Android实现DES和3DES算法

DES算法如下：

import javax.crypto.Cipher;
import javax.crypto.SecretKey;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.DESKeySpec;

public class DESUtils {
private static byte[] parse(String str) {
byte[] b = new byte[str.length() / 2];
for (int i = 0, n = str.length(); i < n; i += 2) {
b[i / 2] = (byte) (Integer.parseInt(str.substring(i, i + 2), 16));
}
return b;
}

/**
* 加密
* @param src
* @param password
* @return
*/
public static byte[] enCode(byte[] src, String password) {
try {
SecretKeyFactory keyFactory = SecretKeyFactory.getInstance("DES");
SecretKey key = keyFactory.generateSecret(new DESKeySpec(parse(password)));// 密钥
Cipher cipher = Cipher.getInstance("DES");
cipher.init(Cipher.ENCRYPT_MODE, key);
return cipher.doFinal(src);// 明文
} catch (Exception e) {
e.printStackTrace();
}
return null;

}

/**
* 解密
* @param src
* @param password
* @return
* @throws Exception
*/
public static byte[] deCode(byte[] src, String password) throws Exception {
SecretKeyFactory keyFactory = SecretKeyFactory.getInstance("DES");
SecretKey key = keyFactory.generateSecret(new DESKeySpec(parse(password)));// 密钥
Cipher cipher = Cipher.getInstance("DES");
cipher.init(Cipher.DECRYPT_MODE, key);
return cipher.doFinal(src);// 密文
}
}

3DES算法是进行了3次DES算法。
E是代表加密，D代表解密，K1,K2,K3代表3个密钥。加密解密都是用DES算法，一般来说密钥需要3个或两个密钥，如果3个密钥都相同，则变成了DES算法，如果对加密强度要求没有那么高，可以用两个密钥，对应的是K1和K3密钥相同。
3DES加密过程：EK1(加密)-->DK2(解密)-->EK3(加密)
3DES解密过程：DK3(解密)-->EK2(加密)-->DK1(解密)

3DES算法如下：

import javax.crypto.Cipher;
import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;

public class DES3Utils {

private static final String Algorithm = "DESede"; //定义加密算法,可用 DES,DESede,Blowfish

//keybyte为加密密钥，长度为24字节
//src为被加密的数据缓冲区（源）
public static byte[] encryptMode(byte[] keybyte, byte[] src) {
try {
//生成密钥
SecretKey deskey = new SecretKeySpec(keybyte, Algorithm);

//加密
Cipher c1 = Cipher.getInstance(Algorithm);
c1.init(Cipher.ENCRYPT_MODE, deskey);
return c1.doFinal(src);
} catch (java.security.NoSuchAlgorithmException e1) {
e1.printStackTrace();
} catch (javax.crypto.NoSuchPaddingException e2) {
e2.printStackTrace();
} catch (java.lang.Exception e3) {
e3.printStackTrace();
}
return null;
}

//keybyte为加密密钥，长度为24字节
//src为加密后的缓冲区
public static byte[] decryptMode(byte[] keybyte, byte[] src) {
try {
//生成密钥
SecretKey deskey = new SecretKeySpec(keybyte, Algorithm);

//解密
Cipher c1 = Cipher.getInstance(Algorithm);
c1.init(Cipher.DECRYPT_MODE, deskey);
return c1.doFinal(src);
} catch (java.security.NoSuchAlgorithmException e1) {
e1.printStackTrace();
} catch (javax.crypto.NoSuchPaddingException e2) {
e2.printStackTrace();
} catch (java.lang.Exception e3) {
e3.printStackTrace();
}
return null;
}

//转换成十六进制字符串
public static String byte2hex(byte[] b) {
String hs="";
String stmp="";

for (int n=0;n<b.length;n++) {
stmp=(java.lang.Integer.toHexString(b[n] & 0XFF));
if (stmp.length()==1) hs=hs+"0"+stmp;
else hs=hs+stmp;
if (n<b.length-1) hs=hs+":";
}
return hs.toUpperCase();
}
}

调用

//DES
//DES加密
byte[] en = DESUtils.enCode(hexStringToBytes("3132333435363738"), "A1A2A3A4A5A6A7A8");
//DES解密
try {
byte[] dn = DESUtils.deCode(hexStringToBytes("B1C3D2A87DBDB68FA73FBBBCD6F083AC"), "A1A2A3A4A5A6A7A8");

} catch (Exception e) {
e.printStackTrace();
}

//3DES
//3DES加密
String key = "A1A2A3A4A5A6A7A8" //K1密钥
+"B1B2B3B4B5B6B7B8" //K2密钥
+"A1A2A3A4A5A6A7A8"; //K3密钥
byte[] result = DES3Utils.encryptMode(hexStringToBytes(key), hexStringToBytes("3132333435363738"));

//3DES解密
byte[] dnresult = DES3Utils.decryptMode(hexStringToBytes(key), hexStringToBytes("B0920ED6520EAF752E22A1F49B243353"));

//***************************************************************************************
//实现String到byte的转换
public static byte[] hexStringToBytes(String string) {
String hexString = string.replaceAll(" ", "").toUpperCase();

if (hexString.length() <= 0)
return null;

int length = hexString.length() / 2;
char[] hexChars = hexString.toCharArray();
byte[] d = new byte[length];
for (int i = 0; i < length; i++) {
int pos = i * 2;
d[i] = (byte) (charToByte(hexChars[pos]) << 4 | charToByte(hexChars[pos + 1]));
}
return d;
}

DES的明文是3132333435363738，密钥是A1A2A3A4A5A6A7A8，加密后得到B1C3D2A87DBDB68FA73FBBBCD6F083AC，这里面前面16位是明文加密而来的，后面的A73FBBBCD6F083AC是由0808080808080808加密而来的。这8个08是算法自动填充上去的。3DES同样会填充8个08上去再加密。B0920ED6520EAF752E22A1F49B243353后面的2E22A1F49B243353是由填充的0808080808080808加密而来。

Android实现DES和3DES算法

猜你喜欢