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tls.go
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package packemon
import (
"bytes"
"crypto"
"crypto/aes"
"crypto/cipher"
"crypto/hmac"
"crypto/rand"
"crypto/rsa"
"crypto/sha256"
"crypto/x509"
"encoding/binary"
"encoding/hex"
"fmt"
"log"
"strconv"
"golang.org/x/crypto/chacha20poly1305"
"golang.org/x/crypto/curve25519"
)
func ParsedTLSToPassive(tcp *TCP, p *Passive) {
// 以下、tcp.Data[1:3] にある(Record Layer) version あてにならないかも。tls version 1.0 の値でも wireshark 上で、tls1.2 or 1.3 の record という表示になってる
// なので、HandshakeProtocol 内の、Version でも確認する.
// が、これもあてにならない。TLS1.3のつもりでリクエストして(curl -s -v --tls-max 1.3 https://192.168.10.112:10443)、Client Hello みると、Version 1.0 / Handshake Protocol Version 1.2
// if bytes.Equal(TLS_VERSION_1_2, tcp.Data[1:3]) {
// TODO: support TLSv1.3
// ref: https://zenn.dev/satoken/articles/golang-tls1_3
if bytes.Equal(TLS_VERSION_1_0, tcp.Data[1:3]) || // 1.0 / 1.1 とか含めちゃってるのは、そういうのが1.2 / 1.3 でも入ってき得るから
bytes.Equal(TLS_VERSION_1_1, tcp.Data[1:3]) ||
bytes.Equal(TLS_VERSION_1_2, tcp.Data[1:3]) ||
bytes.Equal(TLS_VERSION_1_3, tcp.Data[1:3]) ||
bytes.Equal(TLS_VERSION_1_2, tcp.Data[9:11]) {
// TLS の 先頭の Content Type をチェック
// TODO: あくまで先頭の、なので、パケットが分割されて例えば、ChangeChiperSpec のみ来たりする可能性はあるかも
switch tcp.Data[0] {
case TLS_CONTENT_TYPE_HANDSHAKE:
if tcp.Data[5] == TLS_HANDSHAKE_TYPE_CLIENT_HELLO {
tlsClientHello := ParsedTLSClientHello(tcp.Data)
p.TLSClientHello = tlsClientHello
return
}
if tcp.Data[5] == TLS_HANDSHAKE_TYPE_SERVER_HELLO {
// Server Hello の、Extension.supported_versions に、TLS1.3(0x0304) が含まれていれば、それ用のパースをする
serverHello, _ := ParsedTLSServerHelloOnly(tcp.Data) // 以下のParsedTLSServerHelloでもこれ呼んでるからなんとかする
for _, e := range serverHello.HandshakeProtocol.Extentions {
if e.IsTLS13() {
tlsServerHelloFor1_3 := ParsedTLSServerHelloFor1_3(tcp.Data)
p.TLSServerHelloFor1_3 = tlsServerHelloFor1_3
return
}
}
tlsServerHello := ParsedTLSServerHello(tcp.Data)
p.TLSServerHello = tlsServerHello
return
}
if tcp.Data[5] == TLS_HANDSHAKE_TYPE_CLIENT_KEY_EXCHANGE {
tlsClientKeyExchange := ParsedTLSClientKeyexchange(tcp.Data)
p.TLSClientKeyExchange = tlsClientKeyExchange
return
}
case TLS_HANDSHAKE_TYPE_CHANGE_CIPHER_SPEC:
tlsChangeCipherSpecAndEncryptedHandshakeMessage := ParsedTLSChangeCipherSpecAndEncryptedHandshakeMessage(tcp.Data)
p.TLSChangeCipherSpecAndEncryptedHandshakeMessage = tlsChangeCipherSpecAndEncryptedHandshakeMessage
return
case TLS_CONTENT_TYPE_APPLICATION_DATA:
tlsApplicationData := ParsedTLSApplicationData(tcp.Data)
p.TLSApplicationData = tlsApplicationData
return
case TLS_CONTENT_TYPE_ALERT:
tlsEncryptedAlert := ParsedTLSEncryptedAlert(tcp.Data)
p.TLSEncryptedAlert = tlsEncryptedAlert
return
default:
}
}
}
const TLS_CONTENT_TYPE_HANDSHAKE = 0x16
const TLS_CONTENT_TYPE_CHANGE_CIPHER_SPEC = 0x14
const TLS_CONTENT_TYPE_APPLICATION_DATA = 0x17
// ref: https://tls12.xargs.org/#client-hello/annotated
// 以降のstructのフィールドはWiresharkを見つつ補完
type TLSRecordLayer struct {
ContentType []byte
Version []byte
Length []byte
}
func (l *TLSRecordLayer) Bytes() []byte {
buf := []byte{}
buf = append(buf, l.ContentType...)
buf = append(buf, l.Version...)
buf = append(buf, l.Length...)
return buf
}
type TLSHandshakeProtocol struct {
HandshakeType []byte
Length []byte
Version []byte
Random []byte
SessionIDLength []byte
SessionID []byte
CipherSuitesLength []byte
CipherSuites []uint16 // ref: https://tls12.xargs.org/#client-hello/annotated [Ciper Suites]
CompressionMethodsLength []byte
CompressionMethods []byte
ExtensionsLength []byte
Extentions TLSExtensions
}
var TLS_EXTENSION_TYPE_KEY_SHARE = []byte{0x0, 0x33}
type TLSExtension struct {
Type []byte
Length []byte
Data []byte
}
func (e *TLSExtension) Bytes() []byte {
buf := &bytes.Buffer{}
buf.Write(e.Type)
buf.Write(e.Length)
buf.Write(e.Data)
return buf.Bytes()
}
var TLS_EXTENSION_SUPPORTED_VERSIONS = []byte{0x00, 0x2b}
func (e *TLSExtension) IsTLS13() bool {
if !bytes.Equal(e.Type, TLS_EXTENSION_SUPPORTED_VERSIONS) {
return false
}
for i := 0; i < bytesToInt(e.Length); i += 2 {
supportedVersion := e.Data[i : i+2]
if bytes.Equal(supportedVersion, TLS_VERSION_1_3) {
return true
}
}
return false
}
type TLSExtensions []*TLSExtension
func (es TLSExtensions) Bytes() []byte {
buf := &bytes.Buffer{}
for _, e := range es {
buf.Write(e.Bytes())
}
return buf.Bytes()
}
func ParsedTLSExtensions(extensionsLength int, b []byte) TLSExtensions {
if extensionsLength == 0 {
return TLSExtensions{}
}
es := []*TLSExtension{}
for i := 0; i < extensionsLength; {
typ := b[i : i+2]
length := b[i+2 : i+4]
lengthInt := bytesToInt(length)
data := b[i+4 : i+4+lengthInt]
e := &TLSExtension{
Type: typ,
Length: length,
Data: data,
}
es = append(es, e)
i = i + 4 + lengthInt
}
return es
}
func (p *TLSHandshakeProtocol) Bytes(isFromServer bool) []byte {
buf := []byte{}
buf = append(buf, p.HandshakeType...)
buf = append(buf, p.Length...)
buf = append(buf, p.Version...)
buf = append(buf, p.Random...)
buf = append(buf, p.SessionIDLength...)
if !(p.SessionIDLength == nil || bytes.Equal(p.SessionIDLength, []byte{0x00})) {
buf = append(buf, p.SessionID...)
}
if clength := p.lengthCipherSuites(isFromServer); clength != nil {
buf = append(buf, p.lengthCipherSuites(isFromServer)...)
}
buf = append(buf, p.bytesCipherSuites()...)
buf = append(buf, p.CompressionMethodsLength...)
buf = append(buf, p.CompressionMethods...)
buf = append(buf, p.ExtensionsLength...)
buf = append(buf, p.Extentions.Bytes()...)
return buf
}
func (p *TLSHandshakeProtocol) bytesCipherSuites() []byte {
if len(p.CipherSuites) == 0 {
return nil
}
buf := []byte{}
for i := range p.CipherSuites {
buf = binary.BigEndian.AppendUint16(buf, p.CipherSuites[i])
}
return buf
}
func (p *TLSHandshakeProtocol) lengthCipherSuites(isFromServer bool) []byte {
if len(p.CipherSuites) == 0 || isFromServer {
return nil
}
buf := make([]byte, 2)
binary.BigEndian.PutUint16(buf, uint16(len(p.CipherSuites)*2)) // 2byteなため×2
return buf
}
type TLSClientHello struct {
RecordLayer *TLSRecordLayer
HandshakeProtocol *TLSHandshakeProtocol
// TODO: これがこのstruct内にあるのはおかしく、一旦実装を簡単にするため置いてるだけ。要リファクタ
ECDHEKeys *ECDHEKeys
}
const TLS_HANDSHAKE_TYPE_CLIENT_HELLO = 0x01
const TLS_HANDSHAKE_TYPE_SERVER_HELLO = 0x02
const COMPRESSION_METHOD_NULL = 0x00
var TLS_VERSION_1_0 = []byte{0x03, 0x01}
var TLS_VERSION_1_1 = []byte{0x03, 0x02}
var TLS_VERSION_1_2 = []byte{0x03, 0x03}
var TLS_VERSION_1_3 = []byte{0x03, 0x04}
type ECDHEKeys struct {
PrivateKey []byte
PublicKey []byte
SharedKey []byte
}
// TODO: tls1.3 用のと汎用的に
func NewTLSClientHello(tlsVersion []byte, cipherSuites ...uint16) *TLSClientHello {
random := make([]byte, 32)
if _, err := rand.Read(random); err != nil {
panic(err)
}
handshake := &TLSHandshakeProtocol{
HandshakeType: []byte{TLS_HANDSHAKE_TYPE_CLIENT_HELLO},
Length: []byte{0x00, 0x00, 0x00}, // 後で計算して求めるが、初期化のため
Version: TLS_VERSION_1_2,
// TODO: debug 環境の https-server あてにリクエストするときは、以下を使う。復号される
// Random: make([]byte, 32), // 000000....
Random: random,
SessionIDLength: []byte{0x00},
// SessionID: make([]byte, 32),
CipherSuitesLength: []byte{0x00, 0x02}, // 一旦固定
// CipherSuitesLength: []byte{0x00, 0x04}, // 一旦固定
CipherSuites: cipherSuites, // TODO: 外から指定するようにしたので、CipherSuitesLength を計算して求めないといけない
CompressionMethodsLength: []byte{0x00}, // 後で計算して求めるが、初期化のため
CompressionMethods: []byte{COMPRESSION_METHOD_NULL},
ExtensionsLength: []byte{0x00, 0x00}, // 後で計算して求めるが、初期化のため
}
handshake.CompressionMethodsLength = []byte{byte(len(handshake.CompressionMethods))}
tmp := &bytes.Buffer{}
ecdheKeys := &ECDHEKeys{}
if bytes.Equal(tlsVersion, TLS_VERSION_1_3) {
// ref: https://github.com/sat0ken/go-tcpip/blob/7dd5085f8aa25747a6098cc7d8d8e336ec5fcadd/tls1_3.go#L16
clientPrivateKey := make([]byte, 32)
rand.Read(clientPrivateKey)
// clientPrivateKey := noRandomByte(32)
clientPublicKey, err := curve25519.X25519(clientPrivateKey, curve25519.Basepoint)
if err != nil {
panic(err)
}
ecdheKeys.PrivateKey = clientPrivateKey
ecdheKeys.PublicKey = clientPublicKey
handshake.Extentions = []*TLSExtension{
{
// supported_groups
Type: []byte{0x00, 0x0a},
Length: []byte{0x00, 0x04},
Data: []byte{
/*Supported Groups List Length: 2*/ 0x00, 0x02,
/*Supported Groups (1 groups): x25519*/ 0x0, 0x1d,
},
},
{
// ec_point_formats
Type: []byte{0x0, 0x0b},
Length: []byte{0x0, 0x02},
Data: []byte{
0x01, 0x00,
},
},
{
// signature_algorithms
Type: []byte{0x0, 0x0d},
Length: []byte{0x0, 0x1a},
Data: append(
[]byte{0x0, 0x18},
[]byte{
0x08, 0x04,
0x04, 0x03, 0x08, 0x07, 0x08, 0x05, 0x08, 0x06, 0x04, 0x01, 0x05, 0x01, 0x06, 0x01, 0x05, 0x03, 0x06, 0x03, 0x02, 0x01, 0x02, 0x03,
}...,
),
},
{
// renagotiation_info
Type: []byte{0xff, 0x01},
Length: []byte{0x00, 0x01},
Data: []byte{0x00},
},
{
// supported_versions
Type: []byte{0x0, 0x2b},
Length: []byte{0x0, 0x03},
Data: append([]byte{0x02}, TLS_VERSION_1_3...),
},
{
// key_share
Type: []byte{0x0, 0x33},
Length: []byte{0x0, 0x26},
Data: append(
[]byte{
/* Client Key Share Length: 36 */ 0x0, 0x24,
// 以降、Key Share Entry:
/* Group: x25519 (29) */ 0x0, 0x1d,
/* Key Exchange Length: 32 */ 0x0, 0x20,
},
/* Key Exchange: */ ecdheKeys.PublicKey...),
},
// {
// // http2 実装するときに使う
// // application_layer_protocol_negotiation
// },
}
}
WriteUint16(tmp, uint16(len(handshake.Extentions.Bytes())))
handshake.ExtensionsLength = tmp.Bytes()
lengthAll := &bytes.Buffer{}
isFromServer := false
WriteUint16(lengthAll, uint16(len(handshake.Bytes(isFromServer))))
// 全体の長さ - 4 でいいはず
handshake.Length = uintTo3byte(uint32(len(handshake.Bytes(isFromServer))) - 4)
return &TLSClientHello{
RecordLayer: &TLSRecordLayer{
ContentType: []byte{TLS_CONTENT_TYPE_HANDSHAKE},
Version: TLS_VERSION_1_2,
Length: lengthAll.Bytes(),
},
HandshakeProtocol: handshake,
ECDHEKeys: ecdheKeys,
}
}
func ParsedTLSClientHello(b []byte) *TLSClientHello {
sessionIDLength := b[43]
sessionIDLengthInt := int(sessionIDLength)
var sessionID []byte
nextPoint := 44
if sessionIDLengthInt > 0 {
sessionID = b[nextPoint : nextPoint+sessionIDLengthInt]
nextPoint += sessionIDLengthInt
}
cipherSuitesLength := b[nextPoint : nextPoint+2]
nextPoint += 2
cipherSuites := []uint16{}
// たぶん、2byteずつ増えていくでokと思うけど
sum := 0
for i := 0; i < (bytesToInt(cipherSuitesLength) / 2); i++ {
point := i * 2
cipherSuite := binary.BigEndian.Uint16(b[nextPoint+point : nextPoint+point+2])
cipherSuites = append(cipherSuites, cipherSuite)
sum += 2
}
nextPoint += sum
compressionMethodsLength := b[nextPoint]
compressionMethodsLengthInt := int(compressionMethodsLength)
compressionMethods := []byte{}
if compressionMethodsLengthInt > 0 {
compressionMethods = b[nextPoint+1 : nextPoint+1+compressionMethodsLengthInt]
nextPoint = nextPoint + 1 + compressionMethodsLengthInt
}
extensionsLength := b[nextPoint : nextPoint+2]
extensionsLengthInt := bytesToInt(extensionsLength)
nextPoint += 2
var extensions TLSExtensions
if extensionsLengthInt > 0 {
extensions = ParsedTLSExtensions(extensionsLengthInt, b[nextPoint:nextPoint+extensionsLengthInt])
}
return &TLSClientHello{
RecordLayer: &TLSRecordLayer{
ContentType: []byte{b[0]},
Version: b[1:3],
Length: b[3:5],
},
HandshakeProtocol: &TLSHandshakeProtocol{
HandshakeType: []byte{b[5]},
Length: b[6:9],
Version: b[9:11],
Random: b[11:43],
SessionIDLength: []byte{sessionIDLength},
SessionID: sessionID,
CipherSuitesLength: cipherSuitesLength,
CipherSuites: cipherSuites,
CompressionMethodsLength: []byte{compressionMethodsLength},
CompressionMethods: compressionMethods,
ExtensionsLength: extensionsLength,
Extentions: extensions,
},
}
}
// 2byteをintへ変換
func bytesToInt(b []byte) int {
return int(b[0])<<8 + int(b[1])
}
// 3byteをintへ変換
func bytesToInt2(b []byte) int {
return int(b[0])<<16 + int(b[1])<<8 + int(b[2])
}
func (tch *TLSClientHello) Bytes() []byte {
buf := []byte{}
buf = append(buf, tch.RecordLayer.Bytes()...)
isFromServer := false
buf = append(buf, tch.HandshakeProtocol.Bytes(isFromServer)...)
return buf
}
type TLSServerHello struct {
ServerHello *ServerHello
Certificate *Certificate
ServerHelloDone *ServerHelloDone
}
func (tlsserverhello *TLSServerHello) Bytes() []byte {
b := []byte{}
b = append(b, tlsserverhello.ServerHello.Bytes()...)
b = append(b, tlsserverhello.Certificate.Bytes()...)
b = append(b, tlsserverhello.ServerHelloDone.Bytes()...)
return b
}
type ServerHello struct {
RecordLayer *TLSRecordLayer
HandshakeProtocol *TLSHandshakeProtocol
}
func (s *ServerHello) Bytes() []byte {
b := []byte{}
b = append(b, s.RecordLayer.Bytes()...)
isFromServer := true
b = append(b, s.HandshakeProtocol.Bytes(isFromServer)...)
return b
}
type Certificate struct {
RecordLayer *TLSRecordLayer
HandshakeProtocol *TLSHandshakeProtocol
CertificatesLength []byte
Certificates []byte // TODO: ここ更にフィールドあった
certs []*x509.Certificate // parse成功した証明書を格納する
}
func (c *Certificate) Bytes() []byte {
b := []byte{}
b = append(b, c.RecordLayer.Bytes()...)
isFromServer := true
b = append(b, c.HandshakeProtocol.Bytes(isFromServer)...)
b = append(b, c.CertificatesLength...)
b = append(b, c.Certificates...)
return b
}
// ref: https://zenn.dev/satoken/articles/golang-tls1_2#serverhello%2C-certificate%2C-serverhellodone
func (c *Certificate) Validate() error {
// log.Printf("validation cert: \n%x\n", c.Certificates[3:])
length, _ := strconv.ParseUint(fmt.Sprintf("%x", c.Certificates[:3]), 16, 16)
certs, err := x509.ParseCertificates(c.Certificates[3 : 3+length])
if err != nil {
return err
}
// log.Printf("certificate num: %d\n", len(certs))
c.certs = certs
ospool, err := x509.SystemCertPool()
if err != nil {
return err
}
// log.Println("start verify server certificate")
for i := len(c.certs) - 1; i >= 0; i-- {
opts := x509.VerifyOptions{}
if len(c.certs[i].DNSNames) == 0 {
opts.Roots = ospool
} else {
opts.Roots = ospool
opts.DNSName = c.certs[i].DNSNames[0]
// log.Printf("\tDNS name in server certificate: %s\n", c.certs[i].DNSNames[0])
}
if _, err := c.certs[i].Verify(opts); err != nil {
// TODO: 以下対応までエラーとしないようにする
// https://github.com/ddddddO/packemon/issues/63
// log.Printf("\tfailed to verify server certificate: %s\n", err)
return err
}
if i > 0 {
ospool.AddCert(c.certs[1])
}
}
// log.Println("finish verify server certificate")
return nil
}
func (c *Certificate) ServerPublicKey() *rsa.PublicKey {
if len(c.certs) == 0 {
// log.Println("nil ServerPublicKey")
return nil
}
pub, ok := c.certs[0].PublicKey.(*rsa.PublicKey)
if !ok {
// log.Printf("not public key")
return nil
}
return pub
}
type ServerHelloDone struct {
RecordLayer *TLSRecordLayer
HandshakeProtocol *TLSHandshakeProtocol
}
func (sd *ServerHelloDone) Bytes() []byte {
b := []byte{}
b = append(b, sd.RecordLayer.Bytes()...)
isFromServer := true
b = append(b, sd.HandshakeProtocol.Bytes(isFromServer)...)
return b
}
// TLS1.2/1.3 共通
func ParsedTLSServerHelloOnly(b []byte) (*ServerHello, int) {
sessionIDLength := b[43]
sessionIDLengthInt := int(sessionIDLength)
nextPosition := 44
sessionID := []byte{}
if sessionIDLengthInt != 0 {
sessionID = b[nextPosition : nextPosition+sessionIDLengthInt]
nextPosition += sessionIDLengthInt
}
slength := b[3:5]
serverHello := &ServerHello{
RecordLayer: &TLSRecordLayer{
ContentType: []byte{b[0]},
Version: b[1:3],
Length: slength,
},
HandshakeProtocol: &TLSHandshakeProtocol{
HandshakeType: []byte{b[5]},
Length: b[6:9],
Version: b[9:11],
Random: b[11:43],
SessionIDLength: []byte{sessionIDLength},
SessionID: sessionID,
CipherSuites: []uint16{parsedCipherSuites(b[nextPosition : nextPosition+2])},
CompressionMethods: []byte{b[nextPosition+2]},
},
}
nextPosition = nextPosition + 3
if bytesToInt(slength) > 47 {
extentionsLength := b[nextPosition : nextPosition+2]
serverHello.HandshakeProtocol.ExtensionsLength = extentionsLength
nextPosition += 2
serverHello.HandshakeProtocol.Extentions = ParsedTLSExtensions(bytesToInt(extentionsLength), b[nextPosition:nextPosition+bytesToInt(extentionsLength)])
nextPosition += bytesToInt(extentionsLength)
}
return serverHello, nextPosition
}
// tls1.2用
func ParsedTLSServerHello(b []byte) *TLSServerHello {
serverHello, nextPosition := ParsedTLSServerHelloOnly(b)
certificate := &Certificate{
RecordLayer: &TLSRecordLayer{
ContentType: []byte{b[nextPosition]},
Version: b[nextPosition+1 : nextPosition+3],
Length: b[nextPosition+3 : nextPosition+5],
},
HandshakeProtocol: &TLSHandshakeProtocol{
HandshakeType: []byte{b[nextPosition+5]},
Length: b[nextPosition+6 : nextPosition+9],
},
CertificatesLength: b[nextPosition+9 : nextPosition+12],
}
certificateLength := parsedCertificatesLength(b[nextPosition+9 : nextPosition+12])
certificate.Certificates = b[nextPosition+12 : nextPosition+12+certificateLength]
nextPosition += 12 + certificateLength
serverHelloDone := &ServerHelloDone{
RecordLayer: &TLSRecordLayer{
ContentType: []byte{b[nextPosition]},
Version: b[nextPosition+1 : nextPosition+3],
Length: b[nextPosition+3 : nextPosition+5],
},
HandshakeProtocol: &TLSHandshakeProtocol{
HandshakeType: []byte{b[nextPosition+5]},
Length: b[nextPosition+6 : nextPosition+9],
},
}
return &TLSServerHello{
ServerHello: serverHello,
Certificate: certificate,
ServerHelloDone: serverHelloDone,
}
}
type TLSServerHelloFor1_3 struct {
ServerHello *ServerHello
ChangeCipherSpecProtocol *ChangeCipherSpecProtocol
ApplicationDataProtocols []*TLSApplicationData
}
func (t *TLSServerHelloFor1_3) Bytes() []byte {
b := &bytes.Buffer{}
b.Write(t.ServerHello.Bytes())
b.Write(t.ChangeCipherSpecProtocol.Bytes())
for _, app := range t.ApplicationDataProtocols {
b.Write(app.Bytes())
}
return b.Bytes()
}
func (t *TLSServerHelloFor1_3) GetServerKeyShare() []byte {
for _, extension := range t.ServerHello.HandshakeProtocol.Extentions {
if bytes.Equal(TLS_EXTENSION_TYPE_KEY_SHARE, extension.Type) {
return extension.Data[4:]
}
}
return nil
}
// tls1.3用
func ParsedTLSServerHelloFor1_3(b []byte) *TLSServerHelloFor1_3 {
serverHello, nextPosition := ParsedTLSServerHelloOnly(b)
b = b[nextPosition:]
changeCipherSpec, nextPosition := ParsedChangeCipherSpec(b)
b = b[nextPosition:]
as := []*TLSApplicationData{}
// TODO: 多分、パケット2つ結合してからでないとダメかもしれん
// ただ、1パケットでも大丈夫なときがありそう
// ip header の total length が 1500 超えてるとき、連結するようにすればよさそう(そういうパケットでも、Don't fragment なのはそういうものなの？)
// これは確か、Monitor の話
for {
applicationData := ParsedTLSApplicationData(b)
if applicationData == nil || applicationData.RecordLayer.ContentType[0] != TLS_CONTENT_TYPE_APPLICATION_DATA {
break
}
as = append(as, applicationData)
nextPosition = 5 + bytesToInt(applicationData.RecordLayer.Length)
b = b[nextPosition:]
}
return &TLSServerHelloFor1_3{
ServerHello: serverHello,
ChangeCipherSpecProtocol: changeCipherSpec,
ApplicationDataProtocols: as,
}
}
// こちらも拝借させてもらってる
// ref: https://github.com/sat0ken/go-tcpip/blob/7dd5085f8aa25747a6098cc7d8d8e336ec5fcadd/tls1_3.go#L88
func DecryptChacha20(header []byte, chipertext []byte, tlsConn *TLSv12Connection) []byte {
// header := message[0:5]
// chipertext := message[5:]
// chipertext := message
var key, iv, nonce []byte
if tlsConn.currentHandshake {
key = tlsConn.KeyBlockForTLSv13.serverHandshakeKey
iv = tlsConn.KeyBlockForTLSv13.serverHandshakeIV
nonce = getNonce(tlsConn.ServerHandshakeSeq, 8)
} else {
key = tlsConn.KeyBlockForTLSv13.serverAppKey
iv = tlsConn.KeyBlockForTLSv13.serverAppIV
nonce = getNonce(tlsConn.ServerAppSeq, 8)
}
//fmt.Printf("key is %x, iv is %x\n", key, iv)
aead, err := chacha20poly1305.New(key)
if err != nil {
panic(err)
}
xornonce := getXORNonce(nonce, iv)
//fmt.Printf("decrypt nonce is %x xornonce is %x, chipertext is %x, add is %x\n", nonce, xornonce, chipertext, header)
plaintext, err := aead.Open(nil, xornonce, chipertext, header)
if err != nil {
panic(err)
}
// fmt.Printf("plaintext is : %x\n", plaintext)
return plaintext
}
func EncryptChacha20(message []byte, tlsConn *TLSv12Connection) []byte {
var key, iv, nonce []byte
// Finishedメッセージを送るとき
if tlsConn.currentHandshake {
key = tlsConn.KeyBlockForTLSv13.clientHandshakeKey
iv = tlsConn.KeyBlockForTLSv13.clientHandshakeIV
nonce = getNonce(tlsConn.ClientHandshakeSeq, 8)
} else {
// Application Dataを送る時
key = tlsConn.KeyBlockForTLSv13.clientAppKey
iv = tlsConn.KeyBlockForTLSv13.clientAppIV
nonce = getNonce(tlsConn.ClientAppSeq, 8)
}
// fmt.Printf("key is %x, iv is %x\n", key, iv)
aead, err := chacha20poly1305.New(key)
if err != nil {
log.Fatal(err)
}
// ivとnonceをxorのbit演算をする
// 5.3. レコードごとのノンス
// 2.埋め込まれたシーケンス番号は、静的なclient_write_ivまたはserver_write_iv（役割に応じて）とXORされます。
xornonce := getXORNonce(nonce, iv)
header := strtoByte("170303")
// 平文→暗号化したときのOverHeadを足す
totalLength := len(message) + 16
b := &bytes.Buffer{}
WriteUint16(b, uint16(totalLength))
header = append(header, b.Bytes()...)
// fmt.Printf("encrypt now nonce is %x xornonce is %x, plaintext is %x, add is %x\n", nonce, xornonce, message, header)
ciphertext := aead.Seal(header, xornonce, message, header)
return ciphertext
}
type CertificateVerify struct {
HandshakeType byte
Length []byte
SignatureHashAlgorithms []byte
SignatureLength []byte
Signature []byte
}
const str0x20x64 = "20202020202020202020202020202020202020202020202020202020202020202020202020202020202020202020202020202020202020202020202020202020"
var serverCertificateContextString = []byte(`TLS 1.3, server CertificateVerify`)
// ref: https://github.com/sat0ken/go-tcpip/blob/7dd5085f8aa25747a6098cc7d8d8e336ec5fcadd/tls1_3.go#L285
func (c *CertificateVerify) VerifyServerCertificate(pubkey *rsa.PublicKey, handshake_messages []byte) error {
hash_messages := WriteHash(handshake_messages)
hasher := sha256.New()
// 64回繰り返されるオクテット32（0x20）で構成される文字列
hasher.Write(strtoByte(str0x20x64))
// コンテキスト文字列 = "TLS 1.3, server CertificateVerify"
hasher.Write(serverCertificateContextString)
// セパレータとして機能する単一の0バイト
hasher.Write([]byte{0x00})
hasher.Write(hash_messages)
signed := hasher.Sum(nil)
// fmt.Printf("hash_messages is %x\n, signed is %x\n", hash_messages, signed)
signOpts := &rsa.PSSOptions{SaltLength: rsa.PSSSaltLengthEqualsHash}
if err := rsa.VerifyPSS(pubkey, crypto.SHA256, signed, c.Signature, signOpts); err != nil {
return err
}
return nil
}
type FinishedMessage struct {
HandshakeType byte
Length []byte
VerifyData []byte
}
func (f *FinishedMessage) Bytes() []byte {
b := &bytes.Buffer{}
b.WriteByte(f.HandshakeType)
b.Write(f.Length)
b.Write(f.VerifyData)
return b.Bytes()
}
// TLS1.3用
// https://tex2e.github.io/rfc-translater/html/rfc8446.html
// シーケンス番号とwrite_ivをxorした値がnonceになる
func getXORNonce(seqnum, writeiv []byte) []byte {
nonce := make([]byte, len(writeiv))
copy(nonce, writeiv)
for i, b := range seqnum {
nonce[4+i] ^= b
}
return nonce
}
func strtoByte(str string) []byte {
b, _ := hex.DecodeString(str)
return b
}
func parsedCipherSuites(b []byte) uint16 {
return binary.BigEndian.Uint16(b)
}
func parsedCertificatesLength(b []byte) int {
b = append([]byte{0x00}, b...)
return int(binary.BigEndian.Uint32(b))
}
type TLSClientKeyExchange struct {
ClientKeyExchange *ClientKeyExchange
ChangeCipherSpecProtocol *ChangeCipherSpecProtocol
EncryptedHandshakeMessage []byte
}
func ParsedTLSClientKeyexchange(b []byte) *TLSClientKeyExchange {
encryptedPreMasterLength := b[9:11]
clientKeyExchange := &ClientKeyExchange{
RecordLayer: &TLSRecordLayer{
ContentType: []byte{b[0]},
Version: b[1:3],
Length: b[3:5],
},
HandshakeProtocol: &TLSHandshakeProtocol{
HandshakeType: []byte{b[5]},
Length: b[6:9],
},
RSAEncryptedPreMasterSecret: &RSAEncryptedPreMasterSecret{
EncryptedPreMasterLength: encryptedPreMasterLength,
},
}
nextPosition := 11
clientKeyExchange.RSAEncryptedPreMasterSecret.EncryptedPreMaster = b[nextPosition : nextPosition+bytesToInt(encryptedPreMasterLength)]
nextPosition += bytesToInt(encryptedPreMasterLength)
lengthOfChangeCipherSpecProtocol := b[nextPosition+3 : nextPosition+5]
changeCipherSpecProtocol := &ChangeCipherSpecProtocol{
RecordLayer: &TLSRecordLayer{
ContentType: []byte{b[nextPosition]},
Version: b[nextPosition+1 : nextPosition+3],
Length: lengthOfChangeCipherSpecProtocol,
},
ChangeCipherSpecMessage: b[nextPosition+5 : nextPosition+5+bytesToInt(lengthOfChangeCipherSpecProtocol)],
}
nextPosition += 5 + bytesToInt(lengthOfChangeCipherSpecProtocol)
lengthOfEncryptedHandshakeMessage := b[nextPosition+3 : nextPosition+5]
encryptedHandshakeMessage := &EncryptedHandshakeMessage{
RecordLayer: &TLSRecordLayer{
ContentType: []byte{b[nextPosition]},
Version: b[nextPosition+1 : nextPosition+3],
Length: lengthOfEncryptedHandshakeMessage,
},
EncryptedHandshakeMessage_: b[nextPosition+5 : nextPosition+5+bytesToInt(lengthOfEncryptedHandshakeMessage)],
}
return &TLSClientKeyExchange{
ClientKeyExchange: clientKeyExchange,
ChangeCipherSpecProtocol: changeCipherSpecProtocol,
EncryptedHandshakeMessage: encryptedHandshakeMessage.Bytes(),
}
}
func (tlsclientkeyexchange *TLSClientKeyExchange) Bytes() []byte {
b := []byte{}
b = append(b, tlsclientkeyexchange.ClientKeyExchange.Bytes()...)
b = append(b, tlsclientkeyexchange.ChangeCipherSpecProtocol.Bytes()...)
b = append(b, tlsclientkeyexchange.EncryptedHandshakeMessage...)
return b
}
type ClientKeyExchange struct {
RecordLayer *TLSRecordLayer
HandshakeProtocol *TLSHandshakeProtocol
RSAEncryptedPreMasterSecret *RSAEncryptedPreMasterSecret
}
type RSAEncryptedPreMasterSecret struct {
EncryptedPreMasterLength []byte
EncryptedPreMaster []byte
}
func (r *RSAEncryptedPreMasterSecret) Bytes() []byte {
b := []byte{}
b = append(b, r.EncryptedPreMasterLength...)
b = append(b, r.EncryptedPreMaster...)
return b
}
func (c *ClientKeyExchange) Bytes() []byte {
b := []byte{}
b = append(b, c.RecordLayer.Bytes()...)
isFromServer := false
b = append(b, c.HandshakeProtocol.Bytes(isFromServer)...)
b = append(b, c.RSAEncryptedPreMasterSecret.Bytes()...)
return b
}
type ChangeCipherSpecProtocol struct {
RecordLayer *TLSRecordLayer
ChangeCipherSpecMessage []byte
}
func (cc *ChangeCipherSpecProtocol) Bytes() []byte {
b := []byte{}
b = append(b, cc.RecordLayer.Bytes()...)
b = append(b, cc.ChangeCipherSpecMessage...)
return b
}
type EncryptedHandshakeMessage struct {
RecordLayer *TLSRecordLayer
EncryptedHandshakeMessage_ []byte
}
func (e *EncryptedHandshakeMessage) Bytes() []byte {
b := []byte{}
b = append(b, e.RecordLayer.Bytes()...)
b = append(b, e.EncryptedHandshakeMessage_...)
return b
}
const TLS_HANDSHAKE_TYPE_CLIENT_KEY_EXCHANGE = 0x10
const TLS_HANDSHAKE_TYPE_CHANGE_CIPHER_SPEC = 0x14
const TLS_HANDSHAKE_TYPE_FINISHED = 0x14
func NewTLSClientKeyExchangeAndChangeCipherSpecAndFinished(clientHello *TLSClientHello, serverHello *TLSServerHello) (*TLSClientKeyExchange, *KeyBlock, int, []byte, []byte) {
publicKey := serverHello.Certificate.ServerPublicKey()
preMastersecret, encryptedPreMastersecret := generatePreMasterSecret(publicKey)
// log.Printf("pre master secret:\n%x\n", preMastersecret)
// log.Printf("encryptedPreMastersecret:\n%x\n", encryptedPreMastersecret)
encryptedPreMasterLength := &bytes.Buffer{}
WriteUint16(encryptedPreMasterLength, uint16(len(encryptedPreMastersecret)))
rsaEncryptedPreMasterSecret := &RSAEncryptedPreMasterSecret{
EncryptedPreMasterLength: encryptedPreMasterLength.Bytes(),
EncryptedPreMaster: encryptedPreMastersecret,
}
clientKeyExchange := &ClientKeyExchange{
RecordLayer: &TLSRecordLayer{
ContentType: []byte{TLS_CONTENT_TYPE_HANDSHAKE},
Version: TLS_VERSION_1_2,
Length: []byte{0x00, 0x00}, // 後で計算するが、初期化のため
},
HandshakeProtocol: &TLSHandshakeProtocol{