Android实现DES和3DES算法

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本文实现的Android下的是DES和3DES算法，Java同样也适用。

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

 

 

 

 

 

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。