mirror of
https://github.com/autc04/Retro68.git
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215 lines
5.5 KiB
Go
215 lines
5.5 KiB
Go
// Copyright 2012 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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"bytes"
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"crypto/aes"
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"crypto/cipher"
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"crypto/hmac"
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"crypto/sha256"
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"crypto/subtle"
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"errors"
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"internal/x/crypto/cryptobyte"
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"io"
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)
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// sessionState contains the information that is serialized into a session
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// ticket in order to later resume a connection.
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type sessionState struct {
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vers uint16
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cipherSuite uint16
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masterSecret []byte
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certificates [][]byte
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// usedOldKey is true if the ticket from which this session came from
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// was encrypted with an older key and thus should be refreshed.
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usedOldKey bool
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}
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func (s *sessionState) marshal() []byte {
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length := 2 + 2 + 2 + len(s.masterSecret) + 2
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for _, cert := range s.certificates {
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length += 4 + len(cert)
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}
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ret := make([]byte, length)
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x := ret
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x[0] = byte(s.vers >> 8)
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x[1] = byte(s.vers)
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x[2] = byte(s.cipherSuite >> 8)
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x[3] = byte(s.cipherSuite)
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x[4] = byte(len(s.masterSecret) >> 8)
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x[5] = byte(len(s.masterSecret))
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x = x[6:]
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copy(x, s.masterSecret)
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x = x[len(s.masterSecret):]
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x[0] = byte(len(s.certificates) >> 8)
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x[1] = byte(len(s.certificates))
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x = x[2:]
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for _, cert := range s.certificates {
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x[0] = byte(len(cert) >> 24)
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x[1] = byte(len(cert) >> 16)
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x[2] = byte(len(cert) >> 8)
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x[3] = byte(len(cert))
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copy(x[4:], cert)
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x = x[4+len(cert):]
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}
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return ret
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}
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func (s *sessionState) unmarshal(data []byte) bool {
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if len(data) < 8 {
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return false
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}
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s.vers = uint16(data[0])<<8 | uint16(data[1])
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s.cipherSuite = uint16(data[2])<<8 | uint16(data[3])
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masterSecretLen := int(data[4])<<8 | int(data[5])
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data = data[6:]
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if len(data) < masterSecretLen {
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return false
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}
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s.masterSecret = data[:masterSecretLen]
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data = data[masterSecretLen:]
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if len(data) < 2 {
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return false
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}
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numCerts := int(data[0])<<8 | int(data[1])
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data = data[2:]
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s.certificates = make([][]byte, numCerts)
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for i := range s.certificates {
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if len(data) < 4 {
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return false
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}
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certLen := int(data[0])<<24 | int(data[1])<<16 | int(data[2])<<8 | int(data[3])
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data = data[4:]
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if certLen < 0 {
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return false
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}
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if len(data) < certLen {
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return false
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}
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s.certificates[i] = data[:certLen]
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data = data[certLen:]
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}
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return len(data) == 0
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}
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// sessionStateTLS13 is the content of a TLS 1.3 session ticket. Its first
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// version (revision = 0) doesn't carry any of the information needed for 0-RTT
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// validation and the nonce is always empty.
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type sessionStateTLS13 struct {
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// uint8 version = 0x0304;
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// uint8 revision = 0;
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cipherSuite uint16
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createdAt uint64
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resumptionSecret []byte // opaque resumption_master_secret<1..2^8-1>;
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certificate Certificate // CertificateEntry certificate_list<0..2^24-1>;
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}
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func (m *sessionStateTLS13) marshal() []byte {
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var b cryptobyte.Builder
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b.AddUint16(VersionTLS13)
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b.AddUint8(0) // revision
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b.AddUint16(m.cipherSuite)
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addUint64(&b, m.createdAt)
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b.AddUint8LengthPrefixed(func(b *cryptobyte.Builder) {
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b.AddBytes(m.resumptionSecret)
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})
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marshalCertificate(&b, m.certificate)
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return b.BytesOrPanic()
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}
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func (m *sessionStateTLS13) unmarshal(data []byte) bool {
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*m = sessionStateTLS13{}
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s := cryptobyte.String(data)
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var version uint16
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var revision uint8
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return s.ReadUint16(&version) &&
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version == VersionTLS13 &&
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s.ReadUint8(&revision) &&
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revision == 0 &&
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s.ReadUint16(&m.cipherSuite) &&
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readUint64(&s, &m.createdAt) &&
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readUint8LengthPrefixed(&s, &m.resumptionSecret) &&
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len(m.resumptionSecret) != 0 &&
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unmarshalCertificate(&s, &m.certificate) &&
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s.Empty()
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}
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func (c *Conn) encryptTicket(state []byte) ([]byte, error) {
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encrypted := make([]byte, ticketKeyNameLen+aes.BlockSize+len(state)+sha256.Size)
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keyName := encrypted[:ticketKeyNameLen]
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iv := encrypted[ticketKeyNameLen : ticketKeyNameLen+aes.BlockSize]
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macBytes := encrypted[len(encrypted)-sha256.Size:]
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if _, err := io.ReadFull(c.config.rand(), iv); err != nil {
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return nil, err
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}
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key := c.config.ticketKeys()[0]
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copy(keyName, key.keyName[:])
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block, err := aes.NewCipher(key.aesKey[:])
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if err != nil {
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return nil, errors.New("tls: failed to create cipher while encrypting ticket: " + err.Error())
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}
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cipher.NewCTR(block, iv).XORKeyStream(encrypted[ticketKeyNameLen+aes.BlockSize:], state)
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mac := hmac.New(sha256.New, key.hmacKey[:])
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mac.Write(encrypted[:len(encrypted)-sha256.Size])
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mac.Sum(macBytes[:0])
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return encrypted, nil
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}
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func (c *Conn) decryptTicket(encrypted []byte) (plaintext []byte, usedOldKey bool) {
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if len(encrypted) < ticketKeyNameLen+aes.BlockSize+sha256.Size {
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return nil, false
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}
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keyName := encrypted[:ticketKeyNameLen]
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iv := encrypted[ticketKeyNameLen : ticketKeyNameLen+aes.BlockSize]
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macBytes := encrypted[len(encrypted)-sha256.Size:]
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ciphertext := encrypted[ticketKeyNameLen+aes.BlockSize : len(encrypted)-sha256.Size]
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keys := c.config.ticketKeys()
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keyIndex := -1
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for i, candidateKey := range keys {
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if bytes.Equal(keyName, candidateKey.keyName[:]) {
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keyIndex = i
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break
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}
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}
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if keyIndex == -1 {
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return nil, false
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}
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key := &keys[keyIndex]
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mac := hmac.New(sha256.New, key.hmacKey[:])
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mac.Write(encrypted[:len(encrypted)-sha256.Size])
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expected := mac.Sum(nil)
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if subtle.ConstantTimeCompare(macBytes, expected) != 1 {
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return nil, false
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}
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block, err := aes.NewCipher(key.aesKey[:])
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if err != nil {
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return nil, false
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}
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plaintext = make([]byte, len(ciphertext))
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cipher.NewCTR(block, iv).XORKeyStream(plaintext, ciphertext)
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return plaintext, keyIndex > 0
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}
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