Re: RDF Dataset Canonicalization - Formal Proof

Hi Tobias 

Good questions - which I’ve forwarded to the Singapore team for an authoritative answer 

Here’s my non-authoritative attempt 
- salts are an array of uuids I think - see https://edi3.org/specs/edi3-notary/develop/#611-salting-the-data 
- signature correlation - not sure but I’d mention that all use cases for this approach so far are for cross border trade documents where the subject is a public identifier such as a business number.  The design intent is that the identity is correlatable.  
- we haven’t noticed performance issues of any significance but we are talking volumes of only a few million per year 

Steven Capell
Mob: 0410 437854

> On 28 Mar 2021, at 2:53 pm, Tobias Looker <tobias.looker@mattr.global> wrote:
> 
> 
> > I’m a big fan of this approach, a form of redaction distinct from zk forms of selective disclosure.
> 
> > There was an attempt to spec one here in the CCG three-four years ago, but it died on the vine.
> 
> I'm also interested in learning more about this approach too, the questions I had last time were 
> 
> 1. How the salt for each redactable statement would be managed in a way that would not leak the abstraction that "Linked Data Proofs" sets up. For example would the attached proof block have to have a long array of salts?
> 2. Proof sizes, having to have a salt per-statement signed as a part of the proof would significantly increase the size of the proofs representation.
> 3. Signature correlation, perhaps not important in this scheme, but I think the approach would require revealing a fixed signature regardless of which parts are redacted from the original proof?
> 4. Performance? Also perhaps a non-issue but if anyone has info/benchmarks around how the scheme might scale with the size of the data graph signed, that would be great to look at?
> 
> Thanks,
>    
> Tobias Looker
> Mattr
> +64 (0) 27 378 0461
> tobias.looker@mattr.global
>    
> 
> This communication, including any attachments, is confidential. If you are not the intended recipient, you should not read it - please contact me immediately, destroy it, and do not copy or use any part of this communication or disclose anything about it. Thank you. Please note that this communication does not designate an information system for the purposes of the Electronic Transactions Act 2002.
> 
> 
>> On Sun, Mar 28, 2021 at 3:49 PM Christopher Allen <ChristopherA@lifewithalacrity.com> wrote:
>>> On Sat, Mar 27, 2021 at 7:22 PM Steve Capell <steve.capell@gmail.com> wrote:
>> 
>>> The Singapore government https://www.openattestation.com/ does this already . Version 3 is W3C VC data model compliant 
>>> 
>>> Each element is hashed (with salt I think) and then the hash of the hashed is the document hash that is notarised 
>>> 
>>> The main rationale is selective redaction (because the root hash is unchanged when some clear text is hidden). But I suppose it simplifies canonicalisation too...
>> 
>> I’m a big fan of this approach, a form of redaction distinct from zk forms of selective disclosure.
>> 
>> There was an attempt to spec one here in the CCG three-four years ago, but it died on the vine.
>> 
>> I’d be interested is seeing this spec & implementation. Any links?
>> 
>> — Christopher Allen [via iPhone] 
> 
> This communication, including any attachments, is confidential. If you are not the intended recipient, you should not read it - please contact me immediately, destroy it, and do not copy or use any part of this communication or disclose anything about it. Thank you. Please note that this communication does not designate an information system for the purposes of the Electronic Transactions Act 2002.