blob: 9560176259e21929c4866315ea19d671c99dfff4 [file] [log] [blame]
// Copyright 2012 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package tls
import (
"bytes"
"crypto/aes"
"crypto/cipher"
"crypto/hmac"
"crypto/sha256"
"crypto/subtle"
"errors"
"internal/x/crypto/cryptobyte"
"io"
)
// sessionState contains the information that is serialized into a session
// ticket in order to later resume a connection.
type sessionState struct {
vers uint16
cipherSuite uint16
masterSecret []byte
certificates [][]byte
// usedOldKey is true if the ticket from which this session came from
// was encrypted with an older key and thus should be refreshed.
usedOldKey bool
}
func (s *sessionState) marshal() []byte {
length := 2 + 2 + 2 + len(s.masterSecret) + 2
for _, cert := range s.certificates {
length += 4 + len(cert)
}
ret := make([]byte, length)
x := ret
x[0] = byte(s.vers >> 8)
x[1] = byte(s.vers)
x[2] = byte(s.cipherSuite >> 8)
x[3] = byte(s.cipherSuite)
x[4] = byte(len(s.masterSecret) >> 8)
x[5] = byte(len(s.masterSecret))
x = x[6:]
copy(x, s.masterSecret)
x = x[len(s.masterSecret):]
x[0] = byte(len(s.certificates) >> 8)
x[1] = byte(len(s.certificates))
x = x[2:]
for _, cert := range s.certificates {
x[0] = byte(len(cert) >> 24)
x[1] = byte(len(cert) >> 16)
x[2] = byte(len(cert) >> 8)
x[3] = byte(len(cert))
copy(x[4:], cert)
x = x[4+len(cert):]
}
return ret
}
func (s *sessionState) unmarshal(data []byte) bool {
if len(data) < 8 {
return false
}
s.vers = uint16(data[0])<<8 | uint16(data[1])
s.cipherSuite = uint16(data[2])<<8 | uint16(data[3])
masterSecretLen := int(data[4])<<8 | int(data[5])
data = data[6:]
if len(data) < masterSecretLen {
return false
}
s.masterSecret = data[:masterSecretLen]
data = data[masterSecretLen:]
if len(data) < 2 {
return false
}
numCerts := int(data[0])<<8 | int(data[1])
data = data[2:]
s.certificates = make([][]byte, numCerts)
for i := range s.certificates {
if len(data) < 4 {
return false
}
certLen := int(data[0])<<24 | int(data[1])<<16 | int(data[2])<<8 | int(data[3])
data = data[4:]
if certLen < 0 {
return false
}
if len(data) < certLen {
return false
}
s.certificates[i] = data[:certLen]
data = data[certLen:]
}
return len(data) == 0
}
// sessionStateTLS13 is the content of a TLS 1.3 session ticket. Its first
// version (revision = 0) doesn't carry any of the information needed for 0-RTT
// validation and the nonce is always empty.
type sessionStateTLS13 struct {
// uint8 version = 0x0304;
// uint8 revision = 0;
cipherSuite uint16
createdAt uint64
resumptionSecret []byte // opaque resumption_master_secret<1..2^8-1>;
certificate Certificate // CertificateEntry certificate_list<0..2^24-1>;
}
func (m *sessionStateTLS13) marshal() []byte {
var b cryptobyte.Builder
b.AddUint16(VersionTLS13)
b.AddUint8(0) // revision
b.AddUint16(m.cipherSuite)
addUint64(&b, m.createdAt)
b.AddUint8LengthPrefixed(func(b *cryptobyte.Builder) {
b.AddBytes(m.resumptionSecret)
})
marshalCertificate(&b, m.certificate)
return b.BytesOrPanic()
}
func (m *sessionStateTLS13) unmarshal(data []byte) bool {
*m = sessionStateTLS13{}
s := cryptobyte.String(data)
var version uint16
var revision uint8
return s.ReadUint16(&version) &&
version == VersionTLS13 &&
s.ReadUint8(&revision) &&
revision == 0 &&
s.ReadUint16(&m.cipherSuite) &&
readUint64(&s, &m.createdAt) &&
readUint8LengthPrefixed(&s, &m.resumptionSecret) &&
len(m.resumptionSecret) != 0 &&
unmarshalCertificate(&s, &m.certificate) &&
s.Empty()
}
func (c *Conn) encryptTicket(state []byte) ([]byte, error) {
encrypted := make([]byte, ticketKeyNameLen+aes.BlockSize+len(state)+sha256.Size)
keyName := encrypted[:ticketKeyNameLen]
iv := encrypted[ticketKeyNameLen : ticketKeyNameLen+aes.BlockSize]
macBytes := encrypted[len(encrypted)-sha256.Size:]
if _, err := io.ReadFull(c.config.rand(), iv); err != nil {
return nil, err
}
key := c.config.ticketKeys()[0]
copy(keyName, key.keyName[:])
block, err := aes.NewCipher(key.aesKey[:])
if err != nil {
return nil, errors.New("tls: failed to create cipher while encrypting ticket: " + err.Error())
}
cipher.NewCTR(block, iv).XORKeyStream(encrypted[ticketKeyNameLen+aes.BlockSize:], state)
mac := hmac.New(sha256.New, key.hmacKey[:])
mac.Write(encrypted[:len(encrypted)-sha256.Size])
mac.Sum(macBytes[:0])
return encrypted, nil
}
func (c *Conn) decryptTicket(encrypted []byte) (plaintext []byte, usedOldKey bool) {
if len(encrypted) < ticketKeyNameLen+aes.BlockSize+sha256.Size {
return nil, false
}
keyName := encrypted[:ticketKeyNameLen]
iv := encrypted[ticketKeyNameLen : ticketKeyNameLen+aes.BlockSize]
macBytes := encrypted[len(encrypted)-sha256.Size:]
ciphertext := encrypted[ticketKeyNameLen+aes.BlockSize : len(encrypted)-sha256.Size]
keys := c.config.ticketKeys()
keyIndex := -1
for i, candidateKey := range keys {
if bytes.Equal(keyName, candidateKey.keyName[:]) {
keyIndex = i
break
}
}
if keyIndex == -1 {
return nil, false
}
key := &keys[keyIndex]
mac := hmac.New(sha256.New, key.hmacKey[:])
mac.Write(encrypted[:len(encrypted)-sha256.Size])
expected := mac.Sum(nil)
if subtle.ConstantTimeCompare(macBytes, expected) != 1 {
return nil, false
}
block, err := aes.NewCipher(key.aesKey[:])
if err != nil {
return nil, false
}
plaintext = make([]byte, len(ciphertext))
cipher.NewCTR(block, iv).XORKeyStream(plaintext, ciphertext)
return plaintext, keyIndex > 0
}