Error code update and consolidation

[Wind4Greg]

This PR is in response to issues https://github.com/w3c/vc-di-eddsa/issues/82, https://github.com/w3c/vc-di-ecdsa/issues/63, and https://github.com/w3c/vc-di-bbs/issues/168. It aims to unify error handling across cryptosuite specification by reusing a consistent set of error codes from this data integrity specification. It does this by making sure that there are general error code categories for three main classes of errors: (1) proof generation errors, (2) proof verification errors, and (3) proof transformation errors.

In particular this PR generalizes MALFORMED_PROOF_ERROR to PROOF_VERIFICATION_ERROR.; subsumes MISMATCHED_PROOF_PURPOSE_ERROR into PROOF_VERIFICATION_ERROR; and adds PROOF_TRANSFORMATION_ERROR.

Analysis of error codes from issue https://github.com/w3c/vc-di-eddsa/issues/82:

Error Codes in Data Integrity Spec and Suggestions

• PROOF_GENERATION_ERROR (-16): A request to generate a proof failed. See Section 4.3 Add Proof, and Section 4.4 Add Proof Set/Chain. Notes: This could subsume the INVALID_PROOF_CONFIGURATION, INVALID_PROOF_DATETIME errors from EdDSA, ECDSA, and BBS specs.
• MALFORMED_PROOF_ERROR (-17): A proof that is malformed was detected. See Section 4.5 Verify Proof. ==> Propose to change this to the more general PROOF_VERIFICATION_ERROR: An error was encountered during proof verification...
• Propose PROOF_TRANSFORMATION_ERROR (number TBA): An error was encountered during the transformation process. Note: transformation occurs during generation and verification of proofs. Notes: This is currently used in EdDSA and ECDSA specs.
• MISMATCHED_PROOF_PURPOSE_ERROR (-18): The proofPurpose value in a proof did not match the expected value. See Section 4.5 Verify Proof. ==> Propose to subsume this into PROOF_VERIFICATION_ERROR?

Would not change any of the following:

• INVALID_DOMAIN_ERROR (-19): The domain value in a proof did not match the expected value. See Section 4.5 Verify Proof.
• INVALID_CHALLENGE_ERROR (-20): The challenge value in a proof did not match the expected value. See Section 4.5 Verify Proof.
• INVALID_VERIFICATION_METHOD_URL (-21): The verificationMethod value in a proof was malformed. See Section 4.7 Retrieve Verification Method.
• INVALID_CONTROLLER_DOCUMENT_ID (-22): The id value in a controller document was malformed. See Section 4.7 Retrieve Verification Method.
• INVALID_CONTROLLER_DOCUMENT (-23): The controller document was malformed. See Section 4.7 Retrieve Verification Method.
• INVALID_VERIFICATION_METHOD (-24): The verification method in a controller document was malformed. See Section 4.7 Retrieve Verification Method.
• INVALID_PROOF_PURPOSE_FOR_VERIFICATION_METHOD (-25): The verification method in a controller document was not associated using the expected verification relationship as expressed in the proofPurpose property in the proof. See Section 4.7 Retrieve Verification Method.

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Preview | Diff

[Wind4Greg]

Thanks @iherman. Also is there a special way that the cryptosuite specifications should be referencing these error codes? i.e., using links or other special ReSpec notation? I didn't have any examples in the EdDSA, ECDSA, or BBS cryptosuites to guide me. Cheers Greg

[iherman]

Thanks @iherman. Also is there a special way that the cryptosuite specifications should be referencing these error codes? i.e., using links or other special ReSpec notation? I didn't have any examples in the EdDSA, ECDSA, or BBS cryptosuites to guide me. Cheers Greg

I guess something like this should work:

<a data-cite="VC-DATA-INTEGRITY#MALFORMED_PROOF_ERROR">MALFORMED_PROOF_ERROR</a>

should work.

cc @msporny

[msporny]

Normative, multiple reviews, no changes requested, no objections, merging.