Integrate Anoncreds rs into credential and presentation endpoints

AnonCredsWalletType.md

@@ -0,0 +1,106 @@
+# AnonCreds-Rs Support
+
+A new wallet type has been added to Aca-Py to support the new anoncreds-rs library:
+
+```
+--wallet-type askar-anoncreds
+```
+
+When Aca-Py is run with this wallet type it will run with an Askar format wallet (and askar libraries) but will use `anoncreds-rs` instead of `credx`.
+
+There is a new package under `aries_cloudagent/anoncreds` with code that supports the new library.
+
+There are new endpoints (under `/anoncreds`) for creating a Schema and Credential Definition.  However the new anoncreds code is integrated into the existing Credential and Presentation endpoints (V2.0 endpoints only).
+
+Within the protocols, there are new `handler` libraries to support the new `anoncreds` format (these are in parallel to the existing `indy` libraries).
+
+The existing `indy` code are in:
+
+```
+aries_cloudagent/protocols/issue_credential/v2_0/formats/indy/handler.py
+aries_cloudagent/protocols/indy/anoncreds/pres_exch_handler.py
+aries_cloudagent/protocols/present_proof/v2_0/formats/indy/handler.py
+```
+
+The new `anoncreds` code is in:
+
+```
+aries_cloudagent/protocols/issue_credential/v2_0/formats/anoncreds/handler.py
+aries_cloudagent/protocols/present_proof/anoncreds/pres_exch_handler.py
+aries_cloudagent/protocols/present_proof/v2_0/formats/anoncreds/handler.py
+```
+
+The Indy handler checks to see if the wallet type is `askar-anoncreds` and if so delegates the calls to the anoncreds handler, for example:
+
+```
+        # Temporary shim while the new anoncreds library integration is in progress
+        wallet_type = profile.settings.get_value("wallet.type")
+        if wallet_type == "askar-anoncreds":
+            self.anoncreds_handler = AnonCredsPresExchangeHandler(profile)
+```
+
+... and then:
+
+```
+        # Temporary shim while the new anoncreds library integration is in progress
+        if self.anoncreds_handler:
+            return self.anoncreds_handler.get_format_identifier(message_type)
+```
+
+To run the alice/faber demo using the new anoncreds library, start the demo with:
+
+```
+--wallet-type askar-anoncreds
+```
+
+There are no anoncreds-specific integration tests, for the new anoncreds functionality the agents within the integration tests are started with:
+
+```
+--wallet-type askar-anoncreds
+```
+
+Everything should just work!!!
+
+Theoretically ATH should work with anoncreds as well, by setting the wallet type (see https://github.com/hyperledger/aries-agent-test-harness#extra-backchannel-specific-parameters).
+
+## Outstanding work
+
+- unit tests (in the new anoncreds package)
+- unit tests (review and possibly update unit tests for the credential and presentation integration)
+- revocation support - migrate code from `anoncreds-rs` branch
+- revocation support - complete the revocation implementation (support for unhappy path scenarios)
+- endorsement (not implemented with new anoncreds code)
+- testing - various scenarios like mediation, multitenancy etc.
+- wallet upgrade (askar to askar-anoncreds)
+- update V1.0 versions of the Credential and Presentation endpoints to use anoncreds
+- any other anoncreds issues - https://github.com/hyperledger/aries-cloudagent-python/issues?q=is%3Aopen+is%3Aissue+label%3AAnonCreds
+
+## Retiring old Indy and Askar (credx) Code
+
+The main changes for the Credential and Presentation support are in the following two files:
+
+```
+aries_cloudagent/protocols/issue_credential/v2_0/messages/cred_format.py
+aries_cloudagent/protocols/present_proof/v2_0/messages/pres_format.py
+```
+
+The `INDY` handler just need to be re-pointed to the new anoncreds handler, and then all the old Indy code can be retired.
+
+The new code is already in place (in comments).  For example for the Credential handler:
+
+```
+        To make the switch from indy to anoncreds replace the above with the following
+        INDY = FormatSpec(
+            "hlindy/",
+            DeferLoad(
+                "aries_cloudagent.protocols.present_proof.v2_0"
+                ".formats.anoncreds.handler.AnonCredsPresExchangeHandler"
+            ),
+        )
+```
+
+There is a bunch of duplicated code, i.e. the new anoncreds code was added either as new classes (as above) or as new methods within an existing class.
+
+Some new methods were added within the Ledger class.
+
+New unit tests were added - in some cases as methods within existing test classes, and in some cases as new classes (whichever was easiest at the time).

aries_cloudagent/config/argparse.py

@@ -1684,6 +1684,7 @@ def get_settings(self, args: Namespace) -> dict:
         if args.recreate_wallet:
             settings["wallet.recreate"] = True
         # check required settings for 'indy' wallets
+        # TODO should this also include "askar*" wallet types?
         if settings["wallet.type"] == "indy":
             # requires name, key
             if not args.wallet_name or not args.wallet_key: