How to deterministically match the transaction_data_hashes to the transaction_data?

[TimoGlastra]

OID4VP allows to include an array of transaction_data entries, where each entry can specify an array of credential_ids that are allowed to include the transaction data hash. Also an array of hash algorithms can be configured.

Let's say we have a request:

• requesting three credentials, credential A, credential B, credential C
• requesting two transaction hashes to be signed over, the first can be signed over by credential A & B, the second by credential B & C.
• They allow sha-256 and sha-512.

How would i know which of the hashes in the response match to which of the transaction_data entries from the response? We can't match the indexes as not all credentials sign over all hashes. We also can't pre-compute the hashes as there's multiple hashing methods possible (or we would have to pre-compute all possible hash values for all possible hash algorithms?).

Edit: see #443 for possible solution