SDisclosure.parse() rejects array element disclosures

[mat-work]

SDisclosure.parse() rejects array element disclosures

Describe the bug

SDisclosure.parse() throws Invalid selective disclosure for any 2-element disclosure array, making it impossible to process selectively disclosable array elements in an SD-JWT.

To Reproduce

1. Issue an SD-JWT with a selectively disclosable array element (e.g. nationalities: ["DE", "FR"] where "FR" is SD)
2. The resulting disclosure for "FR" is a 2-element array: [salt, value] — no claim name, as required by RFC 9901 §4.2.2
3. Attempt to parse/verify the SD-JWT using SDisclosure.parse()
4. See Exception("Invalid selective disclosure") thrown

Expected behavior

SDisclosure.parse() should accept both:

• 3-element arrays [salt, claimName, claimValue] — object property disclosures
• 2-element arrays [salt, claimValue] — array element disclosures (no claim name)

Actual behavior

SDisclosure.parse() rejects any disclosure that is not exactly 3 elements, throwing Invalid selective disclosure. It always attempts to read it[1] as a claim name, which is incorrect for array element disclosures.

waltid-identity/waltid-libraries/sdjwt/waltid-sdjwt/src/commonMain/kotlin/id/walt/sdjwt/SDisclosure.kt

Line 34 in c4a4ff2

throw Exception("Invalid selective disclosure")

Environment

• os version: N/A (library bug, not environment-specific)
• docker version: N/A
• compose version: N/A
• java version: N/A

Screenshots

N/A

Additional context

RFC 9901 §4.2.2 explicitly defines array element disclosures as 2-element arrays with no claim name:

https://www.ietf.org/rfc/rfc9901.html#name-disclosures-for-array-eleme

The EUDI SD-JWT library (eudi-lib-jvm-sdjwt-kt) handles this correctly by branching on array size — size 2 yields an ArrayElement disclosure with a null claim name:

https://github.com/eu-digital-identity-wallet/eudi-lib-jvm-sdjwt-kt/blob/9e6575cb849942e337ab765903be94cd11f33528/src/main/kotlin/eu/europa/ec/eudi/sdjwt/Disclosure.kt#L92-L94

Fix: parse() should branch on array size — size 3 → object property (current behaviour), size 2 → array element (key absent or null), otherwise → error.

[linear]

WAL-1025

[JakeFernandes98]

Thanks for raising this issue! We have started tracking this on our internal task board and an engineer will pick this up soon. We have taken this on lower priority, but if you have a project that relies on this please reach out to discuss options for support contracts for dedicated support via https://walt.id/contact