Array of numbers should be allowed for _sd in IDisclosureFrame

[mikecat]

Currently, only strings are allowed for elements of the array _sd in IDisclosureFrame.

credo-ts/packages/core/src/modules/sd-jwt-vc/SdJwtVcOptions.ts

Lines 15 to 19 in b9bd214

	export interface IDisclosureFrame {
	_sd?: string[]
	_sd_decoy?: number
	[x: string]: string[] | number | IDisclosureFrame | undefined
	}

However, storing numbers there seems mandatory for enabling selective disclosure of elements of arrays.

https://github.com/openwallet-foundation/sd-jwt-js/blob/213de7e85b9820ca638ba3362fe4deee808e236e/packages/core/src/sdjwt.ts#L280-L284

Therefore, storing numbers should be allowed as elements of the array _sd in IDisclosureFrame.

[TimoGlastra]

Thanks for opening this issue! I think we need to add better support for selectively discloseable array elements in general.

Currently the prettyClaims doesn't correctly filter out array disclosures that are not disclosed i believe (but will have to check).

Regarding the disclosure frame syntax, how would you expect the syntax to look?

E.g. with a payload like this:

{
  "nationalities": ["NL", "DE"]
}

Would the disclosure frame look like this?

{
  "nationalities": {
    "_sd": [0, 1]
  }
}

This may be too limitting, as it won't allow for nested disclosures, so maybe something like this would be better:

{
  "nationalities": [
    { "...": true },
    { "...": true }
  ]
}

note the ... is special syntax from sd-jwt spec, so it would stay consistent (with true being replaced by the digest). That would also allow "_sd" to be added next to "...", to enable nested disclosures. And if there's an array in an array, we could allow an array as value to "...".

I will have to check the support for array disclosures in the sd-jwt-js library first, as i'm not sure if it's supported, and if so, what the disclosure frame syntax is. @berendsliedrecht @cre8 @lukasjhan is this supported in sd-jwt-js?

[TimoGlastra]

Ah i see the second link now, and it seems the first syntax is as supported by sd-jwt-js.

Then a simple typescript type update should be enough, probably with a few tests.

@mikecat are you willing to make a PR for this?

[TimoGlastra]

This also gives an error, not sure if this is supported in sd-jwt-js, but seems like a valid use case:

      driving_privileges: mobileDriversLicensePayload.driving_privileges.map((d) => ({
        _sd: ['vehicle_category_code', 'issue_date', 'expiry_date', 'codes'],
      })),