3t0UA
O6JHkWLuAEYoe58lcxIQneyKdaYSLbV9cKqoUoFQpvKWYRHZbfszIyfsa18rmgTj
zrtLDTPnc09DSJE24aQ8w3i8RXEDthW9T1J6LsTH_vwHdwUgkI-tC2PNeGrnM-dN
SfzF3Y7-lwcGy0FsdXkPXytvDV7y4pZeeUiQ-0VdibIN2AjjfW60nfrPuOjepMFG
6BBBbR37pHcyzext9epOAQ
A.1.6. 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]
Base64url encoding this value yields the Encoded JWE Initialization
Vector value:
48V1_ALb6US04U3b
A.1.7. "Additional Authenticated Data" Parameter
Concatenate the Encoded JWE Header value, a period character ('.'),
the Encoded JWE Encrypted Key, a second period character ('.'), and
the Encoded JWE Initialization Vector to create the "additional
authenticated data" parameter for the AES GCM algorithm. This result
(with line breaks for display purposes only) is:
eyJhbGciOiJSU0EtT0FFUCIsImVuYyI6IkEyNTZHQ00ifQ.
M2XxpbORKezKSzzQL_95-GjiudRBTqn_omS8z9xgoRb7L0Jw5UsEbxmtyHn2T71m
rZLkjg4Mp8gbhYoltPkEOHvAopz25-vZ8C2e1cOaAo5WPcbSIuFcB4DjBOM3t0UA
O6JHkWLuAEYoe58lcxIQneyKdaYSLbV9cKqoUoFQpvKWYRHZbfszIyfsa18rmgTj
zrtLDTPnc09DSJE24aQ8w3i8RXEDthW9T1J6LsTH_vwHdwUgkI-tC2PNeGrnM-dN
SfzF3Y7-lwcGy0FsdXkPXytvDV7y4pZeeUiQ-0VdibIN2AjjfW60nfrPuOjepMFG
6BBBbR37pHcyzext9epOAQ.
48V1_ALb6US04U3b
The representation of 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, 46,
77, 50, 88, 120, 112, 98, 79, 82, 75, 101, 122, 75, 83, 122, 122, 81,
Jones, et al. Expires June 30, 2013 [Page 29]
Internet-Draft JWE December 2012
76, 95, 57, 53, 45, 71, 106, 105, 117, 100, 82, 66, 84, 113, 110, 95,
111, 109, 83, 56, 122, 57, 120, 103, 111, 82, 98, 55, 76, 48, 74,
119, 53, 85, 115, 69, 98, 120, 109, 116, 121, 72, 110, 50, 84, 55,
49, 109, 114, 90, 76, 107, 106, 103, 52, 77, 112, 56, 103, 98, 104,
89, 111, 108, 116, 80, 107, 69, 79, 72, 118, 65, 111, 112, 122, 50,
53, 45, 118, 90, 56, 67, 50, 101, 49, 99, 79, 97, 65, 111, 53, 87,
80, 99, 98, 83, 73, 117, 70, 99, 66, 52, 68, 106, 66, 79, 77, 51,
116, 48, 85, 65, 79, 54, 74, 72, 107, 87, 76, 117, 65, 69, 89, 111,
101, 53, 56, 108, 99, 120, 73, 81, 110, 101, 121, 75, 100, 97, 89,
83, 76, 98, 86, 57, 99, 75, 113, 111, 85, 111, 70, 81, 112, 118, 75,
87, 89, 82, 72, 90, 98, 102, 115, 122, 73, 121, 102, 115, 97, 49, 56,
114, 109, 103, 84, 106, 122, 114, 116, 76, 68, 84, 80, 110, 99, 48,
57, 68, 83, 74, 69, 50, 52, 97, 81, 56, 119, 51, 105, 56, 82, 88, 69,
68, 116, 104, 87, 57, 84, 49, 74, 54, 76, 115, 84, 72, 95, 118, 119,
72, 100, 119, 85, 103, 107, 73, 45, 116, 67, 50, 80, 78, 101, 71,
114, 110, 77, 45, 100, 78, 83, 102, 122, 70, 51, 89, 55, 45, 108,
119, 99, 71, 121, 48, 70, 115, 100, 88, 107, 80, 88, 121, 116, 118,
68, 86, 55, 121, 52, 112, 90, 101, 101, 85, 105, 81, 45, 48, 86, 100,
105, 98, 73, 78, 50, 65, 106, 106, 102, 87, 54, 48, 110, 102, 114,
80, 117, 79, 106, 101, 112, 77, 70, 71, 54, 66, 66, 66, 98, 82, 51,
55, 112, 72, 99, 121, 122, 101, 120, 116, 57, 101, 112, 79, 65, 81,
46, 52, 56, 86, 49, 95, 65, 76, 98, 54, 85, 83, 48, 52, 85, 51, 98]
A.1.8. Plaintext Encryption
Encrypt the Plaintext with AES GCM using the CMK 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:
[253, 237, 181, 180, 97, 161, 105, 207, 233, 120, 65, 100, 45, 122,
246, 116, 195, 212, 102, 37, 36, 175]
The resulting "authentication tag" value is:
[237, 94, 89, 14, 74, 52, 191, 249, 159, 216, 240, 28, 224, 147, 34,
82]
A.1.9. Encoded JWE Ciphertext
Base64url encode the resulting Ciphertext to create the Encoded JWE
Ciphertext. This result is:
_e21tGGhac_peEFkLXr2dMPUZiUkrw
Jones, et al. Expires June 30, 2013 [Page 30]
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A.1.10. Encoded JWE Integrity Value
Base64url encode the resulting "authentication tag" to create the
Encoded JWE Integrity Value. This result is:
7V5ZDko0v_mf2PAc4JMiUg
A.1.11. Complete Representation
Assemble the final representation: The Compact Serialization of this
result is the concatenation of the Encoded JWE Header, the Encoded
JWE Encrypted Key, the Encoded JWE Initialization Vector, the Encoded
JWE Ciphertext, and the Encoded JWE Integrity Value in that order,
with the five strings being separated by four period ('.')
characters.
The final result in this example (with line breaks for display
purposes only) is:
eyJhbGciOiJSU0EtT0FFUCIsImVuYyI6IkEyNTZHQ00ifQ.
M2XxpbORKezKSzzQL_95-GjiudRBTqn_omS8z9xgoRb7L0Jw5UsEbxmtyHn2T71m
rZLkjg4Mp8gbhYoltPkEOHvAopz25-vZ8C2e1cOaAo5WPcbSIuFcB4DjBOM3t0UA
O6JHkWLuAEYoe58lcxIQneyKdaYSLbV9cKqoUoFQpvKWYRHZbfszIyfsa18rmgTj
zrtLDTPnc09DSJE24aQ8w3i8RXEDthW9T1J6LsTH_vwHdwUgkI-tC2PNeGrnM-dN
SfzF3Y7-lwcGy0FsdXkPXytvDV7y4pZeeUiQ-0VdibIN2AjjfW60nfrPuOjepMFG
6BBBbR37pHcyzext9epOAQ.
48V1_ALb6US04U3b.
_e21tGGhac_peEFkLXr2dMPUZiUkrw.
7V5ZDko0v_mf2PAc4JMiUg
A.1.12. Validation
This example illustrates the process of creating a JWE with an
Authenticated Encryption algorithm. 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 CBC
This example encrypts the plaintext "No matter where you go, there
you are." to the recipient using RSAES-PKCS1-V1_5 and AES CBC. AES
CBC does not have an integrated integrity check, so a separate
integrity check calculation is performed using HMAC SHA-256, with
separate encryption and integrity keys being derived from a master
Jones, et al. Expires June 30, 2013 [Page 31]
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key using the Concat KDF with the SHA-256 digest function. The
representation of this plaintext is:
[78, 111, 32, 109, 97, 116, 116, 101, 114, 32, 119, 104, 101, 114,
101, 32, 121, 111, 117, 32, 103, 111, 44, 32, 116, 104, 101, 114,
101, 32, 121, 111, 117, 32, 97, 114, 101, 46]
A.2.1. JWE Header
The following example JWE Header (with line breaks for display
purposes only) declares that:
o the Content Master Key is encrypted to the recipient using the
RSAES-PKCS1-V1_5 algorithm to produce the JWE Encrypted Key and
o the Plaintext is encrypted using the AES CBC algorithm with a 128
bit key to produce the Ciphertext, with the integrity of the
Ciphertext and the parameters used to create it being secured with
the HMAC SHA-256 algorithm.
{"alg":"RSA1_5","enc":"A128CBC+HS256"}
A.2.2. Encoded JWE Header
Base64url encoding the bytes of the UTF-8 representation of the JWE
Header yields this Encoded JWE Header value:
eyJhbGciOiJSU0ExXzUiLCJlbmMiOiJBMTI4Q0JDK0hTMjU2In0
A.2.3. Content Master Key (CMK)
Generate a 256 bit random Content Master Key (CMK). 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.2.4. Key Encryption
Encrypt the CMK with the recipient's public key using the RSAES-
PKCS1-V1_5 algorithm to produce the JWE Encrypted Key. In this
example, the RSA key parameters are:
Jones, et al. Expires June 30, 2013 [Page 32]
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+-----------+-------------------------------------------------------+
| Parameter | Value |
| Name | |
+-----------+-------------------------------------------------------+
| Modulus | [177, 119, 33, 13, 164, 30, 108, 121, 207, 136, 107, |
| | 242, 12, 224, 19, 226, 198, 134, 17, 71, 173, 75, 42, |
| | 61, 48, 162, 206, 161, 97, 108, 185, 234, 226, 219, |
| | 118, 206, 118, 5, 169, 224, 60, 181, 90, 85, 51, 123, |
| | 6, 224, 4, 122, 29, 230, 151, 12, 244, 127, 121, 25, |
| | 4, 85, 220, 144, 215, 110, 130, 17, 68, 228, 129, |
| | 138, 7, 130, 231, 40, 212, 214, 17, 179, 28, 124, |
| | 151, 178, 207, 20, 14, 154, 222, 113, 176, 24, 198, |
| | 73, 211, 113, 9, 33, 178, 80, 13, 25, 21, 25, 153, |
| | 212, 206, 67, 154, 147, 70, 194, 192, 183, 160, 83, |
| | 98, 236, 175, 85, 23, 97, 75, 199, 177, 73, 145, 50, |
| | 253, 206, 32, 179, 254, 236, 190, 82, 73, 67, 129, |
| | 253, 252, 220, 108, 136, 138, 11, 192, 1, 36, 239, |
| | 228, 55, 81, 113, 17, 25, 140, 63, 239, 146, 3, 172, |
| | 96, 60, 227, 233, 64, 255, 224, 173, 225, 228, 229, |
| | 92, 112, 72, 99, 97, 26, 87, 187, 123, 46, 50, 90, |
| | 202, 117, 73, 10, 153, 47, 224, 178, 163, 77, 48, 46, |
| | 154, 33, 148, 34, 228, 33, 172, 216, 89, 46, 225, |
| | 127, 68, 146, 234, 30, 147, 54, 146, 5, 133, 45, 78, |
| | 254, 85, 55, 75, 213, 86, 194, 218, 215, 163, 189, |
| | 194, 54, 6, 83, 36, 18, 153, 53, 7, 48, 89, 35, 66, |
| | 144, 7, 65, 154, 13, 97, 75, 55, 230, 132, 3, 13, |
| | 239, 71] |
| Exponent | [1, 0, 1] |
Jones, et al. Expires June 30, 2013 [Page 33]
Internet-Draft JWE December 2012
| Private | [84, 80, 150, 58, 165, 235, 242, 123, 217, 55, 38, |
| Exponent | 154, 36, 181, 221, 156, 211, 215, 100, 164, 90, 88, |
| | 40, 228, 83, 148, 54, 122, 4, 16, 165, 48, 76, 194, |
| | 26, 107, 51, 53, 179, 165, 31, 18, 198, 173, 78, 61, |
| | 56, 97, 252, 158, 140, 80, 63, 25, 223, 156, 36, 203, |
| | 214, 252, 120, 67, 180, 167, 3, 82, 243, 25, 97, 214, |
| | 83, 133, 69, 16, 104, 54, 160, 200, 41, 83, 164, 187, |
| | 70, 153, 111, 234, 242, 158, 175, 28, 198, 48, 211, |
| | 45, 148, 58, 23, 62, 227, 74, 52, 117, 42, 90, 41, |
| | 249, 130, 154, 80, 119, 61, 26, 193, 40, 125, 10, |
| | 152, 174, 227, 225, 205, 32, 62, 66, 6, 163, 100, 99, |
| | 219, 19, 253, 25, 105, 80, 201, 29, 252, 157, 237, |
| | 69, 1, 80, 171, 167, 20, 196, 156, 109, 249, 88, 0, |
| | 3, 152, 38, 165, 72, 87, 6, 152, 71, 156, 214, 16, |
| | 71, 30, 82, 51, 103, 76, 218, 63, 9, 84, 163, 249, |
| | 91, 215, 44, 238, 85, 101, 240, 148, 1, 82, 224, 91, |
| | 135, 105, 127, 84, 171, 181, 152, 210, 183, 126, 24, |
| | 46, 196, 90, 173, 38, 245, 219, 186, 222, 27, 240, |
| | 212, 194, 15, 66, 135, 226, 178, 190, 52, 245, 74, |
| | 65, 224, 81, 100, 85, 25, 204, 165, 203, 187, 175, |
| | 84, 100, 82, 15, 11, 23, 202, 151, 107, 54, 41, 207, |
| | 3, 136, 229, 134, 131, 93, 139, 50, 182, 204, 93, |
| | 130, 89] |
+-----------+-------------------------------------------------------+
The resulting JWE Encrypted Key value is:
[102, 105, 229, 169, 104, 35, 95, 42, 176, 142, 190, 220, 92, 124,
172, 240, 94, 253, 106, 114, 20, 35, 162, 118, 81, 103, 64, 201, 20,
4, 112, 96, 84, 248, 163, 199, 177, 227, 204, 247, 93, 63, 70, 132,
195, 26, 237, 72, 91, 141, 3, 159, 71, 111, 113, 213, 68, 142, 146,
92, 60, 243, 72, 111, 53, 156, 51, 16, 226, 215, 125, 68, 141, 232,
62, 111, 197, 98, 91, 150, 23, 230, 132, 93, 97, 216, 145, 226, 3,
18, 12, 48, 119, 153, 185, 8, 156, 195, 84, 21, 63, 143, 43, 144,
174, 101, 25, 199, 7, 106, 212, 43, 151, 225, 62, 225, 122, 92, 90,
139, 45, 144, 134, 229, 15, 235, 38, 110, 132, 189, 236, 126, 92,
183, 13, 64, 2, 77, 107, 95, 186, 8, 133, 53, 217, 104, 247, 152,
241, 49, 199, 15, 111, 110, 123, 16, 13, 78, 193, 224, 23, 230, 133,
220, 162, 126, 82, 192, 236, 7, 185, 100, 106, 21, 70, 93, 192, 255,
252, 139, 61, 124, 81, 140, 113, 97, 164, 231, 131, 167, 246, 157,
199, 195, 114, 122, 49, 121, 115, 63, 114, 12, 165, 11, 186, 3, 108,
12, 199, 101, 29, 226, 80, 56, 193, 149, 45, 134, 146, 102, 221, 202,
63, 166, 150, 53, 42, 133, 3, 83, 199, 14, 15, 181, 209, 199, 174,
76, 75, 106, 254, 243, 196, 227, 225, 173, 122, 254, 13, 224, 174, 4,
185, 217, 99, 225]
Jones, et al. Expires June 30, 2013 [Page 34]
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A.2.5. Encoded JWE Encrypted Key
Base64url encode the JWE Encrypted Key to produce the Encoded JWE
Encrypted Key. This result (with line breaks for display purposes
only) is:
ZmnlqWgjXyqwjr7cXHys8F79anIUI6J2UWdAyRQEcGBU-KPHsePM910_RoTDGu1I
W40Dn0dvcdVEjpJcPPNIbzWcMxDi131Ejeg-b8ViW5YX5oRdYdiR4gMSDDB3mbkI
nMNUFT-PK5CuZRnHB2rUK5fhPuF6XFqLLZCG5Q_rJm6Evex-XLcNQAJNa1-6CIU1
2Wj3mPExxw9vbnsQDU7B4BfmhdyiflLA7Ae5ZGoVRl3A__yLPXxRjHFhpOeDp_ad
x8NyejF5cz9yDKULugNsDMdlHeJQOMGVLYaSZt3KP6aWNSqFA1PHDg-10ceuTEtq
_vPE4-Gtev4N4K4Eudlj4Q
A.2.6. Key Derivation
Use the Concat key derivation function to derive Content Encryption
Key (CEK) and Content Integrity Key (CIK) values from the CMK. The
details of this derivation are shown in Appendix A.4. The resulting
CEK value is:
[203, 165, 180, 113, 62, 195, 22, 98, 91, 153, 210, 38, 112, 35, 230,
236]
The resulting CIK value is:
[218, 24, 160, 17, 160, 50, 235, 35, 216, 209, 100, 174, 155, 163,
10, 117, 180, 111, 172, 200, 127, 201, 206, 173, 40, 45, 58, 170, 35,
93, 9, 60]
A.2.7. 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]
Base64url encoding this value yields the Encoded JWE Initialization
Vector value:
AxY8DCtDaGlsbGljb3RoZQ
A.2.8. Plaintext Encryption
Encrypt the Plaintext with AES CBC using the CEK and the JWE
Initialization Vector to produce the Ciphertext. The resulting
Ciphertext is:
Jones, et al. Expires June 30, 2013 [Page 35]
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[71, 27, 35, 131, 163, 200, 19, 23, 38, 25, 33, 123, 46, 116, 132,
144, 58, 150, 32, 167, 192, 195, 92, 25, 207, 101, 233, 105, 181,
121, 63, 4, 44, 162, 82, 176, 17, 171, 150, 97, 147, 68, 245, 13, 97,
100, 145, 25]
A.2.9. Encoded JWE Ciphertext
Base64url encode the resulting Ciphertext to create the Encoded JWE
Ciphertext. This result is:
Rxsjg6PIExcmGSF7LnSEkDqWIKfAw1wZz2XpabV5PwQsolKwEauWYZNE9Q1hZJEZ
A.2.10. Secured Input Value
Concatenate the Encoded JWE Header value, a period character ('.'),
the Encoded JWE Encrypted Key, a second period character, the Encoded
JWE Initialization Vector, a third period ('.') character, and the
Encoded JWE Ciphertext to create the value to integrity protect.
This result (with line breaks for display purposes only) is:
eyJhbGciOiJSU0ExXzUiLCJlbmMiOiJBMTI4Q0JDK0hTMjU2In0.
ZmnlqWgjXyqwjr7cXHys8F79anIUI6J2UWdAyRQEcGBU-KPHsePM910_RoTDGu1I
W40Dn0dvcdVEjpJcPPNIbzWcMxDi131Ejeg-b8ViW5YX5oRdYdiR4gMSDDB3mbkI
nMNUFT-PK5CuZRnHB2rUK5fhPuF6XFqLLZCG5Q_rJm6Evex-XLcNQAJNa1-6CIU1
2Wj3mPExxw9vbnsQDU7B4BfmhdyiflLA7Ae5ZGoVRl3A__yLPXxRjHFhpOeDp_ad
x8NyejF5cz9yDKULugNsDMdlHeJQOMGVLYaSZt3KP6aWNSqFA1PHDg-10ceuTEtq
_vPE4-Gtev4N4K4Eudlj4Q.
AxY8DCtDaGlsbGljb3RoZQ.
Rxsjg6PIExcmGSF7LnSEkDqWIKfAw1wZz2XpabV5PwQsolKwEauWYZNE9Q1hZJEZ
The representation of 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, 75, 48, 104, 84, 77, 106, 85,
50, 73, 110, 48, 46, 90, 109, 110, 108, 113, 87, 103, 106, 88, 121,
113, 119, 106, 114, 55, 99, 88, 72, 121, 115, 56, 70, 55, 57, 97,
110, 73, 85, 73, 54, 74, 50, 85, 87, 100, 65, 121, 82, 81, 69, 99,
71, 66, 85, 45, 75, 80, 72, 115, 101, 80, 77, 57, 49, 48, 95, 82,
111, 84, 68, 71, 117, 49, 73, 87, 52, 48, 68, 110, 48, 100, 118, 99,
100, 86, 69, 106, 112, 74, 99, 80, 80, 78, 73, 98, 122, 87, 99, 77,
120, 68, 105, 49, 51, 49, 69, 106, 101, 103, 45, 98, 56, 86, 105, 87,
53, 89, 88, 53, 111, 82, 100, 89, 100, 105, 82, 52, 103, 77, 83, 68,
68, 66, 51, 109, 98, 107, 73, 110, 77, 78, 85, 70, 84, 45, 80, 75,
53, 67, 117, 90, 82, 110, 72, 66, 50, 114, 85, 75, 53, 102, 104, 80,
117, 70, 54, 88, 70, 113, 76, 76, 90, 67, 71, 53, 81, 95, 114, 74,
109, 54, 69, 118, 101, 120, 45, 88, 76, 99, 78, 81, 65, 74, 78, 97,
49, 45, 54, 67, 73, 85, 49, 50, 87, 106, 51, 109, 80, 69, 120, 120,
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119, 57, 118, 98, 110, 115, 81, 68, 85, 55, 66, 52, 66, 102, 109,
104, 100, 121, 105, 102, 108, 76, 65, 55, 65, 101, 53, 90, 71, 111,
86, 82, 108, 51, 65, 95, 95, 121, 76, 80, 88, 120, 82, 106, 72, 70,
104, 112, 79, 101, 68, 112, 95, 97, 100, 120, 56, 78, 121, 101, 106,
70, 53, 99, 122, 57, 121, 68, 75, 85, 76, 117, 103, 78, 115, 68, 77,
100, 108, 72, 101, 74, 81, 79, 77, 71, 86, 76, 89, 97, 83, 90, 116,
51, 75, 80, 54, 97, 87, 78, 83, 113, 70, 65, 49, 80, 72, 68, 103, 45,
49, 48, 99, 101, 117, 84, 69, 116, 113, 95, 118, 80, 69, 52, 45, 71,
116, 101, 118, 52, 78, 52, 75, 52, 69, 117, 100, 108, 106, 52, 81,
46, 65, 120, 89, 56, 68, 67, 116, 68, 97, 71, 108, 115, 98, 71, 108,
106, 98, 51, 82, 111, 90, 81, 46, 82, 120, 115, 106, 103, 54, 80, 73,
69, 120, 99, 109, 71, 83, 70, 55, 76, 110, 83, 69, 107, 68, 113, 87,
73, 75, 102, 65, 119, 49, 119, 90, 122, 50, 88, 112, 97, 98, 86, 53,
80, 119, 81, 115, 111, 108, 75, 119, 69, 97, 117, 87, 89, 90, 78, 69,
57, 81, 49, 104, 90, 74, 69, 90]
A.2.11. JWE Integrity Value
Compute the HMAC SHA-256 of this value using the CIK to create the
JWE Integrity Value. This result is:
[240, 181, 234, 49, 221, 9, 44, 107, 49, 49, 160, 121, 186, 131, 90,
50, 152, 59, 185, 69, 191, 167, 141, 17, 149, 166, 71, 11, 3, 8, 203,
57]
A.2.12. Encoded JWE Integrity Value
Base64url encode the resulting JWE Integrity Value to create the
Encoded JWE Integrity Value. This result is:
8LXqMd0JLGsxMaB5uoNaMpg7uUW_p40RlaZHCwMIyzk
A.2.13. Complete Representation
Assemble the final representation: The Compact Serialization of this
result is the concatenation of the Encoded JWE Header, the Encoded
JWE Encrypted Key, the Encoded JWE Initialization Vector, the Encoded
JWE Ciphertext, and the Encoded JWE Integrity Value in that order,
with the five strings being separated by four period ('.')
characters.
The final result in this example (with line breaks for display
purposes only) is:
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eyJhbGciOiJSU0ExXzUiLCJlbmMiOiJBMTI4Q0JDK0hTMjU2In0.
ZmnlqWgjXyqwjr7cXHys8F79anIUI6J2UWdAyRQEcGBU-KPHsePM910_RoTDGu1I
W40Dn0dvcdVEjpJcPPNIbzWcMxDi131Ejeg-b8ViW5YX5oRdYdiR4gMSDDB3mbkI
nMNUFT-PK5CuZRnHB2rUK5fhPuF6XFqLLZCG5Q_rJm6Evex-XLcNQAJNa1-6CIU1
2Wj3mPExxw9vbnsQDU7B4BfmhdyiflLA7Ae5ZGoVRl3A__yLPXxRjHFhpOeDp_ad
x8NyejF5cz9yDKULugNsDMdlHeJQOMGVLYaSZt3KP6aWNSqFA1PHDg-10ceuTEtq
_vPE4-Gtev4N4K4Eudlj4Q.
AxY8DCtDaGlsbGljb3RoZQ.
Rxsjg6PIExcmGSF7LnSEkDqWIKfAw1wZz2XpabV5PwQsolKwEauWYZNE9Q1hZJEZ.
8LXqMd0JLGsxMaB5uoNaMpg7uUW_p40RlaZHCwMIyzk
A.2.14. Validation
This example illustrates the process of creating a JWE with a
composite Authenticated Encryption algorithm created from a non-
Authenticated Encryption algorithm by adding a separate integrity
check calculation. 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 GCM
This example encrypts the plaintext "The true sign of intelligence is
not knowledge but imagination." to the recipient using AES Key Wrap
and AES GCM. The representation of this plaintext 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.3.1. JWE Header
The following example JWE Header declares that:
o the Content Master Key is encrypted to the recipient using the AES
Key Wrap algorithm with a 128 bit key to produce the JWE Encrypted
Key and
o the Plaintext is encrypted using the AES GCM algorithm with a 128
bit key to produce the Ciphertext.
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{"alg":"A128KW","enc":"A128GCM"}
A.3.2. Encoded JWE Header
Base64url encoding the bytes of the UTF-8 representation of the JWE
Header yields this Encoded JWE Header value:
eyJhbGciOiJBMTI4S1ciLCJlbmMiOiJBMTI4R0NNIn0
A.3.3. Content Master Key (CMK)
Generate a 128 bit random Content Master Key (CMK). In this example,
the value is:
[64, 154, 239, 170, 64, 40, 195, 99, 19, 84, 192, 142, 192, 238, 207,
217]
A.3.4. Key Encryption
Encrypt the CMK with the shared symmetric key using the AES Key Wrap
algorithm to produce the JWE Encrypted Key. In this example, the
shared symmetric key value is:
[25, 172, 32, 130, 225, 114, 26, 181, 138, 106, 254, 192, 95, 133,
74, 82]
The resulting JWE Encrypted Key value is:
[164, 255, 251, 1, 64, 200, 65, 200, 34, 197, 81, 143, 43, 211, 240,
38, 191, 161, 181, 117, 119, 68, 44, 80]
A.3.5. Encoded JWE Encrypted Key
Base64url encode the JWE Encrypted Key to produce the Encoded JWE
Encrypted Key. This result is:
pP_7AUDIQcgixVGPK9PwJr-htXV3RCxQ
A.3.6. Initialization Vector
Generate a random 96 bit JWE Initialization Vector. In this example,
the value is:
[253, 220, 80, 25, 166, 152, 178, 168, 97, 99, 67, 89]
Base64url encoding this value yields the Encoded JWE Initialization
Vector value:
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_dxQGaaYsqhhY0NZ
A.3.7. "Additional Authenticated Data" Parameter
Concatenate the Encoded JWE Header value, a period character ('.'),
the Encoded JWE Encrypted Key, a second period character ('.'), and
the Encoded JWE Initialization Vector to create the "additional
authenticated data" parameter for the AES GCM algorithm. This result
(with line breaks for display purposes only) is:
eyJhbGciOiJBMTI4S1ciLCJlbmMiOiJBMTI4R0NNIn0.
pP_7AUDIQcgixVGPK9PwJr-htXV3RCxQ.
_dxQGaaYsqhhY0NZ
The representation of 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, 82, 48, 78, 78, 73, 110, 48, 46, 112, 80, 95, 55, 65,
85, 68, 73, 81, 99, 103, 105, 120, 86, 71, 80, 75, 57, 80, 119, 74,
114, 45, 104, 116, 88, 86, 51, 82, 67, 120, 81, 46, 95, 100, 120, 81,
71, 97, 97, 89, 115, 113, 104, 104, 89, 48, 78, 90]
A.3.8. Plaintext Encryption
Encrypt the Plaintext with AES GCM using the CMK 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:
[227, 12, 89, 132, 185, 16, 248, 93, 145, 87, 53, 130, 95, 115, 62,
104, 138, 96, 109, 71, 124, 211, 165, 103, 202, 99, 21, 193, 4, 226,
84, 229, 254, 106, 144, 241, 39, 86, 148, 132, 160, 104, 88, 232,
228, 109, 85, 7, 86, 80, 134, 106, 166, 24, 92, 199, 210, 188, 153,
187, 218, 69, 227]
The resulting "authentication tag" value is:
[154, 35, 80, 107, 37, 148, 81, 6, 103, 4, 60, 206, 171, 165, 113,
67]
A.3.9. Encoded JWE Ciphertext
Base64url encode the resulting Ciphertext to create the Encoded JWE
Ciphertext. This result (with line breaks for display purposes only)
is:
4wxZhLkQ-F2RVzWCX3M-aIpgbUd806VnymMVwQTiVOX-apDxJ1aUhKBoWOjkbVUH
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VlCGaqYYXMfSvJm72kXj
A.3.10. Encoded JWE Integrity Value
Base64url encode the resulting "authentication tag" to create the
Encoded JWE Integrity Value. This result is:
miNQayWUUQZnBDzOq6VxQw
A.3.11. Complete Representation
Assemble the final representation: The Compact Serialization of this
result is the concatenation of the Encoded JWE Header, the Encoded
JWE Encrypted Key, the Encoded JWE Initialization Vector, the Encoded
JWE Ciphertext, and the Encoded JWE Integrity Value in that order,
with the five strings being separated by four period ('.')
characters.
The final result in this example (with line breaks for display
purposes only) is:
eyJhbGciOiJBMTI4S1ciLCJlbmMiOiJBMTI4R0NNIn0.
pP_7AUDIQcgixVGPK9PwJr-htXV3RCxQ.
_dxQGaaYsqhhY0NZ.
4wxZhLkQ-F2RVzWCX3M-aIpgbUd806VnymMVwQTiVOX-apDxJ1aUhKBoWOjkbVUH
VlCGaqYYXMfSvJm72kXj.
miNQayWUUQZnBDzOq6VxQw
A.3.12. Validation
This example illustrates the process of creating a JWE with symmetric
key wrap and an Authenticated Encryption algorithm. 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 Key Derivation for "enc" value "A128CBC+HS256"
This example uses the Concat KDF to derive the Content Encryption Key
(CEK) and Content Integrity Key (CIK) from the Content Master Key
(CMK) in the manner described in Section 4.8.1 of [JWA]. In this
example, a 256 bit CMK is used to derive a 128 bit CEK and a 256 bit
CIK.
The CMK value used is:
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[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.4.1. CEK Generation
These values are concatenated to produce the round 1 hash input:
o the round number 1 as a 32 bit big endian integer ([0, 0, 0, 1]),
o the CMK value (as above),
o the output bit size 128 as a 32 bit big endian number ([0, 0, 0,
128]),
o the bytes of the UTF-8 representation of the "enc" value
"A128CBC+HS256" -- [65, 49, 50, 56, 67, 66, 67, 43, 72, 83, 50,
53, 54],
o the Datalen value of zero for the omitted "epu" (encryption
PartyUInfo) value ([0, 0, 0, 0]),
o the Datalen value of zero for the omitted "epv" (encryption
PartyVInfo) value ([0, 0, 0, 0]),
o the bytes of the ASCII representation of the label "Encryption" --
[69, 110, 99, 114, 121, 112, 116, 105, 111, 110].
Thus the round 1 hash input is:
[0, 0, 0, 1, 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, 0, 0, 0, 128, 65, 49, 50, 56, 67, 66, 67, 43,
72, 83, 50, 53, 54, 0, 0, 0, 0, 0, 0, 0, 0, 69, 110, 99, 114, 121,
112, 116, 105, 111, 110]
The SHA-256 hash of this value, which is the round 1 hash output, is:
[203, 165, 180, 113, 62, 195, 22, 98, 91, 153, 210, 38, 112, 35, 230,
236, 181, 193, 129, 233, 251, 107, 70, 80, 36, 150, 216, 251, 182,
29, 104, 150]
Given that 128 bits are needed for the CEK and the hash has produced
256 bits, the CEK value is the first 128 bits of that value:
[203, 165, 180, 113, 62, 195, 22, 98, 91, 153, 210, 38, 112, 35, 230,
236]
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A.4.2. CIK Generation
These values are concatenated to produce the round 1 hash input:
o the round number 1 as a 32 bit big endian integer ([0, 0, 0, 1]),
o the CMK value (as above),
o the output bit size 256 as a 32 bit big endian number ([0, 0, 1,
0]),
o the bytes of the UTF-8 representation of the "enc" value
"A128CBC+HS256" -- [65, 49, 50, 56, 67, 66, 67, 43, 72, 83, 50,
53, 54],
o the Datalen value of zero for the omitted "epu" (encryption
PartyUInfo) value ([0, 0, 0, 0]),
o the Datalen value of zero for the omitted "epv" (encryption
PartyVInfo) value ([0, 0, 0, 0]),
o the bytes of the ASCII representation of the label "Integrity" --
[73, 110, 116, 101, 103, 114, 105, 116, 121].
Thus the round 1 hash input is:
[0, 0, 0, 1, 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, 0, 0, 1, 0, 65, 49, 50, 56, 67, 66, 67, 43,
72, 83, 50, 53, 54, 0, 0, 0, 0, 0, 0, 0, 0, 73, 110, 116, 101, 103,
114, 105, 116, 121]
The SHA-256 hash of this value, which is the round 1 hash output, is:
[218, 24, 160, 17, 160, 50, 235, 35, 216, 209, 100, 174, 155, 163,
10, 117, 180, 111, 172, 200, 127, 201, 206, 173, 40, 45, 58, 170, 35,
93, 9, 60]
Given that 256 bits are needed for the CIK and the hash has produced
256 bits, the CIK value is that same value:
[218, 24, 160, 17, 160, 50, 235, 35, 216, 209, 100, 174, 155, 163,
10, 117, 180, 111, 172, 200, 127, 201, 206, 173, 40, 45, 58, 170, 35,
93, 9, 60]
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A.5. Example Key Derivation for "enc" value "A256CBC+HS512"
This example uses the Concat KDF to derive the Content Encryption Key
(CEK) and Content Integrity Key (CIK) from the Content Master Key
(CMK) in the manner described in Section 4.8.1 of [JWA]. In this
example, a 512 bit CMK is used to derive a 256 bit CEK and a 512 bit
CIK.
The CMK value used is:
[148, 116, 199, 126, 2, 117, 233, 76, 150, 149, 89, 193, 61, 34, 239,
226, 109, 71, 59, 160, 192, 140, 150, 235, 106, 204, 49, 176, 68,
119, 13, 34, 49, 19, 41, 69, 5, 20, 252, 145, 104, 129, 137, 138, 67,
23, 153, 83, 81, 234, 82, 247, 48, 211, 41, 130, 35, 124, 45, 156,
249, 7, 225, 168]
A.5.1. CEK Generation
These values are concatenated to produce the round 1 hash input:
o the round number 1 as a 32 bit big endian integer ([0, 0, 0, 1]),
o the CMK value (as above),
o the output bit size 256 as a 32 bit big endian number ([0, 0, 1,
0]),
o the bytes of the UTF-8 representation of the "enc" value
"A256CBC+HS512" -- [65, 50, 53, 54, 67, 66, 67, 43, 72, 83, 53,
49, 50],
o the Datalen value of zero for the omitted "epu" (encryption
PartyUInfo) value ([0, 0, 0, 0]),
o the Datalen value of zero for the omitted "epv" (encryption
PartyVInfo) value ([0, 0, 0, 0]),
o the bytes of the ASCII representation of the label "Encryption" --
[69, 110, 99, 114, 121, 112, 116, 105, 111, 110].
Thus the round 1 hash input is:
[0, 0, 0, 1, 148, 116, 199, 126, 2, 117, 233, 76, 150, 149, 89, 193,
61, 34, 239, 226, 109, 71, 59, 160, 192, 140, 150, 235, 106, 204, 49,
176, 68, 119, 13, 34, 49, 19, 41, 69, 5, 20, 252, 145, 104, 129, 137,
138, 67, 23, 153, 83, 81, 234, 82, 247, 48, 211, 41, 130, 35, 124,
45, 156, 249, 7, 225, 168, 0, 0, 1, 0, 65, 50, 53, 54, 67, 66, 67,
43, 72, 83, 53, 49, 50, 0, 0, 0, 0, 0, 0, 0, 0, 69, 110, 99, 114,
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121, 112, 116, 105, 111, 110]
The SHA-512 hash of this value, which is the round 1 hash output, is:
[157, 19, 75, 205, 31, 190, 110, 46, 117, 217, 137, 19, 116, 166,
126, 60, 18, 244, 226, 114, 38, 153, 78, 198, 26, 0, 181, 168, 113,
45, 149, 89, 107, 213, 109, 183, 207, 164, 86, 131, 51, 105, 214, 29,
229, 32, 243, 46, 40, 53, 123, 4, 13, 7, 250, 48, 227, 207, 167, 211,
147, 91, 0, 171]
Given that 256 bits are needed for the CEK and the hash has produced
512 bits, the CEK value is the first 256 bits of that value:
[157, 19, 75, 205, 31, 190, 110, 46, 117, 217, 137, 19, 116, 166,
126, 60, 18, 244, 226, 114, 38, 153, 78, 198, 26, 0, 181, 168, 113,
45, 149, 89]
A.5.2. CIK Generation
These values are concatenated to produce the round 1 hash input:
o the round number 1 as a 32 bit big endian integer ([0, 0, 0, 1]),
o the CMK value (as above),
o the output bit size 512 as a 32 bit big endian number ([0, 0, 2,
0]),
o the bytes of the UTF-8 representation of the "enc" value
"A256CBC+HS512" -- [65, 50, 53, 54, 67, 66, 67, 43, 72, 83, 53,
49, 50],
o the Datalen value of zero for the omitted "epu" (encryption
PartyUInfo) value ([0, 0, 0, 0]),
o the Datalen value of zero for the omitted "epv" (encryption
PartyVInfo) value ([0, 0, 0, 0]),
o the bytes of the ASCII representation of the label "Integrity" --
[73, 110, 116, 101, 103, 114, 105, 116, 121].
Thus the round 1 hash input is:
[0, 0, 0, 1, 148, 116, 199, 126, 2, 117, 233, 76, 150, 149, 89, 193,
61, 34, 239, 226, 109, 71, 59, 160, 192, 140, 150, 235, 106, 204, 49,
176, 68, 119, 13, 34, 49, 19, 41, 69, 5, 20, 252, 145, 104, 129, 137,
138, 67, 23, 153, 83, 81, 234, 82, 247, 48, 211, 41, 130, 35, 124,
45, 156, 249, 7, 225, 168, 0, 0, 2, 0, 65, 50, 53, 54, 67, 66, 67,
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43, 72, 83, 53, 49, 50, 0, 0, 0, 0, 0, 0, 0, 0, 73, 110, 116, 101,
103, 114, 105, 116, 121]
The SHA-512 hash of this value, which is the round 1 hash output, is:
[81, 249, 131, 194, 25, 166, 147, 155, 47, 249, 146, 160, 200, 236,
115, 72, 103, 248, 228, 30, 130, 225, 164, 61, 105, 172, 198, 31,
137, 170, 215, 141, 27, 247, 73, 236, 125, 113, 151, 33, 0, 251, 72,
53, 72, 63, 146, 117, 247, 13, 49, 20, 210, 169, 232, 156, 118, 1,
16, 45, 29, 21, 15, 208]
Given that 512 bits are needed for the CIK and the hash has produced
512 bits, the CIK value is that same value:
[81, 249, 131, 194, 25, 166, 147, 155, 47, 249, 146, 160, 200, 236,
115, 72, 103, 248, 228, 30, 130, 225, 164, 61, 105, 172, 198, 31,
137, 170, 215, 141, 27, 247, 73, 236, 125, 113, 151, 33, 0, 251, 72,
53, 72, 63, 146, 117, 247, 13, 49, 20, 210, 169, 232, 156, 118, 1,
16, 45, 29, 21, 15, 208]
Appendix B. Acknowledgements
Solutions for encrypting JSON content were also explored by JSON
Simple Encryption [JSE] and JavaScript Message Security Format
[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
[W3C.CR-xmlenc-core1-20120313] and RFC 5652 [RFC5652] as possible,
while utilizing simple compact JSON-based data structures.
Special thanks are due to John Bradley and Nat Sakimura for the
discussions that helped inform the content of this specification and
to Eric Rescorla and Joe Hildebrand for allowing the reuse of text
from [I-D.rescorla-jsms] in this document.
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, Tony Nadalin, Axel
Nennker, Emmanuel Raviart, Nat Sakimura, Jim Schaad, Hannes
Tschofenig, and Sean Turner.
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Jim Schaad and Karen O'Donoghue chaired the JOSE working group and
Sean Turner and Stephen Farrell served as Security area directors
during the creation of this specification.
Appendix C. Open Issues
[[ to be removed by the RFC editor before publication as an RFC ]]
The following items remain to be considered or done in this draft:
o Should all header fields continue to be required to be understood
by implementations using them or should a means of declaring that
specific header fields may be safely ignored if not understood
should be defined?
Appendix D. Document History
[[ to be removed by the RFC editor before publication as an RFC ]]
-08
o 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.
o Applied editorial improvements suggested by Jeff Hodges and Hannes
Tschofenig. Many of these simplified the terminology used.
o Clarified statements of the form "This header parameter is
OPTIONAL" to "Use of this header parameter is OPTIONAL".
o Added a Header Parameter Usage Location(s) field to the IANA JSON
Web Signature and Encryption Header Parameters registry.
o Added seriesInfo information to Internet Draft references.
-07
o Added a data length prefix to PartyUInfo and PartyVInfo values.
o Updated values for example AES CBC calculations.
o Made several local editorial changes to clean up loose ends left
over from to the decision to only support block encryption methods
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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
o 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.
o 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.
o 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.
o 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.
o Added an AES Key Wrap example.
o Reordered the encryption steps so CMK creation is first, when
required.
o Correct statements in examples about which algorithms produce
reproducible results.
-05
o 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.
o Added statement that "StringOrURI values are compared as case-
sensitive strings with no transformations or canonicalizations
applied".
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o Updated open issues.
o Indented artwork elements to better distinguish them from the body
text.
-04
o Refer to the registries as the primary sources of defined values
and then secondarily reference the sections defining the initial
contents of the registries.
o Normatively reference XML Encryption 1.1
[W3C.CR-xmlenc-core1-20120313] for its security considerations.
o Reference draft-jones-jose-jwe-json-serialization instead of
draft-jones-json-web-encryption-json-serialization.
o Described additional open issues.
o Applied editorial suggestions.
-03
o 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.
o 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.
o 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.
o Moved description of how to determine whether a header is for a
JWS or a JWE from the JWT spec to the JWE spec.
o Added complete encryption examples for both Authenticated
Encryption and non-Authenticated Encryption algorithms.
o Added complete key derivation examples.
o Added "Collision Resistant Namespace" to the terminology section.
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o Reference ITU.X690.1994 for DER encoding.
o Added Registry Contents sections to populate registry values.
o Numerous editorial improvements.
-02
o 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 Integrity
Value.
o Defined KDF output key sizes.
o Generalized text to allow key agreement to be employed as an
alternative to key wrapping or key encryption.
o Changed compression algorithm from gzip to DEFLATE.
o Clarified that it is an error when a "kid" value is included and
no matching key is found.
o Clarified that JWEs with duplicate Header Parameter Names MUST be
rejected.
o Clarified the relationship between "typ" header parameter values
and MIME types.
o Registered application/jwe MIME type and "JWE" typ header
parameter value.
o 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).
o Added suggestion on defining additional header parameters such as
"x5t#S256" in the future for certificate thumbprints using hash
algorithms other than SHA-1.
o Specify RFC 2818 server identity validation, rather than RFC 6125
(paralleling the same decision in the OAuth specs).
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o 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.
o Reformatted to give each header parameter its own section heading.
-01
o Added an integrity check for non-Authenticated Encryption
algorithms.
o Added "jpk" and "x5c" header parameters for including JWK public
keys and X.509 certificate chains directly in the header.
o Clarified that this specification is defining the JWE Compact
Serialization. Referenced the new JWE-JS spec, which defines the
JWE JSON Serialization.
o Added text "New header parameters should be introduced sparingly
since an implementation that does not understand a parameter MUST
reject the JWE".
o 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.
o Made other editorial improvements suggested by JOSE working group
participants.
-00
o Created the initial IETF draft based upon
draft-jones-json-web-encryption-02 with no normative changes.
o Changed terminology to no longer call both digital signatures and
HMACs "signatures".
Authors' Addresses
Michael B. Jones
Microsoft
Email: mbj@microsoft.com
URI: http://self-issued.info/
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Eric Rescorla
RTFM, Inc.
Email: ekr@rtfm.com
Joe Hildebrand
Cisco Systems, Inc.
Email: jhildebr@cisco.com
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