コード例 #1
0
ファイル: taosupport.go プロジェクト: tmroeder/cloudproxy
// Establishes the Tao Channel for a client using the Program Key.
// This program does all the standard client side channel negotiation.
// After negotiation is complete.  ms is the bi-directional confidentiality and
// integrity protected channel.  OpenTaoChannel returns the stream (ms) for subsequent reads
// and writes as well as the server's Tao Principal Name.
func OpenTaoChannel(programObject *TaoProgramData, serverAddr *string) (
	*util.MessageStream, *string, error) {

	// Parse policy cert and make it the root of our
	// hierarchy for verifying Tao Channel peer.
	policyCert, err := x509.ParseCertificate(programObject.PolicyCert)
	if err != nil {
		return nil, nil, errors.New("OpenTaoChannel: Can't ParseCertificate")
	}
	pool := x509.NewCertPool()
	pool.AddCert(policyCert)

	// Open the Tao Channel using the Program key.
	tlsc, err := tao.EncodeTLSCert(&programObject.ProgramKey)
	if err != nil {
		log.Fatalln("OpenTaoChannel, encode error: ", err)
	}
	// TODO(manferdelli): Replace this with tao.Dial
	conn, err := tls.Dial("tcp", *serverAddr, &tls.Config{
		RootCAs:            pool,
		Certificates:       []tls.Certificate{*tlsc},
		InsecureSkipVerify: false,
	})
	if err != nil {
		fmt.Printf("OpenTaoChannel: Can't establish channel ", err, "\n")
		return nil, nil, errors.New("OpenTaoChannel: Can't establish channel")
	}

	peerName := policyCert.Subject.OrganizationalUnit[0]

	// Stream for Tao Channel.
	ms := util.NewMessageStream(conn)
	return ms, &peerName, nil
}
コード例 #2
0
ファイル: keynegoserver.go プロジェクト: tmroeder/cloudproxy
func main() {
	network := flag.String("network", "tcp", "The network to use for connections")
	addr := flag.String("addr", "localhost:8124", "The address to listen on")
	domainPass := flag.String("password", "nopassword", "The domain password for the policy key")
	configPath := flag.String("config", "tao.config", "The Tao domain config")

	flag.Parse()
	domain, err := tao.LoadDomain(*configPath, []byte(*domainPass))
	if err != nil {
		log.Fatalf("keynegoserver: Couldn't load the config path %s: %s\n", *configPath, err)
	}

	// Set up temporary keys for the connection, since the only thing that
	// matters to the remote client is that they receive a correctly-signed new
	// attestation from the policy key.
	// JLM:  I left this in place but I'm not sure what a TLS connection with a
	//   self signed Cert buys in terms of security.  The security of this protocol should
	//   not depend on the confidentiality or intergity of the channel.  All that said,
	//   if we do ever distribute a signed keynegoserver cert for this TLS channel, it would
	//   be good.
	keys, err := tao.NewTemporaryKeys(tao.Signing)
	if err != nil {
		log.Fatalln("keynegoserver: Couldn't set up temporary keys for the connection:", err)
	}
	keys.Cert, err = keys.SigningKey.CreateSelfSignedX509(&pkix.Name{
		Organization: []string{"Google Tao Demo"}})
	if err != nil {
		log.Fatalln("keynegoserver: Couldn't set up a self-signed cert:", err)
	}
	SerialNumber = int64(time.Now().UnixNano()) / (1000000)
	policyKey, err := tao.NewOnDiskPBEKeys(tao.Signing, []byte(*domainPass), "policy_keys", nil)
	if err != nil {
		log.Fatalln("keynegoserver: Couldn't get policy key:", err)
	}

	tlsc, err := tao.EncodeTLSCert(keys)
	if err != nil {
		log.Fatalln("keynegoserver: Couldn't encode a TLS cert:", err)
	}
	conf := &tls.Config{
		RootCAs:            x509.NewCertPool(),
		Certificates:       []tls.Certificate{*tlsc},
		InsecureSkipVerify: true,
		ClientAuth:         tls.RequireAnyClientCert,
	}
	sock, err := tls.Listen(*network, *addr, conf)
	if err != nil {
		log.Printf("keynegoserver: error: %s", err)
	}
	defer sock.Close()

	for {
		conn, err := sock.Accept()
		if err != nil {
			log.Fatalln("keynegoserver: couldn't accept a connection:", err)
		}

		go handleRequest(conn, policyKey, domain.Guard)
	}
}
コード例 #3
0
ファイル: router.go プロジェクト: William-J-Earl/cloudproxy
// NewRouterContext generates new keys, loads a local domain configuration from
// path and binds an anonymous listener socket to addr on network
// network. A delegation is requested from the Tao t which is  nominally
// the parent of this hosted program.
func NewRouterContext(path, network, addr string, batchSize int, timeout time.Duration,
	x509Identity *pkix.Name, t tao.Tao) (hp *RouterContext, err error) {

	hp = new(RouterContext)
	hp.network = network
	hp.timeout = timeout

	// Generate keys and get attestation from parent.
	if hp.keys, err = tao.NewTemporaryTaoDelegatedKeys(tao.Signing|tao.Crypting, t); err != nil {
		return nil, err
	}

	// Create a certificate.
	if hp.keys.Cert, err = hp.keys.SigningKey.CreateSelfSignedX509(x509Identity); err != nil {
		return nil, err
	}

	// Load domain from local configuration.
	if hp.domain, err = tao.LoadDomain(path, nil); err != nil {
		return nil, err
	}

	// Encode TLS certificate.
	cert, err := tao.EncodeTLSCert(hp.keys)
	if err != nil {
		return nil, err
	}

	tlsConfig := &tls.Config{
		RootCAs:            x509.NewCertPool(),
		Certificates:       []tls.Certificate{*cert},
		InsecureSkipVerify: true,
		ClientAuth:         tls.NoClientCert,
	}

	// Bind address to socket.
	if hp.proxyListener, err = tao.ListenAnonymous(network, addr, tlsConfig,
		hp.domain.Guard, hp.domain.Keys.VerifyingKey, hp.keys.Delegation); err != nil {
		return nil, err
	}

	// Instantiate the queues.
	hp.sendQueue = NewQueue(network, batchSize, timeout)
	hp.replyQueue = NewQueue(network, batchSize, timeout)
	hp.killQueue = make(chan bool)
	hp.killQueueErrorHandler = make(chan bool)
	go hp.sendQueue.DoQueue(hp.killQueue)
	go hp.replyQueue.DoQueue(hp.killQueue)
	go hp.sendQueue.DoQueueErrorHandler(hp.replyQueue, hp.killQueueErrorHandler)
	go hp.replyQueue.DoQueueErrorHandlerLog("reply queue", hp.killQueueErrorHandler)

	return hp, nil
}
コード例 #4
0
ファイル: taosupport.go プロジェクト: tmroeder/cloudproxy
// RequestDomainServiceCert requests the signed Program
// Certificate from simpledomainservice.
//  TODO: This needs to change in a way that is tao supplier dependent.
//     For tpm2 we need the ekCert and the tao and we need the data
//     for ActivateCredential.
//     For tpm1.2, we need the aikCert.
func RequestDomainServiceCert(network, addr string, requesting_key *tao.Keys,
	v *tao.Verifier) (*domain_policy.DomainCertResponse, error) {

	// Note requesting program key contains a self-signed cert to open channel.
	if requesting_key.Cert == nil {
		return nil, errors.New("RequestDomainServiceCert: Can't dial with an empty client certificate")
	}
	tlsCert, err := tao.EncodeTLSCert(requesting_key)
	if err != nil {
		return nil, err
	}
	conn, err := tls.Dial(network, addr, &tls.Config{
		RootCAs:            x509.NewCertPool(),
		Certificates:       []tls.Certificate{*tlsCert},
		InsecureSkipVerify: true,
	})
	if err != nil {
		return nil, err
	}
	defer conn.Close()

	var request domain_policy.DomainCertRequest
	request.Attestation, err = proto.Marshal(requesting_key.Delegation)
	signer := requesting_key.SigningKey.GetSigner()
	if signer == nil {
		return nil, err
	}
	key_type := "ECDSA"
	request.KeyType = &key_type
	request.SubjectPublicKey, err = domain_policy.GetPublicDerFromEcdsaKey(&signer.PublicKey)
	if err != nil {
		return nil, err
	}

	// Tao handshake: send client delegation.
	ms := util.NewMessageStream(conn)
	_, err = ms.WriteMessage(&request)
	if err != nil {
		return nil, err
	}

	// Read the new cert
	var response domain_policy.DomainCertResponse
	err = ms.ReadMessage(&response)
	if err != nil {
		return nil, err
	}
	return &response, nil
}
コード例 #5
0
func serve(serverAddr string, prin string, policyCert []byte, signingKey *tao.Keys, policy *fileproxy.ProgramPolicy, m *fileproxy.RollbackMaster) error {
	pc, err := x509.ParseCertificate(policyCert)
	if err != nil {
		return err
	}
	pool := x509.NewCertPool()
	pool.AddCert(pc)
	tlsc, err := tao.EncodeTLSCert(signingKey)
	if err != nil {
		return err
	}
	conf := &tls.Config{
		RootCAs:            pool,
		Certificates:       []tls.Certificate{*tlsc},
		InsecureSkipVerify: false,
		ClientAuth:         tls.RequireAnyClientCert,
	}
	log.Println("Rollback server listening")
	sock, err := tls.Listen("tcp", serverAddr, conf)
	if err != nil {
		return err
	}

	for {
		conn, err := sock.Accept()
		if err != nil {
			return err
		}
		var clientName string
		if err = conn.(*tls.Conn).Handshake(); err != nil {
			log.Println("TLS handshake failed")
			continue
		}

		peerCerts := conn.(*tls.Conn).ConnectionState().PeerCertificates
		if peerCerts == nil {
			log.Println("rollbackserver: can't get peer list")
			continue
		}

		peerCert := conn.(*tls.Conn).ConnectionState().PeerCertificates[0]
		if peerCert.Raw == nil {
			log.Println("rollbackserver: can't get peer name")
			continue
		}

		if peerCert.Subject.OrganizationalUnit == nil {
			log.Println("No OrganizationalUnit name in the peer certificate. Refusing the connection")
			continue
		}

		clientName = peerCert.Subject.OrganizationalUnit[0]
		ms := util.NewMessageStream(conn)
		// TODO(tmroeder): support multiple simultaneous clients.
		// Add this program as a rollback program.
		log.Printf("Adding a program with name '%s'\n", clientName)
		_ = m.AddRollbackProgram(clientName)
		if err := m.RunMessageLoop(ms, policy, clientName); err != nil {
			log.Printf("rollbackserver: failed to run message loop: %s\n", err)
		}
	}
}
コード例 #6
0
ファイル: simpleserver.go プロジェクト: tmroeder/cloudproxy
// This is the server. It implements the server Tao Channel negotiation corresponding
// to the client's taosupport.OpenTaoChannel.  It's possible we should move this into
// taosupport/taosupport.go since it should not vary very much from implementation to
// implementation.
func server(serverAddr string, serverProgramData *taosupport.TaoProgramData) {

	var sock net.Listener

	// Set up the single root certificate for channel negotiation which is the
	// policy key cert.
	pool := x509.NewCertPool()
	policyCert, err := x509.ParseCertificate(serverProgramData.PolicyCert)
	if err != nil {
		log.Printf("simpleserver, can't parse policyCert: ", err, "\n")
		return
	}
	// Make the policy cert the unique root of the verification chain.
	pool.AddCert(policyCert)
	tlsc, err := tao.EncodeTLSCert(&serverProgramData.ProgramKey)
	if err != nil {
		log.Printf("simpleserver, encode error: ", err, "\n")
		return
	}
	conf := &tls.Config{
		RootCAs:            pool,
		Certificates:       []tls.Certificate{*tlsc},
		InsecureSkipVerify: false,
		ClientAuth:         tls.RequireAnyClientCert,
	}

	// Listen for clients.
	log.Printf("simpleserver: Listening\n")
	sock, err = tls.Listen("tcp", serverAddr, conf)
	if err != nil {
		log.Printf("simpleserver, listen error: ", err, "\n")
		return
	}

	// Service client connections.
	for {
		log.Printf("server: at accept\n")
		conn, err := sock.Accept()
		if err != nil {
			fmt.Printf("simpleserver: can't accept connection: %s\n", err.Error())
			log.Printf("server: can't accept connection: %s\n", err.Error())
			continue
		}
		var clientName string
		err = conn.(*tls.Conn).Handshake()
		if err != nil {
			log.Printf("server: TLS handshake failed\n")
			continue
		}
		peerCerts := conn.(*tls.Conn).ConnectionState().PeerCertificates
		if peerCerts == nil {
			log.Printf("server: can't get peer list\n")
			continue
		}
		peerCert := conn.(*tls.Conn).ConnectionState().PeerCertificates[0]
		if peerCert.Raw == nil {
			log.Printf("server: can't get peer cert\n")
			continue
		}
		if peerCert.Subject.OrganizationalUnit == nil {
			log.Printf("server: can't get peer name\n")
			continue
		}
		clientName = peerCert.Subject.OrganizationalUnit[0]
		log.Printf("server, peer client name: %s\n", clientName)
		ms := util.NewMessageStream(conn)

		// At this point the handshake is complete and we fork a service thread
		// to communicate with this simpleclient.  ms is the bi-directional
		// confidentiality and integrity protected channel corresponding to the
		// channel opened by OpenTaoChannel.
		go serviceThead(ms, clientName, serverProgramData)
	}
}
コード例 #7
0
func serve(addr, fp string, cert []byte, signingKey *tao.Keys, policy *fileproxy.ProgramPolicy) error {
	m := fileproxy.NewResourceMaster(fp)

	policyCert, err := x509.ParseCertificate(cert)
	if err != nil {
		return err
	}
	pool := x509.NewCertPool()
	pool.AddCert(policyCert)
	tlsc, err := tao.EncodeTLSCert(signingKey)
	if err != nil {
		return err
	}
	conf := &tls.Config{
		RootCAs:            pool,
		Certificates:       []tls.Certificate{*tlsc},
		InsecureSkipVerify: false,
		ClientAuth:         tls.RequireAnyClientCert,
	}
	log.Println("fileserver listening")
	sock, err := tls.Listen("tcp", addr, conf)
	if err != nil {
		return err
	}

	for {
		// Accept and handle client connections one at a time.
		conn, err := sock.Accept()
		if err != nil {
			return err
		}

		var clientName string
		if err = conn.(*tls.Conn).Handshake(); err != nil {
			log.Printf("fileserver: couldn't perform handshake: %s\n", err)
			continue
		}

		peerCerts := conn.(*tls.Conn).ConnectionState().PeerCertificates
		if peerCerts == nil {
			log.Println("fileserver: couldn't get peer list")
			continue
		}

		peerCert := conn.(*tls.Conn).ConnectionState().PeerCertificates[0]
		if peerCert.Raw == nil {
			log.Println("fileserver: couldn't get peer name")
			continue
		}

		if peerCert.Subject.OrganizationalUnit != nil {
			clientName = peerCert.Subject.OrganizationalUnit[0]
		}
		log.Printf("fileserver: peer name: '%s'\n", clientName)
		ms := util.NewMessageStream(conn)

		// TODO(tmroeder): support multiple simultaneous clients. This
		// requires, e.g., adding locking to the ResourceMaster.
		if err := m.RunMessageLoop(ms, policy); err != nil {
			log.Printf("fileserver: failed to run message loop: %s\n", err)
			continue
		}

		log.Println("Finished handling the client messages")
	}
}
コード例 #8
0
func doServer() {
	var sock net.Listener
	var err error
	var keys *tao.Keys
	network := "tcp"
	domain, err := tao.LoadDomain(configPath(), nil)
	options.FailIf(err, "error: couldn't load the tao domain from %s\n", configPath())

	switch *demoAuth {
	case "tcp":
		sock, err = net.Listen(network, serverAddr)
		options.FailIf(err, "server: couldn't listen to the network")

	case "tls", "tao":
		// Generate a private/public key for this hosted program (hp) and
		// request attestation from the host of the statement "hp speaksFor
		// host". The resulting certificate, keys.Delegation, is a chain of
		// "says" statements extending to the policy key. The policy is
		// checked by the host before this program is executed.
		keys, err = tao.NewTemporaryTaoDelegatedKeys(tao.Signing, tao.Parent())
		options.FailIf(err, "server: failed to generate delegated keys")

		// Create a certificate for the hp.
		keys.Cert, err = keys.SigningKey.CreateSelfSignedX509(&pkix.Name{
			Organization: []string{"Google Tao Demo"}})
		options.FailIf(err, "server: couldn't create certificate")

		g := domain.Guard
		if *ca != "" {
			// Replace keys.Delegation with a "says" statement directly from
			// the policy key.
			na, err := tao.RequestTruncatedAttestation(network, *ca, keys, domain.Keys.VerifyingKey)
			options.FailIf(err, "server: truncated attestation request failed")
			keys.Delegation = na

			g, err = newTempCAGuard(domain.Keys.VerifyingKey)
			options.FailIf(err, "server: couldn't set up a new guard")
		}

		tlsc, err := tao.EncodeTLSCert(keys)
		options.FailIf(err, "server: couldn't encode TLS certificate")

		conf := &tls.Config{
			RootCAs:            x509.NewCertPool(),
			Certificates:       []tls.Certificate{*tlsc},
			InsecureSkipVerify: true,
			ClientAuth:         tls.RequireAnyClientCert,
		}

		if *demoAuth == "tao" {
			sock, err = tao.Listen(network, serverAddr, conf, g, domain.Keys.VerifyingKey, keys.Delegation)
			options.FailIf(err, "sever: couldn't create a taonet listener")
		} else {
			sock, err = tls.Listen(network, serverAddr, conf)
			options.FailIf(err, "server: couldn't create a tls listener")
		}
	}

	fmt.Printf("server: listening at %s using %s authentication.\n", serverAddr, *demoAuth)
	defer sock.Close()

	pings := make(chan bool, 5)
	connCount := 0

	go func() {
		for connCount = 0; connCount < *pingCount || *pingCount < 0; connCount++ { // negative means forever
			conn, err := sock.Accept()
			options.FailIf(err, "server: can't accept connection")
			go doResponse(conn, pings)
		}
	}()

	pingGood := 0
	pingFail := 0

	for {
		select {
		case ok := <-pings:
			if ok {
				pingGood++
			} else {
				pingFail++
			}
		}
	}
}
コード例 #9
0
func main() {
	flag.Parse()
	domain, err := tao.LoadDomain(*configPath, []byte(*domainPass))
	if domain == nil {
		log.Printf("simpledomainservice: no domain path - %s, pass - %s, err - %s\n",
			*configPath, *domainPass, err)
		return
	} else if err != nil {
		log.Printf("simpledomainservice: Couldn't load the config path %s: %s\n",
			*configPath, err)
		return
	}
	log.Printf("simpledomainservice: Loaded domain\n")

	// Set up temporary keys for the connection, since the only thing that
	// matters to the remote client is that they receive a correctly-signed new
	// attestation from the policy key.
	// JLM:  I left this in place but I'm not sure what a TLS connection with a
	//   self signed Cert buys in terms of security.
	//   The security of this protocol should not depend on the
	//   confidentiality or intergity of the channel.  All that said, if we
	//   do ever distribute a signed simpledomainservice cert
	// for this TLS channel, it would be good.
	keys, err := tao.NewTemporaryKeys(tao.Signing)
	if keys == nil || err != nil {
		log.Fatalln("simpledomainservice: Couldn't set up temporary keys for connection:", err)
		return
	}
	keys.Cert, err = keys.SigningKey.CreateSelfSignedX509(&pkix.Name{
		Organization: []string{"Google Tao Demo"}})
	if err != nil {
		log.Fatalln("simpledomainservice: Couldn't set up a self-signed cert:", err)
		return
	}
	SerialNumber = int64(time.Now().UnixNano()) / (1000000)
	policyKey := domain.Keys
	fmt.Printf("\nSimpleDomainService: policyKey: %x\n", policyKey)

	tlsc, err := tao.EncodeTLSCert(keys)
	if err != nil {
		log.Fatalln("simpledomainservice: Couldn't encode a TLS cert:", err)
	}
	conf := &tls.Config{
		RootCAs:            x509.NewCertPool(),
		Certificates:       []tls.Certificate{*tlsc},
		InsecureSkipVerify: true,
		ClientAuth:         tls.RequireAnyClientCert,
	}
	sock, err := tls.Listen(*network, *addr, conf)
	if err != nil {
		log.Printf("simpledomainservice: error: %s\n", err)
	}
	if sock == nil {
		log.Printf("simpledomainservice: Empty socket, terminating\n")
		return
	}
	defer sock.Close()

	log.Printf("simpledomainservice: accepting connections\n")
	fmt.Printf("\n\nsimpledomainservice: accepting connections\n")
	for {
		conn, err := sock.Accept()
		if conn == nil {
			fmt.Printf("simpledomainservice: Empty connection\n")
			log.Printf("simpledomainservice: Empty connection\n")
			return
		} else if err != nil {
			fmt.Printf("simpledomainservice: Couldn't accept a connection on %s: %s\n", *addr, err)
			log.Printf("simpledomainservice: Couldn't accept a connection on %s: %s\n", *addr, err)
			return
		}
		go DomainRequest(conn, policyKey, domain.Guard)
	}
	log.Printf("simpledomainservice: finishing\n")
}
コード例 #10
0
func main() {
	caAddr := flag.String("caAddr", "localhost:8124", "The address of the CA for setting up a certificate signed by the policy key")
	hostcfg := flag.String("hostconfig", "tao.config", "path to host tao configuration")
	serverHost := flag.String("host", "localhost", "address for client/server")
	serverPort := flag.String("port", "8123", "port for client/server")
	rollbackServerHost := flag.String("rollbackhost", "localhost", "address for rollback client/server")
	rollbackServerPort := flag.String("rollbackport", "8129", "port for client/server")
	fileClientPassword := flag.String("password", "BogusPass", "A password for unlocking the user certificates")
	fileClientPath := flag.String("fileclient_files", "fileclient_files", "fileclient directory")
	fileClientFilePath := flag.String("stored_files", "fileclient_files/stored_files", "fileclient file directory")
	testFile := flag.String("test_file", "originalTestFile", "test file")
	fileClientKeyPath := flag.String("usercreds", "usercreds", "user keys and certs")
	country := flag.String("country", "US", "The country for the fileclient certificate")
	org := flag.String("organization", "Google", "The organization for the fileclient certificate")

	flag.Parse()

	serverAddr := net.JoinHostPort(*serverHost, *serverPort)
	hostDomain, err := tao.LoadDomain(*hostcfg, nil)
	if err != nil {
		log.Fatalln("fileclient: Can't load domain")
	}
	var derPolicyCert []byte
	if hostDomain.Keys.Cert != nil {
		derPolicyCert = hostDomain.Keys.Cert.Raw
	}
	if derPolicyCert == nil {
		log.Fatalln("fileclient: Can't retrieve policy cert")
	}

	parentTao := tao.Parent()
	if err := hostDomain.ExtendTaoName(parentTao); err != nil {
		log.Fatalln("fileclient: can't extend the Tao with the policy key")
	}
	e := auth.PrinExt{Name: "fileclient_version_1"}
	if err = parentTao.ExtendTaoName(auth.SubPrin{e}); err != nil {
		log.Fatalln("fileclient: couldn't extend the tao name with the policy key")
	}

	taoName, err := parentTao.GetTaoName()
	if err != nil {
		log.Fatalln("fileclient: Can't get tao name")
	}

	// Create or read the keys for fileclient.
	fcKeys, err := tao.NewOnDiskTaoSealedKeys(tao.Signing|tao.Crypting, parentTao, *fileClientPath, tao.SealPolicyDefault)
	if err != nil {
		log.Fatalln("fileclient: couldn't set up the Tao-sealed keys:", err)
	}

	// Set up a temporary cert for communication with keyNegoServer.
	fcKeys.Cert, err = fcKeys.SigningKey.CreateSelfSignedX509(tao.NewX509Name(&tao.X509Details{
		Country:      proto.String(*country),
		Organization: proto.String(*org),
		CommonName:   proto.String(taoName.String()),
	}))
	if err != nil {
		log.Fatalln("fileclient: couldn't create a self-signed cert for fileclient keys:", err)
	}

	// Contact keyNegoServer for the certificate.
	if err := fileproxy.EstablishCert("tcp", *caAddr, fcKeys, hostDomain.Keys.VerifyingKey); err != nil {
		log.Fatalf("fileclient: couldn't establish a cert signed by the policy key: %s", err)
	}

	// Get the policy cert and set up TLS.
	pool := x509.NewCertPool()
	pool.AddCert(hostDomain.Keys.Cert)

	tlsc, err := tao.EncodeTLSCert(fcKeys)
	if err != nil {
		log.Fatalln("fileclient, encode error: ", err)
	}
	conn, err := tls.Dial("tcp", serverAddr, &tls.Config{
		RootCAs:            pool,
		Certificates:       []tls.Certificate{*tlsc},
		InsecureSkipVerify: false,
	})
	if err != nil {
		log.Fatalln("fileclient: can't establish channel: ", err)
	}
	ms := util.NewMessageStream(conn)

	// Before doing any tests, create a simple file to send to the server.
	testContents := `
This is a simple file to test
It has some new lines
And it doesn't have very much content.
	`

	if _, err := os.Stat(*fileClientFilePath); err != nil {
		if err := os.MkdirAll(*fileClientFilePath, 0700); err != nil {
			log.Fatalf("fileclient: couldn't create the file storage path %s: %s", *fileClientFilePath, err)
		}
	}

	sentFileName := *testFile
	sentFilePath := path.Join(*fileClientFilePath, sentFileName)
	if err := ioutil.WriteFile(sentFilePath, []byte(testContents), 0600); err != nil {
		log.Fatalf("fileclient: couldn't create a test file at %s: %s", sentFilePath, err)
	}

	// Authenticate user principal(s).
	if _, err := os.Stat(*fileClientKeyPath); err != nil {
		log.Fatalf("fileclient: couldn't get user credentials from %s: %s\n", *fileClientKeyPath, err)
	}

	// This method won't generate the right certificate in general for
	// signing, which is why we check first to make sure the right directory
	// already exists. But it will successfully read the signer and the
	// certificate.
	userKeys, err := tao.NewOnDiskPBEKeys(tao.Signing, []byte(*fileClientPassword), *fileClientKeyPath, nil)
	if err != nil {
		log.Fatalf("Couldn't read the keys from %s: %s\n", *fileClientKeyPath, err)
	}
	userCert := userKeys.Cert.Raw

	// Authenticate a key to use for requests to the server.
	if err = fileproxy.AuthenticatePrincipal(ms, userKeys, userCert); err != nil {
		log.Fatalf("fileclient: can't authenticate principal: %s", err)
	}

	// Create a file.
	if err = fileproxy.CreateFile(ms, userCert, sentFileName); err != nil {
		log.Fatalln("fileclient: can't create file:", err)
	}

	// Send File.
	if err = fileproxy.WriteFile(ms, userCert, *fileClientFilePath, sentFileName); err != nil {
		log.Fatalf("fileclient: couldn't write the file %s to the server: %s", sentFileName, err)
	}

	// Get file.
	outputFileName := sentFileName + ".out"
	if err = fileproxy.ReadFile(ms, userCert, *fileClientFilePath, sentFileName, outputFileName); err != nil {
		log.Fatalf("fileclient: couldn't get file %s to output file %s: %s", sentFileName, outputFileName, err)
	}

	// TODO(tmroeder): compare the received file against the sent file.

	// Set up a TLS connection to the rollback server, just like the one to
	// the file server.
	rollbackServerAddr := net.JoinHostPort(*rollbackServerHost, *rollbackServerPort)
	rbconn, err := tls.Dial("tcp", rollbackServerAddr, &tls.Config{
		RootCAs:            pool,
		Certificates:       []tls.Certificate{*tlsc},
		InsecureSkipVerify: false,
	})
	if err != nil {
		log.Fatalf("fileclient: can't establish rollback channel: %s", err)
	}
	newms := util.NewMessageStream(rbconn)

	// Create a fake hash value, and set this value for an item.
	hashLen := 32
	hash := make([]byte, hashLen)
	if _, err := rand.Read(hash); err != nil {
		log.Fatalf("fileclient: failed to read a random value for the hash")
	}

	progName := taoName.String()
	resName := "test_resource"
	if err := fileproxy.SetHash(newms, resName, hash); err != nil {
		log.Fatalf("Couldn't set the hash for program '%s', resource '%s', hash % x on the remote server: %s", progName, resName, hash, err)
	}

	// Set the counter to 10 and check that we get the same value back.
	if err := fileproxy.SetCounter(newms, uint64(10)); err != nil {
		log.Fatalf("fileclient: couldn't set the counter in the file client")
	}

	c, err := fileproxy.GetCounter(newms)
	if err != nil {
		log.Fatalf("fileclient: couldn't get the value of the counter from the rollback server")
	}

	// Get the hash verification value.
	newHash, err := fileproxy.GetHashedVerifier(newms, resName)
	if err != nil {
		log.Fatalf("fileclient: couldn't get the hashed verifier from the rollback server")
	}

	// Try to recompute the hashed verifier directly to see if it matches.
	sh := sha256.New()
	vi := fileproxy.EncodeCounter(c)
	sh.Write(vi)
	sh.Write(hash)
	sh.Write(vi)
	computed := sh.Sum(nil)
	if subtle.ConstantTimeCompare(newHash, computed) != 1 {
		log.Fatalf("fileclient: the hashed verifier % x returned by the server didn't match the value % x computed locally", newHash, computed)
	}

	log.Println("All fileclient tests pass")
}