feat: KeyRegistrar (#1421)

**Motivation:**

Operator key management should be brought into core and out of
middleware.

**Modifications:**

New core contract, `KeyRegistrar`, that manages operator keys and
supports ECDSA and BN254 signatures.

**Result:**

Simpler for both AVSs and operators.

---------

Co-authored-by: Yash Patil <[email protected]>

Author: eigenmikem

src/contracts/interfaces/IKeyRegistrar.sol

@@ -1,6 +1,23 @@
 // SPDX-License-Identifier: BUSL-1.1
 pragma solidity >=0.5.0;
 
+import {OperatorSet} from "../libraries/OperatorSetLib.sol";
+import {BN254} from "../libraries/BN254.sol";
+import "./ISemVerMixin.sol";
+
+interface IKeyRegistrarErrors {
+    /// Key Management
+    error KeyAlreadyRegistered();
+    error InvalidKeyFormat();
+    error ZeroAddress();
+    error ZeroPubkey();
+    error InvalidCurveType();
+    error InvalidKeypair();
+    error ConfigurationAlreadySet();
+    error OperatorSetNotConfigured();
+    error KeyNotFound(OperatorSet operatorSet, address operator);
+}
+
 interface IKeyRegistrarTypes {
     /// @dev Enum defining supported curve types
     enum CurveType {
@@ -15,3 +32,119 @@ interface IKeyRegistrarTypes {
         bytes keyData; // Flexible storage for different curve types
     }
 }
+
+interface IKeyRegistrarEvents is IKeyRegistrarTypes {
+    event KeyRegistered(OperatorSet operatorSet, address indexed operator, CurveType curveType, bytes pubkey);
+    event KeyDeregistered(OperatorSet operatorSet, address indexed operator, CurveType curveType);
+    event AggregateBN254KeyUpdated(OperatorSet operatorSet, BN254.G1Point newAggregateKey);
+    event OperatorSetConfigured(OperatorSet operatorSet, CurveType curveType);
+}
+
+interface IKeyRegistrar is IKeyRegistrarErrors, IKeyRegistrarEvents, ISemVerMixin {
+    /**
+     * @notice Configures an operator set with curve type
+     * @param operatorSet The operator set to configure
+     * @param curveType Type of curve (ECDSA, BN254)
+     * @dev Only authorized callers for the AVS can configure operator sets
+     */
+    function configureOperatorSet(OperatorSet memory operatorSet, CurveType curveType) external;
+
+    /**
+     * @notice Registers a cryptographic key for an operator with a specific operator set
+     * @param operator Address of the operator to register key for
+     * @param operatorSet The operator set to register the key for
+     * @param pubkey Public key bytes
+     * @param signature Signature proving ownership (only needed for BN254 keys)
+     * @dev Can be called by operator directly or by addresses they've authorized via PermissionController
+     * @dev Reverts if key is already registered
+     */
+    function registerKey(
+        address operator,
+        OperatorSet memory operatorSet,
+        bytes calldata pubkey,
+        bytes calldata signature
+    ) external;
+
+    /**
+     * @notice Deregisters a cryptographic key for an operator with a specific operator set
+     * @param operator Address of the operator to deregister key for
+     * @param operatorSet The operator set to deregister the key from
+     * @dev Can be called by avs directly or by addresses they've authorized via PermissionController
+     * @dev Reverts if key was not registered
+     * @dev Keys remain in global key registry to prevent reuse
+     */
+    function deregisterKey(address operator, OperatorSet memory operatorSet) external;
+
+    /**
+     * @notice Checks if an operator has a registered key
+     * @param operatorSet The operator set to check and update
+     * @param operator Address of the operator
+     * @return whether the operator has a registered key
+     * @dev This function is called by the AVSRegistrar when an operator registers for an AVS
+     * @dev Only authorized callers for the AVS can call this function
+     * @dev Reverts if operator doesn't have a registered key for this operator set
+     */
+    function checkKey(OperatorSet memory operatorSet, address operator) external view returns (bool);
+
+    /**
+     * @notice Checks if a key is registered for an operator with a specific operator set
+     * @param operatorSet The operator set to check
+     * @param operator Address of the operator
+     * @return True if the key is registered
+     */
+    function isRegistered(OperatorSet memory operatorSet, address operator) external view returns (bool);
+
+    /**
+     * @notice Gets the configuration for an operator set
+     * @param operatorSet The operator set to get configuration for
+     * @return The operator set configuration
+     */
+    function getOperatorSetCurveType(
+        OperatorSet memory operatorSet
+    ) external view returns (CurveType);
+
+    /**
+     * @notice Gets the BN254 public key for an operator with a specific operator set
+     * @param operatorSet The operator set to get the key for
+     * @param operator Address of the operator
+     * @return g1Point The BN254 G1 public key
+     * @return g2Point The BN254 G2 public key
+     */
+    function getBN254Key(
+        OperatorSet memory operatorSet,
+        address operator
+    ) external view returns (BN254.G1Point memory g1Point, BN254.G2Point memory g2Point);
+
+    /**
+     * @notice Gets the ECDSA public key for an operator with a specific operator set as bytes
+     * @param operatorSet The operator set to get the key for
+     * @param operator Address of the operator
+     * @return pubkey The ECDSA public key
+     */
+    function getECDSAKey(OperatorSet memory operatorSet, address operator) external view returns (bytes memory);
+
+    /**
+     * @notice Gets the ECDSA public key for an operator with a specific operator set
+     * @param operatorSet The operator set to get the key for
+     * @param operator Address of the operator
+     * @return pubkey The ECDSA public key
+     */
+    function getECDSAAddress(OperatorSet memory operatorSet, address operator) external view returns (address);
+
+    /**
+     * @notice Checks if a key hash is globally registered
+     * @param keyHash Hash of the key
+     * @return True if the key is globally registered
+     */
+    function isKeyGloballyRegistered(
+        bytes32 keyHash
+    ) external view returns (bool);
+
+    /**
+     * @notice Gets the key hash for an operator with a specific operator set
+     * @param operatorSet The operator set to get the key hash for
+     * @param operator Address of the operator
+     * @return keyHash The key hash
+     */
+    function getKeyHash(OperatorSet memory operatorSet, address operator) external view returns (bytes32);
+}