Go: crypto/tls Index | Examples | Files

package tls

import "crypto/tls"

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

Index

Examples

Package Files

alert.go auth.go cipher_suites.go common.go common_string.go conn.go handshake_client.go handshake_client_tls13.go handshake_messages.go handshake_server.go handshake_server_tls13.go key_agreement.go key_schedule.go prf.go ticket.go tls.go

Constants

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

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
)

func CipherSuiteName Uses

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 Listen Uses

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 Uses

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.

type Certificate Uses

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 Uses

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.

Code:play 

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

func X509KeyPair Uses

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.

Code:play 

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

Code:play 

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("", ""))

type CertificateRequestInfo Uses

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
}

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) SupportsCertificate Uses

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 CipherSuite Uses

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 Uses

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.

func InsecureCipherSuites Uses

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 Uses

type ClientAuthType int

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

const (
    NoClientCert ClientAuthType = iota
    RequestClientCert
    RequireAnyClientCert
    VerifyClientCertIfGiven
    RequireAndVerifyClientCert
)

func (ClientAuthType) String Uses

func (i ClientAuthType) String() string

type ClientHelloInfo Uses

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) SupportsCertificate Uses

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 ClientSessionCache Uses

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 Uses

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 Uses

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

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

type Config Uses

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.
    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 supported cipher suites for TLS versions up to
    // TLS 1.2. If CipherSuites is nil, a default list of secure cipher suites
    // is used, with a preference order based on hardware performance. The
    // default cipher suites might change over Go versions. Note that TLS 1.3
    // ciphersuites are not configurable.
    CipherSuites []uint16

    // PreferServerCipherSuites controls whether the server selects the
    // client's most preferred ciphersuite, or the server's most preferred
    // ciphersuite. If true then the server's preference, as expressed in
    // the order of elements in CipherSuites, is used.
    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.
    // If zero, TLS 1.0 is currently taken as the minimum.
    MinVersion uint16

    // MaxVersion contains the maximum TLS version that is acceptable.
    // If zero, 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.

Code:play 

// 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.

Code:play 

// 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.

func (*Config) BuildNameToCertificate Uses

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 Uses

func (c *Config) Clone() *Config

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

func (*Config) SetSessionTicketKeys Uses

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 Uses

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

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

func Client Uses

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 Uses

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.

Code:play 

// 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()

func DialWithDialer Uses

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.

func Server Uses

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 Uses

func (c *Conn) Close() error

Close closes the connection.

func (*Conn) CloseWrite Uses

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 Uses

func (c *Conn) ConnectionState() ConnectionState

ConnectionState returns basic TLS details about the connection.

func (*Conn) Handshake Uses

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 the Dialer's DialContext method.

func (*Conn) LocalAddr Uses

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

LocalAddr returns the local network address.

func (*Conn) OCSPResponse Uses

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 Uses

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

Read can be made to time out and return a net.Error with Timeout() == true after a fixed time limit; see SetDeadline and SetReadDeadline.

func (*Conn) RemoteAddr Uses

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

RemoteAddr returns the remote network address.

func (*Conn) SetDeadline Uses

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 Uses

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 Uses

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 Uses

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 Uses

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

Write writes data to the connection.

type ConnectionState Uses

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.
    //
    // Note that on the client side, this is currently not guaranteed to be from
    // Config.NextProtos.
    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 Uses

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 CurveID Uses

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 Uses

func (i CurveID) String() string

type Dialer Uses

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 Uses

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.

func (*Dialer) DialContext Uses

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 RecordHeaderError Uses

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 Uses

func (e RecordHeaderError) Error() string

type RenegotiationSupport Uses

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 SignatureScheme Uses

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
)

func (SignatureScheme) String Uses

func (i SignatureScheme) String() string

Bugs

The crypto/tls package only implements some countermeasures against Lucky13 attacks on CBC-mode encryption, and only on SHA1 variants. See http://www.isg.rhul.ac.uk/tls/TLStiming.pdf and https://www.imperialviolet.org/2013/02/04/luckythirteen.html.

Package tls imports 38 packages (graph) and is imported by 42519 packages. Updated 2020-09-09. Refresh now. Tools for package owners.