CIP-0036 | Adding the deregistration metadata format

CIP-0010/registry.json

@@ -69,10 +69,10 @@
   },
   {
     "transaction_metadatum_label": 61285,
-    "description": "CIP-0015 - Catalyst registration"
+    "description": "CIP-0015 - Catalyst witness"
   },
   {
     "transaction_metadatum_label": 61286,
-    "description": "CIP-0015 - Catalyst registration"
+    "description": "CIP-0015 - Catalyst deregistration"
   }
 ]

CIP-0036/README.md

@@ -83,7 +83,7 @@ as follows.
 This ensures that the voter's total voting power is never accidentally reduced through poor choices of weights,
 and that all voting powers are exact ADA.
 
-### Example 
+### Example - Registration
 
 Voting registration example:
 ```
@@ -137,6 +137,64 @@ Witness example:
 }
 ```
 
+### Deregistration metadata format (Catalyst)
+
+This deregistration format is currently only specified for Catalyst (vote_purpose=0), other voting chain purposes may handle a deregistration in a different way.
+
+Definition:
+- A deregistration removes all the voting power (associated stake amount) for the provided stake credential from the delegated vote-public-keys.
+- A deregistration resets the state of the stake credential on the voting chain like they were never registered before.
+- A deregistration transaction is a regular Cardano transaction with a specific transaction metadata associated with it.
+
+Notably, there should be three entries inside the metadata map (key 61286):
+ - The public key of the stake signing key
+ - A nonce that identifies that most recent deregistration.
+ - A non-negative integer that indicates the purpose of the vote. For now, we define 0 as the value to use for Catalyst, and leave others for future use.
+
+Be aware, the deregistration metadata key is 61286, and not 61284 like it is used for a registration! The registraton metadata format and specification is independent from the deregistration one, and may not be supported by all wallets/tools.
+
+### Example - Deregistration (Catalyst)
+
+```
+{
+  61286: {
+    // stake_pub - CBOR byte array
+    1: "0x57758911253f6b31df2a87c10eb08a2c9b8450768cb8dd0d378d93f7c2e220f0",
+    // nonce
+    2: 74412400,
+    // voting_purpose: 0 = Catalyst
+    3: 0
+  },
+  61285: {
+    // witness - ED25119 signature CBOR byte array
+    1: "0xadb7c90955c348e432545276798478f02ee7c2be61fd44d22f9de22131d9bcf0b23eb413766b74b9e7ba740e71266467a5d35363411346972db9e7b710b00603"
+  }
+}
+```
+CBOR-Hex:
+`A219EF66A301582057758911253F6B31DF2A87C10EB08A2C9B8450768CB8DD0D378D93F7C2E220F0021A046F7170030019EF65A1015840ADB7C90955C348E432545276798478F02EE7C2BE61FD44D22F9DE22131D9BCF0B23EB413766B74B9E7BA740E71266467A5D35363411346972DB9E7B710B00603`
+
+The entries under keys 1, 2 and 3 represent the staking credential on the Cardano network, a nonce, and a voting purpose, respectively.
+A deregistration with these metadata will be considered valid if the following conditions hold:
+
+- The stake credentials is a stake public-key byte array (of CBOR major type 2)
+- The nonce is an unsigned integer (of CBOR major type 0) that should be 
+  monotonically rising across all transactions with the same staking key.
+  The advised way to construct a nonce is to use the current slot number.
+  This is a simple way to keep the nonce increasing without having to access
+  the previous transaction data.
+- The voting_purpose is an unsigned integer (of CBOR major type 0)
+
+To produce the witness field in case of a staking public key, the CBOR representation of a map containing
+a single entry with key 61286 and the deregistration metadata map in the
+format above is formed, designated here as `sign_data`.
+This data is signed with the staking key as follows: first, the
+blake2b-256 hash of `sign_data` is obtained. This hash is then signed
+using the Ed25519 signature algorithm. The witness metadata entry is
+added to the transaction under key 61285 as a CBOR map with a single entry
+that consists of the integer key 1 and signature as obtained above as the byte array value.
+
+
 ### Metadata schema
 
 See the [schema file](./schema.cddl)
@@ -171,6 +229,9 @@ Fund 8:
  - added the `voting_purpose` field to limit the scope of the delegations.
  - rename the `staking_pub_key` field to `stake_credential` and `registration_signature` to `registration_witness` to allow for future credentials additions.
 
+Fund 10:
+ - added the `deregistration` metadata format.
+
 ## Copyright
 
 This CIP is licensed under [CC-BY-4.0](https://creativecommons.org/licenses/by/4.0/legalcode)

CIP-0036/schema.cddl

@@ -36,3 +36,19 @@ key_registration = {
 registration_witness = {
   1 : $stake_witness
 }
+
+
+deregistration_cbor = {
+  61286: key_deregistration,
+  61285: deregistration_witness
+}
+
+key_deregistration = {
+  1 : $stake_credential,
+  2 : $nonce,
+  ? 3 : $voting_purpose .default 0
+}
+
+deregistration_witness = {
+  1 : $stake_witness
+}