Add Service Endpoint to retrieve Secret Shares based on Tags

[kindlich]

Note: This issue comes from a discussion on carbynestack/ephemeral#17

Currently we have
intra-vcp/secret-shares to download a secret's shares based on their secret id.

For allowing to execute ephemeral games using tag-filters, we need an endpoint that

• Is accessible on the intra-vcp Endpoint /intra-vcp/** so that it later on is not authenticated
• Accepts a Tag-Filter (Query?) Parameter to select all Secrets that have all the provided tags (AND-combined), similar to the currently existing /secret-shares endpoint that retrieves MetaData
• Accepts Sort Property/Direction (Query?) Parameters.
  • This ensures that the output of secrets is the same order on all amphoras across the virtual cloud.
  • Also, some algorithms may depend on the order (e.g. if it's about time series with moving averages etc.)
  • If not provided by the user, it should be sort by creation-date in an ascending order
• Returns the Secret Shares as either
  • A single OutputDeliveryObject containing all Secret Shares concatenated
  • OR a new Transfer Object that is a listing of OutputDeliveryObjects with one per Secret and optionally additional metadata (like the ids of the secrets, etc.)
    EDIT: Preferred to have at least something that tells the number of shares, as this may be required later down the line. Example UseCase: allowing for Placeholders in algorithm code that are filled with parameters like {{NUMBER_OF_SECRETS}} or similar, which may be dynamically be calculated by ephemeral based on the provided inputs

NOT Part of this issue:

• Making sure that all endpoints return the same set of secrets (only the order is guaranteed by the endpoint). If in parallel a request deleted/re-tagged secrets so that some of the VCPs include a given secret while others don't, this is currently the user's responsibility.
  Part of resolving this issue may be adding a Notice to the README, though.

Open questions to discuss:

• Should this endpoint be HTTP or WebSocket (since it may transmit a lot of data, is HTTP enough?)
• Should this endpoint offer Paging or just return everything at once?

[github-actions]

This issue has been marked stale because it has been open for 90 days with no activity. It will be automatically closed in 30 days if no further activity occurs.

[strieflin]

While this functionality would surely add convenience, it also comes with a lot of complexity. Consensus on a common set and order of input objects is at the heart of this functionality and cannot be decoupled. Until this feature is implemented, filtering of objects can be done client-side.

[strieflin]

Part of the implementation has been done in carbynestack/cli#18 and carbynestack/ephemeral#17.

[github-actions]

This issue has been marked stale because it has been open for 90 days with no activity. It will be automatically closed in 30 days if no further activity occurs.