Refactor registry related event and functions to a new interface

Signed-off-by: Jim Zhang <jim.zhang@kaleido.io>

Author: jimthematrix

solidity/contracts/lib/interfaces/izeto.sol

@@ -53,7 +53,6 @@ interface IZeto {
         address indexed submitter,
         bytes data
     );
-    event IdentityRegistered(uint256[2] publicKey, bytes data);
 
     /**
      * @dev Returns the name of the token.

solidity/contracts/lib/interfaces/izeto_kyc.sol

@@ -0,0 +1,33 @@
+// Copyright © 2025 Kaleido, Inc.
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+pragma solidity ^0.8.27;
+
+import {Commonlib} from "../common.sol";
+
+interface IZetoKyc {
+    event IdentityRegistered(uint256[2] publicKey, bytes data);
+
+    function register(
+        uint256[2] memory publicKey,
+        bytes calldata data
+    ) external;
+
+    function isRegistered(
+        uint256[2] memory publicKey
+    ) external view returns (bool);
+
+    function getIdentitiesRoot() external view returns (uint256);
+}

solidity/contracts/lib/registry.sol

@@ -20,6 +20,7 @@ import {SmtLib} from "@iden3/contracts/lib/SmtLib.sol";
 import {PoseidonUnit2L, PoseidonUnit3L} from "@iden3/contracts/lib/Poseidon.sol";
 import {Commonlib} from "./common.sol";
 import {IZeto} from "./interfaces/izeto.sol";
+import {IZetoKyc} from "./interfaces/izeto_kyc.sol";
 
 uint256 constant MAX_SMT_DEPTH = 64;
 
@@ -29,7 +30,7 @@ uint256 constant MAX_SMT_DEPTH = 64;
 ///   submitters can generate proofs of membership for the
 ///   accounts in a privacy-preserving manner.
 /// @author Kaleido, Inc.
-abstract contract Registry is OwnableUpgradeable {
+abstract contract Registry is OwnableUpgradeable, IZetoKyc {
     SmtLib.Data internal _publicKeysTree;
     using SmtLib for SmtLib.Data;
 
@@ -39,19 +40,11 @@ abstract contract Registry is OwnableUpgradeable {
         _publicKeysTree.initialize(MAX_SMT_DEPTH);
     }
 
-    /// @dev Register a new Zeto account
-    /// @param publicKey The public Babyjubjub key to register
-    function _register(
+    function register(
         uint256[2] memory publicKey,
         bytes calldata data
-    ) internal {
-        uint256 nodeHash = _getIdentitiesLeafNodeHash(publicKey);
-        SmtLib.Node memory node = _publicKeysTree.getNode(nodeHash);
-        if (node.nodeType != SmtLib.NodeType.EMPTY) {
-            revert AlreadyRegistered(publicKey);
-        }
-        _publicKeysTree.addLeaf(nodeHash, nodeHash);
-        emit IZeto.IdentityRegistered(publicKey, data);
+    ) public onlyOwner {
+        _register(publicKey, data);
     }
 
     /// @dev returns whether the given public key is registered
@@ -69,6 +62,21 @@ abstract contract Registry is OwnableUpgradeable {
         return _publicKeysTree.getRoot();
     }
 
+    /// @dev Register a new Zeto account
+    /// @param publicKey The public Babyjubjub key to register
+    function _register(
+        uint256[2] memory publicKey,
+        bytes calldata data
+    ) internal {
+        uint256 nodeHash = _getIdentitiesLeafNodeHash(publicKey);
+        SmtLib.Node memory node = _publicKeysTree.getNode(nodeHash);
+        if (node.nodeType != SmtLib.NodeType.EMPTY) {
+            revert AlreadyRegistered(publicKey);
+        }
+        _publicKeysTree.addLeaf(nodeHash, nodeHash);
+        emit IdentityRegistered(publicKey, data);
+    }
+
     function _getIdentitiesLeafNodeHash(
         uint256[2] memory publicKey
     ) internal pure returns (uint256) {

solidity/contracts/zeto_anon_enc_nullifier_kyc.sol

@@ -74,13 +74,6 @@ contract Zeto_AnonEncNullifierKyc is
 
     function _authorizeUpgrade(address) internal override onlyOwner {}
 
-    function register(
-        uint256[2] memory publicKey,
-        bytes calldata data
-    ) public onlyOwner {
-        _register(publicKey, data);
-    }
-
     function constructPublicInputs(
         uint256[] memory nullifiers,
         uint256[] memory outputs,

solidity/contracts/zeto_anon_nullifier_kyc.sol

@@ -89,13 +89,6 @@ contract Zeto_AnonNullifierKyc is
 
     function _authorizeUpgrade(address) internal override onlyOwner {}
 
-    function register(
-        uint256[2] memory publicKey,
-        bytes calldata data
-    ) public onlyOwner {
-        _register(publicKey, data);
-    }
-
     function constructPublicInputs(
         uint256[] memory nullifiers,
         uint256[] memory outputs,