tls

package module
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 Go to latest Published: Sep 18, 2022 License: BSD-3-Clause Imports: 48 Imported by: 0

README

uTLS uTLS

Build Status godoc

uTLS is a fork of "crypto/tls", which provides ClientHello fingerprinting resistance, low-level access to handshake, fake session tickets and some other features. Handshake is still performed by "crypto/tls", this library merely changes ClientHello part of it and provides low-level access.
Golang 1.11+ is required.
If you have any questions, bug reports or contributions, you are welcome to publish those on GitHub. If you want to do so in private, you can contact one of developers personally via sergey.frolov@colorado.edu

Documentation below may not keep up with all the changes and new features at all times, so you are encouraged to use godoc.

Features

Low-level access to handshake

  • Read/write access to all bits of client hello message.
  • Read access to fields of ClientHandshakeState, which, among other things, includes ServerHello and MasterSecret.
  • Read keystream. Can be used, for example, to "write" something in ciphertext.

ClientHello fingerprinting resistance

Golang's ClientHello has a very unique fingerprint, which especially sticks out on mobile clients, where Golang is not too popular yet. Some members of anti-censorship community are concerned that their tools could be trivially blocked based on ClientHello with relatively small collateral damage. There are multiple solutions to this issue.

It is highly recommended to use multiple fingeprints, including randomized ones to avoid relying on a single fingerprint. utls.Roller does this automatically.

Randomized Fingerprint

Randomized Fingerprints are supposedly good at defeating blacklists, since those fingerprints have random ciphersuites and extensions in random order. Note that all used ciphersuites and extensions are fully supported by uTLS, which provides a solid moving target without any compatibility or parrot-is-dead attack risks.

But note that there's a small chance that generated fingerprint won't work, so you may want to keep generating until a working one is found, and then keep reusing the working fingerprint to avoid suspicious behavior of constantly changing fingerprints. utls.Roller reuses working fingerprint automatically.

Generating randomized fingerprints

To generate a randomized fingerprint, simply do:

uTlsConn := tls.UClient(tcpConn, &config, tls.HelloRandomized)

you can use helloRandomizedALPN or helloRandomizedNoALPN to ensure presence or absence of ALPN(Application-Layer Protocol Negotiation) extension. It is recommended, but certainly not required to include ALPN (or use helloRandomized which may or may not include ALPN). If you do use ALPN, you will want to correctly handle potential application layer protocols (likely h2 or http/1.1).

Reusing randomized fingerprint
// oldConn is an old connection that worked before, so we want to reuse it
// newConn is a new connection we'd like to establish
newConn := tls.UClient(tcpConn, &config, oldConn.ClientHelloID)
Parroting

This package can be used to parrot ClientHello of popular browsers. There are some caveats to this parroting:

  • We are forced to offer ciphersuites and tls extensions that are not supported by crypto/tls. This is not a problem, if you fully control the server and turn unsupported things off on server side.
  • Parroting could be imperfect, and there is no parroting beyond ClientHello.
Compatibility risks of available parrots
Parrot Ciphers* Signature* Unsupported extensions TLS Fingerprint ID
Chrome 62 no no ChannelID 0a4a74aeebd1bb66
Chrome 70 no no ChannelID, Encrypted Certs bc4c7e42f4961cd7
Chrome 72 no no ChannelID, Encrypted Certs bbf04e5f1881f506
Chrome 83 no no ChannelID, Encrypted Certs 9c673fd64a32c8dc
Firefox 56 very low no None c884bad7f40bee56
Firefox 65 very low no MaxRecordSize 6bfedc5d5c740d58
iOS 11.1 low** no None 71a81bafd58e1301
iOS 12.1 low** no None ec55e5b4136c7949

* Denotes very rough guesstimate of likelihood that unsupported things will get echoed back by the server in the wild, visibly breaking the connection.
** No risk, if utls.EnableWeakCiphers() is called prior to using it.

Parrots FAQ

Does it really look like, say, Google Chrome with all the GREASE and stuff?

It LGTM, but please open up Wireshark and check. If you see something — say something.

Aren't there side channels? Everybody knows that the bird is a wordparrot is dead

There sure are. If you found one that approaches practicality at line speed — please tell us.

However, there is a difference between this sort of parroting and techniques like SkypeMorth. Namely, TLS is highly standardized protocol, therefore simply not that many subtle things in TLS protocol could be different and/or suddenly change in one of mimicked implementation(potentially undermining the mimicry). It is possible that we have a distinguisher right now, but amount of those potential distinguishers is limited.

Custom Handshake

It is possible to create custom handshake by

  1. Use HelloCustom as an argument for UClient() to get empty config
  2. Fill tls header fields: UConn.Hello.{Random, CipherSuites, CompressionMethods}, if needed, or stick to defaults.
  3. Configure and add various TLS Extensions to UConn.Extensions: they will be marshaled in order.
  4. Set Session and SessionCache, as needed.

If you need to manually control all the bytes on the wire(certainly not recommended!), you can set UConn.HandshakeStateBuilt = true, and marshal clientHello into UConn.HandshakeState.Hello.raw yourself. In this case you will be responsible for modifying other parts of Config and ClientHelloMsg to reflect your setup and not confuse "crypto/tls", which will be processing response from server.

Fingerprinting Captured Client Hello

You can use a captured client hello to generate new ones that mimic/have the same properties as the original. The generated client hellos should look like they were generated from the same client software as the original fingerprinted bytes. In order to do this:

  1. Create a ClientHelloSpec from the raw bytes of the original client hello
  2. Use HelloCustom as an argument for UClient() to get empty config
  3. Use ApplyPreset with the generated ClientHelloSpec to set the appropriate connection properties
uConn := UClient(&net.TCPConn{}, nil, HelloCustom)
fingerprinter := &Fingerprinter{}
generatedSpec, err := fingerprinter.FingerprintClientHello(rawCapturedClientHelloBytes)
if err != nil {
  panic("fingerprinting failed: %v", err)
}
if err := uConn.ApplyPreset(generatedSpec); err != nil {
  panic("applying generated spec failed: %v", err)
}

The rawCapturedClientHelloBytes should be the full tls record, including the record type/version/length header.

Roller

A simple wrapper, that allows to easily use multiple latest(auto-updated) fingerprints.

// NewRoller creates Roller object with default range of HelloIDs to cycle
// through until a working/unblocked one is found.
func NewRoller() (*Roller, error)

// Dial attempts to connect to given address using different HelloIDs.
// If a working HelloID is found, it is used again for subsequent Dials.
// If tcp connection fails or all HelloIDs are tried, returns with last error.
//
// Usage examples:
//
// Dial("tcp4", "google.com:443", "google.com")
// Dial("tcp", "10.23.144.22:443", "mywebserver.org")
func (c *Roller) Dial(network, addr, serverName string) (*UConn, error)

Fake Session Tickets

Fake session tickets is a very nifty trick that allows power users to hide parts of handshake, which may have some very fingerprintable features of handshake, and saves 1 RTT. Currently, there is a simple function to set session ticket to any desired state:

// If you want you session tickets to be reused - use same cache on following connections
func (uconn *UConn) SetSessionState(session *ClientSessionState)

Note that session tickets (fake ones or otherwise) are not reused.
To reuse tickets, create a shared cache and set it on current and further configs:

// If you want you session tickets to be reused - use same cache on following connections
func (uconn *UConn) SetSessionCache(cache ClientSessionCache)

Client Hello IDs

See full list of clientHelloID values here.
There are different behaviors you can get, depending on your clientHelloID:

  1. utls.HelloRandomized adds/reorders extensions, ciphersuites, etc. randomly.
    HelloRandomized adds ALPN in a percentage of cases, you may want to use HelloRandomizedALPN or HelloRandomizedNoALPN to choose specific behavior explicitly, as ALPN might affect application layer.
  2. utls.HelloGolang HelloGolang will use default "crypto/tls" handshake marshaling codepath, which WILL overwrite your changes to Hello(Config, Session are fine). You might want to call BuildHandshakeState() before applying any changes. UConn.Extensions will be completely ignored.
  3. utls.HelloCustom will prepare ClientHello with empty uconn.Extensions so you can fill it with TLSExtension's manually.
  4. The rest will will parrot given browser. Such parrots include, for example:
    • utls.HelloChrome_Auto- parrots recommended(usually latest) Google Chrome version
    • utls.HelloChrome_58 - parrots Google Chrome 58
    • utls.HelloFirefox_Auto - parrots recommended(usually latest) Firefox version
    • utls.HelloFirefox_55 - parrots Firefox 55

Usage

Examples

Find basic examples here.
Here's a more advanced example showing how to generate randomized ClientHello, modify generated ciphersuites a bit, and proceed with the handshake.

Migrating from "crypto/tls"

Here's how default "crypto/tls" is typically used:

    dialConn, err := net.Dial("tcp", "172.217.11.46:443")
    if err != nil {
        fmt.Printf("net.Dial() failed: %+v\n", err)
        return
    }

    config := tls.Config{ServerName: "www.google.com"}
    tlsConn := tls.Client(dialConn, &config)
    n, err = tlsConn.Write("Hello, World!")
    //...

To start using using uTLS:

  1. Import this library (e.g. import tls "github.com/refraction-networking/utls")
  2. Pick the Client Hello ID
  3. Simply substitute tlsConn := tls.Client(dialConn, &config) with tlsConn := tls.UClient(dialConn, &config, tls.clientHelloID)
Customizing handshake

Some customizations(such as setting session ticket/clientHello) have easy-to-use functions for them. The idea is to make common manipulations easy:

    cRandom := []byte{100, 101, 102, 103, 104, 105, 106, 107, 108, 109,
        110, 111, 112, 113, 114, 115, 116, 117, 118, 119,
        120, 121, 122, 123, 124, 125, 126, 127, 128, 129,
        130, 131}
    tlsConn.SetClientRandom(cRandom)
    masterSecret := make([]byte, 48)
    copy(masterSecret, []byte("masterSecret is NOT sent over the wire")) // you may use it for real security

    // Create a session ticket that wasn't actually issued by the server.
    sessionState := utls.MakeClientSessionState(sessionTicket, uint16(tls.VersionTLS12),
        tls.TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256,
        masterSecret,
        nil, nil)
    tlsConn.SetSessionState(sessionState)

For other customizations there are following functions

// you can use this to build the state manually and change it
// for example use Randomized ClientHello, and add more extensions
func (uconn *UConn) BuildHandshakeState() error

// Then apply the changes and marshal final bytes, which will be sent
func (uconn *UConn) MarshalClientHello() error

Contributors' guide

Please refer to this document if you're interested in internals

Credits

The initial development of uTLS was completed during an internship at Google Jigsaw. This is not an official Google product.

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 (
	OLD_TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305_SHA256   = uint16(0xcc13)
	OLD_TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305_SHA256 = uint16(0xcc14)

	DISABLED_TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA384 = uint16(0xc024)
	DISABLED_TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384   = uint16(0xc028)
	DISABLED_TLS_RSA_WITH_AES_256_CBC_SHA256         = uint16(0x003d)

	FAKE_OLD_TLS_DHE_RSA_WITH_CHACHA20_POLY1305_SHA256 = uint16(0xcc15) // we can try to craft these ciphersuites
	FAKE_TLS_DHE_RSA_WITH_AES_128_GCM_SHA256           = uint16(0x009e) // from existing pieces, if needed

	FAKE_TLS_DHE_RSA_WITH_AES_128_CBC_SHA    = uint16(0x0033)
	FAKE_TLS_DHE_RSA_WITH_AES_256_CBC_SHA    = uint16(0x0039)
	FAKE_TLS_DHE_RSA_WITH_AES_256_GCM_SHA384 = uint16(0x009f)
	FAKE_TLS_RSA_WITH_RC4_128_MD5            = uint16(0x0004)
	FAKE_TLS_EMPTY_RENEGOTIATION_INFO_SCSV   = uint16(0x00ff)
)
View Source 
const (
	PskModePlain uint8 = pskModePlain
	PskModeDHE   uint8 = pskModeDHE
)
View Source 
const GREASE_PLACEHOLDER = 0x0a0a

based on spec's GreaseStyle, GREASE_PLACEHOLDER may be replaced by another GREASE value https://tools.ietf.org/html/draft-ietf-tls-grease-01

View Source 
const (
	PRNGSeedLength = 32
)

Variables

View Source 
var (
	FakeFFDHE2048 = uint16(0x0100)
	FakeFFDHE3072 = uint16(0x0101)
)

fake curves(groups)

View Source 
var (
	// HelloGolang will use default "crypto/tls" handshake marshaling codepath, which WILL
	// overwrite your changes to Hello(Config, Session are fine).
	// You might want to call BuildHandshakeState() before applying any changes.
	// UConn.Extensions will be completely ignored.
	HelloGolang = ClientHelloID{helloGolang, helloAutoVers, nil}

	// HelloCustom will prepare ClientHello with empty uconn.Extensions so you can fill it with
	// TLSExtensions manually or use ApplyPreset function
	HelloCustom = ClientHelloID{helloCustom, helloAutoVers, nil}

	// HelloRandomized* randomly adds/reorders extensions, ciphersuites, etc.
	HelloRandomized       = ClientHelloID{helloRandomized, helloAutoVers, nil}
	HelloRandomizedALPN   = ClientHelloID{helloRandomizedALPN, helloAutoVers, nil}
	HelloRandomizedNoALPN = ClientHelloID{helloRandomizedNoALPN, helloAutoVers, nil}

	// The rest will will parrot given browser.
	HelloFirefox_Auto = HelloFirefox_65
	HelloFirefox_55   = ClientHelloID{helloFirefox, "55", nil}
	HelloFirefox_56   = ClientHelloID{helloFirefox, "56", nil}
	HelloFirefox_63   = ClientHelloID{helloFirefox, "63", nil}
	HelloFirefox_65   = ClientHelloID{helloFirefox, "65", nil}

	HelloChrome_Auto = HelloChrome_83
	HelloChrome_58   = ClientHelloID{helloChrome, "58", nil}
	HelloChrome_62   = ClientHelloID{helloChrome, "62", nil}
	HelloChrome_70   = ClientHelloID{helloChrome, "70", nil}
	HelloChrome_72   = ClientHelloID{helloChrome, "72", nil}
	HelloChrome_83   = ClientHelloID{helloChrome, "83", nil}

	HelloIOS_Auto = HelloIOS_12_1
	HelloIOS_11_1 = ClientHelloID{helloIOS, "111", nil} // legacy "111" means 11.1
	HelloIOS_12_1 = ClientHelloID{helloIOS, "12.1", nil}
)

Functions

func BoringPaddingStyle 

func BoringPaddingStyle(unpaddedLen int) (int, bool)

https://github.com/google/boringssl/blob/7d7554b6b3c79e707e25521e61e066ce2b996e4c/ssl/t1_lib.c#L2803

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 DecryptTicketWith 

func DecryptTicketWith(encrypted []byte, tks TicketKeys) (plaintext []byte, usedOldKey bool)

DecryptTicketWith decrypts an encrypted session ticket using a TicketKeys (ie []TicketKey) struct

usedOldKey will be true if the key used for decryption is not the first in the []TicketKey slice

[uTLS] changed to be made public and take a TicketKeys instead of use a Conn receiver

func EnableWeakCiphers 

func EnableWeakCiphers()

EnableWeakCiphers allows utls connections to continue in some cases, when weak cipher was chosen. This provides better compatibility with servers on the web, but weakens security. Feel free to use this option if you establish additional secure connection inside of utls connection. This option does not change the shape of parrots (i.e. same ciphers will be offered either way). Must be called before establishing any connections.

func GetBoringGREASEValue 

func GetBoringGREASEValue(greaseSeed [ssl_grease_last_index]uint16, index int) uint16

will panic if ssl_grease_last_index[index] is out of bounds.

func Listen 

func Listen(network, laddr string, config *Config) (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 *Config) 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.

Types

type ALPNExtension 

type ALPNExtension struct {
	AlpnProtocols []string
}

func (*ALPNExtension) Len 

func (e *ALPNExtension) Len() int

func (*ALPNExtension) Read 

func (e *ALPNExtension) Read(b []byte) (int, error)

type CertCompressionAlgo 

type CertCompressionAlgo uint16

https://tools.ietf.org/html/draft-ietf-tls-certificate-compression-04 

const (
	CertCompressionZlib   CertCompressionAlgo = 0x0001
	CertCompressionBrotli CertCompressionAlgo = 0x0002
	CertCompressionZstd   CertCompressionAlgo = 0x0003
)

type Certificate 

type Certificate struct {
	Certificate [][]byte
	// PrivateKey contains the private key corresponding to the public key in
	// Leaf. This must implement crypto.Signer with an RSA, ECDSA or Ed25519 PublicKey.
	// For a server up to TLS 1.2, it can also implement crypto.Decrypter with
	// an RSA PublicKey.
	PrivateKey crypto.PrivateKey
	// SupportedSignatureAlgorithms is an optional list restricting what
	// signature algorithms the PrivateKey can be used for.
	SupportedSignatureAlgorithms []SignatureScheme
	// OCSPStaple contains an optional OCSP response which will be served
	// to clients that request it.
	OCSPStaple []byte
	// SignedCertificateTimestamps contains an optional list of Signed
	// Certificate Timestamps which will be served to clients that request it.
	SignedCertificateTimestamps [][]byte
	// Leaf is the parsed form of the leaf certificate, which may be initialized
	// using x509.ParseCertificate to reduce per-handshake processing. If nil,
	// the leaf certificate will be parsed as needed.
	Leaf *x509.Certificate
}

A Certificate is a chain of one or more certificates, leaf first.

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 struct {
	// AcceptableCAs contains zero or more, DER-encoded, X.501
	// Distinguished Names. These are the names of root or intermediate CAs
	// that the server wishes the returned certificate to be signed by. An
	// empty slice indicates that the server has no preference.
	AcceptableCAs [][]byte

	// SignatureSchemes lists the signature schemes that the server is
	// willing to verify.
	SignatureSchemes []SignatureScheme

	// Version is the TLS version that was negotiated for this connection.
	Version uint16
	// contains filtered or unexported fields
}

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

func (*CertificateRequestInfo) Context 

func (c *CertificateRequestInfo) Context() context.Context

Context returns the context of the handshake that is in progress. This context is a child of the context passed to HandshakeContext, if any, and is canceled when the handshake concludes.

func (*CertificateRequestInfo) SupportsCertificate 

func (cri *CertificateRequestInfo) SupportsCertificate(c *Certificate) error

SupportsCertificate returns nil if the provided certificate is supported by the server that sent the CertificateRequest. Otherwise, it returns an error describing the reason for the incompatibility.

type CertificateRequestMsgTLS13 

type CertificateRequestMsgTLS13 struct {
	Raw                              []byte
	OcspStapling                     bool
	Scts                             bool
	SupportedSignatureAlgorithms     []SignatureScheme
	SupportedSignatureAlgorithmsCert []SignatureScheme
	CertificateAuthorities           [][]byte
}

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 int

ClientAuthType declares the policy the server will follow for TLS Client Authentication. 

const (
	// NoClientCert indicates that no client certificate should be requested
	// during the handshake, and if any certificates are sent they will not
	// be verified.
	NoClientCert ClientAuthType = iota
	// RequestClientCert indicates that a client certificate should be requested
	// during the handshake, but does not require that the client send any
	// certificates.
	RequestClientCert
	// RequireAnyClientCert indicates that a client certificate should be requested
	// during the handshake, and that at least one certificate is required to be
	// sent by the client, but that certificate is not required to be valid.
	RequireAnyClientCert
	// VerifyClientCertIfGiven indicates that a client certificate should be requested
	// during the handshake, but does not require that the client sends a
	// certificate. If the client does send a certificate it is required to be
	// valid.
	VerifyClientCertIfGiven
	// RequireAndVerifyClientCert indicates that a client certificate should be requested
	// during the handshake, and that at least one valid certificate is required
	// to be sent by the client.
	RequireAndVerifyClientCert
)

func (ClientAuthType) String 

func (i ClientAuthType) String() string

type ClientHelloID 

type ClientHelloID struct {
	Client string

	// Version specifies version of a mimicked clients (e.g. browsers).
	// Not used in randomized, custom handshake, and default Go.
	Version string

	// Seed is only used for randomized fingerprints to seed PRNG.
	// Must not be modified once set.
	Seed *PRNGSeed
}

func (*ClientHelloID) IsSet 

func (p *ClientHelloID) IsSet() bool

func (*ClientHelloID) Str 

func (p *ClientHelloID) Str() string

type ClientHelloInfo 

type ClientHelloInfo struct {
	// CipherSuites lists the CipherSuites supported by the client (e.g.
	// TLS_AES_128_GCM_SHA256, TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256).
	CipherSuites []uint16

	// ServerName indicates the name of the server requested by the client
	// in order to support virtual hosting. ServerName is only set if the
	// client is using SNI (see RFC 4366, Section 3.1).
	ServerName string

	// SupportedCurves lists the elliptic curves supported by the client.
	// SupportedCurves is set only if the Supported Elliptic Curves
	// Extension is being used (see RFC 4492, Section 5.1.1).
	SupportedCurves []CurveID

	// SupportedPoints lists the point formats supported by the client.
	// SupportedPoints is set only if the Supported Point Formats Extension
	// is being used (see RFC 4492, Section 5.1.2).
	SupportedPoints []uint8

	// SignatureSchemes lists the signature and hash schemes that the client
	// is willing to verify. SignatureSchemes is set only if the Signature
	// Algorithms Extension is being used (see RFC 5246, Section 7.4.1.4.1).
	SignatureSchemes []SignatureScheme

	// SupportedProtos lists the application protocols supported by the client.
	// SupportedProtos is set only if the Application-Layer Protocol
	// Negotiation Extension is being used (see RFC 7301, Section 3.1).
	//
	// Servers can select a protocol by setting Config.NextProtos in a
	// GetConfigForClient return value.
	SupportedProtos []string

	// SupportedVersions lists the TLS versions supported by the client.
	// For TLS versions less than 1.3, this is extrapolated from the max
	// version advertised by the client, so values other than the greatest
	// might be rejected if used.
	SupportedVersions []uint16

	// Conn is the underlying net.Conn for the connection. Do not read
	// from, or write to, this connection; that will cause the TLS
	// connection to fail.
	Conn net.Conn
	// contains filtered or unexported fields
}

ClientHelloInfo contains information from a ClientHello message in order to guide application logic in the GetCertificate and GetConfigForClient callbacks.

func (*ClientHelloInfo) Context 

func (c *ClientHelloInfo) Context() context.Context

Context returns the context of the handshake that is in progress. This context is a child of the context passed to HandshakeContext, if any, and is canceled when the handshake concludes.

func (*ClientHelloInfo) SupportsCertificate 

func (chi *ClientHelloInfo) SupportsCertificate(c *Certificate) error

SupportsCertificate returns nil if the provided certificate is supported by the client that sent the ClientHello. Otherwise, it returns an error describing the reason for the incompatibility.

If this ClientHelloInfo was passed to a GetConfigForClient or GetCertificate callback, this method will take into account the associated Config. Note that if GetConfigForClient returns a different Config, the change can't be accounted for by this method.

This function will call x509.ParseCertificate unless c.Leaf is set, which can incur a significant performance cost.

type ClientHelloSpec 

type ClientHelloSpec struct {
	CipherSuites       []uint16       // nil => default
	CompressionMethods []uint8        // nil => no compression
	Extensions         []TLSExtension // nil => no extensions

	TLSVersMin uint16 // [1.0-1.3] default: parse from .Extensions, if SupportedVersions ext is not present => 1.0
	TLSVersMax uint16 // [1.2-1.3] default: parse from .Extensions, if SupportedVersions ext is not present => 1.2

	// GreaseStyle: currently only random
	// sessionID may or may not depend on ticket; nil => random
	GetSessionID func(ticket []byte) [32]byte
}

type ClientSessionCache 

type ClientSessionCache interface {
	// Get searches for a ClientSessionState associated with the given key.
	// On return, ok is true if one was found.
	Get(sessionKey string) (session *ClientSessionState, ok bool)

	// Put adds the ClientSessionState to the cache with the given key. It might
	// get called multiple times in a connection if a TLS 1.3 server provides
	// more than one session ticket. If called with a nil *ClientSessionState,
	// it should remove the cache entry.
	Put(sessionKey string, cs *ClientSessionState)
}

ClientSessionCache is a cache of ClientSessionState objects that can be used by a client to resume a TLS session with a given server. ClientSessionCache implementations should expect to be called concurrently from different goroutines. Up to TLS 1.2, only ticket-based resumption is supported, not SessionID-based resumption. In TLS 1.3 they were merged into PSK modes, which are supported via this interface.

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 struct {
	// contains filtered or unexported fields
}

ClientSessionState contains the state needed by clients to resume TLS sessions.

func MakeClientSessionState 

func MakeClientSessionState(
	SessionTicket []uint8,
	Vers uint16,
	CipherSuite uint16,
	MasterSecret []byte,
	ServerCertificates []*x509.Certificate,
	VerifiedChains [][]*x509.Certificate) *ClientSessionState

ClientSessionState contains the state needed by clients to resume TLS sessions.

func (*ClientSessionState) CipherSuite 

func (css *ClientSessionState) CipherSuite() uint16

Ciphersuite negotiated for the session

func (*ClientSessionState) MasterSecret 

func (css *ClientSessionState) MasterSecret() []byte

MasterSecret generated by client on a full handshake

func (*ClientSessionState) ServerCertificates 

func (css *ClientSessionState) ServerCertificates() []*x509.Certificate

Certificate chain presented by the server

func (*ClientSessionState) SessionTicket 

func (css *ClientSessionState) SessionTicket() []uint8

Encrypted ticket used for session resumption with server

func (*ClientSessionState) SetCipherSuite 

func (css *ClientSessionState) SetCipherSuite(CipherSuite uint16)

func (*ClientSessionState) SetMasterSecret 

func (css *ClientSessionState) SetMasterSecret(MasterSecret []byte)

func (*ClientSessionState) SetServerCertificates 

func (css *ClientSessionState) SetServerCertificates(ServerCertificates []*x509.Certificate)

func (*ClientSessionState) SetSessionTicket 

func (css *ClientSessionState) SetSessionTicket(SessionTicket []uint8)

func (*ClientSessionState) SetVerifiedChains 

func (css *ClientSessionState) SetVerifiedChains(VerifiedChains [][]*x509.Certificate)

func (*ClientSessionState) SetVers 

func (css *ClientSessionState) SetVers(Vers uint16)

func (*ClientSessionState) VerifiedChains 

func (css *ClientSessionState) VerifiedChains() [][]*x509.Certificate

Certificate chains we built for verification

func (*ClientSessionState) Vers 

func (css *ClientSessionState) Vers() uint16

SSL/TLS version negotiated for the session

type Config 

type Config struct {
	// Rand provides the source of entropy for nonces and RSA blinding.
	// If Rand is nil, TLS uses the cryptographic random reader in package
	// crypto/rand.
	// The Reader must be safe for use by multiple goroutines.
	Rand io.Reader

	// Time returns the current time as the number of seconds since the epoch.
	// If Time is nil, TLS uses time.Now.
	Time func() time.Time

	// Certificates contains one or more certificate chains to present to the
	// other side of the connection. The first certificate compatible with the
	// peer's requirements is selected automatically.
	//
	// Server configurations must set one of Certificates, GetCertificate or
	// GetConfigForClient. Clients doing client-authentication may set either
	// Certificates or GetClientCertificate.
	//
	// Note: if there are multiple Certificates, and they don't have the
	// optional field Leaf set, certificate selection will incur a significant
	// per-handshake performance cost.
	Certificates []Certificate

	// NameToCertificate maps from a certificate name to an element of
	// Certificates. Note that a certificate name can be of the form
	// '*.example.com' and so doesn't have to be a domain name as such.
	//
	// Deprecated: NameToCertificate only allows associating a single
	// certificate with a given name. Leave this field nil to let the library
	// select the first compatible chain from Certificates.
	NameToCertificate map[string]*Certificate

	// GetCertificate returns a Certificate based on the given
	// ClientHelloInfo. It will only be called if the client supplies SNI
	// information or if Certificates is empty.
	//
	// If GetCertificate is nil or returns nil, then the certificate is
	// retrieved from NameToCertificate. If NameToCertificate is nil, the
	// best element of Certificates will be used.
	GetCertificate func(*ClientHelloInfo) (*Certificate, error)

	// GetClientCertificate, if not nil, is called when a server requests a
	// certificate from a client. If set, the contents of Certificates will
	// be ignored.
	//
	// If GetClientCertificate returns an error, the handshake will be
	// aborted and that error will be returned. Otherwise
	// GetClientCertificate must return a non-nil Certificate. If
	// Certificate.Certificate is empty then no certificate will be sent to
	// the server. If this is unacceptable to the server then it may abort
	// the handshake.
	//
	// GetClientCertificate may be called multiple times for the same
	// connection if renegotiation occurs or if TLS 1.3 is in use.
	GetClientCertificate func(*CertificateRequestInfo) (*Certificate, error)

	// GetConfigForClient, if not nil, is called after a ClientHello is
	// received from a client. It may return a non-nil Config in order to
	// change the Config that will be used to handle this connection. If
	// the returned Config is nil, the original Config will be used. The
	// Config returned by this callback may not be subsequently modified.
	//
	// If GetConfigForClient is nil, the Config passed to Server() will be
	// used for all connections.
	//
	// If SessionTicketKey was explicitly set on the returned Config, or if
	// SetSessionTicketKeys was called on the returned Config, those keys will
	// be used. Otherwise, the original Config keys will be used (and possibly
	// rotated if they are automatically managed).
	GetConfigForClient func(*ClientHelloInfo) (*Config, error)

	// VerifyPeerCertificate, if not nil, is called after normal
	// certificate verification by either a TLS client or server. It
	// receives the raw ASN.1 certificates provided by the peer and also
	// any verified chains that normal processing found. If it returns a
	// non-nil error, the handshake is aborted and that error results.
	//
	// If normal verification fails then the handshake will abort before
	// considering this callback. If normal verification is disabled by
	// setting InsecureSkipVerify, or (for a server) when ClientAuth is
	// RequestClientCert or RequireAnyClientCert, then this callback will
	// be considered but the verifiedChains argument will always be nil.
	VerifyPeerCertificate func(rawCerts [][]byte, verifiedChains [][]*x509.Certificate) error

	// VerifyConnection, if not nil, is called after normal certificate
	// verification and after VerifyPeerCertificate by either a TLS client
	// or server. If it returns a non-nil error, the handshake is aborted
	// and that error results.
	//
	// If normal verification fails then the handshake will abort before
	// considering this callback. This callback will run for all connections
	// regardless of InsecureSkipVerify or ClientAuth settings.
	VerifyConnection func(ConnectionState) error

	// RootCAs defines the set of root certificate authorities
	// that clients use when verifying server certificates.
	// If RootCAs is nil, TLS uses the host's root CA set.
	RootCAs *x509.CertPool

	// NextProtos is a list of supported application level protocols, in
	// order of preference. If both peers support ALPN, the selected
	// protocol will be one from this list, and the connection will fail
	// if there is no mutually supported protocol. If NextProtos is empty
	// or the peer doesn't support ALPN, the connection will succeed and
	// ConnectionState.NegotiatedProtocol will be empty.
	NextProtos []string

	// ServerName is used to verify the hostname on the returned
	// certificates unless InsecureSkipVerify is given. It is also included
	// in the client's handshake to support virtual hosting unless it is
	// an IP address.
	ServerName string

	// ClientAuth determines the server's policy for
	// TLS Client Authentication. The default is NoClientCert.
	ClientAuth ClientAuthType

	// ClientCAs defines the set of root certificate authorities
	// that servers use if required to verify a client certificate
	// by the policy in ClientAuth.
	ClientCAs *x509.CertPool

	// InsecureSkipVerify controls whether a client verifies the server's
	// certificate chain and host name. If InsecureSkipVerify is true, crypto/tls
	// accepts any certificate presented by the server and any host name in that
	// certificate. In this mode, TLS is susceptible to machine-in-the-middle
	// attacks unless custom verification is used. This should be used only for
	// testing or in combination with VerifyConnection or VerifyPeerCertificate.
	InsecureSkipVerify bool

	// CipherSuites is a list of enabled TLS 1.0–1.2 cipher suites. The order of
	// the list is ignored. Note that TLS 1.3 ciphersuites are not configurable.
	//
	// If CipherSuites is nil, a safe default list is used. The default cipher
	// suites might change over time.
	CipherSuites []uint16

	// PreferServerCipherSuites is a legacy field and has no effect.
	//
	// It used to control whether the server would follow the client's or the
	// server's preference. Servers now select the best mutually supported
	// cipher suite based on logic that takes into account inferred client
	// hardware, server hardware, and security.
	//
	// Deprecated: PreferServerCipherSuites is ignored.
	PreferServerCipherSuites bool

	// SessionTicketsDisabled may be set to true to disable session ticket and
	// PSK (resumption) support. Note that on clients, session ticket support is
	// also disabled if ClientSessionCache is nil.
	SessionTicketsDisabled bool

	// SessionTicketKey is used by TLS servers to provide session resumption.
	// See RFC 5077 and the PSK mode of RFC 8446. If zero, it will be filled
	// with random data before the first server handshake.
	//
	// Deprecated: if this field is left at zero, session ticket keys will be
	// automatically rotated every day and dropped after seven days. For
	// customizing the rotation schedule or synchronizing servers that are
	// terminating connections for the same host, use SetSessionTicketKeys.
	SessionTicketKey [32]byte

	// ClientSessionCache is a cache of ClientSessionState entries for TLS
	// session resumption. It is only used by clients.
	ClientSessionCache ClientSessionCache

	// MinVersion contains the minimum TLS version that is acceptable.
	//
	// By default, TLS 1.2 is currently used as the minimum when acting as a
	// client, and TLS 1.0 when acting as a server. TLS 1.0 is the minimum
	// supported by this package, both as a client and as a server.
	//
	// The client-side default can temporarily be reverted to TLS 1.0 by
	// including the value "x509sha1=1" in the GODEBUG environment variable.
	// Note that this option will be removed in Go 1.19 (but it will still be
	// possible to set this field to VersionTLS10 explicitly).
	MinVersion uint16

	// MaxVersion contains the maximum TLS version that is acceptable.
	//
	// By default, the maximum version supported by this package is used,
	// which is currently TLS 1.3.
	MaxVersion uint16

	// CurvePreferences contains the elliptic curves that will be used in
	// an ECDHE handshake, in preference order. If empty, the default will
	// be used. The client will use the first preference as the type for
	// its key share in TLS 1.3. This may change in the future.
	CurvePreferences []CurveID

	// DynamicRecordSizingDisabled disables adaptive sizing of TLS records.
	// When true, the largest possible TLS record size is always used. When
	// false, the size of TLS records may be adjusted in an attempt to
	// improve latency.
	DynamicRecordSizingDisabled bool

	// Renegotiation controls what types of renegotiation are supported.
	// The default, none, is correct for the vast majority of applications.
	Renegotiation RenegotiationSupport

	// KeyLogWriter optionally specifies a destination for TLS master secrets
	// in NSS key log format that can be used to allow external programs
	// such as Wireshark to decrypt TLS connections.
	// See https://developer.mozilla.org/en-US/docs/Mozilla/Projects/NSS/Key_Log_Format.
	// Use of KeyLogWriter compromises security and should only be
	// used for debugging.
	KeyLogWriter io.Writer
	// contains filtered or unexported fields
}

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:

func (*Config) BuildNameToCertificate deprecated 

func (c *Config) BuildNameToCertificate()

BuildNameToCertificate parses c.Certificates and builds c.NameToCertificate from the CommonName and SubjectAlternateName fields of each of the leaf certificates.

Deprecated: NameToCertificate only allows associating a single certificate with a given name. Leave that field nil to let the library select the first compatible chain from Certificates.

func (*Config) Clone 

func (c *Config) Clone() *Config

Clone returns a shallow clone of c or nil if c is nil. It is safe to clone a Config that is being used concurrently by a TLS client or server.

func (*Config) SetSessionTicketKeys 

func (c *Config) SetSessionTicketKeys(keys [][32]byte)

SetSessionTicketKeys updates the session ticket keys for a server.

The first key will be used when creating new tickets, while all keys can be used for decrypting tickets. It is safe to call this function while the server is running in order to rotate the session ticket keys. The function will panic if keys is empty.

Calling this function will turn off automatic session ticket key rotation.

If multiple servers are terminating connections for the same host they should all have the same session ticket keys. If the session ticket keys leaks, previously recorded and future TLS connections using those keys might be compromised.

type Conn 

type Conn struct {
	ClientHello []byte
	// 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 *Config) *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 MakeConnWithCompleteHandshake 

func MakeConnWithCompleteHandshake(tcpConn net.Conn, version uint16, cipherSuite uint16, masterSecret []byte, clientRandom []byte, serverRandom []byte, isClient bool) *Conn

MakeConnWithCompleteHandshake allows to forge both server and client side TLS connections. Major Hack Alert.

func Server 

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

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 struct {
	// Version is the TLS version used by the connection (e.g. VersionTLS12).
	Version uint16

	// HandshakeComplete is true if the handshake has concluded.
	HandshakeComplete bool

	// DidResume is true if this connection was successfully resumed from a
	// previous session with a session ticket or similar mechanism.
	DidResume bool

	// CipherSuite is the cipher suite negotiated for the connection (e.g.
	// TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256, TLS_AES_128_GCM_SHA256).
	CipherSuite uint16

	// NegotiatedProtocol is the application protocol negotiated with ALPN.
	NegotiatedProtocol string

	// NegotiatedProtocolIsMutual used to indicate a mutual NPN negotiation.
	//
	// Deprecated: this value is always true.
	NegotiatedProtocolIsMutual bool

	// ServerName is the value of the Server Name Indication extension sent by
	// the client. It's available both on the server and on the client side.
	ServerName string

	// PeerCertificates are the parsed certificates sent by the peer, in the
	// order in which they were sent. The first element is the leaf certificate
	// that the connection is verified against.
	//
	// On the client side, it can't be empty. On the server side, it can be
	// empty if Config.ClientAuth is not RequireAnyClientCert or
	// RequireAndVerifyClientCert.
	PeerCertificates []*x509.Certificate

	// VerifiedChains is a list of one or more chains where the first element is
	// PeerCertificates[0] and the last element is from Config.RootCAs (on the
	// client side) or Config.ClientCAs (on the server side).
	//
	// On the client side, it's set if Config.InsecureSkipVerify is false. On
	// the server side, it's set if Config.ClientAuth is VerifyClientCertIfGiven
	// (and the peer provided a certificate) or RequireAndVerifyClientCert.
	VerifiedChains [][]*x509.Certificate

	// SignedCertificateTimestamps is a list of SCTs provided by the peer
	// through the TLS handshake for the leaf certificate, if any.
	SignedCertificateTimestamps [][]byte

	// OCSPResponse is a stapled Online Certificate Status Protocol (OCSP)
	// response provided by the peer for the leaf certificate, if any.
	OCSPResponse []byte

	// TLSUnique contains the "tls-unique" channel binding value (see RFC 5929,
	// Section 3). This value will be nil for TLS 1.3 connections and for all
	// resumed connections.
	//
	// Deprecated: there are conditions in which this value might not be unique
	// to a connection. See the Security Considerations sections of RFC 5705 and
	// RFC 7627, and https://mitls.org/pages/attacks/3SHAKE#channelbindings.
	TLSUnique []byte
	// contains filtered or unexported fields
}

ConnectionState records basic TLS details about the connection.

func (*ConnectionState) ExportKeyingMaterial 

func (cs *ConnectionState) ExportKeyingMaterial(label string, context []byte, length int) ([]byte, error)

ExportKeyingMaterial returns length bytes of exported key material in a new slice as defined in RFC 5705. If context is nil, it is not used as part of the seed. If the connection was set to allow renegotiation via Config.Renegotiation, this function will return an error.

type CookieExtension 

type CookieExtension struct {
	Cookie []byte
}

MUST NOT be part of initial ClientHello

func (*CookieExtension) Len 

func (e *CookieExtension) Len() int

func (*CookieExtension) Read 

func (e *CookieExtension) Read(b []byte) (int, error)

type CurveID 

type CurveID uint16

CurveID is the type of a TLS identifier for an elliptic curve. See https://www.iana.org/assignments/tls-parameters/tls-parameters.xml#tls-parameters-8.

In TLS 1.3, this type is called NamedGroup, but at this time this library only supports Elliptic Curve based groups. See RFC 8446, Section 4.2.7. 

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

func (CurveID) String 

func (i CurveID) String() string

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 EcdheParameters 

type EcdheParameters interface {
	// contains filtered or unexported methods
}

type FakeChannelIDExtension 

type FakeChannelIDExtension struct {
}

func (*FakeChannelIDExtension) Len 

func (e *FakeChannelIDExtension) Len() int

func (*FakeChannelIDExtension) Read 

func (e *FakeChannelIDExtension) Read(b []byte) (int, error)

type FakeRecordSizeLimitExtension 

type FakeRecordSizeLimitExtension struct {
	Limit uint16
}

func (*FakeRecordSizeLimitExtension) Len 

func (e *FakeRecordSizeLimitExtension) Len() int

func (*FakeRecordSizeLimitExtension) Read 

func (e *FakeRecordSizeLimitExtension) Read(b []byte) (int, error)

type Fingerprinter 

type Fingerprinter struct {
	// KeepPSK will ensure that the PreSharedKey extension is passed along into the resulting ClientHelloSpec as-is
	KeepPSK bool
	// AllowBluntMimicry will ensure that unknown extensions are
	// passed along into the resulting ClientHelloSpec as-is
	// It will not ensure that the PSK is passed along, if you require that, use KeepPSK
	// WARNING: there could be numerous subtle issues with ClientHelloSpecs
	// that are generated with this flag which could compromise security and/or mimicry
	AllowBluntMimicry bool
	// AlwaysAddPadding will always add a UtlsPaddingExtension with BoringPaddingStyle
	// at the end of the extensions list if it isn't found in the fingerprinted hello.
	// This could be useful in scenarios where the hello you are fingerprinting does not
	// have any padding, but you suspect that other changes you make to the final hello
	// (including things like different SNI lengths) would cause padding to be necessary
	AlwaysAddPadding bool
}

Fingerprinter is a struct largely for holding options for the FingerprintClientHello func

func (*Fingerprinter) FingerprintClientHello 

func (f *Fingerprinter) FingerprintClientHello(data []byte) (*ClientHelloSpec, error)

FingerprintClientHello returns a ClientHelloSpec which is based on the ClientHello that is passed in as the data argument

If the ClientHello passed in has extensions that are not recognized or cannot be handled it will return a non-nil error and a nil *ClientHelloSpec value

The data should be the full tls record, including the record type/version/length header as well as the handshake type/length/version header https://tools.ietf.org/html/rfc5246#section-6.2 https://tools.ietf.org/html/rfc5246#section-7.4

type FinishedHash 

type FinishedHash struct {
	Client hash.Hash
	Server hash.Hash

	// Prior to TLS 1.2, an additional MD5 hash is required.
	ClientMD5 hash.Hash
	ServerMD5 hash.Hash

	// In TLS 1.2, a full buffer is sadly required.
	Buffer []byte

	Version uint16
	Prf     func(result, secret, label, seed []byte)
}

A FinishedHash calculates the hash of a set of handshake messages suitable for including in a Finished message.

type GenericExtension 

type GenericExtension struct {
	Id   uint16
	Data []byte
}

GenericExtension allows to include in ClientHello arbitrary unsupported extensions.

func (*GenericExtension) Len 

func (e *GenericExtension) Len() int

func (*GenericExtension) Read 

func (e *GenericExtension) Read(b []byte) (int, error)

type KeyShare 

type KeyShare struct {
	Group CurveID
	Data  []byte
}

TLS 1.3 Key Share. See RFC 8446, Section 4.2.8.

type KeyShareExtension 

type KeyShareExtension struct {
	KeyShares []KeyShare
}

TLS 1.3

func (*KeyShareExtension) Len 

func (e *KeyShareExtension) Len() int

func (*KeyShareExtension) Read 

func (e *KeyShareExtension) Read(b []byte) (int, error)

type KeyShares 

type KeyShares []KeyShare

func (KeyShares) ToPrivate 

func (KSS KeyShares) ToPrivate() []keyShare

type NPNExtension 

type NPNExtension struct {
	NextProtos []string
}

func (*NPNExtension) Len 

func (e *NPNExtension) Len() int

func (*NPNExtension) Read 

func (e *NPNExtension) Read(b []byte) (int, error)

type PRNGSeed 

type PRNGSeed [PRNGSeedLength]byte

PRNGSeed is a PRNG seed.

func NewPRNGSeed 

func NewPRNGSeed() (*PRNGSeed, error)

NewPRNGSeed creates a new PRNG seed using crypto/rand.Read.

type PSKKeyExchangeModesExtension 

type PSKKeyExchangeModesExtension struct {
	Modes []uint8
}

func (*PSKKeyExchangeModesExtension) Len 

func (e *PSKKeyExchangeModesExtension) Len() int

func (*PSKKeyExchangeModesExtension) Read 

func (e *PSKKeyExchangeModesExtension) Read(b []byte) (int, error)

type PubCipherSuite 

type PubCipherSuite struct {
	Id uint16
	// the lengths, in bytes, of the key material needed for each component.
	KeyLen int
	MacLen int
	IvLen  int
	Ka     func(version uint16) keyAgreement
	// flags is a bitmask of the suite* values, above.
	Flags  int
	Cipher func(key, iv []byte, isRead bool) interface{}
	Mac    func(macKey []byte) hash.Hash
	Aead   func(key, fixedNonce []byte) aead
}

A CipherSuite is a specific combination of key agreement, cipher and MAC function. All cipher suites currently assume RSA key agreement.

type PubCipherSuiteTLS13 

type PubCipherSuiteTLS13 struct {
	Id     uint16
	KeyLen int
	Aead   func(key, fixedNonce []byte) aead
	Hash   crypto.Hash
}

type PubClientHandshakeState 

type PubClientHandshakeState struct {
	C            *Conn
	ServerHello  *PubServerHelloMsg
	Hello        *PubClientHelloMsg
	MasterSecret []byte
	Session      *ClientSessionState

	State12 TLS12OnlyState
	State13 TLS13OnlyState
	// contains filtered or unexported fields
}

ClientHandshakeState includes both TLS 1.3-only and TLS 1.2-only states, only one of them will be used, depending on negotiated version.

ClientHandshakeState will be converted into and from either

  • clientHandshakeState (TLS 1.2)
  • clientHandshakeStateTLS13 (TLS 1.3)

uTLS will call .handshake() on one of these private internal states, to perform TLS handshake using standard crypto/tls implementation.

type PubClientHelloMsg 

type PubClientHelloMsg struct {
	Raw                          []byte
	Vers                         uint16
	Random                       []byte
	SessionId                    []byte
	CipherSuites                 []uint16
	CompressionMethods           []uint8
	NextProtoNeg                 bool
	ServerName                   string
	OcspStapling                 bool
	Scts                         bool
	Ems                          bool // [uTLS] actually implemented due to its prevalence
	SupportedCurves              []CurveID
	SupportedPoints              []uint8
	TicketSupported              bool
	SessionTicket                []uint8
	SupportedSignatureAlgorithms []SignatureScheme
	SecureRenegotiation          []byte
	SecureRenegotiationSupported bool
	AlpnProtocols                []string

	// 1.3
	SupportedSignatureAlgorithmsCert []SignatureScheme
	SupportedVersions                []uint16
	Cookie                           []byte
	KeyShares                        []KeyShare
	EarlyData                        bool
	PskModes                         []uint8
	PskIdentities                    []pskIdentity
	PskBinders                       [][]byte
}

func UnmarshalClientHello 

func UnmarshalClientHello(data []byte) *PubClientHelloMsg

UnmarshalClientHello allows external code to parse raw client hellos. It returns nil on failure.

type PubServerHelloMsg 

type PubServerHelloMsg struct {
	Raw                          []byte
	Vers                         uint16
	Random                       []byte
	SessionId                    []byte
	CipherSuite                  uint16
	CompressionMethod            uint8
	NextProtoNeg                 bool
	NextProtos                   []string
	OcspStapling                 bool
	Scts                         [][]byte
	Ems                          bool
	TicketSupported              bool
	SecureRenegotiation          []byte
	SecureRenegotiationSupported bool
	AlpnProtocol                 string

	// 1.3
	SupportedVersion        uint16
	ServerShare             keyShare
	SelectedIdentityPresent bool
	SelectedIdentity        uint16
	Cookie                  []byte  // HelloRetryRequest extension
	SelectedGroup           CurveID // HelloRetryRequest extension

}

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 RenegotiationInfoExtension 

type RenegotiationInfoExtension struct {
	// Renegotiation field limits how many times client will perform renegotiation: no limit, once, or never.
	// The extension still will be sent, even if Renegotiation is set to RenegotiateNever.
	Renegotiation RenegotiationSupport
}

func (*RenegotiationInfoExtension) Len 

func (e *RenegotiationInfoExtension) Len() int

func (*RenegotiationInfoExtension) Read 

func (e *RenegotiationInfoExtension) Read(b []byte) (int, error)

type RenegotiationSupport 

type RenegotiationSupport int

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. 

const (
	// RenegotiateNever disables renegotiation.
	RenegotiateNever RenegotiationSupport = iota

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

	// RenegotiateFreelyAsClient allows a remote server to repeatedly
	// request renegotiation.
	RenegotiateFreelyAsClient
)

type Roller 

type Roller struct {
	HelloIDs            []ClientHelloID
	HelloIDMu           sync.Mutex
	WorkingHelloID      *ClientHelloID
	TcpDialTimeout      time.Duration
	TlsHandshakeTimeout time.Duration
	// contains filtered or unexported fields
}

func NewRoller 

func NewRoller() (*Roller, error)

NewRoller creates Roller object with default range of HelloIDs to cycle through until a working/unblocked one is found.

func (*Roller) Dial 

func (c *Roller) Dial(network, addr, serverName string) (*UConn, error)

Dial attempts to establish connection to given address using different HelloIDs. If a working HelloID is found, it is used again for subsequent Dials. If tcp connection fails or all HelloIDs are tried, returns with last error.

Usage examples: 

Dial("tcp4", "google.com:443", "google.com")
Dial("tcp", "10.23.144.22:443", "mywebserver.org")

type SCTExtension 

type SCTExtension struct {
}

func (*SCTExtension) Len 

func (e *SCTExtension) Len() int

func (*SCTExtension) Read 

func (e *SCTExtension) Read(b []byte) (int, error)

type SNIExtension 

type SNIExtension struct {
	ServerName string // not an array because go crypto/tls doesn't support multiple SNIs
}

func (*SNIExtension) Len 

func (e *SNIExtension) Len() int

func (*SNIExtension) Read 

func (e *SNIExtension) Read(b []byte) (int, error)

type SessionTicketExtension 

type SessionTicketExtension struct {
	Session *ClientSessionState
}

func (*SessionTicketExtension) Len 

func (e *SessionTicketExtension) Len() int

func (*SessionTicketExtension) Read 

func (e *SessionTicketExtension) Read(b []byte) (int, error)

type SignatureAlgorithmsExtension 

type SignatureAlgorithmsExtension struct {
	SupportedSignatureAlgorithms []SignatureScheme
}

func (*SignatureAlgorithmsExtension) Len 

func (e *SignatureAlgorithmsExtension) Len() int

func (*SignatureAlgorithmsExtension) Read 

func (e *SignatureAlgorithmsExtension) Read(b []byte) (int, error)

type SignatureScheme 

type SignatureScheme uint16

SignatureScheme identifies a signature algorithm supported by TLS. See RFC 8446, Section 4.2.3. 

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
)
var (
	FakePKCS1WithSHA224 SignatureScheme = 0x0301
	FakeECDSAWithSHA224 SignatureScheme = 0x0303
)

newest signatures

func (SignatureScheme) String 

func (i SignatureScheme) String() string

type StatusRequestExtension 

type StatusRequestExtension struct {
}

func (*StatusRequestExtension) Len 

func (e *StatusRequestExtension) Len() int

func (*StatusRequestExtension) Read 

func (e *StatusRequestExtension) Read(b []byte) (int, error)

type SupportedCurvesExtension 

type SupportedCurvesExtension struct {
	Curves []CurveID
}

func (*SupportedCurvesExtension) Len 

func (e *SupportedCurvesExtension) Len() int

func (*SupportedCurvesExtension) Read 

func (e *SupportedCurvesExtension) Read(b []byte) (int, error)

type SupportedPointsExtension 

type SupportedPointsExtension struct {
	SupportedPoints []uint8
}

func (*SupportedPointsExtension) Len 

func (e *SupportedPointsExtension) Len() int

func (*SupportedPointsExtension) Read 

func (e *SupportedPointsExtension) Read(b []byte) (int, error)

type SupportedVersionsExtension 

type SupportedVersionsExtension struct {
	Versions []uint16
}

func (*SupportedVersionsExtension) Len 

func (e *SupportedVersionsExtension) Len() int

func (*SupportedVersionsExtension) Read 

func (e *SupportedVersionsExtension) Read(b []byte) (int, error)

type TLS12OnlyState 

type TLS12OnlyState struct {
	FinishedHash FinishedHash
	Suite        PubCipherSuite
}

TLS 1.2 and before only

type TLS13OnlyState 

type TLS13OnlyState struct {
	Suite         *PubCipherSuiteTLS13
	EcdheParams   EcdheParameters
	EarlySecret   []byte
	BinderKey     []byte
	CertReq       *CertificateRequestMsgTLS13
	UsingPSK      bool
	SentDummyCCS  bool
	Transcript    hash.Hash
	TrafficSecret []byte // client_application_traffic_secret_0
}

TLS 1.3 only

type TLSExtension 

type TLSExtension interface {
	Len() int // includes header

	// Read reads up to len(p) bytes into p.
	// It returns the number of bytes read (0 <= n <= len(p)) and any error encountered.
	Read(p []byte) (n int, err error) // implements io.Reader
	// contains filtered or unexported methods
}

type TicketKey 

type TicketKey struct {
	// KeyName is an opaque byte string that serves to identify the session
	// ticket key. It's exposed as plaintext in every session ticket.
	KeyName [ticketKeyNameLen]byte
	AesKey  [16]byte
	HmacKey [16]byte
}

TicketKey is the internal representation of a session ticket key.

func TicketKeyFromBytes 

func TicketKeyFromBytes(b [32]byte) TicketKey

func (TicketKey) ToPrivate 

func (TK TicketKey) ToPrivate() ticketKey

type TicketKeys 

type TicketKeys []TicketKey

func (TicketKeys) ToPrivate 

func (TKS TicketKeys) ToPrivate() []ticketKey

type UConn 

type UConn struct {
	*Conn

	Extensions    []TLSExtension
	ClientHelloID ClientHelloID

	ClientHelloBuilt bool
	HandshakeState   PubClientHandshakeState

	// sessionID may or may not depend on ticket; nil => random
	GetSessionID func(ticket []byte) [32]byte
	// contains filtered or unexported fields
}

func UClient 

func UClient(conn net.Conn, config *Config, clientHelloID ClientHelloID) *UConn

UClient returns a new uTLS client, with behavior depending on clientHelloID. Config CAN be nil, but make sure to eventually specify ServerName.

func (*UConn) ApplyConfig 

func (uconn *UConn) ApplyConfig() error

func (*UConn) ApplyPreset 

func (uconn *UConn) ApplyPreset(p *ClientHelloSpec) error

ApplyPreset should only be used in conjunction with HelloCustom to apply custom specs. Fields of TLSExtensions that are slices/pointers are shared across different connections with same ClientHelloSpec. It is advised to use different specs and avoid any shared state.

func (*UConn) BuildHandshakeState 

func (uconn *UConn) BuildHandshakeState() error

BuildHandshakeState behavior varies based on ClientHelloID and whether it was already called before. If HelloGolang: 

[only once] make default ClientHello and overwrite existing state

If any other mimicking ClientHelloID is used: 

[only once] make ClientHello based on ID and overwrite existing state
[each call] apply uconn.Extensions config to internal crypto/tls structures
[each call] marshal ClientHello.

BuildHandshakeState is automatically called before uTLS performs handshake, amd should only be called explicitly to inspect/change fields of default/mimicked ClientHello.

func (*UConn) GetOutKeystream 

func (uconn *UConn) GetOutKeystream(length int) ([]byte, error)

get current state of cipher and encrypt zeros to get keystream

func (*UConn) GetUnderlyingConn 

func (uconn *UConn) GetUnderlyingConn() net.Conn

func (*UConn) Handshake 

func (c *UConn) Handshake() error

Handshake runs the client handshake using given clientHandshakeState Requires hs.hello, and, optionally, hs.session to be set.

func (*UConn) HandshakeContext 

func (c *UConn) 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.

func (*UConn) MarshalClientHello 

func (uconn *UConn) MarshalClientHello() error

func (*UConn) RemoveSNIExtension 

func (uconn *UConn) RemoveSNIExtension() error

RemoveSNIExtension removes SNI from the list of extensions sent in ClientHello It returns an error when used with HelloGolang ClientHelloID

func (*UConn) SetClientRandom 

func (uconn *UConn) SetClientRandom(r []byte) error

SetClientRandom sets client random explicitly. BuildHandshakeFirst() must be called before SetClientRandom. r must to be 32 bytes long.

func (*UConn) SetSNI 

func (uconn *UConn) SetSNI(sni string)

func (*UConn) SetSessionCache 

func (uconn *UConn) SetSessionCache(cache ClientSessionCache)

If you want session tickets to be reused - use same cache on following connections

func (*UConn) SetSessionState 

func (uconn *UConn) SetSessionState(session *ClientSessionState) error

SetSessionState sets the session ticket, which may be preshared or fake. If session is nil, the body of session ticket extension will be unset, but the extension itself still MAY be present for mimicking purposes. Session tickets to be reused - use same cache on following connections.

func (*UConn) SetTLSVers 

func (uconn *UConn) SetTLSVers(minTLSVers, maxTLSVers uint16, specExtensions []TLSExtension) error

SetTLSVers sets min and max TLS version in all appropriate places. Function will use first non-zero version parsed in following order:

  1. Provided minTLSVers, maxTLSVers
  2. specExtensions may have SupportedVersionsExtension
  3. [default] min = TLS 1.0, max = TLS 1.2

Error is only returned if things are in clearly undesirable state to help user fix them.

func (*UConn) SetUnderlyingConn 

func (uconn *UConn) SetUnderlyingConn(c net.Conn)

func (*UConn) Write 

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

Copy-pasted from tls.Conn in its entirety. But c.Handshake() is now utls' one, not tls. Write writes data to the connection.

type UtlsCompressCertExtension 

type UtlsCompressCertExtension struct {
	Algorithms []CertCompressionAlgo
}

UtlsCompressCertExtension is only implemented client-side, for server certificates. Alternate certificate message formats (https://datatracker.ietf.org/doc/html/rfc7250) are not supported.

See https://datatracker.ietf.org/doc/html/rfc8879#section-3

func (*UtlsCompressCertExtension) Len 

func (e *UtlsCompressCertExtension) Len() int

func (*UtlsCompressCertExtension) Read 

func (e *UtlsCompressCertExtension) Read(b []byte) (int, error)

type UtlsExtendedMasterSecretExtension 

type UtlsExtendedMasterSecretExtension struct {
}

func (*UtlsExtendedMasterSecretExtension) Len 

func (e *UtlsExtendedMasterSecretExtension) Len() int

func (*UtlsExtendedMasterSecretExtension) Read 

func (e *UtlsExtendedMasterSecretExtension) Read(b []byte) (int, error)

type UtlsGREASEExtension 

type UtlsGREASEExtension struct {
	Value uint16
	Body  []byte // in Chrome first grease has empty body, second grease has a single zero byte
}

it is responsibility of user not to generate multiple grease extensions with same value

func (*UtlsGREASEExtension) Len 

func (e *UtlsGREASEExtension) Len() int

func (*UtlsGREASEExtension) Read 

func (e *UtlsGREASEExtension) Read(b []byte) (int, error)

type UtlsPaddingExtension 

type UtlsPaddingExtension struct {
	PaddingLen int
	WillPad    bool // set to false to disable extension

	// Functor for deciding on padding length based on unpadded ClientHello length.
	// If willPad is false, then this extension should not be included.
	GetPaddingLen func(clientHelloUnpaddedLen int) (paddingLen int, willPad bool)
}

func (*UtlsPaddingExtension) Len 

func (e *UtlsPaddingExtension) Len() int

func (*UtlsPaddingExtension) Read 

func (e *UtlsPaddingExtension) Read(b []byte) (int, error)

func (*UtlsPaddingExtension) Update 

func (e *UtlsPaddingExtension) Update(clientHelloUnpaddedLen int)

Notes

Bugs

Source Files

View all Source files

Directories

Path Synopsis
Package cpu implements processor feature detection used by the Go standard library.
 Package cpu implements processor feature detection used by the Go standard library.
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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