You may have read the most basics of Sign whitepaper but what I m going to tell you is most technical and most important part of Sign whitepaper.
Basically most projects are just loud noise but Sign is basically the most performing project which focuses on performance rather then just talking idle.
SIGN Supports VC-JWT and SD-JWT as Credential Formats. They Look the Same to Citizens. They Have Diferent Privacy Properties.
just noticed something in the SIGN identity technical specifications that most citizens using the system would never know about
the national digital identity stack supports multiple credential formats — VC-JWT, SD-JWT VC, and JSON-LD with BBS+. the whitepaper lists all three as supported.
a citizen using the system gets a credential. they dont know which Format it is. it looks the same in their wallet either way.
but the formats have different privacy properties.
VC-JWT is the Simplest and most widely supported format. every presentation of a VC-JWT credential produces a signature that can potentially be linked back to the issued credential. SD-JWT adds selective disclosure — you can present only some attributes.
but both VC-JWT and SD-JWT can be linked across presentations if the same credential is used multiple times at different verifiers
JSON-LD with BBS+ prevents this entirely. presentations are mathematically unlinkable. same credential, different verifier, different proof each time — cannot be Correlated.
the citizen gets whichever format the government chose during deployment. they have no visibility into which format their national ID credential uses. and the privacy difference between the formats is not minor it is the difference between a credential that builds a cross-verifier behavioral trail and one that doesnt.
still watching: whether any SIGN deployment publicly disclose which credential format their national ID uses and whether citizen's are told what that choice means for their privacy 👀