diff --git a/contracts/checkpointoracle/oracle.go b/contracts/checkpointoracle/oracle.go
index 2d725397b..1f273272a 100644
--- a/contracts/checkpointoracle/oracle.go
+++ b/contracts/checkpointoracle/oracle.go
@@ -29,8 +29,9 @@ import (
 	"github.com/ethereum/go-ethereum/core/types"
 )
 
-// CheckpointOracle is a Go wrapper around an on-chain light client checkpoint oracle.
+// CheckpointOracle is a Go wrapper around an on-chain checkpoint oracle contract.
 type CheckpointOracle struct {
+	address  common.Address
 	contract *contract.CheckpointOracle
 }
 
@@ -40,7 +41,12 @@ func NewCheckpointOracle(contractAddr common.Address, backend bind.ContractBacke
 	if err != nil {
 		return nil, err
 	}
-	return &CheckpointOracle{contract: c}, nil
+	return &CheckpointOracle{address: contractAddr, contract: c}, nil
+}
+
+// ContractAddr returns the address of contract.
+func (oracle *CheckpointOracle) ContractAddr() common.Address {
+	return oracle.address
 }
 
 // Contract returns the underlying contract instance.
diff --git a/go.sum b/go.sum
index edbb5ea2e..4d18c8c20 100644
--- a/go.sum
+++ b/go.sum
@@ -101,6 +101,7 @@ github.com/influxdata/influxdb v1.2.3-0.20180221223340-01288bdb0883 h1:FSeK4fZCo
 github.com/influxdata/influxdb v1.2.3-0.20180221223340-01288bdb0883/go.mod h1:qZna6X/4elxqT3yI9iZYdZrWWdeFOOprn86kgg4+IzY=
 github.com/jackpal/go-nat-pmp v1.0.2-0.20160603034137-1fa385a6f458 h1:6OvNmYgJyexcZ3pYbTI9jWx5tHo1Dee/tWbLMfPe2TA=
 github.com/jackpal/go-nat-pmp v1.0.2-0.20160603034137-1fa385a6f458/go.mod h1:QPH045xvCAeXUZOxsnwmrtiCoxIr9eob+4orBN1SBKc=
+github.com/jmespath/go-jmespath v0.0.0-20180206201540-c2b33e8439af h1:pmfjZENx5imkbgOkpRUYLnmbU7UEFbjtDA2hxJ1ichM=
 github.com/jmespath/go-jmespath v0.0.0-20180206201540-c2b33e8439af/go.mod h1:Nht3zPeWKUH0NzdCt2Blrr5ys8VGpn0CEB0cQHVjt7k=
 github.com/julienschmidt/httprouter v1.1.1-0.20170430222011-975b5c4c7c21 h1:F/iKcka0K2LgnKy/fgSBf235AETtm1n1TvBzqu40LE0=
 github.com/julienschmidt/httprouter v1.1.1-0.20170430222011-975b5c4c7c21/go.mod h1:SYymIcj16QtmaHHD7aYtjjsJG7VTCxuUUipMqKk8s4w=
diff --git a/les/api.go b/les/api.go
index ad511c9d6..f9b8c3445 100644
--- a/les/api.go
+++ b/les/api.go
@@ -350,5 +350,5 @@ func (api *PrivateLightAPI) GetCheckpointContractAddress() (string, error) {
 	if api.backend.oracle == nil {
 		return "", errNotActivated
 	}
-	return api.backend.oracle.config.Address.Hex(), nil
+	return api.backend.oracle.Contract().ContractAddr().Hex(), nil
 }
diff --git a/les/checkpointoracle.go b/les/checkpointoracle/oracle.go
similarity index 65%
rename from les/checkpointoracle.go
rename to les/checkpointoracle/oracle.go
index 5494e3d6d..c3983e1a9 100644
--- a/les/checkpointoracle.go
+++ b/les/checkpointoracle/oracle.go
@@ -14,7 +14,10 @@
 // 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 les
+// Package checkpointoracle is a wrapper of checkpoint oracle contract with
+// additional rules defined. This package can be used both in LES client or
+// server side for offering oracle related APIs.
+package checkpointoracle
 
 import (
 	"encoding/binary"
@@ -28,10 +31,10 @@ import (
 	"github.com/ethereum/go-ethereum/params"
 )
 
-// checkpointOracle is responsible for offering the latest stable checkpoint
-// generated and announced by the contract admins on-chain. The checkpoint is
-// verified by clients locally during the checkpoint syncing.
-type checkpointOracle struct {
+// CheckpointOracle is responsible for offering the latest stable checkpoint
+// generated and announced by the contract admins on-chain. The checkpoint can
+// be verified by clients locally during the checkpoint syncing.
+type CheckpointOracle struct {
 	config   *params.CheckpointOracleConfig
 	contract *checkpointoracle.CheckpointOracle
 
@@ -39,8 +42,8 @@ type checkpointOracle struct {
 	getLocal func(uint64) params.TrustedCheckpoint // Function used to retrieve local checkpoint
 }
 
-// newCheckpointOracle returns a checkpoint registrar handler.
-func newCheckpointOracle(config *params.CheckpointOracleConfig, getLocal func(uint64) params.TrustedCheckpoint) *checkpointOracle {
+// New creates a checkpoint oracle handler with given configs and callback.
+func New(config *params.CheckpointOracleConfig, getLocal func(uint64) params.TrustedCheckpoint) *CheckpointOracle {
 	if config == nil {
 		log.Info("Checkpoint registrar is not enabled")
 		return nil
@@ -51,41 +54,46 @@ func newCheckpointOracle(config *params.CheckpointOracleConfig, getLocal func(ui
 	}
 	log.Info("Configured checkpoint registrar", "address", config.Address, "signers", len(config.Signers), "threshold", config.Threshold)
 
-	return &checkpointOracle{
+	return &CheckpointOracle{
 		config:   config,
 		getLocal: getLocal,
 	}
 }
 
-// start binds the registrar contract and start listening to the
-// newCheckpointEvent for the server side.
-func (reg *checkpointOracle) start(backend bind.ContractBackend) {
-	contract, err := checkpointoracle.NewCheckpointOracle(reg.config.Address, backend)
+// Start binds the contract backend, initializes the oracle instance
+// and marks the status as available.
+func (oracle *CheckpointOracle) Start(backend bind.ContractBackend) {
+	contract, err := checkpointoracle.NewCheckpointOracle(oracle.config.Address, backend)
 	if err != nil {
 		log.Error("Oracle contract binding failed", "err", err)
 		return
 	}
-	if !atomic.CompareAndSwapInt32(&reg.running, 0, 1) {
+	if !atomic.CompareAndSwapInt32(&oracle.running, 0, 1) {
 		log.Error("Already bound and listening to registrar")
 		return
 	}
-	reg.contract = contract
+	oracle.contract = contract
 }
 
-// isRunning returns an indicator whether the registrar is running.
-func (reg *checkpointOracle) isRunning() bool {
-	return atomic.LoadInt32(&reg.running) == 1
+// IsRunning returns an indicator whether the oracle is running.
+func (oracle *CheckpointOracle) IsRunning() bool {
+	return atomic.LoadInt32(&oracle.running) == 1
 }
 
-// stableCheckpoint returns the stable checkpoint which was generated by local
+// Contract returns the underlying raw checkpoint oracle contract.
+func (oracle *CheckpointOracle) Contract() *checkpointoracle.CheckpointOracle {
+	return oracle.contract
+}
+
+// StableCheckpoint returns the stable checkpoint which was generated by local
 // indexers and announced by trusted signers.
-func (reg *checkpointOracle) stableCheckpoint() (*params.TrustedCheckpoint, uint64) {
+func (oracle *CheckpointOracle) StableCheckpoint() (*params.TrustedCheckpoint, uint64) {
 	// Retrieve the latest checkpoint from the contract, abort if empty
-	latest, hash, height, err := reg.contract.Contract().GetLatestCheckpoint(nil)
+	latest, hash, height, err := oracle.contract.Contract().GetLatestCheckpoint(nil)
 	if err != nil || (latest == 0 && hash == [32]byte{}) {
 		return nil, 0
 	}
-	local := reg.getLocal(latest)
+	local := oracle.getLocal(latest)
 
 	// The following scenarios may occur:
 	//
@@ -93,19 +101,18 @@ func (reg *checkpointOracle) stableCheckpoint() (*params.TrustedCheckpoint, uint
 	//   checkpoint which registered in the contract.
 	// * local checkpoint doesn't match with the registered one.
 	//
-	// In both cases, server won't send the **stable** checkpoint
-	// to the client(no worry, client can use hardcoded one instead).
-	if local.HashEqual(common.Hash(hash)) {
+	// In both cases, no stable checkpoint will be returned.
+	if local.HashEqual(hash) {
 		return &local, height.Uint64()
 	}
 	return nil, 0
 }
 
-// verifySigners recovers the signer addresses according to the signature and
+// VerifySigners recovers the signer addresses according to the signature and
 // checks whether there are enough approvals to finalize the checkpoint.
-func (reg *checkpointOracle) verifySigners(index uint64, hash [32]byte, signatures [][]byte) (bool, []common.Address) {
+func (oracle *CheckpointOracle) VerifySigners(index uint64, hash [32]byte, signatures [][]byte) (bool, []common.Address) {
 	// Short circuit if the given signatures doesn't reach the threshold.
-	if len(signatures) < int(reg.config.Threshold) {
+	if len(signatures) < int(oracle.config.Threshold) {
 		return false, nil
 	}
 	var (
@@ -128,7 +135,7 @@ func (reg *checkpointOracle) verifySigners(index uint64, hash [32]byte, signatur
 		//     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(reg.config.Address.Bytes(), append(buf, hash[:]...)...)...)
+		data := append([]byte{0x19, 0x00}, append(oracle.config.Address.Bytes(), append(buf, hash[:]...)...)...)
 		signatures[i][64] -= 27 // Transform V from 27/28 to 0/1 according to the yellow paper for verification.
 		pubkey, err := crypto.Ecrecover(crypto.Keccak256(data), signatures[i])
 		if err != nil {
@@ -139,14 +146,14 @@ func (reg *checkpointOracle) verifySigners(index uint64, hash [32]byte, signatur
 		if _, exist := checked[signer]; exist {
 			continue
 		}
-		for _, s := range reg.config.Signers {
+		for _, s := range oracle.config.Signers {
 			if s == signer {
 				signers = append(signers, signer)
 				checked[signer] = struct{}{}
 			}
 		}
 	}
-	threshold := reg.config.Threshold
+	threshold := oracle.config.Threshold
 	if uint64(len(signers)) < threshold {
 		log.Warn("Not enough signers to approve checkpoint", "signers", len(signers), "threshold", threshold)
 		return false, nil
diff --git a/les/client.go b/les/client.go
index c460f4c09..36d5a8d2f 100644
--- a/les/client.go
+++ b/les/client.go
@@ -36,6 +36,7 @@ import (
 	"github.com/ethereum/go-ethereum/eth/gasprice"
 	"github.com/ethereum/go-ethereum/event"
 	"github.com/ethereum/go-ethereum/internal/ethapi"
+	"github.com/ethereum/go-ethereum/les/checkpointoracle"
 	"github.com/ethereum/go-ethereum/light"
 	"github.com/ethereum/go-ethereum/log"
 	"github.com/ethereum/go-ethereum/node"
@@ -123,7 +124,7 @@ func New(ctx *node.ServiceContext, config *eth.Config) (*LightEthereum, error) {
 	if oracle == nil {
 		oracle = params.CheckpointOracles[genesisHash]
 	}
-	leth.oracle = newCheckpointOracle(oracle, leth.localCheckpoint)
+	leth.oracle = checkpointoracle.New(oracle, leth.localCheckpoint)
 
 	// Note: AddChildIndexer starts the update process for the child
 	leth.bloomIndexer.AddChildIndexer(leth.bloomTrieIndexer)
@@ -275,5 +276,5 @@ func (s *LightEthereum) SetContractBackend(backend bind.ContractBackend) {
 	if s.oracle == nil {
 		return
 	}
-	s.oracle.start(backend)
+	s.oracle.Start(backend)
 }
diff --git a/les/commons.go b/les/commons.go
index ad3c5aef3..b402c5176 100644
--- a/les/commons.go
+++ b/les/commons.go
@@ -27,6 +27,7 @@ import (
 	"github.com/ethereum/go-ethereum/core/types"
 	"github.com/ethereum/go-ethereum/eth"
 	"github.com/ethereum/go-ethereum/ethdb"
+	"github.com/ethereum/go-ethereum/les/checkpointoracle"
 	"github.com/ethereum/go-ethereum/light"
 	"github.com/ethereum/go-ethereum/p2p"
 	"github.com/ethereum/go-ethereum/p2p/discv5"
@@ -63,7 +64,7 @@ type lesCommons struct {
 	peers                        *peerSet
 	chainReader                  chainReader
 	chtIndexer, bloomTrieIndexer *core.ChainIndexer
-	oracle                       *checkpointOracle
+	oracle                       *checkpointoracle.CheckpointOracle
 
 	closeCh chan struct{}
 	wg      sync.WaitGroup
diff --git a/les/peer.go b/les/peer.go
index 801147df6..feb3910be 100644
--- a/les/peer.go
+++ b/les/peer.go
@@ -616,8 +616,8 @@ func (p *peer) Handshake(td *big.Int, head common.Hash, headNum uint64, genesis
 
 		// Add advertised checkpoint and register block height which
 		// client can verify the checkpoint validity.
-		if server.oracle != nil && server.oracle.isRunning() {
-			cp, height := server.oracle.stableCheckpoint()
+		if server.oracle != nil && server.oracle.IsRunning() {
+			cp, height := server.oracle.StableCheckpoint()
 			if cp != nil {
 				send = send.add("checkpoint/value", cp)
 				send = send.add("checkpoint/registerHeight", height)
diff --git a/les/server.go b/les/server.go
index e68903dd8..664eba971 100644
--- a/les/server.go
+++ b/les/server.go
@@ -24,6 +24,7 @@ import (
 	"github.com/ethereum/go-ethereum/common/mclock"
 	"github.com/ethereum/go-ethereum/core"
 	"github.com/ethereum/go-ethereum/eth"
+	"github.com/ethereum/go-ethereum/les/checkpointoracle"
 	"github.com/ethereum/go-ethereum/les/flowcontrol"
 	"github.com/ethereum/go-ethereum/light"
 	"github.com/ethereum/go-ethereum/log"
@@ -96,7 +97,7 @@ func NewLesServer(e *eth.Ethereum, config *eth.Config) (*LesServer, error) {
 	if oracle == nil {
 		oracle = params.CheckpointOracles[e.BlockChain().Genesis().Hash()]
 	}
-	srv.oracle = newCheckpointOracle(oracle, srv.localCheckpoint)
+	srv.oracle = checkpointoracle.New(oracle, srv.localCheckpoint)
 
 	// Initialize server capacity management fields.
 	srv.defParams = flowcontrol.ServerParams{
@@ -216,7 +217,7 @@ func (s *LesServer) SetContractBackend(backend bind.ContractBackend) {
 	if s.oracle == nil {
 		return
 	}
-	s.oracle.start(backend)
+	s.oracle.Start(backend)
 }
 
 // capacityManagement starts an event handler loop that updates the recharge curve of
diff --git a/les/sync.go b/les/sync.go
index 1214fefca..207686403 100644
--- a/les/sync.go
+++ b/les/sync.go
@@ -66,7 +66,7 @@ func (h *clientHandler) validateCheckpoint(peer *peer) error {
 	if err != nil {
 		return err
 	}
-	events := h.backend.oracle.contract.LookupCheckpointEvents(logs, cp.SectionIndex, cp.Hash())
+	events := h.backend.oracle.Contract().LookupCheckpointEvents(logs, cp.SectionIndex, cp.Hash())
 	if len(events) == 0 {
 		return errInvalidCheckpoint
 	}
@@ -78,7 +78,7 @@ func (h *clientHandler) validateCheckpoint(peer *peer) error {
 	for _, event := range events {
 		signatures = append(signatures, append(event.R[:], append(event.S[:], event.V)...))
 	}
-	valid, signers := h.backend.oracle.verifySigners(index, hash, signatures)
+	valid, signers := h.backend.oracle.VerifySigners(index, hash, signatures)
 	if !valid {
 		return errInvalidCheckpoint
 	}
@@ -134,7 +134,7 @@ func (h *clientHandler) synchronise(peer *peer) {
 	case hardcoded:
 		mode = legacyCheckpointSync
 		log.Debug("Disable checkpoint syncing", "reason", "checkpoint is hardcoded")
-	case h.backend.oracle == nil || !h.backend.oracle.isRunning():
+	case h.backend.oracle == nil || !h.backend.oracle.IsRunning():
 		if h.checkpoint == nil {
 			mode = lightSync // Downgrade to light sync unfortunately.
 		} else {
diff --git a/les/sync_test.go b/les/sync_test.go
index 8df6223b8..1c157b4fb 100644
--- a/les/sync_test.go
+++ b/les/sync_test.go
@@ -80,14 +80,14 @@ func testCheckpointSyncing(t *testing.T, protocol int, syncMode int) {
 			data := append([]byte{0x19, 0x00}, append(registrarAddr.Bytes(), append([]byte{0, 0, 0, 0, 0, 0, 0, 0}, cp.Hash().Bytes()...)...)...)
 			sig, _ := crypto.Sign(crypto.Keccak256(data), signerKey)
 			sig[64] += 27 // Transform V from 0/1 to 27/28 according to the yellow paper
-			if _, err := server.handler.server.oracle.contract.RegisterCheckpoint(bind.NewKeyedTransactor(signerKey), cp.SectionIndex, cp.Hash().Bytes(), new(big.Int).Sub(header.Number, big.NewInt(1)), header.ParentHash, [][]byte{sig}); err != nil {
+			if _, err := server.handler.server.oracle.Contract().RegisterCheckpoint(bind.NewKeyedTransactor(signerKey), cp.SectionIndex, cp.Hash().Bytes(), new(big.Int).Sub(header.Number, big.NewInt(1)), header.ParentHash, [][]byte{sig}); err != nil {
 				t.Error("register checkpoint failed", err)
 			}
 			server.backend.Commit()
 
 			// Wait for the checkpoint registration
 			for {
-				_, hash, _, err := server.handler.server.oracle.contract.Contract().GetLatestCheckpoint(nil)
+				_, hash, _, err := server.handler.server.oracle.Contract().Contract().GetLatestCheckpoint(nil)
 				if err != nil || hash == [32]byte{} {
 					time.Sleep(10 * time.Millisecond)
 					continue
@@ -164,14 +164,14 @@ func testMissOracleBackend(t *testing.T, hasCheckpoint bool) {
 	data := append([]byte{0x19, 0x00}, append(registrarAddr.Bytes(), append([]byte{0, 0, 0, 0, 0, 0, 0, 0}, cp.Hash().Bytes()...)...)...)
 	sig, _ := crypto.Sign(crypto.Keccak256(data), signerKey)
 	sig[64] += 27 // Transform V from 0/1 to 27/28 according to the yellow paper
-	if _, err := server.handler.server.oracle.contract.RegisterCheckpoint(bind.NewKeyedTransactor(signerKey), cp.SectionIndex, cp.Hash().Bytes(), new(big.Int).Sub(header.Number, big.NewInt(1)), header.ParentHash, [][]byte{sig}); err != nil {
+	if _, err := server.handler.server.oracle.Contract().RegisterCheckpoint(bind.NewKeyedTransactor(signerKey), cp.SectionIndex, cp.Hash().Bytes(), new(big.Int).Sub(header.Number, big.NewInt(1)), header.ParentHash, [][]byte{sig}); err != nil {
 		t.Error("register checkpoint failed", err)
 	}
 	server.backend.Commit()
 
 	// Wait for the checkpoint registration
 	for {
-		_, hash, _, err := server.handler.server.oracle.contract.Contract().GetLatestCheckpoint(nil)
+		_, hash, _, err := server.handler.server.oracle.Contract().Contract().GetLatestCheckpoint(nil)
 		if err != nil || hash == [32]byte{} {
 			time.Sleep(100 * time.Millisecond)
 			continue
diff --git a/les/test_helper.go b/les/test_helper.go
index ee3d7a32e..fb1965eeb 100644
--- a/les/test_helper.go
+++ b/les/test_helper.go
@@ -39,6 +39,7 @@ import (
 	"github.com/ethereum/go-ethereum/eth"
 	"github.com/ethereum/go-ethereum/ethdb"
 	"github.com/ethereum/go-ethereum/event"
+	"github.com/ethereum/go-ethereum/les/checkpointoracle"
 	"github.com/ethereum/go-ethereum/les/flowcontrol"
 	"github.com/ethereum/go-ethereum/light"
 	"github.com/ethereum/go-ethereum/p2p"
@@ -174,7 +175,7 @@ func newTestClientHandler(backend *backends.SimulatedBackend, odr *LesOdr, index
 			Alloc:    core.GenesisAlloc{bankAddr: {Balance: bankFunds}},
 			GasLimit: 100000000,
 		}
-		oracle *checkpointOracle
+		oracle *checkpointoracle.CheckpointOracle
 	)
 	genesis := gspec.MustCommit(db)
 	chain, _ := light.NewLightChain(odr, gspec.Config, engine, nil)
@@ -194,7 +195,7 @@ func newTestClientHandler(backend *backends.SimulatedBackend, odr *LesOdr, index
 				BloomRoot:    light.GetBloomTrieRoot(db, index, sectionHead),
 			}
 		}
-		oracle = newCheckpointOracle(checkpointConfig, getLocal)
+		oracle = checkpointoracle.New(checkpointConfig, getLocal)
 	}
 	client := &LightEthereum{
 		lesCommons: lesCommons{
@@ -218,7 +219,7 @@ func newTestClientHandler(backend *backends.SimulatedBackend, odr *LesOdr, index
 	client.handler = newClientHandler(ulcServers, ulcFraction, nil, client)
 
 	if client.oracle != nil {
-		client.oracle.start(backend)
+		client.oracle.Start(backend)
 	}
 	return client.handler
 }
@@ -230,7 +231,7 @@ func newTestServerHandler(blocks int, indexers []*core.ChainIndexer, db ethdb.Da
 			Alloc:    core.GenesisAlloc{bankAddr: {Balance: bankFunds}},
 			GasLimit: 100000000,
 		}
-		oracle *checkpointOracle
+		oracle *checkpointoracle.CheckpointOracle
 	)
 	genesis := gspec.MustCommit(db)
 
@@ -257,7 +258,7 @@ func newTestServerHandler(blocks int, indexers []*core.ChainIndexer, db ethdb.Da
 				BloomRoot:    light.GetBloomTrieRoot(db, index, sectionHead),
 			}
 		}
-		oracle = newCheckpointOracle(checkpointConfig, getLocal)
+		oracle = checkpointoracle.New(checkpointConfig, getLocal)
 	}
 	server := &LesServer{
 		lesCommons: lesCommons{
@@ -284,7 +285,7 @@ func newTestServerHandler(blocks int, indexers []*core.ChainIndexer, db ethdb.Da
 	server.clientPool.setLimits(10000, 10000) // Assign enough capacity for clientpool
 	server.handler = newServerHandler(server, simulation.Blockchain(), db, txpool, func() bool { return true })
 	if server.oracle != nil {
-		server.oracle.start(simulation)
+		server.oracle.Start(simulation)
 	}
 	server.servingQueue.setThreads(4)
 	server.handler.start()