forked from MetaCubeX/quic-go
/
header_protector.go
135 lines (114 loc) · 3.58 KB
/
header_protector.go
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package handshake
import (
"crypto/aes"
"crypto/cipher"
"crypto/tls"
"encoding/binary"
"fmt"
"golang.org/x/crypto/chacha20"
"github.com/MerlinKodo/quic-go/internal/protocol"
)
type headerProtector interface {
EncryptHeader(sample []byte, firstByte *byte, hdrBytes []byte)
DecryptHeader(sample []byte, firstByte *byte, hdrBytes []byte)
}
func hkdfHeaderProtectionLabel(v protocol.VersionNumber) string {
if v == protocol.Version2 {
return "quicv2 hp"
}
return "quic hp"
}
func newHeaderProtector(suite *cipherSuite, trafficSecret []byte, isLongHeader bool, v protocol.VersionNumber) headerProtector {
hkdfLabel := hkdfHeaderProtectionLabel(v)
switch suite.ID {
case tls.TLS_AES_128_GCM_SHA256, tls.TLS_AES_256_GCM_SHA384:
return newAESHeaderProtector(suite, trafficSecret, isLongHeader, hkdfLabel)
case tls.TLS_CHACHA20_POLY1305_SHA256:
return newChaChaHeaderProtector(suite, trafficSecret, isLongHeader, hkdfLabel)
default:
panic(fmt.Sprintf("Invalid cipher suite id: %d", suite.ID))
}
}
type aesHeaderProtector struct {
mask []byte
block cipher.Block
isLongHeader bool
}
var _ headerProtector = &aesHeaderProtector{}
func newAESHeaderProtector(suite *cipherSuite, trafficSecret []byte, isLongHeader bool, hkdfLabel string) headerProtector {
hpKey := hkdfExpandLabel(suite.Hash, trafficSecret, []byte{}, hkdfLabel, suite.KeyLen)
block, err := aes.NewCipher(hpKey)
if err != nil {
panic(fmt.Sprintf("error creating new AES cipher: %s", err))
}
return &aesHeaderProtector{
block: block,
mask: make([]byte, block.BlockSize()),
isLongHeader: isLongHeader,
}
}
func (p *aesHeaderProtector) DecryptHeader(sample []byte, firstByte *byte, hdrBytes []byte) {
p.apply(sample, firstByte, hdrBytes)
}
func (p *aesHeaderProtector) EncryptHeader(sample []byte, firstByte *byte, hdrBytes []byte) {
p.apply(sample, firstByte, hdrBytes)
}
func (p *aesHeaderProtector) apply(sample []byte, firstByte *byte, hdrBytes []byte) {
if len(sample) != len(p.mask) {
panic("invalid sample size")
}
p.block.Encrypt(p.mask, sample)
if p.isLongHeader {
*firstByte ^= p.mask[0] & 0xf
} else {
*firstByte ^= p.mask[0] & 0x1f
}
for i := range hdrBytes {
hdrBytes[i] ^= p.mask[i+1]
}
}
type chachaHeaderProtector struct {
mask [5]byte
key [32]byte
isLongHeader bool
}
var _ headerProtector = &chachaHeaderProtector{}
func newChaChaHeaderProtector(suite *cipherSuite, trafficSecret []byte, isLongHeader bool, hkdfLabel string) headerProtector {
hpKey := hkdfExpandLabel(suite.Hash, trafficSecret, []byte{}, hkdfLabel, suite.KeyLen)
p := &chachaHeaderProtector{
isLongHeader: isLongHeader,
}
copy(p.key[:], hpKey)
return p
}
func (p *chachaHeaderProtector) DecryptHeader(sample []byte, firstByte *byte, hdrBytes []byte) {
p.apply(sample, firstByte, hdrBytes)
}
func (p *chachaHeaderProtector) EncryptHeader(sample []byte, firstByte *byte, hdrBytes []byte) {
p.apply(sample, firstByte, hdrBytes)
}
func (p *chachaHeaderProtector) apply(sample []byte, firstByte *byte, hdrBytes []byte) {
if len(sample) != 16 {
panic("invalid sample size")
}
for i := 0; i < 5; i++ {
p.mask[i] = 0
}
cipher, err := chacha20.NewUnauthenticatedCipher(p.key[:], sample[4:])
if err != nil {
panic(err)
}
cipher.SetCounter(binary.LittleEndian.Uint32(sample[:4]))
cipher.XORKeyStream(p.mask[:], p.mask[:])
p.applyMask(firstByte, hdrBytes)
}
func (p *chachaHeaderProtector) applyMask(firstByte *byte, hdrBytes []byte) {
if p.isLongHeader {
*firstByte ^= p.mask[0] & 0xf
} else {
*firstByte ^= p.mask[0] & 0x1f
}
for i := range hdrBytes {
hdrBytes[i] ^= p.mask[i+1]
}
}