Dear JOSE WG,
[This will be better covered by the chair's minutes from the interim, but I
wanted to go ahead and post a summary so that related key wrapping
discussion can happen.]
One of the topics discussed at the JOSE interim was how to deal with header
integrity for multiple recipients. There was agreement in the room to
proceed with a strategy of removing some header parameters from integrity
protection -- especially per-recipient parameters.
At a high-level, the change to the syntax is as follows:
-- For JWE, header parameters may be included at the top level of a JWE-JS
or within the "recipients" objects
-- Unprotected parameters are expressed as a JSON dictionary under the
"header" parameter
-- Protected parameters are base64-encoded and included under the
"protected" parameter
Thus, for example, a JWE might have the following form:
{
"protected": "eyJlbmMiOiJBMTI4R0NNIn0K",
"recipients": [{
"header": { "alg": "A128KW", "kid": "42" },
"encrypted_key": "w_6lbR8WRO0-pxm3MyEXmg"
}],
"initialization_vector": "vKjNIAhMfYW3zq-TikHfXQ",
"ciphertext": "PTRhlo61rZ9bcVFLGK6sIi21r9-Zez03",
"authentication_tag": "Zurj775FrQgnI-EPZmbUCg"
}
A complete set of examples is included below. Comments welcome!
One area where comments would be especially helpful is the compact
serialization. In the examples below, there are two proposed compact
serializations based on the new format. Variant 1 maps "global" parameters
and "recipient" parameters to separate base64url-encoded parts. Variant 2
combines them into a single dictionary. On the one hand, Variant 1 maps
more simply to the JSON format; on the other hand, Variant 2 keeps the same
number of components as the current compact serialization.
Thanks,
--Richard
// Examples:
// 1. Current JWE-JS format
// 2. Proposed JWE-JS format
// 3. Simple example of proposed JWE-JS format
// 4. Current JWS-JS format
// 5. Proposed JWS-JS format
// 6. Proposed JWE-compact format (variant 1)
// 7. Proposed JWE-compact format (variant 2)
// JWE-CURRENT
// header = base64({"alg":"A128KW","enc":"A128GCM","kid":"42"})
{
"recipients": [{
"header":
"eyJhbGciOiJBMTI4S1ciLCJlbmMiOiJBMTI4R0NNIiwia2lkIjoiNDIifQo",
"encrypted_key": "w_6lbR8WRO0-pxm3MyEXmg"
}],
"initialization_vector": "vKjNIAhMfYW3zq-TikHfXQ",
"ciphertext": "PTRhlo61rZ9bcVFLGK6sIi21r9-Zez03",
"authentication_tag": "Zurj775FrQgnI-EPZmbUCg"
}
// JWE-PROPOSED
// protected = base64({"enc":"A128GCM"})
{
"header": { "typ": "JWE" },
"protected": "eyJlbmMiOiJBMTI4R0NNIn0K",
"recipients": [{
"header": { "alg": "A128KW", "kid": "42" },
"encrypted_key": "w_6lbR8WRO0-pxm3MyEXmg"
}],
"initialization_vector": "vKjNIAhMfYW3zq-TikHfXQ",
"ciphertext": "PTRhlo61rZ9bcVFLGK6sIi21r9-Zez03",
"authentication_tag": "Zurj775FrQgnI-EPZmbUCg"
}
// JWE-PROPOSED-SUPER-SIMPLE
// Single recipient, no protected parameters
{
"header": {
"typ": "JWE",
"alg": "A128KW",
"enc": "A128GCM",
"kid": "42"
},
"initialization_vector": "vKjNIAhMfYW3zq-TikHfXQ",
"ciphertext": "PTRhlo61rZ9bcVFLGK6sIi21r9-Zez03",
"authentication_tag": "Zurj775FrQgnI-EPZmbUCg"
}
// JWS-CURRENT
// header = base64({"alg":"RS256","kid": "42"})
{
"payload": "4_0ZISMX1I8xmdPTeBi6eg",
"signatures": [{
"header": "eyJhbGciOiJSUzI1NiIsImtpZCI6ICI0MiJ9Cg",
"signature": "3Hu6Av79mEzu6...NcF16ls8gJDe2OmSY"
}]
}
// JWS-PROPOSED
// protected = base64({"alg":"RS256"})
{
"payload": "4_0ZISMX1I8xmdPTeBi6eg",
"signatures": [{
"header": { "kid": "42" },
"protected": "eyJhbGciOiJSUzI1NiJ9Cg",
"signature": "3Hu6Av79mEzu6...NcF16ls8gJDe2OmSY"
}]
}
// JWE-PROPOSED-COMPACT-1
// protected = base64({"typ":"JWE","enc":"A128GCM"})
{
"protected": "eyJ0eXAiOiJKV0UiLCJlbmMiOiJBMTI4R0NNIn0K",
"recipients": [{
"header": {"alg":"A128KW","kid":"42"},
"encrypted_key": "w_6lbR8WRO0-pxm3MyEXmg"
}],
"initialization_vector": "vKjNIAhMfYW3zq-TikHfXQ",
"ciphertext": "PTRhlo61rZ9bcVFLGK6sIi21r9-Zez03",
"authentication_tag": "Zurj775FrQgnI-EPZmbUCg"
}
=====COMPACT====
eyJ0eXAiOiJKV0UiLCJlbmMiOiJBMTI4R0NNIn0K
.eyJhbGciOiJBMTI4S1ciLCJraWQiOiI0MiJ9Cg
.w_6lbR8WRO0-pxm3MyEXmg
.vKjNIAhMfYW3zq-TikHfXQ
.PTRhlo61rZ9bcVFLGK6sIi21r9-Zez03
.Zurj775FrQgnI-EPZmbUCg
// JWE-PROPOSED-COMPACT-2
// Header parameters from single recipient header folded into base header
// protected =
base64({"typ":"JWE","enc":"A128GCM","alg":"A128KW","kid":"42"})
{
"protected":
"eyJ0eXAiOiJKV0UiLCJlbmMiOiJBMTI4R0NNIiwiYWxnIjoiQTEyOEtXIiwia2lkIjoiNDIifQo",
"encrypted_key": "w_6lbR8WRO0-pxm3MyEXmg"
"initialization_vector": "vKjNIAhMfYW3zq-TikHfXQ",
"ciphertext": "PTRhlo61rZ9bcVFLGK6sIi21r9-Zez03",
"authentication_tag": "Zurj775FrQgnI-EPZmbUCg"
}
=====COMPACT====
eyJ0eXAiOiJKV0UiLCJlbmMiOiJBMTI4R0NNIiwiYWxnIjoiQTEyOEtXIiwia2lkIjoiNDIifQo
.w_6lbR8WRO0-pxm3MyEXmg
.vKjNIAhMfYW3zq-TikHfXQ
.PTRhlo61rZ9bcVFLGK6sIi21r9-Zez03
.Zurj775FrQgnI-EPZmbUCg
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