Credential verification fails when did:web issuer contains multiple verificationMethods

[shev-pro]

Credential verification fails when the credential issuer uses did:web with multiple verification methods (verificationMethods). According to the [DID Core Specification](https://www.w3.org/TR/did-core/), did:web supports multiple keys, but walt.id verification currently breaks when resolving such DIDs.

To Reproduce

Steps to reproduce the behavior:

1. Create a did:web with multiple keys in the DID Document, it is not possible actually with current version of WaltID (but still possible with other providers)
2. Issue a Verifiable Credential where the issuer is the did:web DID.
3. Use walt.id (version 0.11) to verify the credential.
4. Verification fails with an error related to key resolution.

Expected behavior

Verification should work with did:web issuers that have multiple keys, correctly identifying the correct key either from the kid field (if present) or by iterating through the available keys until a valid one is found.

Actual behavior

Verification eventually fails when did:web issuer has multiple keys, because is taken the first one from the set. The current implementation expects only one key in the DID Document and does not handle multi-key resolution.

Additional context

• Suggested fix: Update resolveToKey to handle kid directly (resolving to did:web#key-id when provided) and fallback to iterating over all verification methods if kid is absent.
• This is important for compatibility with W3C DID Core Specification, particularly for ecosystems with key rotation or multi-key issuers.
• Relevant spec section: [Verification Methods](https://www.w3.org/TR/did-core/#verification-methods)

[alegomes]

Hi and thanks again, @shev-pro

We are aware of that and the fix is already in the roadmap. I just can't guarantee when exactly it will be released. :-(

Best,
Ale

[shev-pro]

Hi @alegomes . I've created PR 986