tls

package module
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 Go to latest Published: Mar 1, 2024 License: BSD-3-Clause Imports: 45 Imported by: 0

Documentation

Overview

Package tls partially implements TLS 1.2, as specified in RFC 5246, and TLS 1.3, as specified in RFC 8446.

Index

Examples

Constants

View Source 
const (
	// TLS 1.0 - 1.2 cipher suites.
	TLS_RSA_WITH_RC4_128_SHA                      uint16 = 0x0005
	TLS_RSA_WITH_3DES_EDE_CBC_SHA                 uint16 = 0x000a
	TLS_RSA_WITH_AES_128_CBC_SHA                  uint16 = 0x002f
	TLS_RSA_WITH_AES_256_CBC_SHA                  uint16 = 0x0035
	TLS_RSA_WITH_AES_128_CBC_SHA256               uint16 = 0x003c
	TLS_RSA_WITH_AES_128_GCM_SHA256               uint16 = 0x009c
	TLS_RSA_WITH_AES_256_GCM_SHA384               uint16 = 0x009d
	TLS_ECDHE_ECDSA_WITH_RC4_128_SHA              uint16 = 0xc007
	TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA          uint16 = 0xc009
	TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA          uint16 = 0xc00a
	TLS_ECDHE_RSA_WITH_RC4_128_SHA                uint16 = 0xc011
	TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA           uint16 = 0xc012
	TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA            uint16 = 0xc013
	TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA            uint16 = 0xc014
	TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256       uint16 = 0xc023
	TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256         uint16 = 0xc027
	TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256         uint16 = 0xc02f
	TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256       uint16 = 0xc02b
	TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384         uint16 = 0xc030
	TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384       uint16 = 0xc02c
	TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305_SHA256   uint16 = 0xcca8
	TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305_SHA256 uint16 = 0xcca9

	// TLS 1.3 cipher suites.
	TLS_AES_128_GCM_SHA256       uint16 = 0x1301
	TLS_AES_256_GCM_SHA384       uint16 = 0x1302
	TLS_CHACHA20_POLY1305_SHA256 uint16 = 0x1303

	// TLS_FALLBACK_SCSV isn't a standard cipher suite but an indicator
	// that the client is doing version fallback. See RFC 7507.
	TLS_FALLBACK_SCSV uint16 = 0x5600

	// Legacy names for the corresponding cipher suites with the correct _SHA256
	// suffix, retained for backward compatibility.
	TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305   = TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305_SHA256
	TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305 = TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305_SHA256
)

A list of cipher suite IDs that are, or have been, implemented by this package.

See https://www.iana.org/assignments/tls-parameters/tls-parameters.xml

View Source 
const (
	VersionTLS10 = 0x0301
	VersionTLS11 = 0x0302
	VersionTLS12 = 0x0303
	VersionTLS13 = 0x0304

	// Deprecated: SSLv3 is cryptographically broken, and is no longer
	// supported by this package. See golang.org/issue/32716.
	VersionSSL30 = 0x0300
)
View Source 
const (
	NoClientCert               = tls.NoClientCert
	RequestClientCert          = tls.RequestClientCert
	RequireAnyClientCert       = tls.RequireAnyClientCert
	VerifyClientCertIfGiven    = tls.VerifyClientCertIfGiven
	RequireAndVerifyClientCert = tls.RequireAndVerifyClientCert
)
View Source 
const (
	// RenegotiateNever disables renegotiation.
	RenegotiateNever = tls.RenegotiateNever

	// RenegotiateOnceAsClient allows a remote server to request
	// renegotiation once per connection.
	RenegotiateOnceAsClient = tls.RenegotiateOnceAsClient

	// RenegotiateFreelyAsClient allows a remote server to repeatedly
	// request renegotiation.
	RenegotiateFreelyAsClient = tls.RenegotiateFreelyAsClient
)
View Source 
const (
	QUICEncryptionLevelInitial = QUICEncryptionLevel(iota)
	QUICEncryptionLevelEarly
	QUICEncryptionLevelHandshake
	QUICEncryptionLevelApplication
)

Variables

This section is empty.

Functions

func CipherSuiteName 

func CipherSuiteName(id uint16) string

CipherSuiteName returns the standard name for the passed cipher suite ID (e.g. "TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256"), or a fallback representation of the ID value if the cipher suite is not implemented by this package.

func ContainsObfuscatedSessionTicketCipherSuite 

func ContainsObfuscatedSessionTicketCipherSuite(cipherSuites []uint16) bool

func InitSessionTicketKeys 

func InitSessionTicketKeys(conf *Config)

InitSessionTicketKeys triggers the initialization of session ticket keys.

func Listen 

func Listen(network, laddr string, config *ExtendedTLSConfig) (net.Listener, error)

Listen creates a TLS listener accepting connections on the given network address using net.Listen. The configuration config must be non-nil and must include at least one certificate or else set GetCertificate.

func NewListener 

func NewListener(inner net.Listener, config *ExtendedTLSConfig) net.Listener

NewListener creates a Listener which accepts connections from an inner Listener and wraps each connection with Server. The configuration config must be non-nil and must include at least one certificate or else set GetCertificate.

func ParseSessionState 

func ParseSessionState(data []byte) (*sessionState, error)

ParseSessionState parses a SessionState encoded by [SessionState.Bytes].

func ReadClientHelloRandom 

func ReadClientHelloRandom(data []byte) ([]byte, error)

[Psiphon]

func VersionName 

func VersionName(version uint16) string

VersionName returns the name for the provided TLS version number (e.g. "TLS 1.3"), or a fallback representation of the value if the version is not implemented by this package.

Types

type AlertError 

type AlertError uint8

An AlertError is a TLS alert.

When using a QUIC transport, QUICConn methods will return an error which wraps AlertError rather than sending a TLS alert.

func (AlertError) Error 

func (e AlertError) Error() string

type Certificate 

type Certificate = tls.Certificate

func LoadX509KeyPair 

func LoadX509KeyPair(certFile, keyFile string) (Certificate, error)

LoadX509KeyPair reads and parses a public/private key pair from a pair of files. The files must contain PEM encoded data. The certificate file may contain intermediate certificates following the leaf certificate to form a certificate chain. On successful return, Certificate.Leaf will be nil because the parsed form of the certificate is not retained.

Example 
package main

import (
	"crypto/tls"
	"log"
)

func main() {
	cert, err := tls.LoadX509KeyPair("testdata/example-cert.pem", "testdata/example-key.pem")
	if err != nil {
		log.Fatal(err)
	}
	cfg := &tls.Config{Certificates: []tls.Certificate{cert}}
	listener, err := tls.Listen("tcp", ":2000", cfg)
	if err != nil {
		log.Fatal(err)
	}
	_ = listener
}

Output:

func X509KeyPair 

func X509KeyPair(certPEMBlock, keyPEMBlock []byte) (Certificate, error)

X509KeyPair parses a public/private key pair from a pair of PEM encoded data. On successful return, Certificate.Leaf will be nil because the parsed form of the certificate is not retained.

Example 
package main

import (
	"crypto/tls"
	"log"
)

func main() {
	certPem := []byte(`-----BEGIN CERTIFICATE-----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-----END CERTIFICATE-----`)
	keyPem := []byte(`-----BEGIN EC PRIVATE KEY-----
MHcCAQEEIIrYSSNQFaA2Hwf1duRSxKtLYX5CB04fSeQ6tF1aY/PuoAoGCCqGSM49
AwEHoUQDQgAEPR3tU2Fta9ktY+6P9G0cWO+0kETA6SFs38GecTyudlHz6xvCdz8q
EKTcWGekdmdDPsHloRNtsiCa697B2O9IFA==
-----END EC PRIVATE KEY-----`)
	cert, err := tls.X509KeyPair(certPem, keyPem)
	if err != nil {
		log.Fatal(err)
	}
	cfg := &tls.Config{Certificates: []tls.Certificate{cert}}
	listener, err := tls.Listen("tcp", ":2000", cfg)
	if err != nil {
		log.Fatal(err)
	}
	_ = listener
}

Output:
Example (HttpServer) 
package main

import (
	"crypto/tls"
	"log"
	"net/http"
	"time"
)

func main() {
	certPem := []byte(`-----BEGIN CERTIFICATE-----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-----END CERTIFICATE-----`)
	keyPem := []byte(`-----BEGIN EC PRIVATE KEY-----
MHcCAQEEIIrYSSNQFaA2Hwf1duRSxKtLYX5CB04fSeQ6tF1aY/PuoAoGCCqGSM49
AwEHoUQDQgAEPR3tU2Fta9ktY+6P9G0cWO+0kETA6SFs38GecTyudlHz6xvCdz8q
EKTcWGekdmdDPsHloRNtsiCa697B2O9IFA==
-----END EC PRIVATE KEY-----`)
	cert, err := tls.X509KeyPair(certPem, keyPem)
	if err != nil {
		log.Fatal(err)
	}
	cfg := &tls.Config{Certificates: []tls.Certificate{cert}}
	srv := &http.Server{
		TLSConfig:    cfg,
		ReadTimeout:  time.Minute,
		WriteTimeout: time.Minute,
	}
	log.Fatal(srv.ListenAndServeTLS("", ""))
}

Output:

type CertificateRequestInfo 

type CertificateRequestInfo = tls.CertificateRequestInfo

CertificateRequestInfo contains information from a server's CertificateRequest message, which is used to demand a certificate and proof of control from a client.

type CertificateVerificationError 

type CertificateVerificationError = tls.CertificateVerificationError

CertificateVerificationError is returned when certificate verification fails during the handshake.

type CipherSuite 

type CipherSuite struct {
	ID   uint16
	Name string

	// Supported versions is the list of TLS protocol versions that can
	// negotiate this cipher suite.
	SupportedVersions []uint16

	// Insecure is true if the cipher suite has known security issues
	// due to its primitives, design, or implementation.
	Insecure bool
}

CipherSuite is a TLS cipher suite. Note that most functions in this package accept and expose cipher suite IDs instead of this type.

func CipherSuites 

func CipherSuites() []*CipherSuite

CipherSuites returns a list of cipher suites currently implemented by this package, excluding those with security issues, which are returned by InsecureCipherSuites.

The list is sorted by ID. Note that the default cipher suites selected by this package might depend on logic that can't be captured by a static list, and might not match those returned by this function.

func InsecureCipherSuites 

func InsecureCipherSuites() []*CipherSuite

InsecureCipherSuites returns a list of cipher suites currently implemented by this package and which have security issues.

Most applications should not use the cipher suites in this list, and should only use those returned by CipherSuites.

type ClientAuthType 

type ClientAuthType = tls.ClientAuthType

ClientAuthType is tls.ClientAuthType

type ClientHelloInfo 

type ClientHelloInfo = tls.ClientHelloInfo

type ClientSessionCache 

type ClientSessionCache = tls.ClientSessionCache

func NewLRUClientSessionCache 

func NewLRUClientSessionCache(capacity int) ClientSessionCache

NewLRUClientSessionCache returns a ClientSessionCache with the given capacity that uses an LRU strategy. If capacity is < 1, a default capacity is used instead.

type ClientSessionState 

type ClientSessionState = tls.ClientSessionState

func NewResumptionState 

func NewResumptionState(ticket []byte, state *sessionState) (*ClientSessionState, error)

NewResumptionState returns a state value that can be returned by [ClientSessionCache.Get] to resume a previous session.

state needs to be returned by ParseSessionState, and the ticket and session state must have been returned by [ClientSessionState.ResumptionState].

type Config 

type Config = tls.Config

A Config structure is used to configure a TLS client or server. After one has been passed to a TLS function it must not be modified. A Config may be reused; the tls package will also not modify it.

Example (KeyLogWriter) 
package main

import (
	"crypto/tls"
	"log"
	"net/http"
	"net/http/httptest"
	"os"
)

// zeroSource is an io.Reader that returns an unlimited number of zero bytes.
type zeroSource struct{}

func (zeroSource) Read(b []byte) (n int, err error) {
	for i := range b {
		b[i] = 0
	}

	return len(b), nil
}

func main() {
	// Debugging TLS applications by decrypting a network traffic capture.

	// WARNING: Use of KeyLogWriter compromises security and should only be
	// used for debugging.

	// Dummy test HTTP server for the example with insecure random so output is
	// reproducible.
	server := httptest.NewUnstartedServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {}))
	server.TLS = &tls.Config{
		Rand: zeroSource{}, // for example only; don't do this.
	}
	server.StartTLS()
	defer server.Close()

	// Typically the log would go to an open file:
	// w, err := os.OpenFile("tls-secrets.txt", os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0600)
	w := os.Stdout

	client := &http.Client{
		Transport: &http.Transport{
			TLSClientConfig: &tls.Config{
				KeyLogWriter: w,

				Rand:               zeroSource{}, // for reproducible output; don't do this.
				InsecureSkipVerify: true,         // test server certificate is not trusted.
			},
		},
	}
	resp, err := client.Get(server.URL)
	if err != nil {
		log.Fatalf("Failed to get URL: %v", err)
	}
	resp.Body.Close()

	// The resulting file can be used with Wireshark to decrypt the TLS
	// connection by setting (Pre)-Master-Secret log filename in SSL Protocol
	// preferences.
}

Output:
Example (VerifyConnection) 
package main

import (
	"crypto/tls"
	"crypto/x509"
)

func main() {
	// VerifyConnection can be used to replace and customize connection
	// verification. This example shows a VerifyConnection implementation that
	// will be approximately equivalent to what crypto/tls does normally to
	// verify the peer's certificate.

	// Client side configuration.
	_ = &tls.Config{
		// Set InsecureSkipVerify to skip the default validation we are
		// replacing. This will not disable VerifyConnection.
		InsecureSkipVerify: true,
		VerifyConnection: func(cs tls.ConnectionState) error {
			opts := x509.VerifyOptions{
				DNSName:       cs.ServerName,
				Intermediates: x509.NewCertPool(),
			}
			for _, cert := range cs.PeerCertificates[1:] {
				opts.Intermediates.AddCert(cert)
			}
			_, err := cs.PeerCertificates[0].Verify(opts)
			return err
		},
	}

	// Server side configuration.
	_ = &tls.Config{
		// Require client certificates (or VerifyConnection will run anyway and
		// panic accessing cs.PeerCertificates[0]) but don't verify them with the
		// default verifier. This will not disable VerifyConnection.
		ClientAuth: tls.RequireAnyClientCert,
		VerifyConnection: func(cs tls.ConnectionState) error {
			opts := x509.VerifyOptions{
				DNSName:       cs.ServerName,
				Intermediates: x509.NewCertPool(),
				KeyUsages:     []x509.ExtKeyUsage{x509.ExtKeyUsageClientAuth},
			}
			for _, cert := range cs.PeerCertificates[1:] {
				opts.Intermediates.AddCert(cert)
			}
			_, err := cs.PeerCertificates[0].Verify(opts)
			return err
		},
	}

	// Note that when certificates are not handled by the default verifier
	// ConnectionState.VerifiedChains will be nil.
}

Output:

type Conn 

type Conn struct {
	// contains filtered or unexported fields
}

A Conn represents a secured connection. It implements the net.Conn interface.

func Client 

func Client(conn net.Conn, config *ExtendedTLSConfig) *Conn

Client returns a new TLS client side connection using conn as the underlying transport. The config cannot be nil: users must set either ServerName or InsecureSkipVerify in the config.

func Dial 

func Dial(network, addr string, config *Config) (*Conn, error)

Dial connects to the given network address using net.Dial and then initiates a TLS handshake, returning the resulting TLS connection. Dial interprets a nil configuration as equivalent to the zero configuration; see the documentation of Config for the defaults.

Example 
package main

import (
	"crypto/tls"
	"crypto/x509"
)

func main() {
	// Connecting with a custom root-certificate set.

	const rootPEM = `
-- GlobalSign Root R2, valid until Dec 15, 2021
-----BEGIN CERTIFICATE-----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==
-----END CERTIFICATE-----`

	// First, create the set of root certificates. For this example we only
	// have one. It's also possible to omit this in order to use the
	// default root set of the current operating system.
	roots := x509.NewCertPool()
	ok := roots.AppendCertsFromPEM([]byte(rootPEM))
	if !ok {
		panic("failed to parse root certificate")
	}

	conn, err := tls.Dial("tcp", "mail.google.com:443", &tls.Config{
		RootCAs: roots,
	})
	if err != nil {
		panic("failed to connect: " + err.Error())
	}
	conn.Close()
}

Output:

func DialWithDialer 

func DialWithDialer(dialer *net.Dialer, network, addr string, config *Config) (*Conn, error)

DialWithDialer connects to the given network address using dialer.Dial and then initiates a TLS handshake, returning the resulting TLS connection. Any timeout or deadline given in the dialer apply to connection and TLS handshake as a whole.

DialWithDialer interprets a nil configuration as equivalent to the zero configuration; see the documentation of Config for the defaults.

DialWithDialer uses context.Background internally; to specify the context, use Dialer.DialContext with NetDialer set to the desired dialer.

func Server 

func Server(conn net.Conn, config *ExtendedTLSConfig) *Conn

Server returns a new TLS server side connection using conn as the underlying transport. The configuration config must be non-nil and must include at least one certificate or else set GetCertificate.

func (*Conn) Close 

func (c *Conn) Close() error

Close closes the connection.

func (*Conn) CloseWrite 

func (c *Conn) CloseWrite() error

CloseWrite shuts down the writing side of the connection. It should only be called once the handshake has completed and does not call CloseWrite on the underlying connection. Most callers should just use Close.

func (*Conn) ConnectionState 

func (c *Conn) ConnectionState() ConnectionState

ConnectionState returns basic TLS details about the connection.

func (*Conn) Handshake 

func (c *Conn) Handshake() error

Handshake runs the client or server handshake protocol if it has not yet been run.

Most uses of this package need not call Handshake explicitly: the first Read or Write will call it automatically.

For control over canceling or setting a timeout on a handshake, use HandshakeContext or the Dialer's DialContext method instead.

In order to avoid denial of service attacks, the maximum RSA key size allowed in certificates sent by either the TLS server or client is limited to 8192 bits. This limit can be overridden by setting tlsmaxrsasize in the GODEBUG environment variable (e.g. GODEBUG=tlsmaxrsasize=4096).

func (*Conn) HandshakeContext 

func (c *Conn) HandshakeContext(ctx context.Context) error

HandshakeContext runs the client or server handshake protocol if it has not yet been run.

The provided Context must be non-nil. If the context is canceled before the handshake is complete, the handshake is interrupted and an error is returned. Once the handshake has completed, cancellation of the context will not affect the connection.

Most uses of this package need not call HandshakeContext explicitly: the first Read or Write will call it automatically.

func (*Conn) LocalAddr 

func (c *Conn) LocalAddr() net.Addr

LocalAddr returns the local network address.

func (*Conn) NetConn 

func (c *Conn) NetConn() net.Conn

NetConn returns the underlying connection that is wrapped by c. Note that writing to or reading from this connection directly will corrupt the TLS session.

func (*Conn) OCSPResponse 

func (c *Conn) OCSPResponse() []byte

OCSPResponse returns the stapled OCSP response from the TLS server, if any. (Only valid for client connections.)

func (*Conn) Read 

func (c *Conn) Read(b []byte) (int, error)

Read reads data from the connection.

As Read calls Handshake, in order to prevent indefinite blocking a deadline must be set for both Read and Write before Read is called when the handshake has not yet completed. See SetDeadline, SetReadDeadline, and SetWriteDeadline.

func (*Conn) RemoteAddr 

func (c *Conn) RemoteAddr() net.Addr

RemoteAddr returns the remote network address.

func (*Conn) SetDeadline 

func (c *Conn) SetDeadline(t time.Time) error

SetDeadline sets the read and write deadlines associated with the connection. A zero value for t means Read and Write will not time out. After a Write has timed out, the TLS state is corrupt and all future writes will return the same error.

func (*Conn) SetReadDeadline 

func (c *Conn) SetReadDeadline(t time.Time) error

SetReadDeadline sets the read deadline on the underlying connection. A zero value for t means Read will not time out.

func (*Conn) SetWriteDeadline 

func (c *Conn) SetWriteDeadline(t time.Time) error

SetWriteDeadline sets the write deadline on the underlying connection. A zero value for t means Write will not time out. After a Write has timed out, the TLS state is corrupt and all future writes will return the same error.

func (*Conn) VerifyHostname 

func (c *Conn) VerifyHostname(host string) error

VerifyHostname checks that the peer certificate chain is valid for connecting to host. If so, it returns nil; if not, it returns an error describing the problem.

func (*Conn) Write 

func (c *Conn) Write(b []byte) (int, error)

Write writes data to the connection.

As Write calls Handshake, in order to prevent indefinite blocking a deadline must be set for both Read and Write before Write is called when the handshake has not yet completed. See SetDeadline, SetReadDeadline, and SetWriteDeadline.

type ConnectionState 

type ConnectionState = tls.ConnectionState

ConnectionState records basic TLS details about the connection.

type CurveID 

type CurveID = tls.CurveID

CurveID is a tls.CurveID 

const (
	CurveP256 CurveID = 23
	CurveP384 CurveID = 24
	CurveP521 CurveID = 25
	X25519    CurveID = 29
)

type Dialer 

type Dialer struct {
	// NetDialer is the optional dialer to use for the TLS connections'
	// underlying TCP connections.
	// A nil NetDialer is equivalent to the net.Dialer zero value.
	NetDialer *net.Dialer

	// Config is the TLS configuration to use for new connections.
	// A nil configuration is equivalent to the zero
	// configuration; see the documentation of Config for the
	// defaults.
	Config *Config
}

Dialer dials TLS connections given a configuration and a Dialer for the underlying connection.

func (*Dialer) Dial 

func (d *Dialer) Dial(network, addr string) (net.Conn, error)

Dial connects to the given network address and initiates a TLS handshake, returning the resulting TLS connection.

The returned Conn, if any, will always be of type *Conn.

Dial uses context.Background internally; to specify the context, use DialContext.

func (*Dialer) DialContext 

func (d *Dialer) DialContext(ctx context.Context, network, addr string) (net.Conn, error)

DialContext connects to the given network address and initiates a TLS handshake, returning the resulting TLS connection.

The provided Context must be non-nil. If the context expires before the connection is complete, an error is returned. Once successfully connected, any expiration of the context will not affect the connection.

The returned Conn, if any, will always be of type *Conn.

type ExtendedTLSConfig 

type ExtendedTLSConfig struct {
	TLSConfig   *Config
	ExtraConfig *ExtraConfig
}

[Psiphon] ExtendedTLSConfig wraps crypto/tls.Config and Psiphon-specific configurations.

type ExtraConfig 

type ExtraConfig struct {
	// ClientHelloPRNG is used for Client Hello randomization and replay.
	ClientHelloPRNG *prng.PRNG

	// GetClientHelloRandom is used to supply a specific value in the TLS
	// Client Hello random field. This is used to send an anti-probing
	// message, indistinguishable from random, that proves knowlegde of a
	// shared secret key.
	GetClientHelloRandom func() ([]byte, error)

	// UseObfuscatedSessionTickets should be set when using obfuscated session
	// tickets. This setting ensures that checkForResumption operates in a way
	// that is compatible with the obfuscated session ticket scheme.
	//
	// This flag doesn't fully configure obfuscated session tickets.
	// SessionTicketKey and SetSessionTicketKeys must also be intialized. See the
	// setup in psiphon/server.MeekServer.makeMeekTLSConfig.
	//
	// See the comment for NewObfuscatedClientSessionState for more details on
	// obfuscated session tickets.
	UseObfuscatedSessionTickets bool

	// PassthroughAddress, when not blank, enables passthrough mode. It is a
	// network address, host and port, to which client traffic is relayed when
	// the client fails anti-probing tests.
	//
	// The PassthroughAddress is expected to be a TCP endpoint. Passthrough is
	// triggered when a ClientHello random field doesn't have a valid value, as
	// determined by PassthroughKey.
	PassthroughAddress string

	// PassthroughVerifyMessage must be set when passthrough mode is enabled. The
	// function must return true for valid passthrough messages and false
	// otherwise.
	PassthroughVerifyMessage func([]byte) bool

	// PassthroughHistoryAddNew must be set when passthough mode is enabled. The
	// function should check that a ClientHello random value has not been
	// previously observed, returning true only for a newly observed value. Any
	// logging is the callback's responsibility.
	PassthroughHistoryAddNew func(
		clientIP string,
		clientRandom []byte) bool

	// PassthroughLogInvalidMessage must be set when passthough mode is enabled.
	// The function should log an invalid ClientHello random value event.
	PassthroughLogInvalidMessage func(clientIP string)
}

[Psiphon]

type ObfuscatedClientSessionState 

type ObfuscatedClientSessionState struct {
	SessionTicket      []uint8
	Vers               uint16
	CipherSuite        uint16
	MasterSecret       []byte
	ServerCertificates []*x509.Certificate
	VerifiedChains     [][]*x509.Certificate
	UseEMS             bool
}

[Psiphon]

func NewObfuscatedClientSessionState 

func NewObfuscatedClientSessionState(sharedSecret [32]byte) (*ObfuscatedClientSessionState, error)

[Psiphon] NewObfuscatedClientSessionState produces obfuscated session tickets.

Obfuscated Session Tickets

Obfuscated session tickets is a network traffic obfuscation protocol that appears to be valid TLS using session tickets. The client actually generates the session ticket and encrypts it with a shared secret, enabling a TLS session that entirely skips the most fingerprintable aspects of TLS. The scheme is described here: https://lists.torproject.org/pipermail/tor-dev/2016-September/011354.html

Circumvention notes:

  • TLS session ticket implementations are widespread: https://istlsfastyet.com/#cdn-paas.
  • An adversary cannot easily block session ticket capability, as this requires a downgrade attack against TLS.
  • Anti-probing defence is provided, as the adversary must use the correct obfuscation shared secret to form valid obfuscation session ticket; otherwise server offers standard session tickets.
  • Limitation: an adversary with the obfuscation shared secret can decrypt the session ticket and observe the plaintext traffic. It's assumed that the adversary will not learn the obfuscated shared secret without also learning the address of the TLS server and blocking it anyway; it's also assumed that the TLS payload is not plaintext but is protected with some other security layer (e.g., SSH).

Implementation notes:

  • The TLS ClientHello includes an SNI field, even when using session tickets, so the client should populate the ServerName.
  • Server should set its SetSessionTicketKeys with first a standard key, followed by the obfuscation shared secret.
  • Since the client creates the session ticket, it selects parameters that were not negotiated with the server, such as the cipher suite. It's implicitly assumed that the server can support the selected parameters.
  • Obfuscated session tickets are not supported for TLS 1.3 _clients_, which use a distinct scheme. Obfuscated session ticket support in this package is intended to support TLS 1.2 clients.

type QUICConfig 

type QUICConfig struct {
	TLSConfig *Config
	// [Psiphon]
	ExtraConfig *ExtraConfig
}

A QUICConfig configures a QUICConn.

type QUICConn 

type QUICConn struct {
	// contains filtered or unexported fields
}

A QUICConn represents a connection which uses a QUIC implementation as the underlying transport as described in RFC 9001.

Methods of QUICConn are not safe for concurrent use.

func QUICClient 

func QUICClient(config *QUICConfig) *QUICConn

QUICClient returns a new TLS client side connection using QUICTransport as the underlying transport. The config cannot be nil.

The config's MinVersion must be at least TLS 1.3.

func QUICServer 

func QUICServer(config *QUICConfig) *QUICConn

QUICServer returns a new TLS server side connection using QUICTransport as the underlying transport. The config cannot be nil.

The config's MinVersion must be at least TLS 1.3.

func (*QUICConn) Close 

func (q *QUICConn) Close() error

Close closes the connection and stops any in-progress handshake.

func (*QUICConn) ConnectionState 

func (q *QUICConn) ConnectionState() ConnectionState

ConnectionState returns basic TLS details about the connection.

func (*QUICConn) HandleData 

func (q *QUICConn) HandleData(level QUICEncryptionLevel, data []byte) error

HandleData handles handshake bytes received from the peer. It may produce connection events, which may be read with NextEvent.

func (*QUICConn) NextEvent 

func (q *QUICConn) NextEvent() QUICEvent

NextEvent returns the next event occurring on the connection. It returns an event with a Kind of QUICNoEvent when no events are available.

func (*QUICConn) SendSessionTicket 

func (q *QUICConn) SendSessionTicket(opts QUICSessionTicketOptions) error

SendSessionTicket sends a session ticket to the client. It produces connection events, which may be read with NextEvent. Currently, it can only be called once.

func (*QUICConn) SetTransportParameters 

func (q *QUICConn) SetTransportParameters(params []byte)

SetTransportParameters sets the transport parameters to send to the peer.

Server connections may delay setting the transport parameters until after receiving the client's transport parameters. See QUICTransportParametersRequired.

func (*QUICConn) Start 

func (q *QUICConn) Start(ctx context.Context) error

Start starts the client or server handshake protocol. It may produce connection events, which may be read with NextEvent.

Start must be called at most once.

type QUICEncryptionLevel 

type QUICEncryptionLevel int

QUICEncryptionLevel represents a QUIC encryption level used to transmit handshake messages.

func (QUICEncryptionLevel) String 

func (l QUICEncryptionLevel) String() string

type QUICEvent 

type QUICEvent struct {
	Kind QUICEventKind

	// Set for QUICSetReadSecret, QUICSetWriteSecret, and QUICWriteData.
	Level QUICEncryptionLevel

	// Set for QUICTransportParameters, QUICSetReadSecret, QUICSetWriteSecret, and QUICWriteData.
	// The contents are owned by crypto/tls, and are valid until the next NextEvent call.
	Data []byte

	// Set for QUICSetReadSecret and QUICSetWriteSecret.
	Suite uint16
}

A QUICEvent is an event occurring on a QUIC connection.

The type of event is specified by the Kind field. The contents of the other fields are kind-specific.

type QUICEventKind 

type QUICEventKind int

A QUICEventKind is a type of operation on a QUIC connection. 

const (
	// QUICNoEvent indicates that there are no events available.
	QUICNoEvent QUICEventKind = iota

	// QUICSetReadSecret and QUICSetWriteSecret provide the read and write
	// secrets for a given encryption level.
	// QUICEvent.Level, QUICEvent.Data, and QUICEvent.Suite are set.
	//
	// Secrets for the Initial encryption level are derived from the initial
	// destination connection ID, and are not provided by the QUICConn.
	QUICSetReadSecret
	QUICSetWriteSecret

	// QUICWriteData provides data to send to the peer in CRYPTO frames.
	// QUICEvent.Data is set.
	QUICWriteData

	// QUICTransportParameters provides the peer's QUIC transport parameters.
	// QUICEvent.Data is set.
	QUICTransportParameters

	// QUICTransportParametersRequired indicates that the caller must provide
	// QUIC transport parameters to send to the peer. The caller should set
	// the transport parameters with QUICConn.SetTransportParameters and call
	// QUICConn.NextEvent again.
	//
	// If transport parameters are set before calling QUICConn.Start, the
	// connection will never generate a QUICTransportParametersRequired event.
	QUICTransportParametersRequired

	// QUICRejectedEarlyData indicates that the server rejected 0-RTT data even
	// if we offered it. It's returned before QUICEncryptionLevelApplication
	// keys are returned.
	QUICRejectedEarlyData

	// QUICHandshakeDone indicates that the TLS handshake has completed.
	QUICHandshakeDone
)

type QUICSessionTicketOptions 

type QUICSessionTicketOptions struct {
	// EarlyData specifies whether the ticket may be used for 0-RTT.
	EarlyData bool
}

type RecordHeaderError 

type RecordHeaderError struct {
	// Msg contains a human readable string that describes the error.
	Msg string
	// RecordHeader contains the five bytes of TLS record header that
	// triggered the error.
	RecordHeader [5]byte
	// Conn provides the underlying net.Conn in the case that a client
	// sent an initial handshake that didn't look like TLS.
	// It is nil if there's already been a handshake or a TLS alert has
	// been written to the connection.
	Conn net.Conn
}

RecordHeaderError is returned when a TLS record header is invalid.

func (RecordHeaderError) Error 

func (e RecordHeaderError) Error() string

type RenegotiationSupport 

type RenegotiationSupport = tls.RenegotiationSupport

RenegotiationSupport enumerates the different levels of support for TLS renegotiation. TLS renegotiation is the act of performing subsequent handshakes on a connection after the first. This significantly complicates the state machine and has been the source of numerous, subtle security issues. Initiating a renegotiation is not supported, but support for accepting renegotiation requests may be enabled.

Even when enabled, the server may not change its identity between handshakes (i.e. the leaf certificate must be the same). Additionally, concurrent handshake and application data flow is not permitted so renegotiation can only be used with protocols that synchronise with the renegotiation, such as HTTPS.

Renegotiation is not defined in TLS 1.3.

type SessionState 

type SessionState = tls.SessionState

A sessionState is a resumable session.

type SignatureScheme 

type SignatureScheme = tls.SignatureScheme

SignatureScheme is a tls.SignatureScheme 

const (
	// RSASSA-PKCS1-v1_5 algorithms.
	PKCS1WithSHA256 SignatureScheme = 0x0401
	PKCS1WithSHA384 SignatureScheme = 0x0501
	PKCS1WithSHA512 SignatureScheme = 0x0601

	// RSASSA-PSS algorithms with public key OID rsaEncryption.
	PSSWithSHA256 SignatureScheme = 0x0804
	PSSWithSHA384 SignatureScheme = 0x0805
	PSSWithSHA512 SignatureScheme = 0x0806

	// ECDSA algorithms. Only constrained to a specific curve in TLS 1.3.
	ECDSAWithP256AndSHA256 SignatureScheme = 0x0403
	ECDSAWithP384AndSHA384 SignatureScheme = 0x0503
	ECDSAWithP521AndSHA512 SignatureScheme = 0x0603

	// EdDSA algorithms.
	Ed25519 SignatureScheme = 0x0807

	// Legacy signature and hash algorithms for TLS 1.2.
	PKCS1WithSHA1 SignatureScheme = 0x0201
	ECDSAWithSHA1 SignatureScheme = 0x0203
)

Notes

Bugs

Source Files

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Directories

Path Synopsis
Package testenv provides information about what functionality is available in different testing environments run by the Go team.
 Package testenv provides information about what functionality is available in different testing environments run by the Go team.

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