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Editorial improvements to the Explainer.
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Wind4Greg committed Dec 15, 2023
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21 changes: 11 additions & 10 deletions EXPLAINER.md
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Expand Up @@ -93,7 +93,7 @@ provides for selective disclosure and unlinkable proofs. It provides four
high-level functions that work within the issuer, holder, verifier model.
Specifically, an issuer uses the BBS Sign function to create a cryptographic
value known as a "BBS signature" which is used in signing the original
credential. A holder, on receipt of a credential signed with BBS, then verifies
credential. A holder, on receipt of a credential signed with BBS, can then verify
the credential with the BBS Verify function.

The holder then chooses information to selectively disclose from the received
Expand All @@ -107,7 +107,7 @@ ProofVerify function to verify the derived credential received from the holder.

Applying the BBS signature scheme to verifiable credentials involves the
processing specified in this specification. In general the suite uses the RDF
Dataset Normalization Algorithm to transform an input document into its
Dataset Canonicalization Algorithm to transform an input document into its
canonical form. An issuer then uses selective disclosure primitives to separate
the canonical form into mandatory and non-mandatory statements. These are
processed separately with other information to serve as the inputs to the BBS
Expand All @@ -117,10 +117,10 @@ functions and the BBS Verify function on receipt of the credential to ascertain
validity.

Similarly, on receipt of a BBS signed credential, a holder uses the RDF Dataset
Normalization Algorithm to transform an input document into its canonical form,
Canonicalization Algorithm to transform an input document into its canonical form,
and then applies selective disclosure primitives to separate the canonical form
into mandatory and selectively disclosed statements, which are appropriately
processed and serve as inputs to the BBS ProofGen function. Suitably processed,
processed and which serve as inputs to the BBS ProofGen function. Suitably processed,
the output of this function becomes the signed selectively disclosed credential
sent to a verifier. Using canonicalization and selective disclosure primitives,
the verifier can then use the BBS verifyProof function to validate the
Expand All @@ -138,8 +138,9 @@ the document that's shared.

### Unlinkability

Repeatedly sharing information in a document can create a correlation and
tracking risk. For example, repeatedly sharing a driver's license to prove that
Repeatedly sharing information in a document can result in undesirable
correlation and
tracking. For example, repeatedly sharing a driver's license to prove that
one is above a certain age can lead to using the driver's license number to
track the individual. A more appropriate sharing would be to just share one's
age in a way that cannot be used to track the individual. Note that a digital
Expand All @@ -159,10 +160,11 @@ with its *selective disclosure* option provides mechanisms for taking a
verifiable credential and reducing it to an ordered set of *statements*. These
procedures are slightly modified as to preserve the desirable unlinkability
properties of the BBS signature scheme, i.e., removing or reducing artifacts
that can lead to correlation/tracking. Hence we maximally reuse existing
that can lead to unwanted correlation/tracking. Hence we maximally reuse existing
procedures while preserving the desirable properties of the BBS signature scheme.
See the *privacy considerations* section of the document for a full analysis of
data leakage and unlinkability.
See the
[privacy considerations](https://w3c.github.io/vc-di-bbs/#privacy-considerations)
section of the document for a full analysis of data leakage and unlinkability.

## Considered alternatives

Expand All @@ -184,4 +186,3 @@ Additionally, the US Federal Government (DHS) has aligned their latest profile
for digital identity to use Verifiable Credentials and Data Integrity.

## Acknowledgements

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