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Re: Verifiable Text-based Claims

From: David Chadwick <D.W.Chadwick@kent.ac.uk>
Date: Sun, 17 Sep 2017 08:03:11 +0100
To: Adam Sobieski <adamsobieski@hotmail.com>, "public-credentials@w3.org" <public-credentials@w3.org>
Message-ID: <bdcd144d-02cf-8964-440e-8aaeda570611@kent.ac.uk>
Hi Adam

Given the broad remit of your supersession, I would suggest the
following for consideration
1. supporting suspension and resumption
2. when a VC is superceded, the new VC points to a different revocation
URL than the superceded VC

regards

David

On 16/09/2017 19:37, Adam Sobieski wrote:
> David,
> 
> Thank you. Supersession is described in more detail here:
> https://w3c-ccg.github.io/verifiable-news/sketchpad.html#supersession-of-statements.
> Though it differs from revocation, I’m thinking that, since supersession
> extends revocation, a supersession object could be at a URL
> indicated for a revocation object, providing additional information. If
> a system doesn’t process supersession, then it can process a
> supersession as a revocation, and, if a system does process
> supersession, then it obtains the additional information.
> 
> Here is an updated version:
> 
> {
>   "id":"https://example.com/users/1/revocations/ebfeb1f712ebc6f1/",
>   "type":["Revocation","Supersession"],
>   "issuer":"https://example.com/users/1/issuer/",
>   "issued":"2017-06-19T21:19:10Z",
>   "revoked":"https://example.com/facts/ebfeb1f712ebc6f1/",
>   "supersededBy":"https://example.com/facts/a3cc92841ac9c3f2/",
>   "reason":{
>     "id":"https://example.com/users/1/rationale/a3cc92841ac9c3f2/",
>     "type":"HTMLEmbeddedRationale"
>   },
>   "signature":{
>     "type":"LinkedDataSignature2017",
>     "created":"2017-06-19T21:19:10Z",
>     "creator":"https://example.com/users/1/keys/",
>     "nonce":"c0ae1c8e-c7e7-469f-b252-86e6a0e7387e",
>     "signatureValue":"BavEll0/I1zpYw8XNi1bgVg/sCneO4Jugez8RwDg/+MCR
>     VpjOboDoe4SxxKjkCOvKiCHGDvc4krqi6Z1n0UfqzxGfmatCuFibcC1wpsPRdW+g
>     GsutPTLzvueMWmFhwYmfIFpbBu95t501+rSLHIEuujM/+PXr9Cky6Ed+W3JT24="
>   }
> }
> 
> I’m still considering whether the features and expressiveness are worth
> the additional complexity.
> 
> 
> Best regards,
> Adam
> 
> *From:* David Chadwick <mailto:D.W.Chadwick@kent.ac.uk>
> *Sent:* ‎Saturday‎, ‎September‎ ‎16‎, ‎2017 ‎1‎:‎57‎ ‎PM
> *To:* Adam Sobieski <mailto:adamsobieski@hotmail.com>,
> public-credentials@w3.org <mailto:public-credentials@w3.org>
> 
> 
> 
> On 15/09/2017 15:27, Adam Sobieski wrote:
>> David,
>>
>> I see your point. I was thinking about the special case of journalistic
>> retractions. I updated the example indicating a revocation object.
>>
>> I’m thinking that we can also use revocations for superseding
>> statements, which allows features including the updating of and the
>> moving/redirection of statements.
> 
> This is conceptually something different from a revocation statement.
> Consequently I would suggest that the original statement is revoked and
> a new statement is issued.
> 
> regards
> 
> David
> 
>>
>> {
>>   "id":"https://example.com/users/1/revocations/ebfeb1f712ebc6f1/",
>>   "type":"Revocation",
>>   "issuer":"https://example.com/users/1/issuer/",
>>   "issued":"2017-06-19T21:19:10Z",
>>   "revoked":"https://example.com/facts/ebfeb1f712ebc6f1/",
>>   "supersededBy": "https://example.com/facts/a3cc92841ac9c3f2/"
>>   "signature":{
>>     "type":"LinkedDataSignature2017",
>>     "created":"2017-06-19T21:19:10Z",
>>     "creator":"https://example.com/users/1/keys/",
>>     "nonce":"c0ae1c8e-c7e7-469f-b252-86e6a0e7387e",
>>     "signatureValue":"BavEll0/I1zpYw8XNi1bgVg/sCneO4Jugez8RwDg/+MCR
>>     VpjOboDoe4SxxKjkCOvKiCHGDvc4krqi6Z1n0UfqzxGfmatCuFibcC1wpsPRdW+g
>>     GsutPTLzvueMWmFhwYmfIFpbBu95t501+rSLHIEuujM/+PXr9Cky6Ed+W3JT24="
>>   }
>> }
>>
>>
>> Best regards,
>> Adam
>>
>> *From:* David Chadwick <mailto:D.W.Chadwick@kent.ac.uk>
>> *Sent:* ‎Friday‎, ‎September‎ ‎15‎, ‎2017 ‎5‎:‎51‎ ‎AM
>> *To:* Adam Sobieski <mailto:adamsobieski@hotmail.com>,
>> public-credentials@w3.org <mailto:public-credentials@w3.org>
>>
>> Hi Adam
>>
>> the revocation statement should not contain details of the VC that has
>> been revoked as this is privacy invasive. There are no ACLs on
>> revocation lists (usually). All it should contain is the ID of the VC
>> that has been revoked, signed by the issuer (in a similar way to an
>> X.509 CRL). In this was an inspector who has the VC, has the unique ID
>> and can therefore check if the VC was revoked or not
>>
>> regards
>>
>> David
>>
>> On 15/09/2017 02:52, Adam Sobieski wrote:
>>> David,
>>>
>>> Updated the sketchpad per your recommendation:
>>>
>>
> https://w3c-ccg.github.io/verifiable-news/sketchpad.html#revocation-of-statements.
>>>
>>>
>>> Best regards,
>>> Adam
>>>
>>> *From:* David Chadwick <mailto:D.W.Chadwick@kent.ac.uk>
>>> *Sent:* ‎Thursday‎, ‎September‎ ‎14‎, ‎2017 ‎6‎:‎33‎ ‎PM
>>> *To:* public-credentials@w3.org <mailto:public-credentials@w3.org>
>>>
>>> Hi Adam
>>>
>>> On 14/09/2017 02:50, Adam Sobieski wrote:
>>>> David,
>>>>
>>>> Thank you. At
>>>>
>>>
>>
> https://w3c-ccg.github.io/verifiable-news/sketchpad.html#http-based-revocation,
>>>> I describe a system where Not found (404, 410) means revoked and Ok
>>>> (200) means not revoked. I see what you’re saying about Not found
>>>> meaning not revoked and Ok with a credential ID meaning revoked as well
>>>> as the feature of retrieving lists of revoked credentials. I think that
>>>> we should have both HTTP-based approaches. I updated the document with
>>>> these ideas.
>>>>
>>>
>>> In order to make the revocation more secure we placed a digitally signed
>>> CRL at the revoke URL. In this way a hacker is not able to hack the web
>>> site and get it to return OK with a message, because he does not have
>>> access to the issuer's private key
>>>
>>> regards
>>>
>>> David
>>>>
>>>> Best regards,
>>>> Adam
>>>>
>>>> *From:* David Chadwick <mailto:D.W.Chadwick@kent.ac.uk>
>>>> *Sent:* ‎Wednesday‎, ‎September‎ ‎13‎, ‎2017 ‎3‎:‎21‎ ‎PM
>>>> *To:* public-credentials@w3.org <mailto:public-credentials@w3.org>
>>>>
>>>> Hi Adam
>>>>
>>>> I notice that you are also including a revocation mechanism in your
>>>> claims. I produced an IETF draft 10 years ago which proposed something
>>>> very similar for X.509 certificates
>>>> ( See https://www.ietf.org/archive/id/draft-chadwick-webdav-00.txt).
>>>> Conceptually they are the same: the credential contains the URL where
>>>> the revocation information can be found. If Not found is returned the
>>>> credential has not been revoked, otherwise Ok is returned along with a
>>>> CRL of length 1 containing the ID of the revoked credential. My ID
>>>> contains other features as well, such as the ability to retrieve all the
>>>> revoked credentials of a particular issuer. You might wish to consider
>>>> this as well
>>>>
>>>> regards
>>>>
>>>> David
>>>>
>>>> On 12/09/2017 22:13, Adam Sobieski wrote:
>>>>> I’m exploring and sketching some ideas with regard to verifiable
>>>>> text-based claims.
>>>>>
>>>>> https://w3c-ccg.github.io/verifiable-news/sketchpad.html
>>>>>
>>>>> Questions, comments and suggestions welcomed.
>>>>>
>>>>>
>>>>> Best regards,
>>>>> Adam Sobieski
>>>>>
>>>>
>>>
Received on Sunday, 17 September 2017 07:03:38 UTC

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