284 lines
8.4 KiB
Go
284 lines
8.4 KiB
Go
// Copyright 2009 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 qtls
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import (
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"crypto"
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"crypto/hmac"
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"crypto/md5"
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"crypto/sha1"
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"crypto/sha256"
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"crypto/sha512"
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"errors"
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"fmt"
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"hash"
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)
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// Split a premaster secret in two as specified in RFC 4346, Section 5.
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func splitPreMasterSecret(secret []byte) (s1, s2 []byte) {
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s1 = secret[0 : (len(secret)+1)/2]
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s2 = secret[len(secret)/2:]
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return
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}
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// pHash implements the P_hash function, as defined in RFC 4346, Section 5.
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func pHash(result, secret, seed []byte, hash func() hash.Hash) {
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h := hmac.New(hash, secret)
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h.Write(seed)
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a := h.Sum(nil)
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j := 0
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for j < len(result) {
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h.Reset()
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h.Write(a)
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h.Write(seed)
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b := h.Sum(nil)
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copy(result[j:], b)
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j += len(b)
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h.Reset()
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h.Write(a)
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a = h.Sum(nil)
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}
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}
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// prf10 implements the TLS 1.0 pseudo-random function, as defined in RFC 2246, Section 5.
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func prf10(result, secret, label, seed []byte) {
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hashSHA1 := sha1.New
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hashMD5 := md5.New
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labelAndSeed := make([]byte, len(label)+len(seed))
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copy(labelAndSeed, label)
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copy(labelAndSeed[len(label):], seed)
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s1, s2 := splitPreMasterSecret(secret)
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pHash(result, s1, labelAndSeed, hashMD5)
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result2 := make([]byte, len(result))
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pHash(result2, s2, labelAndSeed, hashSHA1)
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for i, b := range result2 {
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result[i] ^= b
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}
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}
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// prf12 implements the TLS 1.2 pseudo-random function, as defined in RFC 5246, Section 5.
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func prf12(hashFunc func() hash.Hash) func(result, secret, label, seed []byte) {
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return func(result, secret, label, seed []byte) {
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labelAndSeed := make([]byte, len(label)+len(seed))
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copy(labelAndSeed, label)
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copy(labelAndSeed[len(label):], seed)
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pHash(result, secret, labelAndSeed, hashFunc)
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}
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}
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const (
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masterSecretLength = 48 // Length of a master secret in TLS 1.1.
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finishedVerifyLength = 12 // Length of verify_data in a Finished message.
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)
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var masterSecretLabel = []byte("master secret")
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var keyExpansionLabel = []byte("key expansion")
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var clientFinishedLabel = []byte("client finished")
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var serverFinishedLabel = []byte("server finished")
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func prfAndHashForVersion(version uint16, suite *cipherSuite) (func(result, secret, label, seed []byte), crypto.Hash) {
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switch version {
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case VersionTLS10, VersionTLS11:
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return prf10, crypto.Hash(0)
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case VersionTLS12:
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if suite.flags&suiteSHA384 != 0 {
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return prf12(sha512.New384), crypto.SHA384
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}
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return prf12(sha256.New), crypto.SHA256
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default:
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panic("unknown version")
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}
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}
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func prfForVersion(version uint16, suite *cipherSuite) func(result, secret, label, seed []byte) {
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prf, _ := prfAndHashForVersion(version, suite)
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return prf
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}
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// masterFromPreMasterSecret generates the master secret from the pre-master
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// secret. See RFC 5246, Section 8.1.
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func masterFromPreMasterSecret(version uint16, suite *cipherSuite, preMasterSecret, clientRandom, serverRandom []byte) []byte {
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seed := make([]byte, 0, len(clientRandom)+len(serverRandom))
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seed = append(seed, clientRandom...)
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seed = append(seed, serverRandom...)
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masterSecret := make([]byte, masterSecretLength)
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prfForVersion(version, suite)(masterSecret, preMasterSecret, masterSecretLabel, seed)
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return masterSecret
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}
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// keysFromMasterSecret generates the connection keys from the master
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// secret, given the lengths of the MAC key, cipher key and IV, as defined in
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// RFC 2246, Section 6.3.
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func keysFromMasterSecret(version uint16, suite *cipherSuite, masterSecret, clientRandom, serverRandom []byte, macLen, keyLen, ivLen int) (clientMAC, serverMAC, clientKey, serverKey, clientIV, serverIV []byte) {
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seed := make([]byte, 0, len(serverRandom)+len(clientRandom))
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seed = append(seed, serverRandom...)
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seed = append(seed, clientRandom...)
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n := 2*macLen + 2*keyLen + 2*ivLen
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keyMaterial := make([]byte, n)
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prfForVersion(version, suite)(keyMaterial, masterSecret, keyExpansionLabel, seed)
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clientMAC = keyMaterial[:macLen]
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keyMaterial = keyMaterial[macLen:]
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serverMAC = keyMaterial[:macLen]
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keyMaterial = keyMaterial[macLen:]
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clientKey = keyMaterial[:keyLen]
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keyMaterial = keyMaterial[keyLen:]
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serverKey = keyMaterial[:keyLen]
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keyMaterial = keyMaterial[keyLen:]
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clientIV = keyMaterial[:ivLen]
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keyMaterial = keyMaterial[ivLen:]
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serverIV = keyMaterial[:ivLen]
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return
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}
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func newFinishedHash(version uint16, cipherSuite *cipherSuite) finishedHash {
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var buffer []byte
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if version >= VersionTLS12 {
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buffer = []byte{}
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}
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prf, hash := prfAndHashForVersion(version, cipherSuite)
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if hash != 0 {
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return finishedHash{hash.New(), hash.New(), nil, nil, buffer, version, prf}
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}
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return finishedHash{sha1.New(), sha1.New(), md5.New(), md5.New(), buffer, version, prf}
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}
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// A finishedHash calculates the hash of a set of handshake messages suitable
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// for including in a Finished message.
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type finishedHash struct {
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client hash.Hash
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server hash.Hash
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// Prior to TLS 1.2, an additional MD5 hash is required.
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clientMD5 hash.Hash
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serverMD5 hash.Hash
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// In TLS 1.2, a full buffer is sadly required.
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buffer []byte
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version uint16
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prf func(result, secret, label, seed []byte)
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}
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func (h *finishedHash) Write(msg []byte) (n int, err error) {
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h.client.Write(msg)
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h.server.Write(msg)
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if h.version < VersionTLS12 {
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h.clientMD5.Write(msg)
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h.serverMD5.Write(msg)
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}
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if h.buffer != nil {
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h.buffer = append(h.buffer, msg...)
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}
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return len(msg), nil
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}
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func (h finishedHash) Sum() []byte {
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if h.version >= VersionTLS12 {
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return h.client.Sum(nil)
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}
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out := make([]byte, 0, md5.Size+sha1.Size)
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out = h.clientMD5.Sum(out)
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return h.client.Sum(out)
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}
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// clientSum returns the contents of the verify_data member of a client's
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// Finished message.
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func (h finishedHash) clientSum(masterSecret []byte) []byte {
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out := make([]byte, finishedVerifyLength)
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h.prf(out, masterSecret, clientFinishedLabel, h.Sum())
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return out
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}
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// serverSum returns the contents of the verify_data member of a server's
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// Finished message.
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func (h finishedHash) serverSum(masterSecret []byte) []byte {
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out := make([]byte, finishedVerifyLength)
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h.prf(out, masterSecret, serverFinishedLabel, h.Sum())
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return out
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}
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// hashForClientCertificate returns the handshake messages so far, pre-hashed if
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// necessary, suitable for signing by a TLS client certificate.
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func (h finishedHash) hashForClientCertificate(sigType uint8, hashAlg crypto.Hash, masterSecret []byte) []byte {
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if (h.version >= VersionTLS12 || sigType == signatureEd25519) && h.buffer == nil {
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panic("tls: handshake hash for a client certificate requested after discarding the handshake buffer")
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}
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if sigType == signatureEd25519 {
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return h.buffer
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}
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if h.version >= VersionTLS12 {
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hash := hashAlg.New()
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hash.Write(h.buffer)
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return hash.Sum(nil)
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}
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if sigType == signatureECDSA {
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return h.server.Sum(nil)
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}
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return h.Sum()
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}
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// discardHandshakeBuffer is called when there is no more need to
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// buffer the entirety of the handshake messages.
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func (h *finishedHash) discardHandshakeBuffer() {
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h.buffer = nil
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}
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// noExportedKeyingMaterial is used as a value of
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// ConnectionState.ekm when renegotiation is enabled and thus
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// we wish to fail all key-material export requests.
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func noExportedKeyingMaterial(label string, context []byte, length int) ([]byte, error) {
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return nil, errors.New("crypto/tls: ExportKeyingMaterial is unavailable when renegotiation is enabled")
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}
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// ekmFromMasterSecret generates exported keying material as defined in RFC 5705.
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func ekmFromMasterSecret(version uint16, suite *cipherSuite, masterSecret, clientRandom, serverRandom []byte) func(string, []byte, int) ([]byte, error) {
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return func(label string, context []byte, length int) ([]byte, error) {
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switch label {
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case "client finished", "server finished", "master secret", "key expansion":
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// These values are reserved and may not be used.
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return nil, fmt.Errorf("crypto/tls: reserved ExportKeyingMaterial label: %s", label)
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}
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seedLen := len(serverRandom) + len(clientRandom)
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if context != nil {
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seedLen += 2 + len(context)
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}
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seed := make([]byte, 0, seedLen)
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seed = append(seed, clientRandom...)
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seed = append(seed, serverRandom...)
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if context != nil {
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if len(context) >= 1<<16 {
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return nil, fmt.Errorf("crypto/tls: ExportKeyingMaterial context too long")
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}
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seed = append(seed, byte(len(context)>>8), byte(len(context)))
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seed = append(seed, context...)
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}
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keyMaterial := make([]byte, length)
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prfForVersion(version, suite)(keyMaterial, masterSecret, []byte(label), seed)
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return keyMaterial, nil
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}
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}
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