320cfd8f47
TLS clients send ciphersuites in preference order (most prefereable first). This change alters the order so that ECDHE comes before plain RSA, and RC4 comes before AES (because of the Lucky13 attack). This is unlikely to have much effect: as a server, the code uses the client's ciphersuite order by default and, as a client, the non-Go server probably imposes its order. R=golang-dev, r, raggi, jsing CC=golang-dev https://golang.org/cl/10372045
196 lines
6.2 KiB
Go
196 lines
6.2 KiB
Go
// Copyright 2010 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package tls
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import (
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"crypto/aes"
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"crypto/cipher"
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"crypto/des"
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"crypto/hmac"
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"crypto/rc4"
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"crypto/sha1"
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"crypto/x509"
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"hash"
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)
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// a keyAgreement implements the client and server side of a TLS key agreement
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// protocol by generating and processing key exchange messages.
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type keyAgreement interface {
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// On the server side, the first two methods are called in order.
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// In the case that the key agreement protocol doesn't use a
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// ServerKeyExchange message, generateServerKeyExchange can return nil,
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// nil.
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generateServerKeyExchange(*Config, *Certificate, *clientHelloMsg, *serverHelloMsg) (*serverKeyExchangeMsg, error)
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processClientKeyExchange(*Config, *Certificate, *clientKeyExchangeMsg, uint16) ([]byte, error)
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// On the client side, the next two methods are called in order.
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// This method may not be called if the server doesn't send a
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// ServerKeyExchange message.
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processServerKeyExchange(*Config, *clientHelloMsg, *serverHelloMsg, *x509.Certificate, *serverKeyExchangeMsg) error
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generateClientKeyExchange(*Config, *clientHelloMsg, *x509.Certificate) ([]byte, *clientKeyExchangeMsg, error)
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}
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// A cipherSuite is a specific combination of key agreement, cipher and MAC
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// function. All cipher suites currently assume RSA key agreement.
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type cipherSuite struct {
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id uint16
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// the lengths, in bytes, of the key material needed for each component.
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keyLen int
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macLen int
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ivLen int
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ka func() keyAgreement
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// If elliptic is set, a server will only consider this ciphersuite if
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// the ClientHello indicated that the client supports an elliptic curve
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// and point format that we can handle.
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elliptic bool
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cipher func(key, iv []byte, isRead bool) interface{}
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mac func(version uint16, macKey []byte) macFunction
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}
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var cipherSuites = []*cipherSuite{
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// Ciphersuite order is chosen so that ECDHE comes before plain RSA
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// and RC4 comes before AES (because of the Lucky13 attack).
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{TLS_ECDHE_RSA_WITH_RC4_128_SHA, 16, 20, 0, ecdheRSAKA, true, cipherRC4, macSHA1},
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{TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA, 16, 20, 16, ecdheRSAKA, true, cipherAES, macSHA1},
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{TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA, 32, 20, 16, ecdheRSAKA, true, cipherAES, macSHA1},
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{TLS_RSA_WITH_RC4_128_SHA, 16, 20, 0, rsaKA, false, cipherRC4, macSHA1},
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{TLS_RSA_WITH_AES_128_CBC_SHA, 16, 20, 16, rsaKA, false, cipherAES, macSHA1},
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{TLS_RSA_WITH_AES_256_CBC_SHA, 32, 20, 16, rsaKA, false, cipherAES, macSHA1},
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{TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA, 24, 20, 8, ecdheRSAKA, true, cipher3DES, macSHA1},
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{TLS_RSA_WITH_3DES_EDE_CBC_SHA, 24, 20, 8, rsaKA, false, cipher3DES, macSHA1},
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}
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func cipherRC4(key, iv []byte, isRead bool) interface{} {
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cipher, _ := rc4.NewCipher(key)
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return cipher
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}
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func cipher3DES(key, iv []byte, isRead bool) interface{} {
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block, _ := des.NewTripleDESCipher(key)
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if isRead {
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return cipher.NewCBCDecrypter(block, iv)
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}
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return cipher.NewCBCEncrypter(block, iv)
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}
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func cipherAES(key, iv []byte, isRead bool) interface{} {
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block, _ := aes.NewCipher(key)
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if isRead {
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return cipher.NewCBCDecrypter(block, iv)
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}
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return cipher.NewCBCEncrypter(block, iv)
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}
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// macSHA1 returns a macFunction for the given protocol version.
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func macSHA1(version uint16, key []byte) macFunction {
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if version == VersionSSL30 {
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mac := ssl30MAC{
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h: sha1.New(),
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key: make([]byte, len(key)),
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}
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copy(mac.key, key)
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return mac
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}
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return tls10MAC{hmac.New(sha1.New, key)}
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}
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type macFunction interface {
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Size() int
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MAC(digestBuf, seq, header, data []byte) []byte
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}
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// ssl30MAC implements the SSLv3 MAC function, as defined in
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// www.mozilla.org/projects/security/pki/nss/ssl/draft302.txt section 5.2.3.1
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type ssl30MAC struct {
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h hash.Hash
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key []byte
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}
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func (s ssl30MAC) Size() int {
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return s.h.Size()
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}
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var ssl30Pad1 = [48]byte{0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36}
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var ssl30Pad2 = [48]byte{0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c}
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func (s ssl30MAC) MAC(digestBuf, seq, header, data []byte) []byte {
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padLength := 48
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if s.h.Size() == 20 {
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padLength = 40
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}
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s.h.Reset()
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s.h.Write(s.key)
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s.h.Write(ssl30Pad1[:padLength])
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s.h.Write(seq)
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s.h.Write(header[:1])
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s.h.Write(header[3:5])
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s.h.Write(data)
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digestBuf = s.h.Sum(digestBuf[:0])
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s.h.Reset()
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s.h.Write(s.key)
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s.h.Write(ssl30Pad2[:padLength])
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s.h.Write(digestBuf)
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return s.h.Sum(digestBuf[:0])
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}
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// tls10MAC implements the TLS 1.0 MAC function. RFC 2246, section 6.2.3.
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type tls10MAC struct {
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h hash.Hash
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}
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func (s tls10MAC) Size() int {
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return s.h.Size()
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}
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func (s tls10MAC) MAC(digestBuf, seq, header, data []byte) []byte {
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s.h.Reset()
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s.h.Write(seq)
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s.h.Write(header)
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s.h.Write(data)
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return s.h.Sum(digestBuf[:0])
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}
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func rsaKA() keyAgreement {
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return rsaKeyAgreement{}
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}
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func ecdheRSAKA() keyAgreement {
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return new(ecdheRSAKeyAgreement)
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}
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// mutualCipherSuite returns a cipherSuite given a list of supported
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// ciphersuites and the id requested by the peer.
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func mutualCipherSuite(have []uint16, want uint16) *cipherSuite {
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for _, id := range have {
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if id == want {
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for _, suite := range cipherSuites {
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if suite.id == want {
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return suite
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}
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}
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return nil
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}
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}
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return nil
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}
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// A list of the possible cipher suite ids. Taken from
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// http://www.iana.org/assignments/tls-parameters/tls-parameters.xml
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const (
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TLS_RSA_WITH_RC4_128_SHA uint16 = 0x0005
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TLS_RSA_WITH_3DES_EDE_CBC_SHA uint16 = 0x000a
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TLS_RSA_WITH_AES_128_CBC_SHA uint16 = 0x002f
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TLS_RSA_WITH_AES_256_CBC_SHA uint16 = 0x0035
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TLS_ECDHE_RSA_WITH_RC4_128_SHA uint16 = 0xc011
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TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA uint16 = 0xc012
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TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA uint16 = 0xc013
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TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA uint16 = 0xc014
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)
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