Add RC4 Cipher.

shadowsocks/encrypt.go

@@ -3,6 +3,7 @@ package shadowsocks
 import (
 	"bytes"
 	"crypto/md5"
+	"crypto/rc4"
 	"encoding/binary"
 	"errors"
 	"io"
@@ -19,9 +20,10 @@ type TableCipher struct {
 	decTbl []byte
 }
 
-func NewTableCipher(key string) (tbl *TableCipher) {
+// Creates a new table based cipher. err is always nil.
+func NewTableCipher(key string) (c Cipher, err error) {
 	const tbl_size = 256
-	tbl = &TableCipher{
+	tbl := TableCipher{
 		make([]byte, tbl_size, tbl_size),
 		make([]byte, tbl_size, tbl_size),
 	}
@@ -50,7 +52,7 @@ func NewTableCipher(key string) (tbl *TableCipher) {
 	for i = 0; i < tbl_size; i++ {
 		tbl.decTbl[tbl.encTbl[i]] = byte(i)
 	}
-	return
+	return &tbl, nil
 }
 
 func (c *TableCipher) Encrypt(dst, src []byte) {
@@ -65,14 +67,43 @@ func (c *TableCipher) Decrypt(dst, src []byte) {
 	}
 }
 
+type RC4Cipher struct {
+	dec *rc4.Cipher
+	enc *rc4.Cipher
+}
+
+func NewRC4Cipher(key string) (c Cipher, err error) {
+	keybytes := []byte(key)
+	enc, err := rc4.NewCipher(keybytes)
+	if err != nil {
+		return
+	}
+	dec, _ := rc4.NewCipher(keybytes)
+	c = &RC4Cipher{dec, enc}
+	return
+}
+
+func (c RC4Cipher) Encrypt(dst, src []byte) {
+	c.enc.XORKeyStream(dst, src)
+}
+
+func (c RC4Cipher) Decrypt(dst, src []byte) {
+	c.dec.XORKeyStream(dst, src)
+}
+
 // Function to get default cipher
 var NewCipher = NewTableCipher
 
 // Set default cipher. Empty string of cipher name uses the simple table
 // cipher.
 func SetDefaultCipher(cipherName string) (err error) {
-	if cipherName == "" {
-		return
+	switch cipherName {
+	case "":
+		NewCipher = NewTableCipher
+	case "rc4":
+		NewCipher = NewRC4Cipher
+	default:
+		return errors.New("cipher " + cipherName + " not supported")
 	}
-	return errors.New("cipher " + cipherName + " not supported")
+	return
 }

shadowsocks/encrypt_test.go

@@ -19,21 +19,23 @@ func checkTable(t *testing.T, tbl *TableCipher, encTarget, decTarget []byte, msg
 func TestEncrypTable1(t *testing.T) {
 	enc := []byte{60, 53, 84, 138, 217, 94, 88, 23, 39, 242, 219, 35, 12, 157, 165, 181, 255, 143, 83, 247, 162, 16, 31, 209, 190, 171, 115, 65, 38, 41, 21, 245, 236, 46, 121, 62, 166, 233, 44, 154, 153, 145, 230, 49, 128, 216, 173, 29, 241, 119, 64, 229, 194, 103, 131, 110, 26, 197, 218, 59, 204, 56, 27, 34, 141, 221, 149, 239, 192, 195, 24, 155, 170, 183, 11, 254, 213, 37, 137, 226, 75, 203, 55, 19, 72, 248, 22, 129, 33, 175, 178, 10, 198, 71, 77, 36, 113, 167, 48, 2, 117, 140, 142, 66, 199, 232, 243, 32, 123, 54, 51, 82, 57, 177, 87, 251, 150, 196, 133, 5, 253, 130, 8, 184, 14, 152, 231, 3, 186, 159, 76, 89, 228, 205, 156, 96, 163, 146, 18, 91, 132, 85, 80, 109, 172, 176, 105, 13, 50, 235, 127, 0, 189, 95, 98, 136, 250, 200, 108, 179, 211, 214, 106, 168, 78, 79, 74, 210, 30, 73, 201, 151, 208, 114, 101, 174, 92, 52, 120, 240, 15, 169, 220, 182, 81, 224, 43, 185, 40, 99, 180, 17, 212, 158, 42, 90, 9, 191, 45, 6, 25, 4, 222, 67, 126, 1, 116, 124, 206, 69, 61, 7, 68, 97, 202, 63, 244, 20, 28, 58, 93, 134, 104, 144, 227, 147, 102, 118, 135, 148, 47, 238, 86, 112, 122, 70, 107, 215, 100, 139, 223, 225, 164, 237, 111, 125, 207, 160, 187, 246, 234, 161, 188, 193, 249, 252}
 	dec := []byte{151, 205, 99, 127, 201, 119, 199, 211, 122, 196, 91, 74, 12, 147, 124, 180, 21, 191, 138, 83, 217, 30, 86, 7, 70, 200, 56, 62, 218, 47, 168, 22, 107, 88, 63, 11, 95, 77, 28, 8, 188, 29, 194, 186, 38, 198, 33, 230, 98, 43, 148, 110, 177, 1, 109, 82, 61, 112, 219, 59, 0, 210, 35, 215, 50, 27, 103, 203, 212, 209, 235, 93, 84, 169, 166, 80, 130, 94, 164, 165, 142, 184, 111, 18, 2, 141, 232, 114, 6, 131, 195, 139, 176, 220, 5, 153, 135, 213, 154, 189, 238, 174, 226, 53, 222, 146, 162, 236, 158, 143, 55, 244, 233, 96, 173, 26, 206, 100, 227, 49, 178, 34, 234, 108, 207, 245, 204, 150, 44, 87, 121, 54, 140, 118, 221, 228, 155, 78, 3, 239, 101, 64, 102, 17, 223, 41, 137, 225, 229, 66, 116, 171, 125, 40, 39, 71, 134, 13, 193, 129, 247, 251, 20, 136, 242, 14, 36, 97, 163, 181, 72, 25, 144, 46, 175, 89, 145, 113, 90, 159, 190, 15, 183, 73, 123, 187, 128, 248, 252, 152, 24, 197, 68, 253, 52, 69, 117, 57, 92, 104, 157, 170, 214, 81, 60, 133, 208, 246, 172, 23, 167, 160, 192, 76, 161, 237, 45, 4, 58, 10, 182, 65, 202, 240, 185, 241, 79, 224, 132, 51, 42, 126, 105, 37, 250, 149, 32, 243, 231, 67, 179, 48, 9, 106, 216, 31, 249, 19, 85, 254, 156, 115, 255, 120, 75, 16}
-	tbl := NewTableCipher("foobar!")
+	SetDefaultCipher("")
+	cipher, _ := NewCipher("foobar!")
+	tbl, _ := cipher.(*TableCipher)
 	checkTable(t, tbl, enc, dec, "Error for password foobar!")
 }
 
 func TestEncryptTable2(t *testing.T) {
 	enc := []byte{124, 30, 170, 247, 27, 127, 224, 59, 13, 22, 196, 76, 72, 154, 32, 209, 4, 2, 131, 62, 101, 51, 230, 9, 166, 11, 99, 80, 208, 112, 36, 248, 81, 102, 130, 88, 218, 38, 168, 15, 241, 228, 167, 117, 158, 41, 10, 180, 194, 50, 204, 243, 246, 251, 29, 198, 219, 210, 195, 21, 54, 91, 203, 221, 70, 57, 183, 17, 147, 49, 133, 65, 77, 55, 202, 122, 162, 169, 188, 200, 190, 125, 63, 244, 96, 31, 107, 106, 74, 143, 116, 148, 78, 46, 1, 137, 150, 110, 181, 56, 95, 139, 58, 3, 231, 66, 165, 142, 242, 43, 192, 157, 89, 175, 109, 220, 128, 0, 178, 42, 255, 20, 214, 185, 83, 160, 253, 7, 23, 92, 111, 153, 26, 226, 33, 176, 144, 18, 216, 212, 28, 151, 71, 206, 222, 182, 8, 174, 205, 201, 152, 240, 155, 108, 223, 104, 239, 98, 164, 211, 184, 34, 193, 14, 114, 187, 40, 254, 12, 67, 93, 217, 6, 94, 16, 19, 82, 86, 245, 24, 197, 134, 132, 138, 229, 121, 5, 235, 238, 85, 47, 103, 113, 179, 69, 250, 45, 135, 156, 25, 61, 75, 44, 146, 189, 84, 207, 172, 119, 53, 123, 186, 120, 171, 68, 227, 145, 136, 100, 90, 48, 79, 159, 149, 39, 213, 236, 126, 52, 60, 225, 199, 105, 73, 233, 252, 118, 215, 35, 115, 64, 37, 97, 129, 161, 177, 87, 237, 141, 173, 191, 163, 140, 234, 232, 249}
 	dec := []byte{117, 94, 17, 103, 16, 186, 172, 127, 146, 23, 46, 25, 168, 8, 163, 39, 174, 67, 137, 175, 121, 59, 9, 128, 179, 199, 132, 4, 140, 54, 1, 85, 14, 134, 161, 238, 30, 241, 37, 224, 166, 45, 119, 109, 202, 196, 93, 190, 220, 69, 49, 21, 228, 209, 60, 73, 99, 65, 102, 7, 229, 200, 19, 82, 240, 71, 105, 169, 214, 194, 64, 142, 12, 233, 88, 201, 11, 72, 92, 221, 27, 32, 176, 124, 205, 189, 177, 246, 35, 112, 219, 61, 129, 170, 173, 100, 84, 242, 157, 26, 218, 20, 33, 191, 155, 232, 87, 86, 153, 114, 97, 130, 29, 192, 164, 239, 90, 43, 236, 208, 212, 185, 75, 210, 0, 81, 227, 5, 116, 243, 34, 18, 182, 70, 181, 197, 217, 95, 183, 101, 252, 248, 107, 89, 136, 216, 203, 68, 91, 223, 96, 141, 150, 131, 13, 152, 198, 111, 44, 222, 125, 244, 76, 251, 158, 106, 24, 42, 38, 77, 2, 213, 207, 249, 147, 113, 135, 245, 118, 193, 47, 98, 145, 66, 160, 123, 211, 165, 78, 204, 80, 250, 110, 162, 48, 58, 10, 180, 55, 231, 79, 149, 74, 62, 50, 148, 143, 206, 28, 15, 57, 159, 139, 225, 122, 237, 138, 171, 36, 56, 115, 63, 144, 154, 6, 230, 133, 215, 41, 184, 22, 104, 254, 234, 253, 187, 226, 247, 188, 156, 151, 40, 108, 51, 83, 178, 52, 3, 31, 255, 195, 53, 235, 126, 167, 120}
-	tbl := NewTableCipher("barfoo!")
+	cipher, _ := NewCipher("barfoo!")
+	tbl, _ := cipher.(*TableCipher)
 	checkTable(t, tbl, enc, dec, "Error for password barfoo!")
 }
 
 const text = "Don't tell me the moon is shining; show me the glint of light on broken glass."
 
-func testCiphter(t *testing.T, msg string) {
-	c := NewCipher("OpenSesame")
+func testCiphter(t *testing.T, c Cipher, msg string) {
 	n := len(text)
 	cipherBuf := make([]byte, n, n)
 	originTxt := make([]byte, n, n)
@@ -47,6 +49,35 @@ func testCiphter(t *testing.T, msg string) {
 }
 
 func TestTableCipher(t *testing.T) {
-	SetDefaultCipher("")
-	testCiphter(t, "TableCipher")
+	if err := SetDefaultCipher(""); err != nil {
+		t.Error("Error setting default table cipher")
+	}
+	cipher, err := NewCipher("OpenSesame!")
+	if err != nil {
+		t.Error("Should not get error generating table cipher")
+	}
+	if _, ok := cipher.(*TableCipher); !ok {
+		t.Error("Should get table cipher")
+	} else {
+		testCiphter(t, cipher, "TableCipher")
+	}
+}
+
+func TestRC4Cipher(t *testing.T) {
+	if err := SetDefaultCipher("rc4"); err != nil {
+		t.Error("Error setting default rc4 cipher")
+	}
+	cipher, err := NewCipher("")
+	if err == nil {
+		t.Error("Should get error for empty key creating rc4 cipher")
+	}
+	cipher, err = NewCipher("Alibaba")
+	if err != nil {
+		t.Error("Should not error creating rc4 cipher with key Alibaba")
+	}
+	if _, ok := cipher.(*RC4Cipher); !ok {
+		t.Error("Should get rc4 cipher")
+	} else {
+		testCiphter(t, cipher, "RC4Cipher")
+	}
 }