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From Anders Rundgren <>
Subject Re: Digitally Signed JSON
Date Mon, 14 May 2018 14:21:44 GMT
On 2018-05-14 15:04, Romain Manni-Bucau wrote:
> Hi Anders

Hi Romain,

> I miss one thing I think.
> If you take jwt or derivatives it signs/validates json without need of any
> normalization cause it mainly works on the raw payload. 

Right.  At the expense of obscuring both the message and the message structure.

Anybody can try out clear text JSON signatures in seconds if they like:

> Is the issue you speak about being idempotent?

I'd rather describe this as accomplishing what the XML folks did 15Y+ ago.

> If so what is the issue? while we use the same defaults it works, no? If
> not you need a business key which is quite common too since json order is
> never guaranteed too.

This is a core issue.  The IETF draft builds on exploiting the fact that ECMAScript do guarantee
property order.
I implemented that in Java and it was dead simple:

However, I have recently changed my mind on that and now push for canonicalization
because it can be provided as a "dumb filter" which is quicker than standardizing features
on the parser/serializer level.

This is only really difficult part:
Microsoft is actually testing their JS serializer with my 100 million test value set :-)

Cordialement (we are both in France),

> Le lun. 14 mai 2018 11:45, Anders Rundgren <>
> a écrit :
>> Hi Johnzoners!
>> In case you want to digitally sign JSON messages/documents, the
>> standardized way of doing that is dressing the JSON data in Base64Url.  IMO
>> this defeats the value of clear text formats.
>> Current standard (JWS):
>> eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzI1NiJ9.eyJ1c2VySWQiOiJiMDhmODZhZi0zNWRhLTQ4ZjItOGZhYi1jZWYzOTA0NjYwYmQifQ.-xN_h82PHVTCMA9vdoHrcZxH-x5mb11y1537t3rGzcM
>> The (AFAIK...) only workable solution around that problem is normalization
>> of JSON data so that it gets a unique/stable representation.  Proposed
>> alternative (Cleartext JWS):
>> {
>>     "now": "2018-04-16T11:23:06Z",
>>     "name": "Joe",
>>     "id": 2200063,
>>     "signature": {
>>       "alg": "ES256",
>>       "kid": "",
>>       "val":
>> "GagHnDBKhU7ynzLLH1Qs3tYmzbwxyokDtu7f0Iz1mB0GL-9ER_J5fJA9qz3IG6IR_jLHh3fsUEKAzB4GzLex2A"
>>     }
>> }
>> The "signature" property contains the signature, the other properties are
>> just arbitrary application data.
>> The #1 problem is the serialization of JSON Numbers [1].  It would be
>> FANTASTIC if this feature (which is 100% compatible with JSON), became a
>> part of the Java/JSON standards.
>> Recent standardization activity supported by Microsoft relying on this
>> feature:
>> Cheers,
>> Anders
>> 1] The idea is using ECMAScript's definition which I currently have
>> running for Java, C# .NET and Python 3

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