Clash.Meta/transport/vmess/header.go
2021-10-10 23:44:09 +08:00

104 lines
3.5 KiB
Go

package vmess
import (
"bytes"
"crypto/aes"
"crypto/cipher"
"crypto/hmac"
"crypto/rand"
"crypto/sha256"
"encoding/binary"
"hash"
"hash/crc32"
"time"
)
const (
kdfSaltConstAuthIDEncryptionKey = "AES Auth ID Encryption"
kdfSaltConstAEADRespHeaderLenKey = "AEAD Resp Header Len Key"
kdfSaltConstAEADRespHeaderLenIV = "AEAD Resp Header Len IV"
kdfSaltConstAEADRespHeaderPayloadKey = "AEAD Resp Header Key"
kdfSaltConstAEADRespHeaderPayloadIV = "AEAD Resp Header IV"
kdfSaltConstVMessAEADKDF = "VMess AEAD KDF"
kdfSaltConstVMessHeaderPayloadAEADKey = "VMess Header AEAD Key"
kdfSaltConstVMessHeaderPayloadAEADIV = "VMess Header AEAD Nonce"
kdfSaltConstVMessHeaderPayloadLengthAEADKey = "VMess Header AEAD Key_Length"
kdfSaltConstVMessHeaderPayloadLengthAEADIV = "VMess Header AEAD Nonce_Length"
)
func kdf(key []byte, path ...string) []byte {
hmacCreator := &hMacCreator{value: []byte(kdfSaltConstVMessAEADKDF)}
for _, v := range path {
hmacCreator = &hMacCreator{value: []byte(v), parent: hmacCreator}
}
hmacf := hmacCreator.Create()
hmacf.Write(key)
return hmacf.Sum(nil)
}
type hMacCreator struct {
parent *hMacCreator
value []byte
}
func (h *hMacCreator) Create() hash.Hash {
if h.parent == nil {
return hmac.New(sha256.New, h.value)
}
return hmac.New(h.parent.Create, h.value)
}
func createAuthID(cmdKey []byte, time int64) [16]byte {
buf := &bytes.Buffer{}
binary.Write(buf, binary.BigEndian, time)
random := make([]byte, 4)
rand.Read(random)
buf.Write(random)
zero := crc32.ChecksumIEEE(buf.Bytes())
binary.Write(buf, binary.BigEndian, zero)
aesBlock, _ := aes.NewCipher(kdf(cmdKey[:], kdfSaltConstAuthIDEncryptionKey)[:16])
var result [16]byte
aesBlock.Encrypt(result[:], buf.Bytes())
return result
}
func sealVMessAEADHeader(key [16]byte, data []byte, t time.Time) []byte {
generatedAuthID := createAuthID(key[:], t.Unix())
connectionNonce := make([]byte, 8)
rand.Read(connectionNonce)
aeadPayloadLengthSerializedByte := make([]byte, 2)
binary.BigEndian.PutUint16(aeadPayloadLengthSerializedByte, uint16(len(data)))
var payloadHeaderLengthAEADEncrypted []byte
{
payloadHeaderLengthAEADKey := kdf(key[:], kdfSaltConstVMessHeaderPayloadLengthAEADKey, string(generatedAuthID[:]), string(connectionNonce))[:16]
payloadHeaderLengthAEADNonce := kdf(key[:], kdfSaltConstVMessHeaderPayloadLengthAEADIV, string(generatedAuthID[:]), string(connectionNonce))[:12]
payloadHeaderLengthAEADAESBlock, _ := aes.NewCipher(payloadHeaderLengthAEADKey)
payloadHeaderAEAD, _ := cipher.NewGCM(payloadHeaderLengthAEADAESBlock)
payloadHeaderLengthAEADEncrypted = payloadHeaderAEAD.Seal(nil, payloadHeaderLengthAEADNonce, aeadPayloadLengthSerializedByte, generatedAuthID[:])
}
var payloadHeaderAEADEncrypted []byte
{
payloadHeaderAEADKey := kdf(key[:], kdfSaltConstVMessHeaderPayloadAEADKey, string(generatedAuthID[:]), string(connectionNonce))[:16]
payloadHeaderAEADNonce := kdf(key[:], kdfSaltConstVMessHeaderPayloadAEADIV, string(generatedAuthID[:]), string(connectionNonce))[:12]
payloadHeaderAEADAESBlock, _ := aes.NewCipher(payloadHeaderAEADKey)
payloadHeaderAEAD, _ := cipher.NewGCM(payloadHeaderAEADAESBlock)
payloadHeaderAEADEncrypted = payloadHeaderAEAD.Seal(nil, payloadHeaderAEADNonce, data, generatedAuthID[:])
}
outputBuffer := &bytes.Buffer{}
outputBuffer.Write(generatedAuthID[:])
outputBuffer.Write(payloadHeaderLengthAEADEncrypted)
outputBuffer.Write(connectionNonce)
outputBuffer.Write(payloadHeaderAEADEncrypted)
return outputBuffer.Bytes()
}