all: on-chain oracle checkpoint syncing (#19543)

* all: implement simple checkpoint syncing

cmd, les, node: remove callback mechanism

cmd, node: remove callback definition

les: simplify the registrar

les: expose checkpoint rpc services in the light client

les, light: don't store untrusted receipt

cmd, contracts, les: discard stale checkpoint

cmd, contracts/registrar: loose restriction of registeration

cmd, contracts: add replay-protection

all: off-chain multi-signature contract

params: deploy checkpoint contract for rinkeby

cmd/registrar: add raw signing mode for registrar

cmd/registrar, contracts/registrar, les: fixed messages

* cmd/registrar, contracts/registrar: fix lints

* accounts/abi/bind, les: address comments

* cmd, contracts, les, light, params: minor checkpoint sync cleanups

* cmd, eth, les, light: move checkpoint config to config file

* cmd, eth, les, params: address comments

* eth, les, params: address comments

* cmd: polish up the checkpoint admin CLI

* cmd, contracts, params: deploy new version contract

* cmd/checkpoint-admin: add another flag for clef mode signing

* cmd, contracts, les: rename and regen checkpoint oracle with abigen

4 files changed, 1013 insertions, 0 deletions

diff --git a/contracts/checkpointoracle/contract/oracle.go b/contracts/checkpointoracle/contract/oracle.go
new file mode 100644
index 000000000..3bb351792
--- /dev/null
+++ b/contracts/checkpointoracle/contract/oracle.go
@@ -0,0 +1,415 @@
+// Code generated - DO NOT EDIT.
+// This file is a generated binding and any manual changes will be lost.
+
+package contract
+
+import (
+	"math/big"
+	"strings"
+
+	ethereum "github.com/ethereum/go-ethereum"
+	"github.com/ethereum/go-ethereum/accounts/abi"
+	"github.com/ethereum/go-ethereum/accounts/abi/bind"
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/core/types"
+	"github.com/ethereum/go-ethereum/event"
+)
+
+// Reference imports to suppress errors if they are not otherwise used.
+var (
+	_ = big.NewInt
+	_ = strings.NewReader
+	_ = ethereum.NotFound
+	_ = abi.U256
+	_ = bind.Bind
+	_ = common.Big1
+	_ = types.BloomLookup
+	_ = event.NewSubscription
+)
+
+// CheckpointOracleABI is the input ABI used to generate the binding from.
+const CheckpointOracleABI = "[{\"constant\":true,\"inputs\":[],\"name\":\"GetAllAdmin\",\"outputs\":[{\"name\":\"\",\"type\":\"address[]\"}],\"payable\":false,\"stateMutability\":\"view\",\"type\":\"function\"},{\"constant\":true,\"inputs\":[],\"name\":\"GetLatestCheckpoint\",\"outputs\":[{\"name\":\"\",\"type\":\"uint64\"},{\"name\":\"\",\"type\":\"bytes32\"},{\"name\":\"\",\"type\":\"uint256\"}],\"payable\":false,\"stateMutability\":\"view\",\"type\":\"function\"},{\"constant\":false,\"inputs\":[{\"name\":\"_recentNumber\",\"type\":\"uint256\"},{\"name\":\"_recentHash\",\"type\":\"bytes32\"},{\"name\":\"_hash\",\"type\":\"bytes32\"},{\"name\":\"_sectionIndex\",\"type\":\"uint64\"},{\"name\":\"v\",\"type\":\"uint8[]\"},{\"name\":\"r\",\"type\":\"bytes32[]\"},{\"name\":\"s\",\"type\":\"bytes32[]\"}],\"name\":\"SetCheckpoint\",\"outputs\":[{\"name\":\"\",\"type\":\"bool\"}],\"payable\":false,\"stateMutability\":\"nonpayable\",\"type\":\"function\"},{\"inputs\":[{\"name\":\"_adminlist\",\"type\":\"address[]\"},{\"name\":\"_sectionSize\",\"type\":\"uint256\"},{\"name\":\"_processConfirms\",\"type\":\"uint256\"},{\"name\":\"_threshold\",\"type\":\"uint256\"}],\"payable\":false,\"stateMutability\":\"nonpayable\",\"type\":\"constructor\"},{\"anonymous\":false,\"inputs\":[{\"indexed\":true,\"name\":\"index\",\"type\":\"uint64\"},{\"indexed\":false,\"name\":\"checkpointHash\",\"type\":\"bytes32\"},{\"indexed\":false,\"name\":\"v\",\"type\":\"uint8\"},{\"indexed\":false,\"name\":\"r\",\"type\":\"bytes32\"},{\"indexed\":false,\"name\":\"s\",\"type\":\"bytes32\"}],\"name\":\"NewCheckpointVote\",\"type\":\"event\"}]"
+
+// CheckpointOracleBin is the compiled bytecode used for deploying new contracts.
+const CheckpointOracleBin = `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`
+
+// DeployCheckpointOracle deploys a new Ethereum contract, binding an instance of CheckpointOracle to it.
+func DeployCheckpointOracle(auth *bind.TransactOpts, backend bind.ContractBackend, _adminlist []common.Address, _sectionSize *big.Int, _processConfirms *big.Int, _threshold *big.Int) (common.Address, *types.Transaction, *CheckpointOracle, error) {
+	parsed, err := abi.JSON(strings.NewReader(CheckpointOracleABI))
+	if err != nil {
+		return common.Address{}, nil, nil, err
+	}
+	address, tx, contract, err := bind.DeployContract(auth, parsed, common.FromHex(CheckpointOracleBin), backend, _adminlist, _sectionSize, _processConfirms, _threshold)
+	if err != nil {
+		return common.Address{}, nil, nil, err
+	}
+	return address, tx, &CheckpointOracle{CheckpointOracleCaller: CheckpointOracleCaller{contract: contract}, CheckpointOracleTransactor: CheckpointOracleTransactor{contract: contract}, CheckpointOracleFilterer: CheckpointOracleFilterer{contract: contract}}, nil
+}
+
+// CheckpointOracle is an auto generated Go binding around an Ethereum contract.
+type CheckpointOracle struct {
+	CheckpointOracleCaller     // Read-only binding to the contract
+	CheckpointOracleTransactor // Write-only binding to the contract
+	CheckpointOracleFilterer   // Log filterer for contract events
+}
+
+// CheckpointOracleCaller is an auto generated read-only Go binding around an Ethereum contract.
+type CheckpointOracleCaller struct {
+	contract *bind.BoundContract // Generic contract wrapper for the low level calls
+}
+
+// CheckpointOracleTransactor is an auto generated write-only Go binding around an Ethereum contract.
+type CheckpointOracleTransactor struct {
+	contract *bind.BoundContract // Generic contract wrapper for the low level calls
+}
+
+// CheckpointOracleFilterer is an auto generated log filtering Go binding around an Ethereum contract events.
+type CheckpointOracleFilterer struct {
+	contract *bind.BoundContract // Generic contract wrapper for the low level calls
+}
+
+// CheckpointOracleSession is an auto generated Go binding around an Ethereum contract,
+// with pre-set call and transact options.
+type CheckpointOracleSession struct {
+	Contract     *CheckpointOracle // Generic contract binding to set the session for
+	CallOpts     bind.CallOpts     // Call options to use throughout this session
+	TransactOpts bind.TransactOpts // Transaction auth options to use throughout this session
+}
+
+// CheckpointOracleCallerSession is an auto generated read-only Go binding around an Ethereum contract,
+// with pre-set call options.
+type CheckpointOracleCallerSession struct {
+	Contract *CheckpointOracleCaller // Generic contract caller binding to set the session for
+	CallOpts bind.CallOpts           // Call options to use throughout this session
+}
+
+// CheckpointOracleTransactorSession is an auto generated write-only Go binding around an Ethereum contract,
+// with pre-set transact options.
+type CheckpointOracleTransactorSession struct {
+	Contract     *CheckpointOracleTransactor // Generic contract transactor binding to set the session for
+	TransactOpts bind.TransactOpts           // Transaction auth options to use throughout this session
+}
+
+// CheckpointOracleRaw is an auto generated low-level Go binding around an Ethereum contract.
+type CheckpointOracleRaw struct {
+	Contract *CheckpointOracle // Generic contract binding to access the raw methods on
+}
+
+// CheckpointOracleCallerRaw is an auto generated low-level read-only Go binding around an Ethereum contract.
+type CheckpointOracleCallerRaw struct {
+	Contract *CheckpointOracleCaller // Generic read-only contract binding to access the raw methods on
+}
+
+// CheckpointOracleTransactorRaw is an auto generated low-level write-only Go binding around an Ethereum contract.
+type CheckpointOracleTransactorRaw struct {
+	Contract *CheckpointOracleTransactor // Generic write-only contract binding to access the raw methods on
+}
+
+// NewCheckpointOracle creates a new instance of CheckpointOracle, bound to a specific deployed contract.
+func NewCheckpointOracle(address common.Address, backend bind.ContractBackend) (*CheckpointOracle, error) {
+	contract, err := bindCheckpointOracle(address, backend, backend, backend)
+	if err != nil {
+		return nil, err
+	}
+	return &CheckpointOracle{CheckpointOracleCaller: CheckpointOracleCaller{contract: contract}, CheckpointOracleTransactor: CheckpointOracleTransactor{contract: contract}, CheckpointOracleFilterer: CheckpointOracleFilterer{contract: contract}}, nil
+}
+
+// NewCheckpointOracleCaller creates a new read-only instance of CheckpointOracle, bound to a specific deployed contract.
+func NewCheckpointOracleCaller(address common.Address, caller bind.ContractCaller) (*CheckpointOracleCaller, error) {
+	contract, err := bindCheckpointOracle(address, caller, nil, nil)
+	if err != nil {
+		return nil, err
+	}
+	return &CheckpointOracleCaller{contract: contract}, nil
+}
+
+// NewCheckpointOracleTransactor creates a new write-only instance of CheckpointOracle, bound to a specific deployed contract.
+func NewCheckpointOracleTransactor(address common.Address, transactor bind.ContractTransactor) (*CheckpointOracleTransactor, error) {
+	contract, err := bindCheckpointOracle(address, nil, transactor, nil)
+	if err != nil {
+		return nil, err
+	}
+	return &CheckpointOracleTransactor{contract: contract}, nil
+}
+
+// NewCheckpointOracleFilterer creates a new log filterer instance of CheckpointOracle, bound to a specific deployed contract.
+func NewCheckpointOracleFilterer(address common.Address, filterer bind.ContractFilterer) (*CheckpointOracleFilterer, error) {
+	contract, err := bindCheckpointOracle(address, nil, nil, filterer)
+	if err != nil {
+		return nil, err
+	}
+	return &CheckpointOracleFilterer{contract: contract}, nil
+}
+
+// bindCheckpointOracle binds a generic wrapper to an already deployed contract.
+func bindCheckpointOracle(address common.Address, caller bind.ContractCaller, transactor bind.ContractTransactor, filterer bind.ContractFilterer) (*bind.BoundContract, error) {
+	parsed, err := abi.JSON(strings.NewReader(CheckpointOracleABI))
+	if err != nil {
+		return nil, err
+	}
+	return bind.NewBoundContract(address, parsed, caller, transactor, filterer), nil
+}
+
+// Call invokes the (constant) contract method with params as input values and
+// sets the output to result. The result type might be a single field for simple
+// returns, a slice of interfaces for anonymous returns and a struct for named
+// returns.
+func (_CheckpointOracle *CheckpointOracleRaw) Call(opts *bind.CallOpts, result interface{}, method string, params ...interface{}) error {
+	return _CheckpointOracle.Contract.CheckpointOracleCaller.contract.Call(opts, result, method, params...)
+}
+
+// Transfer initiates a plain transaction to move funds to the contract, calling
+// its default method if one is available.
+func (_CheckpointOracle *CheckpointOracleRaw) Transfer(opts *bind.TransactOpts) (*types.Transaction, error) {
+	return _CheckpointOracle.Contract.CheckpointOracleTransactor.contract.Transfer(opts)
+}
+
+// Transact invokes the (paid) contract method with params as input values.
+func (_CheckpointOracle *CheckpointOracleRaw) Transact(opts *bind.TransactOpts, method string, params ...interface{}) (*types.Transaction, error) {
+	return _CheckpointOracle.Contract.CheckpointOracleTransactor.contract.Transact(opts, method, params...)
+}
+
+// Call invokes the (constant) contract method with params as input values and
+// sets the output to result. The result type might be a single field for simple
+// returns, a slice of interfaces for anonymous returns and a struct for named
+// returns.
+func (_CheckpointOracle *CheckpointOracleCallerRaw) Call(opts *bind.CallOpts, result interface{}, method string, params ...interface{}) error {
+	return _CheckpointOracle.Contract.contract.Call(opts, result, method, params...)
+}
+
+// Transfer initiates a plain transaction to move funds to the contract, calling
+// its default method if one is available.
+func (_CheckpointOracle *CheckpointOracleTransactorRaw) Transfer(opts *bind.TransactOpts) (*types.Transaction, error) {
+	return _CheckpointOracle.Contract.contract.Transfer(opts)
+}
+
+// Transact invokes the (paid) contract method with params as input values.
+func (_CheckpointOracle *CheckpointOracleTransactorRaw) Transact(opts *bind.TransactOpts, method string, params ...interface{}) (*types.Transaction, error) {
+	return _CheckpointOracle.Contract.contract.Transact(opts, method, params...)
+}
+
+// GetAllAdmin is a free data retrieval call binding the contract method 0x45848dfc.
+//
+// Solidity: function GetAllAdmin() constant returns(address[])
+func (_CheckpointOracle *CheckpointOracleCaller) GetAllAdmin(opts *bind.CallOpts) ([]common.Address, error) {
+	var (
+		ret0 = new([]common.Address)
+	)
+	out := ret0
+	err := _CheckpointOracle.contract.Call(opts, out, "GetAllAdmin")
+	return *ret0, err
+}
+
+// GetAllAdmin is a free data retrieval call binding the contract method 0x45848dfc.
+//
+// Solidity: function GetAllAdmin() constant returns(address[])
+func (_CheckpointOracle *CheckpointOracleSession) GetAllAdmin() ([]common.Address, error) {
+	return _CheckpointOracle.Contract.GetAllAdmin(&_CheckpointOracle.CallOpts)
+}
+
+// GetAllAdmin is a free data retrieval call binding the contract method 0x45848dfc.
+//
+// Solidity: function GetAllAdmin() constant returns(address[])
+func (_CheckpointOracle *CheckpointOracleCallerSession) GetAllAdmin() ([]common.Address, error) {
+	return _CheckpointOracle.Contract.GetAllAdmin(&_CheckpointOracle.CallOpts)
+}
+
+// GetLatestCheckpoint is a free data retrieval call binding the contract method 0x4d6a304c.
+//
+// Solidity: function GetLatestCheckpoint() constant returns(uint64, bytes32, uint256)
+func (_CheckpointOracle *CheckpointOracleCaller) GetLatestCheckpoint(opts *bind.CallOpts) (uint64, [32]byte, *big.Int, error) {
+	var (
+		ret0 = new(uint64)
+		ret1 = new([32]byte)
+		ret2 = new(*big.Int)
+	)
+	out := &[]interface{}{
+		ret0,
+		ret1,
+		ret2,
+	}
+	err := _CheckpointOracle.contract.Call(opts, out, "GetLatestCheckpoint")
+	return *ret0, *ret1, *ret2, err
+}
+
+// GetLatestCheckpoint is a free data retrieval call binding the contract method 0x4d6a304c.
+//
+// Solidity: function GetLatestCheckpoint() constant returns(uint64, bytes32, uint256)
+func (_CheckpointOracle *CheckpointOracleSession) GetLatestCheckpoint() (uint64, [32]byte, *big.Int, error) {
+	return _CheckpointOracle.Contract.GetLatestCheckpoint(&_CheckpointOracle.CallOpts)
+}
+
+// GetLatestCheckpoint is a free data retrieval call binding the contract method 0x4d6a304c.
+//
+// Solidity: function GetLatestCheckpoint() constant returns(uint64, bytes32, uint256)
+func (_CheckpointOracle *CheckpointOracleCallerSession) GetLatestCheckpoint() (uint64, [32]byte, *big.Int, error) {
+	return _CheckpointOracle.Contract.GetLatestCheckpoint(&_CheckpointOracle.CallOpts)
+}
+
+// SetCheckpoint is a paid mutator transaction binding the contract method 0xd459fc46.
+//
+// Solidity: function SetCheckpoint(uint256 _recentNumber, bytes32 _recentHash, bytes32 _hash, uint64 _sectionIndex, uint8[] v, bytes32[] r, bytes32[] s) returns(bool)
+func (_CheckpointOracle *CheckpointOracleTransactor) SetCheckpoint(opts *bind.TransactOpts, _recentNumber *big.Int, _recentHash [32]byte, _hash [32]byte, _sectionIndex uint64, v []uint8, r [][32]byte, s [][32]byte) (*types.Transaction, error) {
+	return _CheckpointOracle.contract.Transact(opts, "SetCheckpoint", _recentNumber, _recentHash, _hash, _sectionIndex, v, r, s)
+}
+
+// SetCheckpoint is a paid mutator transaction binding the contract method 0xd459fc46.
+//
+// Solidity: function SetCheckpoint(uint256 _recentNumber, bytes32 _recentHash, bytes32 _hash, uint64 _sectionIndex, uint8[] v, bytes32[] r, bytes32[] s) returns(bool)
+func (_CheckpointOracle *CheckpointOracleSession) SetCheckpoint(_recentNumber *big.Int, _recentHash [32]byte, _hash [32]byte, _sectionIndex uint64, v []uint8, r [][32]byte, s [][32]byte) (*types.Transaction, error) {
+	return _CheckpointOracle.Contract.SetCheckpoint(&_CheckpointOracle.TransactOpts, _recentNumber, _recentHash, _hash, _sectionIndex, v, r, s)
+}
+
+// SetCheckpoint is a paid mutator transaction binding the contract method 0xd459fc46.
+//
+// Solidity: function SetCheckpoint(uint256 _recentNumber, bytes32 _recentHash, bytes32 _hash, uint64 _sectionIndex, uint8[] v, bytes32[] r, bytes32[] s) returns(bool)
+func (_CheckpointOracle *CheckpointOracleTransactorSession) SetCheckpoint(_recentNumber *big.Int, _recentHash [32]byte, _hash [32]byte, _sectionIndex uint64, v []uint8, r [][32]byte, s [][32]byte) (*types.Transaction, error) {
+	return _CheckpointOracle.Contract.SetCheckpoint(&_CheckpointOracle.TransactOpts, _recentNumber, _recentHash, _hash, _sectionIndex, v, r, s)
+}
+
+// CheckpointOracleNewCheckpointVoteIterator is returned from FilterNewCheckpointVote and is used to iterate over the raw logs and unpacked data for NewCheckpointVote events raised by the CheckpointOracle contract.
+type CheckpointOracleNewCheckpointVoteIterator struct {
+	Event *CheckpointOracleNewCheckpointVote // Event containing the contract specifics and raw log
+
+	contract *bind.BoundContract // Generic contract to use for unpacking event data
+	event    string              // Event name to use for unpacking event data
+
+	logs chan types.Log        // Log channel receiving the found contract events
+	sub  ethereum.Subscription // Subscription for errors, completion and termination
+	done bool                  // Whether the subscription completed delivering logs
+	fail error                 // Occurred error to stop iteration
+}
+
+// Next advances the iterator to the subsequent event, returning whether there
+// are any more events found. In case of a retrieval or parsing error, false is
+// returned and Error() can be queried for the exact failure.
+func (it *CheckpointOracleNewCheckpointVoteIterator) Next() bool {
+	// If the iterator failed, stop iterating
+	if it.fail != nil {
+		return false
+	}
+	// If the iterator completed, deliver directly whatever's available
+	if it.done {
+		select {
+		case log := <-it.logs:
+			it.Event = new(CheckpointOracleNewCheckpointVote)
+			if err := it.contract.UnpackLog(it.Event, it.event, log); err != nil {
+				it.fail = err
+				return false
+			}
+			it.Event.Raw = log
+			return true
+
+		default:
+			return false
+		}
+	}
+	// Iterator still in progress, wait for either a data or an error event
+	select {
+	case log := <-it.logs:
+		it.Event = new(CheckpointOracleNewCheckpointVote)
+		if err := it.contract.UnpackLog(it.Event, it.event, log); err != nil {
+			it.fail = err
+			return false
+		}
+		it.Event.Raw = log
+		return true
+
+	case err := <-it.sub.Err():
+		it.done = true
+		it.fail = err
+		return it.Next()
+	}
+}
+
+// Error returns any retrieval or parsing error occurred during filtering.
+func (it *CheckpointOracleNewCheckpointVoteIterator) Error() error {
+	return it.fail
+}
+
+// Close terminates the iteration process, releasing any pending underlying
+// resources.
+func (it *CheckpointOracleNewCheckpointVoteIterator) Close() error {
+	it.sub.Unsubscribe()
+	return nil
+}
+
+// CheckpointOracleNewCheckpointVote represents a NewCheckpointVote event raised by the CheckpointOracle contract.
+type CheckpointOracleNewCheckpointVote struct {
+	Index          uint64
+	CheckpointHash [32]byte
+	V              uint8
+	R              [32]byte
+	S              [32]byte
+	Raw            types.Log // Blockchain specific contextual infos
+}
+
+// FilterNewCheckpointVote is a free log retrieval operation binding the contract event 0xce51ffa16246bcaf0899f6504f473cd0114f430f566cef71ab7e03d3dde42a41.
+//
+// Solidity: event NewCheckpointVote(uint64 indexed index, bytes32 checkpointHash, uint8 v, bytes32 r, bytes32 s)
+func (_CheckpointOracle *CheckpointOracleFilterer) FilterNewCheckpointVote(opts *bind.FilterOpts, index []uint64) (*CheckpointOracleNewCheckpointVoteIterator, error) {
+
+	var indexRule []interface{}
+	for _, indexItem := range index {
+		indexRule = append(indexRule, indexItem)
+	}
+
+	logs, sub, err := _CheckpointOracle.contract.FilterLogs(opts, "NewCheckpointVote", indexRule)
+	if err != nil {
+		return nil, err
+	}
+	return &CheckpointOracleNewCheckpointVoteIterator{contract: _CheckpointOracle.contract, event: "NewCheckpointVote", logs: logs, sub: sub}, nil
+}
+
+// WatchNewCheckpointVote is a free log subscription operation binding the contract event 0xce51ffa16246bcaf0899f6504f473cd0114f430f566cef71ab7e03d3dde42a41.
+//
+// Solidity: event NewCheckpointVote(uint64 indexed index, bytes32 checkpointHash, uint8 v, bytes32 r, bytes32 s)
+func (_CheckpointOracle *CheckpointOracleFilterer) WatchNewCheckpointVote(opts *bind.WatchOpts, sink chan<- *CheckpointOracleNewCheckpointVote, index []uint64) (event.Subscription, error) {
+
+	var indexRule []interface{}
+	for _, indexItem := range index {
+		indexRule = append(indexRule, indexItem)
+	}
+
+	logs, sub, err := _CheckpointOracle.contract.WatchLogs(opts, "NewCheckpointVote", indexRule)
+	if err != nil {
+		return nil, err
+	}
+	return event.NewSubscription(func(quit <-chan struct{}) error {
+		defer sub.Unsubscribe()
+		for {
+			select {
+			case log := <-logs:
+				// New log arrived, parse the event and forward to the user
+				event := new(CheckpointOracleNewCheckpointVote)
+				if err := _CheckpointOracle.contract.UnpackLog(event, "NewCheckpointVote", log); err != nil {
+					return err
+				}
+				event.Raw = log
+
+				select {
+				case sink <- event:
+				case err := <-sub.Err():
+					return err
+				case <-quit:
+					return nil
+				}
+			case err := <-sub.Err():
+				return err
+			case <-quit:
+				return nil
+			}
+		}
+	}), nil
+}
+
+// ParseNewCheckpointVote is a log parse operation binding the contract event 0xce51ffa16246bcaf0899f6504f473cd0114f430f566cef71ab7e03d3dde42a41.
+//
+// Solidity: event NewCheckpointVote(uint64 indexed index, bytes32 checkpointHash, uint8 v, bytes32 r, bytes32 s)
+func (_CheckpointOracle *CheckpointOracleFilterer) ParseNewCheckpointVote(log types.Log) (*CheckpointOracleNewCheckpointVote, error) {
+	event := new(CheckpointOracleNewCheckpointVote)
+	if err := _CheckpointOracle.contract.UnpackLog(event, "NewCheckpointVote", log); err != nil {
+		return nil, err
+	}
+	return event, nil
+}
diff --git a/contracts/checkpointoracle/contract/oracle.sol b/contracts/checkpointoracle/contract/oracle.sol
new file mode 100644
index 000000000..010644727
--- /dev/null
+++ b/contracts/checkpointoracle/contract/oracle.sol
@@ -0,0 +1,174 @@
+pragma solidity ^0.5.10;
+
+/**
+ * @title CheckpointOracle
+ * @author Gary Rong<garyrong@ethereum.org>, Martin Swende <martin.swende@ethereum.org>
+ * @dev Implementation of the blockchain checkpoint registrar.
+ */
+contract CheckpointOracle {
+    /*
+        Events
+    */
+
+    // NewCheckpointVote is emitted when a new checkpoint proposal receives a vote.
+    event NewCheckpointVote(uint64 indexed index, bytes32 checkpointHash, uint8 v, bytes32 r, bytes32 s);
+
+    /*
+        Public Functions
+    */
+    constructor(address[] memory _adminlist, uint _sectionSize, uint _processConfirms, uint _threshold) public {
+        for (uint i = 0; i < _adminlist.length; i++) {
+            admins[_adminlist[i]] = true;
+            adminList.push(_adminlist[i]);
+        }
+        sectionSize = _sectionSize;
+        processConfirms = _processConfirms;
+        threshold = _threshold;
+    }
+
+    /**
+     * @dev Get latest stable checkpoint information.
+     * @return section index
+     * @return checkpoint hash
+     * @return block height associated with checkpoint
+     */
+    function GetLatestCheckpoint()
+    view
+    public
+    returns(uint64, bytes32, uint) {
+        return (sectionIndex, hash, height);
+    }
+
+    // SetCheckpoint sets  a new checkpoint. It accepts a list of signatures
+    // @_recentNumber: a recent blocknumber, for replay protection
+    // @_recentHash : the hash of `_recentNumber`
+    // @_hash : the hash to set at _sectionIndex
+    // @_sectionIndex : the section index to set
+    // @v : the list of v-values
+    // @r : the list or r-values
+    // @s : the list of s-values
+    function SetCheckpoint(
+        uint _recentNumber,
+        bytes32 _recentHash,
+        bytes32 _hash,
+        uint64 _sectionIndex,
+        uint8[] memory v,
+        bytes32[] memory r,
+        bytes32[] memory s)
+        public
+        returns (bool)
+    {
+        // Ensure the sender is authorized.
+        require(admins[msg.sender]);
+
+        // These checks replay protection, so it cannot be replayed on forks,
+        // accidentally or intentionally
+        require(blockhash(_recentNumber) == _recentHash);
+
+        // Ensure the batch of signatures are valid.
+        require(v.length == r.length);
+        require(v.length == s.length);
+
+        // Filter out "future" checkpoint.
+        if (block.number < (_sectionIndex+1)*sectionSize+processConfirms) {
+            return false;
+        }
+        // Filter out "old" announcement
+        if (_sectionIndex < sectionIndex) {
+            return false;
+        }
+        // Filter out "stale" announcement
+        if (_sectionIndex == sectionIndex && (_sectionIndex != 0 || height != 0)) {
+            return false;
+        }
+        // Filter out "invalid" announcement
+        if (_hash == ""){
+            return false;
+        }
+
+        // EIP 191 style signatures
+        //
+        // Arguments when calculating hash to validate
+        // 1: byte(0x19) - the initial 0x19 byte
+        // 2: byte(0) - the version byte (data with intended validator)
+        // 3: this - the validator address
+        // --  Application specific data
+        // 4 : checkpoint section_index(uint64)
+        // 5 : checkpoint hash (bytes32)
+        //     hash = keccak256(checkpoint_index, section_head, cht_root, bloom_root)
+        bytes32 signedHash = keccak256(abi.encodePacked(byte(0x19), byte(0), this, _sectionIndex, _hash));
+
+        address lastVoter = address(0);
+
+        // In order for us not to have to maintain a mapping of who has already
+        // voted, and we don't want to count a vote twice, the signatures must
+        // be submitted in strict ordering.
+        for (uint idx = 0; idx < v.length; idx++){
+            address signer = ecrecover(signedHash, v[idx], r[idx], s[idx]);
+            require(admins[signer]);
+            require(uint256(signer) > uint256(lastVoter));
+            lastVoter = signer;
+            emit NewCheckpointVote(_sectionIndex, _hash, v[idx], r[idx], s[idx]);
+
+            // Sufficient signatures present, update latest checkpoint.
+            if (idx+1 >= threshold){
+                hash = _hash;
+                height = block.number;
+                sectionIndex = _sectionIndex;
+                return true;
+            }
+        }
+        // We shouldn't wind up here, reverting un-emits the events
+        revert();
+    }
+
+    /**
+     * @dev Get all admin addresses
+     * @return address list
+     */
+    function GetAllAdmin()
+    public
+    view
+    returns(address[] memory)
+    {
+        address[] memory ret = new address[](adminList.length);
+        for (uint i = 0; i < adminList.length; i++) {
+            ret[i] = adminList[i];
+        }
+        return ret;
+    }
+
+    /*
+        Fields
+    */
+    // A map of admin users who have the permission to update CHT and bloom Trie root
+    mapping(address => bool) admins;
+
+    // A list of admin users so that we can obtain all admin users.
+    address[] adminList;
+
+    // Latest stored section id
+    uint64 sectionIndex;
+
+    // The block height associated with latest registered checkpoint.
+    uint height;
+
+    // The hash of latest registered checkpoint.
+    bytes32 hash;
+
+    // The frequency for creating a checkpoint
+    //
+    // The default value should be the same as the checkpoint size(32768) in the ethereum.
+    uint sectionSize;
+
+    // The number of confirmations needed before a checkpoint can be registered.
+    // We have to make sure the checkpoint registered will not be invalid due to
+    // chain reorg.
+    //
+    // The default value should be the same as the checkpoint process confirmations(256)
+    // in the ethereum.
+    uint processConfirms;
+
+    // The required signatures to finalize a stable checkpoint.
+    uint threshold;
+}
diff --git a/contracts/checkpointoracle/oracle.go b/contracts/checkpointoracle/oracle.go
new file mode 100644
index 000000000..702e27d95
--- /dev/null
+++ b/contracts/checkpointoracle/oracle.go
@@ -0,0 +1,91 @@
+// Copyright 2018 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+// Package checkpointoracle is a an on-chain light client checkpoint oracle.
+package checkpointoracle
+
+//go:generate abigen --sol contract/oracle.sol --pkg contract --out contract/oracle.go
+
+import (
+	"crypto/ecdsa"
+	"errors"
+	"math/big"
+
+	"github.com/ethereum/go-ethereum/accounts/abi/bind"
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/contracts/checkpointoracle/contract"
+	"github.com/ethereum/go-ethereum/core/types"
+)
+
+// CheckpointOracle is a Go wrapper around an on-chain light client checkpoint oracle.
+type CheckpointOracle struct {
+	contract *contract.CheckpointOracle
+}
+
+// NewCheckpointOracle binds checkpoint contract and returns a registrar instance.
+func NewCheckpointOracle(contractAddr common.Address, backend bind.ContractBackend) (*CheckpointOracle, error) {
+	c, err := contract.NewCheckpointOracle(contractAddr, backend)
+	if err != nil {
+		return nil, err
+	}
+	return &CheckpointOracle{contract: c}, nil
+}
+
+// Contract returns the underlying contract instance.
+func (oracle *CheckpointOracle) Contract() *contract.CheckpointOracle {
+	return oracle.contract
+}
+
+// LookupCheckpointEvents searches checkpoint event for specific section in the
+// given log batches.
+func (oracle *CheckpointOracle) LookupCheckpointEvents(blockLogs [][]*types.Log, section uint64, hash common.Hash) []*contract.CheckpointOracleNewCheckpointVote {
+	var votes []*contract.CheckpointOracleNewCheckpointVote
+
+	for _, logs := range blockLogs {
+		for _, log := range logs {
+			event, err := oracle.contract.ParseNewCheckpointVote(*log)
+			if err != nil {
+				continue
+			}
+			if event.Index == section && common.Hash(event.CheckpointHash) == hash {
+				votes = append(votes, event)
+			}
+		}
+	}
+	return votes
+}
+
+// RegisterCheckpoint registers the checkpoint with a batch of associated signatures
+// that are collected off-chain and sorted by lexicographical order.
+//
+// Notably all signatures given should be transformed to "ethereum style" which transforms
+// v from 0/1 to 27/28 according to the yellow paper.
+func (oracle *CheckpointOracle) RegisterCheckpoint(key *ecdsa.PrivateKey, index uint64, hash []byte, rnum *big.Int, rhash [32]byte, sigs [][]byte) (*types.Transaction, error) {
+	var (
+		r [][32]byte
+		s [][32]byte
+		v []uint8
+	)
+	for i := 0; i < len(sigs); i++ {
+		if len(sigs[i]) != 65 {
+			return nil, errors.New("invalid signature")
+		}
+		r = append(r, common.BytesToHash(sigs[i][:32]))
+		s = append(s, common.BytesToHash(sigs[i][32:64]))
+		v = append(v, sigs[i][64])
+	}
+	return oracle.contract.SetCheckpoint(bind.NewKeyedTransactor(key), rnum, rhash, common.BytesToHash(hash), index, v, r, s)
+}
diff --git a/contracts/checkpointoracle/oracle_test.go b/contracts/checkpointoracle/oracle_test.go
new file mode 100644
index 000000000..8c123a3b4
--- /dev/null
+++ b/contracts/checkpointoracle/oracle_test.go
@@ -0,0 +1,333 @@
+// Copyright 2018 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+package checkpointoracle
+
+import (
+	"bytes"
+	"crypto/ecdsa"
+	"encoding/binary"
+	"errors"
+	"math/big"
+	"reflect"
+	"sort"
+	"testing"
+	"time"
+
+	"github.com/ethereum/go-ethereum/accounts/abi/bind"
+	"github.com/ethereum/go-ethereum/accounts/abi/bind/backends"
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/contracts/checkpointoracle/contract"
+	"github.com/ethereum/go-ethereum/core"
+	"github.com/ethereum/go-ethereum/crypto"
+	"github.com/ethereum/go-ethereum/params"
+)
+
+var (
+	emptyHash = [32]byte{}
+
+	checkpoint0 = params.TrustedCheckpoint{
+		SectionIndex: 0,
+		SectionHead:  common.HexToHash("0x7fa3c32f996c2bfb41a1a65b3d8ea3e0a33a1674cde43678ad6f4235e764d17d"),
+		CHTRoot:      common.HexToHash("0x98fc5d3de23a0fecebad236f6655533c157d26a1aedcd0852a514dc1169e6350"),
+		BloomRoot:    common.HexToHash("0x99b5adb52b337fe25e74c1c6d3835b896bd638611b3aebddb2317cce27a3f9fa"),
+	}
+	checkpoint1 = params.TrustedCheckpoint{
+		SectionIndex: 1,
+		SectionHead:  common.HexToHash("0x2d4dee68102125e59b0cc61b176bd89f0d12b3b91cfaf52ef8c2c82fb920c2d2"),
+		CHTRoot:      common.HexToHash("0x7d428008ece3b4c4ef5439f071930aad0bb75108d381308df73beadcd01ded95"),
+		BloomRoot:    common.HexToHash("0x652571f7736de17e7bbb427ac881474da684c6988a88bf51b10cca9a2ee148f4"),
+	}
+	checkpoint2 = params.TrustedCheckpoint{
+		SectionIndex: 2,
+		SectionHead:  common.HexToHash("0x61c0de578c0115b1dff8ef39aa600588c7c6ecb8a2f102003d7cf4c4146e9291"),
+		CHTRoot:      common.HexToHash("0x407a08a407a2bc3838b74ca3eb206903c9c8a186ccf5ef14af07794efff1970b"),
+		BloomRoot:    common.HexToHash("0x058b4161f558ce295a92925efc57f34f9210d5a30088d7475c183e0d3e58f5ac"),
+	}
+)
+
+var (
+	// The block frequency for creating checkpoint(only used in test)
+	sectionSize = big.NewInt(512)
+
+	// The number of confirmations needed to generate a checkpoint(only used in test).
+	processConfirms = big.NewInt(4)
+)
+
+// validateOperation executes the operation, watches and delivers all events fired by the backend and ensures the
+// correctness by assert function.
+func validateOperation(t *testing.T, c *contract.CheckpointOracle, backend *backends.SimulatedBackend, operation func(),
+	assert func(<-chan *contract.CheckpointOracleNewCheckpointVote) error, opName string) {
+	// Watch all events and deliver them to assert function
+	var (
+		sink   = make(chan *contract.CheckpointOracleNewCheckpointVote)
+		sub, _ = c.WatchNewCheckpointVote(nil, sink, nil)
+	)
+	defer func() {
+		// Close all subscribers
+		sub.Unsubscribe()
+	}()
+	operation()
+
+	// flush pending block
+	backend.Commit()
+	if err := assert(sink); err != nil {
+		t.Errorf("operation {%s} failed, err %s", opName, err)
+	}
+}
+
+// validateEvents checks that the correct number of contract events
+// fired by contract backend.
+func validateEvents(target int, sink interface{}) (bool, []reflect.Value) {
+	chanval := reflect.ValueOf(sink)
+	chantyp := chanval.Type()
+	if chantyp.Kind() != reflect.Chan || chantyp.ChanDir()&reflect.RecvDir == 0 {
+		return false, nil
+	}
+	count := 0
+	var recv []reflect.Value
+	timeout := time.After(1 * time.Second)
+	cases := []reflect.SelectCase{{Chan: chanval, Dir: reflect.SelectRecv}, {Chan: reflect.ValueOf(timeout), Dir: reflect.SelectRecv}}
+	for {
+		chose, v, _ := reflect.Select(cases)
+		if chose == 1 {
+			// Not enough event received
+			return false, nil
+		}
+		count += 1
+		recv = append(recv, v)
+		if count == target {
+			break
+		}
+	}
+	done := time.After(50 * time.Millisecond)
+	cases = cases[:1]
+	cases = append(cases, reflect.SelectCase{Chan: reflect.ValueOf(done), Dir: reflect.SelectRecv})
+	chose, _, _ := reflect.Select(cases)
+	// If chose equal 0, it means receiving redundant events.
+	return chose == 1, recv
+}
+
+func signCheckpoint(addr common.Address, privateKey *ecdsa.PrivateKey, index uint64, hash common.Hash) []byte {
+	// EIP 191 style signatures
+	//
+	// Arguments when calculating hash to validate
+	// 1: byte(0x19) - the initial 0x19 byte
+	// 2: byte(0) - the version byte (data with intended validator)
+	// 3: this - the validator address
+	// --  Application specific data
+	// 4 : checkpoint section_index(uint64)
+	// 5 : checkpoint hash (bytes32)
+	//     hash = keccak256(checkpoint_index, section_head, cht_root, bloom_root)
+	buf := make([]byte, 8)
+	binary.BigEndian.PutUint64(buf, index)
+	data := append([]byte{0x19, 0x00}, append(addr.Bytes(), append(buf, hash.Bytes()...)...)...)
+	sig, _ := crypto.Sign(crypto.Keccak256(data), privateKey)
+	sig[64] += 27 // Transform V from 0/1 to 27/28 according to the yellow paper
+	return sig
+}
+
+// assertSignature verifies whether the recovered signers are equal with expected.
+func assertSignature(addr common.Address, index uint64, hash [32]byte, r, s [32]byte, v uint8, expect common.Address) bool {
+	buf := make([]byte, 8)
+	binary.BigEndian.PutUint64(buf, index)
+	data := append([]byte{0x19, 0x00}, append(addr.Bytes(), append(buf, hash[:]...)...)...)
+	pubkey, err := crypto.Ecrecover(crypto.Keccak256(data), append(r[:], append(s[:], v-27)...))
+	if err != nil {
+		return false
+	}
+	var signer common.Address
+	copy(signer[:], crypto.Keccak256(pubkey[1:])[12:])
+	return bytes.Equal(signer.Bytes(), expect.Bytes())
+}
+
+type Account struct {
+	key  *ecdsa.PrivateKey
+	addr common.Address
+}
+type Accounts []Account
+
+func (a Accounts) Len() int           { return len(a) }
+func (a Accounts) Swap(i, j int)      { a[i], a[j] = a[j], a[i] }
+func (a Accounts) Less(i, j int) bool { return bytes.Compare(a[i].addr.Bytes(), a[j].addr.Bytes()) < 0 }
+
+func TestCheckpointRegister(t *testing.T) {
+	// Initialize test accounts
+	var accounts Accounts
+	for i := 0; i < 3; i++ {
+		key, _ := crypto.GenerateKey()
+		addr := crypto.PubkeyToAddress(key.PublicKey)
+		accounts = append(accounts, Account{key: key, addr: addr})
+	}
+	sort.Sort(accounts)
+
+	// Deploy registrar contract
+	transactOpts := bind.NewKeyedTransactor(accounts[0].key)
+	contractBackend := backends.NewSimulatedBackend(core.GenesisAlloc{accounts[0].addr: {Balance: big.NewInt(1000000000)}, accounts[1].addr: {Balance: big.NewInt(1000000000)}, accounts[2].addr: {Balance: big.NewInt(1000000000)}}, 10000000)
+	// 3 trusted signers, threshold 2
+	contractAddr, _, c, err := contract.DeployCheckpointOracle(transactOpts, contractBackend, []common.Address{accounts[0].addr, accounts[1].addr, accounts[2].addr}, sectionSize, processConfirms, big.NewInt(2))
+	if err != nil {
+		t.Error("Failed to deploy registrar contract", err)
+	}
+	contractBackend.Commit()
+
+	// getRecent returns block height and hash of the head parent.
+	getRecent := func() (*big.Int, common.Hash) {
+		parentNumber := new(big.Int).Sub(contractBackend.Blockchain().CurrentHeader().Number, big.NewInt(1))
+		parentHash := contractBackend.Blockchain().CurrentHeader().ParentHash
+		return parentNumber, parentHash
+	}
+	// collectSig generates specified number signatures.
+	collectSig := func(index uint64, hash common.Hash, n int, unauthorized *ecdsa.PrivateKey) (v []uint8, r [][32]byte, s [][32]byte) {
+		for i := 0; i < n; i++ {
+			sig := signCheckpoint(contractAddr, accounts[i].key, index, hash)
+			if unauthorized != nil {
+				sig = signCheckpoint(contractAddr, unauthorized, index, hash)
+			}
+			r = append(r, common.BytesToHash(sig[:32]))
+			s = append(s, common.BytesToHash(sig[32:64]))
+			v = append(v, sig[64])
+		}
+		return v, r, s
+	}
+	// insertEmptyBlocks inserts a batch of empty blocks to blockchain.
+	insertEmptyBlocks := func(number int) {
+		for i := 0; i < number; i++ {
+			contractBackend.Commit()
+		}
+	}
+	// assert checks whether the current contract status is same with
+	// the expected.
+	assert := func(index uint64, hash [32]byte, height *big.Int) error {
+		lindex, lhash, lheight, err := c.GetLatestCheckpoint(nil)
+		if err != nil {
+			return err
+		}
+		if lindex != index {
+			return errors.New("latest checkpoint index mismatch")
+		}
+		if !bytes.Equal(lhash[:], hash[:]) {
+			return errors.New("latest checkpoint hash mismatch")
+		}
+		if lheight.Cmp(height) != 0 {
+			return errors.New("latest checkpoint height mismatch")
+		}
+		return nil
+	}
+
+	// Test future checkpoint registration
+	validateOperation(t, c, contractBackend, func() {
+		number, hash := getRecent()
+		v, r, s := collectSig(0, checkpoint0.Hash(), 2, nil)
+		c.SetCheckpoint(transactOpts, number, hash, checkpoint0.Hash(), 0, v, r, s)
+	}, func(events <-chan *contract.CheckpointOracleNewCheckpointVote) error {
+		return assert(0, emptyHash, big.NewInt(0))
+	}, "test future checkpoint registration")
+
+	insertEmptyBlocks(int(sectionSize.Uint64() + processConfirms.Uint64()))
+
+	// Test transaction replay protection
+	validateOperation(t, c, contractBackend, func() {
+		number, hash := getRecent()
+		v, r, s := collectSig(0, checkpoint0.Hash(), 2, nil)
+		hash = common.HexToHash("deadbeef")
+		c.SetCheckpoint(transactOpts, number, hash, checkpoint0.Hash(), 0, v, r, s)
+	}, func(events <-chan *contract.CheckpointOracleNewCheckpointVote) error {
+		return assert(0, emptyHash, big.NewInt(0))
+	}, "test transaction replay protection")
+
+	// Test unauthorized signature checking
+	validateOperation(t, c, contractBackend, func() {
+		number, hash := getRecent()
+		u, _ := crypto.GenerateKey()
+		v, r, s := collectSig(0, checkpoint0.Hash(), 2, u)
+		c.SetCheckpoint(transactOpts, number, hash, checkpoint0.Hash(), 0, v, r, s)
+	}, func(events <-chan *contract.CheckpointOracleNewCheckpointVote) error {
+		return assert(0, emptyHash, big.NewInt(0))
+	}, "test unauthorized signature checking")
+
+	// Test un-multi-signature checkpoint registration
+	validateOperation(t, c, contractBackend, func() {
+		number, hash := getRecent()
+		v, r, s := collectSig(0, checkpoint0.Hash(), 1, nil)
+		c.SetCheckpoint(transactOpts, number, hash, checkpoint0.Hash(), 0, v, r, s)
+	}, func(events <-chan *contract.CheckpointOracleNewCheckpointVote) error {
+		return assert(0, emptyHash, big.NewInt(0))
+	}, "test un-multi-signature checkpoint registration")
+
+	// Test valid checkpoint registration
+	validateOperation(t, c, contractBackend, func() {
+		number, hash := getRecent()
+		v, r, s := collectSig(0, checkpoint0.Hash(), 2, nil)
+		c.SetCheckpoint(transactOpts, number, hash, checkpoint0.Hash(), 0, v, r, s)
+	}, func(events <-chan *contract.CheckpointOracleNewCheckpointVote) error {
+		if valid, recv := validateEvents(2, events); !valid {
+			return errors.New("receive incorrect number of events")
+		} else {
+			for i := 0; i < len(recv); i++ {
+				event := recv[i].Interface().(*contract.CheckpointOracleNewCheckpointVote)
+				if !assertSignature(contractAddr, event.Index, event.CheckpointHash, event.R, event.S, event.V, accounts[i].addr) {
+					return errors.New("recover signer failed")
+				}
+			}
+		}
+		number, _ := getRecent()
+		return assert(0, checkpoint0.Hash(), number.Add(number, big.NewInt(1)))
+	}, "test valid checkpoint registration")
+
+	distance := 3*sectionSize.Uint64() + processConfirms.Uint64() - contractBackend.Blockchain().CurrentHeader().Number.Uint64()
+	insertEmptyBlocks(int(distance))
+
+	// Test uncontinuous checkpoint registration
+	validateOperation(t, c, contractBackend, func() {
+		number, hash := getRecent()
+		v, r, s := collectSig(2, checkpoint2.Hash(), 2, nil)
+		c.SetCheckpoint(transactOpts, number, hash, checkpoint2.Hash(), 2, v, r, s)
+	}, func(events <-chan *contract.CheckpointOracleNewCheckpointVote) error {
+		if valid, recv := validateEvents(2, events); !valid {
+			return errors.New("receive incorrect number of events")
+		} else {
+			for i := 0; i < len(recv); i++ {
+				event := recv[i].Interface().(*contract.CheckpointOracleNewCheckpointVote)
+				if !assertSignature(contractAddr, event.Index, event.CheckpointHash, event.R, event.S, event.V, accounts[i].addr) {
+					return errors.New("recover signer failed")
+				}
+			}
+		}
+		number, _ := getRecent()
+		return assert(2, checkpoint2.Hash(), number.Add(number, big.NewInt(1)))
+	}, "test uncontinuous checkpoint registration")
+
+	// Test old checkpoint registration
+	validateOperation(t, c, contractBackend, func() {
+		number, hash := getRecent()
+		v, r, s := collectSig(1, checkpoint1.Hash(), 2, nil)
+		c.SetCheckpoint(transactOpts, number, hash, checkpoint1.Hash(), 1, v, r, s)
+	}, func(events <-chan *contract.CheckpointOracleNewCheckpointVote) error {
+		number, _ := getRecent()
+		return assert(2, checkpoint2.Hash(), number)
+	}, "test uncontinuous checkpoint registration")
+
+	// Test stale checkpoint registration
+	validateOperation(t, c, contractBackend, func() {
+		number, hash := getRecent()
+		v, r, s := collectSig(2, checkpoint2.Hash(), 2, nil)
+		c.SetCheckpoint(transactOpts, number, hash, checkpoint2.Hash(), 2, v, r, s)
+	}, func(events <-chan *contract.CheckpointOracleNewCheckpointVote) error {
+		number, _ := getRecent()
+		return assert(2, checkpoint2.Hash(), number.Sub(number, big.NewInt(1)))
+	}, "test stale checkpoint registration")
+}