292 lines
10 KiB
Go
292 lines
10 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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const (
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// suiteECDH indicates that the cipher suite involves elliptic curve
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// Diffie-Hellman. This means that it should only be selected when the
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// client indicates that it supports ECC with a curve and point format
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// that we're happy with.
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suiteECDHE = 1 << iota
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// suiteECDSA indicates that the cipher suite involves an ECDSA
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// signature and therefore may only be selected when the server's
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// certificate is ECDSA. If this is not set then the cipher suite is
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// RSA based.
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suiteECDSA
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// suiteTLS12 indicates that the cipher suite should only be advertised
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// and accepted when using TLS 1.2.
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suiteTLS12
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// suiteSHA384 indicates that the cipher suite uses SHA384 as the
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// handshake hash.
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suiteSHA384
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// suiteDefaultOff indicates that this cipher suite is not included by
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// default.
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suiteDefaultOff
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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(version uint16) keyAgreement
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// flags is a bitmask of the suite* values, above.
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flags int
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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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aead func(key, fixedNonce []byte) cipher.AEAD
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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-CBC (because of the Lucky13 attack).
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{TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256, 16, 0, 4, ecdheRSAKA, suiteECDHE | suiteTLS12, nil, nil, aeadAESGCM},
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{TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256, 16, 0, 4, ecdheECDSAKA, suiteECDHE | suiteECDSA | suiteTLS12, nil, nil, aeadAESGCM},
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{TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384, 32, 0, 4, ecdheRSAKA, suiteECDHE | suiteTLS12 | suiteSHA384, nil, nil, aeadAESGCM},
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{TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384, 32, 0, 4, ecdheECDSAKA, suiteECDHE | suiteECDSA | suiteTLS12 | suiteSHA384, nil, nil, aeadAESGCM},
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{TLS_ECDHE_RSA_WITH_RC4_128_SHA, 16, 20, 0, ecdheRSAKA, suiteECDHE | suiteDefaultOff, cipherRC4, macSHA1, nil},
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{TLS_ECDHE_ECDSA_WITH_RC4_128_SHA, 16, 20, 0, ecdheECDSAKA, suiteECDHE | suiteECDSA | suiteDefaultOff, cipherRC4, macSHA1, nil},
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{TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA, 16, 20, 16, ecdheRSAKA, suiteECDHE, cipherAES, macSHA1, nil},
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{TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA, 16, 20, 16, ecdheECDSAKA, suiteECDHE | suiteECDSA, cipherAES, macSHA1, nil},
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{TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA, 32, 20, 16, ecdheRSAKA, suiteECDHE, cipherAES, macSHA1, nil},
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{TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA, 32, 20, 16, ecdheECDSAKA, suiteECDHE | suiteECDSA, cipherAES, macSHA1, nil},
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{TLS_RSA_WITH_AES_128_GCM_SHA256, 16, 0, 4, rsaKA, suiteTLS12, nil, nil, aeadAESGCM},
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{TLS_RSA_WITH_AES_256_GCM_SHA384, 32, 0, 4, rsaKA, suiteTLS12 | suiteSHA384, nil, nil, aeadAESGCM},
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{TLS_RSA_WITH_RC4_128_SHA, 16, 20, 0, rsaKA, suiteDefaultOff, cipherRC4, macSHA1, nil},
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{TLS_RSA_WITH_AES_128_CBC_SHA, 16, 20, 16, rsaKA, 0, cipherAES, macSHA1, nil},
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{TLS_RSA_WITH_AES_256_CBC_SHA, 32, 20, 16, rsaKA, 0, cipherAES, macSHA1, nil},
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{TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA, 24, 20, 8, ecdheRSAKA, suiteECDHE, cipher3DES, macSHA1, nil},
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{TLS_RSA_WITH_3DES_EDE_CBC_SHA, 24, 20, 8, rsaKA, 0, cipher3DES, macSHA1, nil},
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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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// fixedNonceAEAD wraps an AEAD and prefixes a fixed portion of the nonce to
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// each call.
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type fixedNonceAEAD struct {
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// sealNonce and openNonce are buffers where the larger nonce will be
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// constructed. Since a seal and open operation may be running
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// concurrently, there is a separate buffer for each.
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sealNonce, openNonce []byte
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aead cipher.AEAD
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}
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func (f *fixedNonceAEAD) NonceSize() int { return 8 }
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func (f *fixedNonceAEAD) Overhead() int { return f.aead.Overhead() }
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func (f *fixedNonceAEAD) Seal(out, nonce, plaintext, additionalData []byte) []byte {
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copy(f.sealNonce[len(f.sealNonce)-8:], nonce)
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return f.aead.Seal(out, f.sealNonce, plaintext, additionalData)
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}
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func (f *fixedNonceAEAD) Open(out, nonce, plaintext, additionalData []byte) ([]byte, error) {
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copy(f.openNonce[len(f.openNonce)-8:], nonce)
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return f.aead.Open(out, f.openNonce, plaintext, additionalData)
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}
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func aeadAESGCM(key, fixedNonce []byte) cipher.AEAD {
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aes, err := aes.NewCipher(key)
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if err != nil {
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panic(err)
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}
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aead, err := cipher.NewGCM(aes)
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if err != nil {
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panic(err)
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}
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nonce1, nonce2 := make([]byte, 12), make([]byte, 12)
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copy(nonce1, fixedNonce)
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copy(nonce2, fixedNonce)
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return &fixedNonceAEAD{nonce1, nonce2, aead}
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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(version uint16) keyAgreement {
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return rsaKeyAgreement{}
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}
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func ecdheECDSAKA(version uint16) keyAgreement {
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return &ecdheKeyAgreement{
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sigType: signatureECDSA,
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version: version,
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}
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}
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func ecdheRSAKA(version uint16) keyAgreement {
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return &ecdheKeyAgreement{
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sigType: signatureRSA,
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version: version,
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}
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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 cipher suite IDs that are, or have been, implemented by this
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// package.
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//
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// Taken from 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_RSA_WITH_AES_128_GCM_SHA256 uint16 = 0x009c
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TLS_RSA_WITH_AES_256_GCM_SHA384 uint16 = 0x009d
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TLS_ECDHE_ECDSA_WITH_RC4_128_SHA uint16 = 0xc007
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TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA uint16 = 0xc009
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TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA uint16 = 0xc00a
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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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TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 uint16 = 0xc02f
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TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256 uint16 = 0xc02b
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TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 uint16 = 0xc030
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TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384 uint16 = 0xc02c
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// TLS_FALLBACK_SCSV isn't a standard cipher suite but an indicator
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// that the client is doing version fallback. See
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// https://tools.ietf.org/html/rfc7507.
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TLS_FALLBACK_SCSV uint16 = 0x5600
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)
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