Ambiguity in `batch_size`: maximum number of keys or proofs array size?

[christol129]

Section 12.2.4-2.9.1 of OpenID4VCI states:

batch_size: REQUIRED. Integer value specifying the maximum array size for the proofs parameter in a Credential Request. It MUST be 2 or greater.

Considering appendices F and D, which allow key attestations with multiple keys provided within a single JWT, batch_size should arguably define the maximum number of keys, and not the size of the proofs array.

[jogu]

Agreed; we should be able to fix this in 1.1 or perhaps in an errata.

[joelposti]

Please see issue https://github.com/openid/OpenID4VCI/issues/645 and the associated pull request https://github.com/openid/OpenID4VCI/pull/640. The issue and the pull request aim to introduce the Proven Key term and use it in the batch_size description and in other places. The suggested change in that pull request would fix the ambiguity raised in this issue:

• batch_size: REQUIRED. Integer value specifying the maximum number of Proven Keys in the proofs parameter in a Credential Request. It MUST be 2 or greater.