diff --git a/vendor/github.com/mongodb/mongo-go-driver/x/mongo/driver/auth/default.go b/vendor/github.com/mongodb/mongo-go-driver/x/mongo/driver/auth/default.go
new file mode 100644
index 0000000..52d07e9
--- /dev/null
+++ b/vendor/github.com/mongodb/mongo-go-driver/x/mongo/driver/auth/default.go
@@ -0,0 +1,67 @@
+// Copyright (C) MongoDB, Inc. 2017-present.
+//
+// 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
+
+package auth
+
+import (
+	"context"
+
+	"github.com/mongodb/mongo-go-driver/x/network/description"
+	"github.com/mongodb/mongo-go-driver/x/network/wiremessage"
+)
+
+func newDefaultAuthenticator(cred *Cred) (Authenticator, error) {
+	return &DefaultAuthenticator{
+		Cred: cred,
+	}, nil
+}
+
+// DefaultAuthenticator uses SCRAM-SHA-1 or MONGODB-CR depending
+// on the server version.
+type DefaultAuthenticator struct {
+	Cred *Cred
+}
+
+// Auth authenticates the connection.
+func (a *DefaultAuthenticator) Auth(ctx context.Context, desc description.Server, rw wiremessage.ReadWriter) error {
+	var actual Authenticator
+	var err error
+
+	switch chooseAuthMechanism(desc) {
+	case SCRAMSHA256:
+		actual, err = newScramSHA256Authenticator(a.Cred)
+	case SCRAMSHA1:
+		actual, err = newScramSHA1Authenticator(a.Cred)
+	default:
+		actual, err = newMongoDBCRAuthenticator(a.Cred)
+	}
+
+	if err != nil {
+		return newAuthError("error creating authenticator", err)
+	}
+
+	return actual.Auth(ctx, desc, rw)
+}
+
+// If a server provides a list of supported mechanisms, we choose
+// SCRAM-SHA-256 if it exists or else MUST use SCRAM-SHA-1.
+// Otherwise, we decide based on what is supported.
+func chooseAuthMechanism(desc description.Server) string {
+	if desc.SaslSupportedMechs != nil {
+		for _, v := range desc.SaslSupportedMechs {
+			if v == SCRAMSHA256 {
+				return v
+			}
+		}
+		return SCRAMSHA1
+	}
+
+	if err := description.ScramSHA1Supported(desc.WireVersion); err == nil {
+		return SCRAMSHA1
+	}
+
+	return MONGODBCR
+}