diff --git a/vendor/google.golang.org/grpc/credentials/credentials.go b/vendor/google.golang.org/grpc/credentials/credentials.go
index 8ea3d4a..845ce5d 100644
--- a/vendor/google.golang.org/grpc/credentials/credentials.go
+++ b/vendor/google.golang.org/grpc/credentials/credentials.go
@@ -24,16 +24,12 @@
 
 import (
 	"context"
-	"crypto/tls"
-	"crypto/x509"
 	"errors"
 	"fmt"
-	"io/ioutil"
 	"net"
-	"strings"
 
 	"github.com/golang/protobuf/proto"
-	"google.golang.org/grpc/credentials/internal"
+	"google.golang.org/grpc/internal"
 )
 
 // PerRPCCredentials defines the common interface for the credentials which need to
@@ -45,7 +41,8 @@
 	// context. If a status code is returned, it will be used as the status
 	// for the RPC. uri is the URI of the entry point for the request.
 	// When supported by the underlying implementation, ctx can be used for
-	// timeout and cancellation.
+	// timeout and cancellation. Additionally, RequestInfo data will be
+	// available via ctx to this call.
 	// TODO(zhaoq): Define the set of the qualified keys instead of leaving
 	// it as an arbitrary string.
 	GetRequestMetadata(ctx context.Context, uri ...string) (map[string]string, error)
@@ -54,6 +51,48 @@
 	RequireTransportSecurity() bool
 }
 
+// SecurityLevel defines the protection level on an established connection.
+//
+// This API is experimental.
+type SecurityLevel int
+
+const (
+	// NoSecurity indicates a connection is insecure.
+	// The zero SecurityLevel value is invalid for backward compatibility.
+	NoSecurity SecurityLevel = iota + 1
+	// IntegrityOnly indicates a connection only provides integrity protection.
+	IntegrityOnly
+	// PrivacyAndIntegrity indicates a connection provides both privacy and integrity protection.
+	PrivacyAndIntegrity
+)
+
+// String returns SecurityLevel in a string format.
+func (s SecurityLevel) String() string {
+	switch s {
+	case NoSecurity:
+		return "NoSecurity"
+	case IntegrityOnly:
+		return "IntegrityOnly"
+	case PrivacyAndIntegrity:
+		return "PrivacyAndIntegrity"
+	}
+	return fmt.Sprintf("invalid SecurityLevel: %v", int(s))
+}
+
+// CommonAuthInfo contains authenticated information common to AuthInfo implementations.
+// It should be embedded in a struct implementing AuthInfo to provide additional information
+// about the credentials.
+//
+// This API is experimental.
+type CommonAuthInfo struct {
+	SecurityLevel SecurityLevel
+}
+
+// GetCommonAuthInfo returns the pointer to CommonAuthInfo struct.
+func (c *CommonAuthInfo) GetCommonAuthInfo() *CommonAuthInfo {
+	return c
+}
+
 // ProtocolInfo provides information regarding the gRPC wire protocol version,
 // security protocol, security protocol version in use, server name, etc.
 type ProtocolInfo struct {
@@ -68,6 +107,8 @@
 }
 
 // AuthInfo defines the common interface for the auth information the users are interested in.
+// A struct that implements AuthInfo should embed CommonAuthInfo by including additional
+// information about the credentials in it.
 type AuthInfo interface {
 	AuthType() string
 }
@@ -82,7 +123,8 @@
 	// ClientHandshake does the authentication handshake specified by the corresponding
 	// authentication protocol on rawConn for clients. It returns the authenticated
 	// connection and the corresponding auth information about the connection.
-	// Implementations must use the provided context to implement timely cancellation.
+	// The auth information should embed CommonAuthInfo to return additional information about
+	// the credentials. Implementations must use the provided context to implement timely cancellation.
 	// gRPC will try to reconnect if the error returned is a temporary error
 	// (io.EOF, context.DeadlineExceeded or err.Temporary() == true).
 	// If the returned error is a wrapper error, implementations should make sure that
@@ -92,7 +134,8 @@
 	ClientHandshake(context.Context, string, net.Conn) (net.Conn, AuthInfo, error)
 	// ServerHandshake does the authentication handshake for servers. It returns
 	// the authenticated connection and the corresponding auth information about
-	// the connection.
+	// the connection. The auth information should embed CommonAuthInfo to return additional information
+	// about the credentials.
 	//
 	// If the returned net.Conn is closed, it MUST close the net.Conn provided.
 	ServerHandshake(net.Conn) (net.Conn, AuthInfo, error)
@@ -125,145 +168,63 @@
 	NewWithMode(mode string) (Bundle, error)
 }
 
-// TLSInfo contains the auth information for a TLS authenticated connection.
-// It implements the AuthInfo interface.
-type TLSInfo struct {
-	State tls.ConnectionState
+// RequestInfo contains request data attached to the context passed to GetRequestMetadata calls.
+//
+// This API is experimental.
+type RequestInfo struct {
+	// The method passed to Invoke or NewStream for this RPC. (For proto methods, this has the format "/some.Service/Method")
+	Method string
+	// AuthInfo contains the information from a security handshake (TransportCredentials.ClientHandshake, TransportCredentials.ServerHandshake)
+	AuthInfo AuthInfo
 }
 
-// AuthType returns the type of TLSInfo as a string.
-func (t TLSInfo) AuthType() string {
-	return "tls"
+// requestInfoKey is a struct to be used as the key when attaching a RequestInfo to a context object.
+type requestInfoKey struct{}
+
+// RequestInfoFromContext extracts the RequestInfo from the context if it exists.
+//
+// This API is experimental.
+func RequestInfoFromContext(ctx context.Context) (ri RequestInfo, ok bool) {
+	ri, ok = ctx.Value(requestInfoKey{}).(RequestInfo)
+	return
 }
 
-// GetSecurityValue returns security info requested by channelz.
-func (t TLSInfo) GetSecurityValue() ChannelzSecurityValue {
-	v := &TLSChannelzSecurityValue{
-		StandardName: cipherSuiteLookup[t.State.CipherSuite],
+// CheckSecurityLevel checks if a connection's security level is greater than or equal to the specified one.
+// It returns success if 1) the condition is satisified or 2) AuthInfo struct does not implement GetCommonAuthInfo() method
+// or 3) CommonAuthInfo.SecurityLevel has an invalid zero value. For 2) and 3), it is for the purpose of backward-compatibility.
+//
+// This API is experimental.
+func CheckSecurityLevel(ctx context.Context, level SecurityLevel) error {
+	type internalInfo interface {
+		GetCommonAuthInfo() *CommonAuthInfo
 	}
-	// Currently there's no way to get LocalCertificate info from tls package.
-	if len(t.State.PeerCertificates) > 0 {
-		v.RemoteCertificate = t.State.PeerCertificates[0].Raw
+	ri, _ := RequestInfoFromContext(ctx)
+	if ri.AuthInfo == nil {
+		return errors.New("unable to obtain SecurityLevel from context")
 	}
-	return v
-}
-
-// tlsCreds is the credentials required for authenticating a connection using TLS.
-type tlsCreds struct {
-	// TLS configuration
-	config *tls.Config
-}
-
-func (c tlsCreds) Info() ProtocolInfo {
-	return ProtocolInfo{
-		SecurityProtocol: "tls",
-		SecurityVersion:  "1.2",
-		ServerName:       c.config.ServerName,
-	}
-}
-
-func (c *tlsCreds) ClientHandshake(ctx context.Context, authority string, rawConn net.Conn) (_ net.Conn, _ AuthInfo, err error) {
-	// use local cfg to avoid clobbering ServerName if using multiple endpoints
-	cfg := cloneTLSConfig(c.config)
-	if cfg.ServerName == "" {
-		colonPos := strings.LastIndex(authority, ":")
-		if colonPos == -1 {
-			colonPos = len(authority)
+	if ci, ok := ri.AuthInfo.(internalInfo); ok {
+		// CommonAuthInfo.SecurityLevel has an invalid value.
+		if ci.GetCommonAuthInfo().SecurityLevel == 0 {
+			return nil
 		}
-		cfg.ServerName = authority[:colonPos]
-	}
-	conn := tls.Client(rawConn, cfg)
-	errChannel := make(chan error, 1)
-	go func() {
-		errChannel <- conn.Handshake()
-	}()
-	select {
-	case err := <-errChannel:
-		if err != nil {
-			return nil, nil, err
+		if ci.GetCommonAuthInfo().SecurityLevel < level {
+			return fmt.Errorf("requires SecurityLevel %v; connection has %v", level, ci.GetCommonAuthInfo().SecurityLevel)
 		}
-	case <-ctx.Done():
-		return nil, nil, ctx.Err()
 	}
-	return internal.WrapSyscallConn(rawConn, conn), TLSInfo{conn.ConnectionState()}, nil
-}
-
-func (c *tlsCreds) ServerHandshake(rawConn net.Conn) (net.Conn, AuthInfo, error) {
-	conn := tls.Server(rawConn, c.config)
-	if err := conn.Handshake(); err != nil {
-		return nil, nil, err
-	}
-	return internal.WrapSyscallConn(rawConn, conn), TLSInfo{conn.ConnectionState()}, nil
-}
-
-func (c *tlsCreds) Clone() TransportCredentials {
-	return NewTLS(c.config)
-}
-
-func (c *tlsCreds) OverrideServerName(serverNameOverride string) error {
-	c.config.ServerName = serverNameOverride
+	// The condition is satisfied or AuthInfo struct does not implement GetCommonAuthInfo() method.
 	return nil
 }
 
-const alpnProtoStrH2 = "h2"
-
-func appendH2ToNextProtos(ps []string) []string {
-	for _, p := range ps {
-		if p == alpnProtoStrH2 {
-			return ps
-		}
+func init() {
+	internal.NewRequestInfoContext = func(ctx context.Context, ri RequestInfo) context.Context {
+		return context.WithValue(ctx, requestInfoKey{}, ri)
 	}
-	ret := make([]string, 0, len(ps)+1)
-	ret = append(ret, ps...)
-	return append(ret, alpnProtoStrH2)
-}
-
-// NewTLS uses c to construct a TransportCredentials based on TLS.
-func NewTLS(c *tls.Config) TransportCredentials {
-	tc := &tlsCreds{cloneTLSConfig(c)}
-	tc.config.NextProtos = appendH2ToNextProtos(tc.config.NextProtos)
-	return tc
-}
-
-// NewClientTLSFromCert constructs TLS credentials from the input certificate for client.
-// serverNameOverride is for testing only. If set to a non empty string,
-// it will override the virtual host name of authority (e.g. :authority header field) in requests.
-func NewClientTLSFromCert(cp *x509.CertPool, serverNameOverride string) TransportCredentials {
-	return NewTLS(&tls.Config{ServerName: serverNameOverride, RootCAs: cp})
-}
-
-// NewClientTLSFromFile constructs TLS credentials from the input certificate file for client.
-// serverNameOverride is for testing only. If set to a non empty string,
-// it will override the virtual host name of authority (e.g. :authority header field) in requests.
-func NewClientTLSFromFile(certFile, serverNameOverride string) (TransportCredentials, error) {
-	b, err := ioutil.ReadFile(certFile)
-	if err != nil {
-		return nil, err
-	}
-	cp := x509.NewCertPool()
-	if !cp.AppendCertsFromPEM(b) {
-		return nil, fmt.Errorf("credentials: failed to append certificates")
-	}
-	return NewTLS(&tls.Config{ServerName: serverNameOverride, RootCAs: cp}), nil
-}
-
-// NewServerTLSFromCert constructs TLS credentials from the input certificate for server.
-func NewServerTLSFromCert(cert *tls.Certificate) TransportCredentials {
-	return NewTLS(&tls.Config{Certificates: []tls.Certificate{*cert}})
-}
-
-// NewServerTLSFromFile constructs TLS credentials from the input certificate file and key
-// file for server.
-func NewServerTLSFromFile(certFile, keyFile string) (TransportCredentials, error) {
-	cert, err := tls.LoadX509KeyPair(certFile, keyFile)
-	if err != nil {
-		return nil, err
-	}
-	return NewTLS(&tls.Config{Certificates: []tls.Certificate{cert}}), nil
 }
 
 // ChannelzSecurityInfo defines the interface that security protocols should implement
 // in order to provide security info to channelz.
+//
+// This API is experimental.
 type ChannelzSecurityInfo interface {
 	GetSecurityValue() ChannelzSecurityValue
 }
@@ -271,66 +232,20 @@
 // ChannelzSecurityValue defines the interface that GetSecurityValue() return value
 // should satisfy. This interface should only be satisfied by *TLSChannelzSecurityValue
 // and *OtherChannelzSecurityValue.
+//
+// This API is experimental.
 type ChannelzSecurityValue interface {
 	isChannelzSecurityValue()
 }
 
-// TLSChannelzSecurityValue defines the struct that TLS protocol should return
-// from GetSecurityValue(), containing security info like cipher and certificate used.
-type TLSChannelzSecurityValue struct {
-	ChannelzSecurityValue
-	StandardName      string
-	LocalCertificate  []byte
-	RemoteCertificate []byte
-}
-
 // OtherChannelzSecurityValue defines the struct that non-TLS protocol should return
 // from GetSecurityValue(), which contains protocol specific security info. Note
 // the Value field will be sent to users of channelz requesting channel info, and
 // thus sensitive info should better be avoided.
+//
+// This API is experimental.
 type OtherChannelzSecurityValue struct {
 	ChannelzSecurityValue
 	Name  string
 	Value proto.Message
 }
-
-var cipherSuiteLookup = map[uint16]string{
-	tls.TLS_RSA_WITH_RC4_128_SHA:                "TLS_RSA_WITH_RC4_128_SHA",
-	tls.TLS_RSA_WITH_3DES_EDE_CBC_SHA:           "TLS_RSA_WITH_3DES_EDE_CBC_SHA",
-	tls.TLS_RSA_WITH_AES_128_CBC_SHA:            "TLS_RSA_WITH_AES_128_CBC_SHA",
-	tls.TLS_RSA_WITH_AES_256_CBC_SHA:            "TLS_RSA_WITH_AES_256_CBC_SHA",
-	tls.TLS_RSA_WITH_AES_128_GCM_SHA256:         "TLS_RSA_WITH_AES_128_GCM_SHA256",
-	tls.TLS_RSA_WITH_AES_256_GCM_SHA384:         "TLS_RSA_WITH_AES_256_GCM_SHA384",
-	tls.TLS_ECDHE_ECDSA_WITH_RC4_128_SHA:        "TLS_ECDHE_ECDSA_WITH_RC4_128_SHA",
-	tls.TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA:    "TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA",
-	tls.TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA:    "TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA",
-	tls.TLS_ECDHE_RSA_WITH_RC4_128_SHA:          "TLS_ECDHE_RSA_WITH_RC4_128_SHA",
-	tls.TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA:     "TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA",
-	tls.TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA:      "TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA",
-	tls.TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA:      "TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA",
-	tls.TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256:   "TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256",
-	tls.TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256: "TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256",
-	tls.TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384:   "TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384",
-	tls.TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384: "TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384",
-	tls.TLS_FALLBACK_SCSV:                       "TLS_FALLBACK_SCSV",
-	tls.TLS_RSA_WITH_AES_128_CBC_SHA256:         "TLS_RSA_WITH_AES_128_CBC_SHA256",
-	tls.TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256: "TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256",
-	tls.TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256:   "TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256",
-	tls.TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305:    "TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305",
-	tls.TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305:  "TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305",
-}
-
-// cloneTLSConfig returns a shallow clone of the exported
-// fields of cfg, ignoring the unexported sync.Once, which
-// contains a mutex and must not be copied.
-//
-// If cfg is nil, a new zero tls.Config is returned.
-//
-// TODO: inline this function if possible.
-func cloneTLSConfig(cfg *tls.Config) *tls.Config {
-	if cfg == nil {
-		return &tls.Config{}
-	}
-
-	return cfg.Clone()
-}