From 7f778a4e2f123dc03fe57fbf24da59dcaf270f8a Mon Sep 17 00:00:00 2001
From: RPRX <63339210+RPRX@users.noreply.github.com>
Date: Wed, 13 Aug 2025 21:37:06 +0000
Subject: [PATCH] SHA256(nfsEKeyBytes) for XOR's key

https://github.com/XTLS/Xray-core/pull/4952#issuecomment-3185590465
---
 proxy/vless/encryption/client.go | 19 ++++++++++---------
 proxy/vless/encryption/server.go | 17 +++++++++--------
 2 files changed, 19 insertions(+), 17 deletions(-)

diff --git a/proxy/vless/encryption/client.go b/proxy/vless/encryption/client.go
index a51f2930..2faf745a 100644
--- a/proxy/vless/encryption/client.go
+++ b/proxy/vless/encryption/client.go
@@ -5,6 +5,7 @@ import (
 	"crypto/cipher"
 	"crypto/mlkem"
 	"crypto/rand"
+	"crypto/sha256"
 	"io"
 	"net"
 	"sync"
@@ -25,13 +26,13 @@ func init() {
 
 type ClientInstance struct {
 	sync.RWMutex
-	nfsEKey      *mlkem.EncapsulationKey768
-	nfsEKeyBytes []byte
-	xor          uint32
-	minutes      time.Duration
-	expire       time.Time
-	baseKey      []byte
-	ticket       []byte
+	nfsEKey       *mlkem.EncapsulationKey768
+	nfsEKeySha256 [32]byte
+	xor           uint32
+	minutes       time.Duration
+	expire        time.Time
+	baseKey       []byte
+	ticket        []byte
 }
 
 type ClientConn struct {
@@ -50,7 +51,7 @@ type ClientConn struct {
 func (i *ClientInstance) Init(nfsEKeyBytes []byte, xor uint32, minutes time.Duration) (err error) {
 	i.nfsEKey, err = mlkem.NewEncapsulationKey768(nfsEKeyBytes)
 	if xor > 0 {
-		i.nfsEKeyBytes = nfsEKeyBytes
+		i.nfsEKeySha256 = sha256.Sum256(nfsEKeyBytes)
 		i.xor = xor
 	}
 	i.minutes = minutes
@@ -62,7 +63,7 @@ func (i *ClientInstance) Handshake(conn net.Conn) (net.Conn, error) {
 		return nil, errors.New("uninitialized")
 	}
 	if i.xor > 0 {
-		conn = NewXorConn(conn, i.nfsEKeyBytes)
+		conn = NewXorConn(conn, i.nfsEKeySha256[:])
 	}
 	c := &ClientConn{Conn: conn}
 
diff --git a/proxy/vless/encryption/server.go b/proxy/vless/encryption/server.go
index 99b73ce4..49e0b9df 100644
--- a/proxy/vless/encryption/server.go
+++ b/proxy/vless/encryption/server.go
@@ -5,6 +5,7 @@ import (
 	"crypto/cipher"
 	"crypto/mlkem"
 	"crypto/rand"
+	"crypto/sha256"
 	"io"
 	"net"
 	"sync"
@@ -23,12 +24,12 @@ type ServerSession struct {
 
 type ServerInstance struct {
 	sync.RWMutex
-	nfsDKey      *mlkem.DecapsulationKey768
-	nfsEKeyBytes []byte
-	xor          uint32
-	minutes      time.Duration
-	sessions     map[[21]byte]*ServerSession
-	closed       bool
+	nfsDKey       *mlkem.DecapsulationKey768
+	nfsEKeySha256 [32]byte
+	xor           uint32
+	minutes       time.Duration
+	sessions      map[[21]byte]*ServerSession
+	closed        bool
 }
 
 type ServerConn struct {
@@ -47,7 +48,7 @@ type ServerConn struct {
 func (i *ServerInstance) Init(nfsDKeySeed []byte, xor uint32, minutes time.Duration) (err error) {
 	i.nfsDKey, err = mlkem.NewDecapsulationKey768(nfsDKeySeed)
 	if xor > 0 {
-		i.nfsEKeyBytes = i.nfsDKey.EncapsulationKey().Bytes()
+		i.nfsEKeySha256 = sha256.Sum256(i.nfsDKey.EncapsulationKey().Bytes())
 		i.xor = xor
 	}
 	if minutes > 0 {
@@ -86,7 +87,7 @@ func (i *ServerInstance) Handshake(conn net.Conn) (net.Conn, error) {
 		return nil, errors.New("uninitialized")
 	}
 	if i.xor > 0 {
-		conn = NewXorConn(conn, i.nfsEKeyBytes)
+		conn = NewXorConn(conn, i.nfsEKeySha256[:])
 	}
 	c := &ServerConn{Conn: conn}