Add content to section on selective disclosure

[msporny]

This PR adds content to the section on selective disclosure.

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Preview | Diff

[dlongley]

Suggested change

	Selective disclosure is a technique that enables the sender of a pre-signed
	message to reveal parts of the message without revealing the entire message. For
	example, selectively disclosing a digital driver's license for the purposes of
	renting a car might involve the entity presenting the license to only reveal the
	issuing authority, license number, birthday, and authorized motor vehicle class.
	Note that in this case, the license number is correlatable information that is
	being shared but some amount of privacy is still being preserved because the
	driver's full name and address are not being shared.
	Selective disclosure is a technique where the sender of a pre-signed
	message reveals only parts of the whole message without the receiver
	losing confidence in their authenticity. For example, one might selectively
	disclose a digital driver's license for the purpose of renting a car. This could
	involve revealing only the issuing authority, license number, birthday, and
	authorized motor vehicle class from the license. Note that in this case, the
	license number is correlatable information, but some amount of privacy
	is preserved because the driver's full name and address are not shared.

[decentralgabe]

Hmm, "without the receiver losing confidence in their authenticity" is a little unclear to me. Perhaps something like "....reveals only parts of the whole message without the receiver losing confidence in the authenticity of the parts"

or "....reveals only parts of the whole message while maintaining confidence in the authenticity of each of the parts"

[brentzundel]

fwiw, I prefer Ted's suggestion over this one

[msporny]

I've applied @TallTed's suggestion. @dlongley could you please re-review to make sure your suggestions made it in (based on Ted's changes).

[decentralgabe]

the correlation message is important. I know there are selective disclosure schemes which are correlation-resistant, such as https://github.com/decentralized-identity/crypto-wg/blob/main/work_items/spartan_zkSNARK_signatures.md -- maybe some language noting that this capability is implementation specific and correlation is a separate problem to solve for?

[mprorock]

would should also add language that notes that there are cases involving selective disclosure to meet need to know requirements, but that also require correlation - for example inspection results related to a shipment - the shipment id or lot number is correlatable, and must be for regulatory means, but you may wish to selectively release just the pass/fail result, rather than the details of the inspection to certain parties

[msporny]

@decentralgabe I added language pointing to the section on unlinkability to address your concern in 355186b.

[msporny]

@decentralgabe I added language pointing to the section on unlinkability to address your concern in 355186b.

[msporny]

@mprorock added your example here: f5fd469.

[decentralgabe]

what do you think about a note mentioning that not only does the creator of the initial message needs to utilize this capability, but the holder (receiver) needs to support it too (in a wallet, or however they may receive it), and also any potential verifiers -- or is this implied?

[msporny]

Done in c238ace.

[TallTed]

Will need another read-over after the suggestions above have been acted upon.

[mprorock]

generally approve - we will want to update and PR again after some of the suggestions are covered - especially around correlation and selective disclosure

[mprorock]

would should also add language that notes that there are cases involving selective disclosure to meet need to know requirements, but that also require correlation - for example inspection results related to a shipment - the shipment id or lot number is correlatable, and must be for regulatory means, but you may wish to selectively release just the pass/fail result, rather than the details of the inspection to certain parties

[mkhraisha]

Probably need to mention that some requirements around selective disclosure include that if a property is to be disclosed an accompanying property must also be disclosed. (not sure of the term/wording for something like this)

[mkhraisha]

would like ted's intro added.

[msporny]

@mkhraisha wrote:

Probably need to mention that some requirements around selective disclosure include that if a property is to be disclosed an accompanying property must also be disclosed. (not sure of the term/wording for something like this)

Done in 6b48a93.

[dlongley]

Thanks for managing all of the suggestions people have made here! Approved with... a few more suggestions. :)

[decentralgabe]

thanks for the changes Manu, this looks good.

[msporny]

Editorial, multiple reviews, changes requested and made, no objections, merging.