v1.0.0

transport/internet/kcp/crypt.go

@@ -0,0 +1,78 @@
+// +build !confonly
+
+package kcp
+
+import (
+	"crypto/cipher"
+	"encoding/binary"
+	"hash/fnv"
+
+	"github.com/xtls/xray-core/v1/common"
+)
+
+// SimpleAuthenticator is a legacy AEAD used for KCP encryption.
+type SimpleAuthenticator struct{}
+
+// NewSimpleAuthenticator creates a new SimpleAuthenticator
+func NewSimpleAuthenticator() cipher.AEAD {
+	return &SimpleAuthenticator{}
+}
+
+// NonceSize implements cipher.AEAD.NonceSize().
+func (*SimpleAuthenticator) NonceSize() int {
+	return 0
+}
+
+// Overhead implements cipher.AEAD.NonceSize().
+func (*SimpleAuthenticator) Overhead() int {
+	return 6
+}
+
+// Seal implements cipher.AEAD.Seal().
+func (a *SimpleAuthenticator) Seal(dst, nonce, plain, extra []byte) []byte {
+	dst = append(dst, 0, 0, 0, 0, 0, 0) // 4 bytes for hash, and then 2 bytes for length
+	binary.BigEndian.PutUint16(dst[4:], uint16(len(plain)))
+	dst = append(dst, plain...)
+
+	fnvHash := fnv.New32a()
+	common.Must2(fnvHash.Write(dst[4:]))
+	fnvHash.Sum(dst[:0])
+
+	dstLen := len(dst)
+	xtra := 4 - dstLen%4
+	if xtra != 4 {
+		dst = append(dst, make([]byte, xtra)...)
+	}
+	xorfwd(dst)
+	if xtra != 4 {
+		dst = dst[:dstLen]
+	}
+	return dst
+}
+
+// Open implements cipher.AEAD.Open().
+func (a *SimpleAuthenticator) Open(dst, nonce, cipherText, extra []byte) ([]byte, error) {
+	dst = append(dst, cipherText...)
+	dstLen := len(dst)
+	xtra := 4 - dstLen%4
+	if xtra != 4 {
+		dst = append(dst, make([]byte, xtra)...)
+	}
+	xorbkd(dst)
+	if xtra != 4 {
+		dst = dst[:dstLen]
+	}
+
+	fnvHash := fnv.New32a()
+	common.Must2(fnvHash.Write(dst[4:]))
+	if binary.BigEndian.Uint32(dst[:4]) != fnvHash.Sum32() {
+		return nil, newError("invalid auth")
+	}
+
+	length := binary.BigEndian.Uint16(dst[4:6])
+	if len(dst)-6 != int(length) {
+		return nil, newError("invalid auth")
+	}
+
+	return dst[6:], nil
+}