diff --git a/auth/store.go b/auth/store.go
index dd1bd199d..ec1ecbf0b 100644
--- a/auth/store.go
+++ b/auth/store.go
@@ -25,6 +25,7 @@ import (
 	"sync/atomic"
 
 	"github.com/coreos/etcd/auth/authpb"
+	"github.com/coreos/etcd/etcdserver/api/v3rpc/rpctypes"
 	pb "github.com/coreos/etcd/etcdserver/etcdserverpb"
 	"github.com/coreos/etcd/mvcc/backend"
 
@@ -999,9 +1000,9 @@ func (as *authStore) AuthInfoFromCtx(ctx context.Context) (*AuthInfo, error) {
 	}
 
 	//TODO(mitake|hexfusion) review unifying key names
-	ts, ok := md["token"]
+	ts, ok := md[rpctypes.TokenFieldNameGRPC]
 	if !ok {
-		ts, ok = md["authorization"]
+		ts, ok = md[rpctypes.TokenFieldNameSwagger]
 	}
 	if !ok {
 		return nil, nil
@@ -1092,7 +1093,7 @@ func (as *authStore) WithRoot(ctx context.Context) context.Context {
 	}
 
 	mdMap := map[string]string{
-		"token": token,
+		rpctypes.TokenFieldNameGRPC: token,
 	}
 	tokenMD := metadata.New(mdMap)
 
diff --git a/auth/store_test.go b/auth/store_test.go
index 842c0f8ae..b50db7488 100644
--- a/auth/store_test.go
+++ b/auth/store_test.go
@@ -25,6 +25,7 @@ import (
 	"time"
 
 	"github.com/coreos/etcd/auth/authpb"
+	"github.com/coreos/etcd/etcdserver/api/v3rpc/rpctypes"
 	pb "github.com/coreos/etcd/etcdserver/etcdserverpb"
 	"github.com/coreos/etcd/mvcc/backend"
 
@@ -467,19 +468,19 @@ func TestAuthInfoFromCtx(t *testing.T) {
 		t.Error(err)
 	}
 
-	ctx = metadata.NewIncomingContext(context.Background(), metadata.New(map[string]string{"token": "Invalid Token"}))
+	ctx = metadata.NewIncomingContext(context.Background(), metadata.New(map[string]string{rpctypes.TokenFieldNameGRPC: "Invalid Token"}))
 	_, err = as.AuthInfoFromCtx(ctx)
 	if err != ErrInvalidAuthToken {
 		t.Errorf("expected %v, got %v", ErrInvalidAuthToken, err)
 	}
 
-	ctx = metadata.NewIncomingContext(context.Background(), metadata.New(map[string]string{"token": "Invalid.Token"}))
+	ctx = metadata.NewIncomingContext(context.Background(), metadata.New(map[string]string{rpctypes.TokenFieldNameGRPC: "Invalid.Token"}))
 	_, err = as.AuthInfoFromCtx(ctx)
 	if err != ErrInvalidAuthToken {
 		t.Errorf("expected %v, got %v", ErrInvalidAuthToken, err)
 	}
 
-	ctx = metadata.NewIncomingContext(context.Background(), metadata.New(map[string]string{"token": resp.Token}))
+	ctx = metadata.NewIncomingContext(context.Background(), metadata.New(map[string]string{rpctypes.TokenFieldNameGRPC: resp.Token}))
 	ai, err = as.AuthInfoFromCtx(ctx)
 	if err != nil {
 		t.Error(err)
@@ -523,7 +524,7 @@ func TestAuthInfoFromCtxRace(t *testing.T) {
 	donec := make(chan struct{})
 	go func() {
 		defer close(donec)
-		ctx := metadata.NewIncomingContext(context.Background(), metadata.New(map[string]string{"token": "test"}))
+		ctx := metadata.NewIncomingContext(context.Background(), metadata.New(map[string]string{rpctypes.TokenFieldNameGRPC: "test"}))
 		as.AuthInfoFromCtx(ctx)
 	}()
 	as.UserAdd(&pb.AuthUserAddRequest{Name: "test"})
diff --git a/clientv3/auth.go b/clientv3/auth.go
index d03372b9f..023892032 100644
--- a/clientv3/auth.go
+++ b/clientv3/auth.go
@@ -100,70 +100,70 @@ type Auth interface {
 	RoleDelete(ctx context.Context, role string) (*AuthRoleDeleteResponse, error)
 }
 
-type auth struct {
+type authClient struct {
 	remote   pb.AuthClient
 	callOpts []grpc.CallOption
 }
 
 func NewAuth(c *Client) Auth {
-	api := &auth{remote: RetryAuthClient(c)}
+	api := &authClient{remote: RetryAuthClient(c)}
 	if c != nil {
 		api.callOpts = c.callOpts
 	}
 	return api
 }
 
-func (auth *auth) AuthEnable(ctx context.Context) (*AuthEnableResponse, error) {
+func (auth *authClient) AuthEnable(ctx context.Context) (*AuthEnableResponse, error) {
 	resp, err := auth.remote.AuthEnable(ctx, &pb.AuthEnableRequest{}, auth.callOpts...)
 	return (*AuthEnableResponse)(resp), toErr(ctx, err)
 }
 
-func (auth *auth) AuthDisable(ctx context.Context) (*AuthDisableResponse, error) {
+func (auth *authClient) AuthDisable(ctx context.Context) (*AuthDisableResponse, error) {
 	resp, err := auth.remote.AuthDisable(ctx, &pb.AuthDisableRequest{}, auth.callOpts...)
 	return (*AuthDisableResponse)(resp), toErr(ctx, err)
 }
 
-func (auth *auth) UserAdd(ctx context.Context, name string, password string) (*AuthUserAddResponse, error) {
+func (auth *authClient) UserAdd(ctx context.Context, name string, password string) (*AuthUserAddResponse, error) {
 	resp, err := auth.remote.UserAdd(ctx, &pb.AuthUserAddRequest{Name: name, Password: password}, auth.callOpts...)
 	return (*AuthUserAddResponse)(resp), toErr(ctx, err)
 }
 
-func (auth *auth) UserDelete(ctx context.Context, name string) (*AuthUserDeleteResponse, error) {
+func (auth *authClient) UserDelete(ctx context.Context, name string) (*AuthUserDeleteResponse, error) {
 	resp, err := auth.remote.UserDelete(ctx, &pb.AuthUserDeleteRequest{Name: name}, auth.callOpts...)
 	return (*AuthUserDeleteResponse)(resp), toErr(ctx, err)
 }
 
-func (auth *auth) UserChangePassword(ctx context.Context, name string, password string) (*AuthUserChangePasswordResponse, error) {
+func (auth *authClient) UserChangePassword(ctx context.Context, name string, password string) (*AuthUserChangePasswordResponse, error) {
 	resp, err := auth.remote.UserChangePassword(ctx, &pb.AuthUserChangePasswordRequest{Name: name, Password: password}, auth.callOpts...)
 	return (*AuthUserChangePasswordResponse)(resp), toErr(ctx, err)
 }
 
-func (auth *auth) UserGrantRole(ctx context.Context, user string, role string) (*AuthUserGrantRoleResponse, error) {
+func (auth *authClient) UserGrantRole(ctx context.Context, user string, role string) (*AuthUserGrantRoleResponse, error) {
 	resp, err := auth.remote.UserGrantRole(ctx, &pb.AuthUserGrantRoleRequest{User: user, Role: role}, auth.callOpts...)
 	return (*AuthUserGrantRoleResponse)(resp), toErr(ctx, err)
 }
 
-func (auth *auth) UserGet(ctx context.Context, name string) (*AuthUserGetResponse, error) {
+func (auth *authClient) UserGet(ctx context.Context, name string) (*AuthUserGetResponse, error) {
 	resp, err := auth.remote.UserGet(ctx, &pb.AuthUserGetRequest{Name: name}, auth.callOpts...)
 	return (*AuthUserGetResponse)(resp), toErr(ctx, err)
 }
 
-func (auth *auth) UserList(ctx context.Context) (*AuthUserListResponse, error) {
+func (auth *authClient) UserList(ctx context.Context) (*AuthUserListResponse, error) {
 	resp, err := auth.remote.UserList(ctx, &pb.AuthUserListRequest{}, auth.callOpts...)
 	return (*AuthUserListResponse)(resp), toErr(ctx, err)
 }
 
-func (auth *auth) UserRevokeRole(ctx context.Context, name string, role string) (*AuthUserRevokeRoleResponse, error) {
+func (auth *authClient) UserRevokeRole(ctx context.Context, name string, role string) (*AuthUserRevokeRoleResponse, error) {
 	resp, err := auth.remote.UserRevokeRole(ctx, &pb.AuthUserRevokeRoleRequest{Name: name, Role: role}, auth.callOpts...)
 	return (*AuthUserRevokeRoleResponse)(resp), toErr(ctx, err)
 }
 
-func (auth *auth) RoleAdd(ctx context.Context, name string) (*AuthRoleAddResponse, error) {
+func (auth *authClient) RoleAdd(ctx context.Context, name string) (*AuthRoleAddResponse, error) {
 	resp, err := auth.remote.RoleAdd(ctx, &pb.AuthRoleAddRequest{Name: name}, auth.callOpts...)
 	return (*AuthRoleAddResponse)(resp), toErr(ctx, err)
 }
 
-func (auth *auth) RoleGrantPermission(ctx context.Context, name string, key, rangeEnd string, permType PermissionType) (*AuthRoleGrantPermissionResponse, error) {
+func (auth *authClient) RoleGrantPermission(ctx context.Context, name string, key, rangeEnd string, permType PermissionType) (*AuthRoleGrantPermissionResponse, error) {
 	perm := &authpb.Permission{
 		Key:      []byte(key),
 		RangeEnd: []byte(rangeEnd),
@@ -173,22 +173,22 @@ func (auth *auth) RoleGrantPermission(ctx context.Context, name string, key, ran
 	return (*AuthRoleGrantPermissionResponse)(resp), toErr(ctx, err)
 }
 
-func (auth *auth) RoleGet(ctx context.Context, role string) (*AuthRoleGetResponse, error) {
+func (auth *authClient) RoleGet(ctx context.Context, role string) (*AuthRoleGetResponse, error) {
 	resp, err := auth.remote.RoleGet(ctx, &pb.AuthRoleGetRequest{Role: role}, auth.callOpts...)
 	return (*AuthRoleGetResponse)(resp), toErr(ctx, err)
 }
 
-func (auth *auth) RoleList(ctx context.Context) (*AuthRoleListResponse, error) {
+func (auth *authClient) RoleList(ctx context.Context) (*AuthRoleListResponse, error) {
 	resp, err := auth.remote.RoleList(ctx, &pb.AuthRoleListRequest{}, auth.callOpts...)
 	return (*AuthRoleListResponse)(resp), toErr(ctx, err)
 }
 
-func (auth *auth) RoleRevokePermission(ctx context.Context, role string, key, rangeEnd string) (*AuthRoleRevokePermissionResponse, error) {
+func (auth *authClient) RoleRevokePermission(ctx context.Context, role string, key, rangeEnd string) (*AuthRoleRevokePermissionResponse, error) {
 	resp, err := auth.remote.RoleRevokePermission(ctx, &pb.AuthRoleRevokePermissionRequest{Role: role, Key: []byte(key), RangeEnd: []byte(rangeEnd)}, auth.callOpts...)
 	return (*AuthRoleRevokePermissionResponse)(resp), toErr(ctx, err)
 }
 
-func (auth *auth) RoleDelete(ctx context.Context, role string) (*AuthRoleDeleteResponse, error) {
+func (auth *authClient) RoleDelete(ctx context.Context, role string) (*AuthRoleDeleteResponse, error) {
 	resp, err := auth.remote.RoleDelete(ctx, &pb.AuthRoleDeleteRequest{Role: role}, auth.callOpts...)
 	return (*AuthRoleDeleteResponse)(resp), toErr(ctx, err)
 }
diff --git a/clientv3/client.go b/clientv3/client.go
index 01a93f5a3..a4e0fe8ea 100644
--- a/clientv3/client.go
+++ b/clientv3/client.go
@@ -185,7 +185,7 @@ func (cred authTokenCredential) GetRequestMetadata(ctx context.Context, s ...str
 	cred.tokenMu.RLock()
 	defer cred.tokenMu.RUnlock()
 	return map[string]string{
-		"token": cred.token,
+		rpctypes.TokenFieldNameGRPC: cred.token,
 	}, nil
 }
 
diff --git a/e2e/v3_curl_test.go b/e2e/v3_curl_test.go
index 1f65ebe2a..42150c94b 100644
--- a/e2e/v3_curl_test.go
+++ b/e2e/v3_curl_test.go
@@ -22,6 +22,7 @@ import (
 	"testing"
 
 	epb "github.com/coreos/etcd/etcdserver/api/v3election/v3electionpb"
+	"github.com/coreos/etcd/etcdserver/api/v3rpc/rpctypes"
 	pb "github.com/coreos/etcd/etcdserver/etcdserverpb"
 	"github.com/coreos/etcd/pkg/testutil"
 
@@ -236,7 +237,7 @@ func testV3CurlAuth(cx ctlCtx) {
 	authRes := make(map[string]interface{})
 	testutil.AssertNil(cx.t, json.Unmarshal([]byte(cURLRes), &authRes))
 
-	token, ok := authRes["token"].(string)
+	token, ok := authRes[rpctypes.TokenFieldNameGRPC].(string)
 	if !ok {
 		cx.t.Fatalf("failed invalid token in authenticate response with curl")
 	}
diff --git a/etcdserver/api/v3rpc/rpctypes/metadatafields.go b/etcdserver/api/v3rpc/rpctypes/metadatafields.go
new file mode 100644
index 000000000..8f8ac60ff
--- /dev/null
+++ b/etcdserver/api/v3rpc/rpctypes/metadatafields.go
@@ -0,0 +1,20 @@
+// Copyright 2018 The etcd Authors
+//
+// 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.
+
+package rpctypes
+
+var (
+	TokenFieldNameGRPC    = "token"
+	TokenFieldNameSwagger = "authorization"
+)
diff --git a/proxy/grpcproxy/util.go b/proxy/grpcproxy/util.go
index 2b226fa74..45a51d8c5 100644
--- a/proxy/grpcproxy/util.go
+++ b/proxy/grpcproxy/util.go
@@ -17,6 +17,8 @@ package grpcproxy
 import (
 	"context"
 
+	"github.com/coreos/etcd/etcdserver/api/v3rpc/rpctypes"
+
 	"google.golang.org/grpc"
 	"google.golang.org/grpc/metadata"
 )
@@ -24,7 +26,7 @@ import (
 func getAuthTokenFromClient(ctx context.Context) string {
 	md, ok := metadata.FromIncomingContext(ctx)
 	if ok {
-		ts, ok := md["token"]
+		ts, ok := md[rpctypes.TokenFieldNameGRPC]
 		if ok {
 			return ts[0]
 		}
@@ -35,7 +37,7 @@ func getAuthTokenFromClient(ctx context.Context) string {
 func withClientAuthToken(ctx context.Context, ctxWithToken context.Context) context.Context {
 	token := getAuthTokenFromClient(ctxWithToken)
 	if token != "" {
-		ctx = context.WithValue(ctx, "token", token)
+		ctx = context.WithValue(ctx, rpctypes.TokenFieldNameGRPC, token)
 	}
 	return ctx
 }
@@ -50,7 +52,7 @@ func (cred *proxyTokenCredential) RequireTransportSecurity() bool {
 
 func (cred *proxyTokenCredential) GetRequestMetadata(ctx context.Context, s ...string) (map[string]string, error) {
 	return map[string]string{
-		"token": cred.token,
+		rpctypes.TokenFieldNameGRPC: cred.token,
 	}, nil
 }
 
@@ -64,7 +66,7 @@ func AuthUnaryClientInterceptor(ctx context.Context, method string, req, reply i
 }
 
 func AuthStreamClientInterceptor(ctx context.Context, desc *grpc.StreamDesc, cc *grpc.ClientConn, method string, streamer grpc.Streamer, opts ...grpc.CallOption) (grpc.ClientStream, error) {
-	tokenif := ctx.Value("token")
+	tokenif := ctx.Value(rpctypes.TokenFieldNameGRPC)
 	if tokenif != nil {
 		tokenCred := &proxyTokenCredential{tokenif.(string)}
 		opts = append(opts, grpc.PerRPCCredentials(tokenCred))