JAVA使用RC4解密C#的RC4密文问题

最近公司买了wifi探针设备，主要探测用户进出时间以及mac地址

设备通过http post请求发送数据到 配置的服务器上，然后解密数据。

流程： 获取设备post过来的body内容-->判空-->解密（前16位字符串作为key，16位以后的作为内容解密）--->入库

网上随便搜了个RC4 JAVA版本的解密程序，使用。结果一团乱码

网上代码：

package com.powercn.util;

public class RC4 {
public static String HloveyRC4(String aInput, String aKey) {
int[] iS = new int[256];
byte[] iK = new byte[256];
for (int i = 0; i < 256; i++)
iS[i] = i;
int j = 1;
for (short i = 0; i < 256; i++) {
iK[i] = (byte) aKey.charAt((i % aKey.length()));
}
j = 0;
for (int i = 0; i < 255; i++) {
j = (j + iS[i] + iK[i]) % 256;
int temp = iS[i];
iS[i] = iS[j];
iS[j] = temp;
}
int i = 0;
j = 0;
char[] iInputChar = aInput.toCharArray();
char[] iOutputChar = new char[iInputChar.length];
for (short x = 0; x < iInputChar.length; x++) {
i = (i + 1) % 256;
j = (j + iS[i]) % 256;
int temp = iS[i];
iS[i] = iS[j];
iS[j] = temp;
int t = (iS[i] + (iS[j] % 256)) % 256;
int iY = iS[t];
char iCY = (char) iY;
iOutputChar[x] = (char) (iInputChar[x] ^ iCY);
}
return new String(iOutputChar);
}

public static String decry_RC4(byte[] data, String key) {
if (data == null || key == null) {
return null;
}
return asString(RC4Base(data, key));
}

public static String decry_RC4(String data, String key) {
if (data == null || key == null) {
return null;
}
return new String(RC4Base(HexString2Bytes(data), key));
}

public static byte[] encry_RC4_byte(String data, String key) {
if (data == null || key == null) {
return null;
}
byte b_data[] = data.getBytes();
return RC4Base(b_data, key);
}

public static String encry_RC4_string(String data, String key) {
if (data == null || key == null) {
return null;
}
return toHexString(asString(encry_RC4_byte(data, key)));
}

private static String asString(byte[] buf) {
StringBuffer strbuf = new StringBuffer(buf.length);
for (int i = 0; i < buf.length; i++) {
strbuf.append((char) buf[i]);
}
return strbuf.toString();
}

private static byte[] initKey(String aKey) {
byte[] b_key = aKey.getBytes();
byte state[] = new byte[256];

for (int i = 0; i < 256; i++) {
state[i] = (byte) i;
}
int index1 = 0;
int index2 = 0;
if (b_key == null || b_key.length == 0) {
return null;
}
for (int i = 0; i < 256; i++) {
index2 = ((b_key[index1] & 0xff) + (state[i] & 0xff) + index2) & 0xff;
byte tmp = state[i];
state[i] = state[index2];
state[index2] = tmp;
index1 = (index1 + 1) % b_key.length;
}
return state;
}

private static String toHexString(String s) {
String str = "";
for (int i = 0; i < s.length(); i++) {
int ch = (int) s.charAt(i);
String s4 = Integer.toHexString(ch & 0xFF);
if (s4.length() == 1) {
s4 = '0' + s4;
}
str = str + s4;
}
return str;// 0x表示十六进制
}

private static byte[] HexString2Bytes(String src) {
int size = src.length();
byte[] ret = new byte[size / 2];
byte[] tmp = src.getBytes();
for (int i = 0; i < size / 2; i++) {
ret[i] = uniteBytes(tmp[i * 2], tmp[i * 2 + 1]);
}
return ret;
}

private static byte uniteBytes(byte src0, byte src1) {
char _b0 = (char) Byte.decode("0x" + new String(new byte[] { src0 }))
.byteValue();
_b0 = (char) (_b0 << 4);
char _b1 = (char) Byte.decode("0x" + new String(new byte[] { src1 }))
.byteValue();
byte ret = (byte) (_b0 ^ _b1);
return ret;
}

private static byte[] RC4Base(byte[] input, String mKkey) {
int x = 0;
int y = 0;
byte key[] = initKey(mKkey);
int xorIndex;
byte[] result = new byte[input.length];

for (int i = 0; i < input.length; i++) {
x = (x + 1) & 0xff;
y = ((key[x] & 0xff) + y) & 0xff;
byte tmp = key[x];
key[x] = key[y];
key[y] = tmp;
xorIndex = ((key[x] & 0xff) + (key[y] & 0xff)) & 0xff;
result[i] = (byte) (input[i] ^ key[xorIndex]);
}
return result;
}

public static void main(String[] args) throws Exception {
String inputStr = "Hello World 你好";
String str = encry_RC4_string(inputStr, "123456");
System.out.println(str);
System.out.println(decry_RC4(str, "123456"));
// Cipher cipher=Cipher.getInstance("RC4");
// String pwd="123456";
// String ptext="Hello World 你好";
// SecretKeySpec key=new SecretKeySpec(pwd.getBytes("UTF-8"), "RC4");
// cipher.init(Cipher.ENCRYPT_MODE, key);
// byte[] cdata =cipher.update(ptext.getBytes("UTF-8"));
// //解密
// cipher.init(Cipher.DECRYPT_MODE, key);
// byte[] ddata =cipher.update(cdata);
// System.out.println("key: "+pwd);
// System.out.println("明文: "+ptext);
// System.out.println("密文: "+DatatypeConverter.printHexBinary(cdata));
// System.out.println("解密文: "+new String(ddata,"UTF-8"));
String str123 = HloveyRC4("Hello World 你好", "123456");
System.out.println(str123);
String str1234 = HloveyRC4(str123, "123456");
System.out.println(str1234);
}

} 

java接收端解密代码：

request.setCharacterEncoding("UTF-8");
br = new BufferedReader(new InputStreamReader(in,"UTF-8"));
String line = null;
StringBuilder sb = new StringBuilder();
while((line = br.readLine())!=null){
    sb.append(line);
}

System.out.println("recive post str: "+sb.toString());

if (null !=sb && !StringUtils.isEmpty(sb.toString())) {
System.out.println("RC4 decrypt:"+RC4.HloveyRC4(sb.substring(16), sb.substring(0,16)));
}

解密结果是一堆乱码

但是通过main方法运行的加密解密都是正常结果

然后找原因，秘钥，需要解密的字符串都是正确的，

怀疑是不是C那边加密程序有问题，

然后google一下，主要是说java这边需要使用byte数组接收，以及截取byte数组的内容key，以及内容解密，因为c那边会把key在body中传输过来放在前16个字符中

java代码如下：

in = request.getInputStream();
byte[] getArr = readBytes(in, request.getContentLength());
byte[] key = new byte[16];
System.arraycopy(getArr, 0, key, 0, key.length);
System.out.println("key:"+new String(key));

int contentLength = request.getContentLength()-16;
byte[] content = new byte[contentLength];
System.arraycopy(getArr, 16, content, 0, content.length);
System.out.println("content"+new String(content));

String result = RC4T2.decry_RC4(content, new String(key));
System.out.println("RC4 decrypt:"+result);

解密程序代码如下：

package com.powercn.util;

public class RC4T2 {

public static String decry_RC4(byte[] data, String key) {
if (data == null || key == null) {
return null;
}
return asString(RC4Base(data, key));
}

public static String decry_RC4(String data, String key) {
if (data == null || key == null) {
return null;
}
return new String(RC4Base(HexString2Bytes(data), key));
}

public static byte[] encry_RC4_byte(String data, String key) {
if (data == null || key == null) {
return null;
}
byte b_data[] = data.getBytes();
return RC4Base(b_data, key);
}

public static String encry_RC4_string(String data, String key) {
if (data == null || key == null) {
return null;
}
return toHexString(asString(encry_RC4_byte(data, key)));
}

private static String asString(byte[] buf) {
StringBuffer strbuf = new StringBuffer(buf.length);
for (int i = 0; i < buf.length; i++) {
strbuf.append((char) buf[i]);
}
return strbuf.toString();
}

private static byte[] initKey(String aKey) {
byte[] b_key = aKey.getBytes();
byte state[] = new byte[256];

for (int i = 0; i < 256; i++) {
state[i] = (byte) i;
}
int index1 = 0;
int index2 = 0;
if (b_key == null || b_key.length == 0) {
return null;
}
for (int i = 0; i < 256; i++) {
index2 = ((b_key[index1] & 0xff) + (state[i] & 0xff) + index2) & 0xff;
byte tmp = state[i];
state[i] = state[index2];
state[index2] = tmp;
index1 = (index1 + 1) % b_key.length;
}
return state;
}

private static String toHexString(String s) {
String str = "";
for (int i = 0; i < s.length(); i++) {
int ch = (int) s.charAt(i);
String s4 = Integer.toHexString(ch & 0xFF);
if (s4.length() == 1) {
s4 = '0' + s4;
}
str = str + s4;
}
return str;// 0x表示十六进制
}

private static byte[] HexString2Bytes(String src) {
int size = src.length();
byte[] ret = new byte[size / 2];
byte[] tmp = src.getBytes();
for (int i = 0; i < size / 2; i++) {
ret[i] = uniteBytes(tmp[i * 2], tmp[i * 2 + 1]);
}
return ret;
}

private static byte uniteBytes(byte src0, byte src1) {
char _b0 = (char) Byte.decode("0x" + new String(new byte[] { src0 }))
.byteValue();
_b0 = (char) (_b0 << 4);
char _b1 = (char) Byte.decode("0x" + new String(new byte[] { src1 }))
.byteValue();
byte ret = (byte) (_b0 ^ _b1);
return ret;
}

private static byte[] RC4Base(byte[] input, String mKkey) {
int x = 0;
int y = 0;
byte key[] = initKey(mKkey);
int xorIndex;
byte[] result = new byte[input.length];

for (int i = 0; i < input.length; i++) {
x = (x + 1) & 0xff;
y = ((key[x] & 0xff) + y) & 0xff;
byte tmp = key[x];
key[x] = key[y];
key[y] = tmp;
xorIndex = ((key[x] & 0xff) + (key[y] & 0xff)) & 0xff;
result[i] = (byte) (input[i] ^ key[xorIndex]);
}
return result;
}

public static void main(String args[]) {
String txt = "你好china";
String key = "12srditmgijt";
String enc = encry_RC4_string(txt, key);
System.out.println(enc);
String dec = decry_RC4(enc, key);
System.out.println(dec);
}

}

结果完全解密正确