DES、MD五、RSA加密算法

時間 2019-11-12

原文原文鏈接

本篇主要是實現標題中的三個加密算法，至於機制你們自行百度吧。java

1、DES算法

實現類：DES.java數組

package com.kale.des;

import java.security.SecureRandom;

import javax.crypto.Cipher;
import javax.crypto.SecretKey;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.DESKeySpec;
/*
 * DES加密介紹
    DES是一種對稱加密算法，所謂對稱加密算法即：加密和解密使用相同密鑰的算法。
    DES加密算法出自IBM的研究，後來被美國政府正式採用，以後開始普遍流傳，可是近些年使用愈來愈少，
     由於DES使用56位密鑰，以現代計算能力，24小時內便可被破解。雖然如此，在某些簡單應用中，咱們仍是可
    以 使用DES加密算法，本文簡單講解DES的JAVA實現。
 */
public class DES{
    
    /**
     * 加密過程，密鑰長度都必須是8的倍數
     * @param datasource
     * @param password
     * @return 加密後的結果
     */
    public static byte[] desLock(byte[] datasource, String password) {            
        try{
            SecureRandom random = new SecureRandom();
            DESKeySpec desKey = new DESKeySpec(password.getBytes());
            //建立一個密匙工廠，而後用它把DESKeySpec轉換成
            SecretKeyFactory keyFactory = SecretKeyFactory.getInstance("DES");
            SecretKey securekey = keyFactory.generateSecret(desKey);
            //Cipher對象實際完成加密操做
            Cipher cipher = Cipher.getInstance("DES");
            //用密匙初始化Cipher對象
            cipher.init(Cipher.ENCRYPT_MODE, securekey, random);
            //如今，獲取數據並加密
            //正式執行加密操做
            return cipher.doFinal(datasource);
        }catch(Throwable e){
            e.printStackTrace();
        }
        return null;
    }
    
    /**
     * 解密過程，密鑰長度都必須是8的倍數
     * @param src
     * @param password
     * @return 解密後的內容
     * @throws Exception
     */
    public static byte[] desUnclock(byte[] src, String password) throws Exception {
        // DES算法要求有一個可信任的隨機數源
        SecureRandom random = new SecureRandom();
        // 建立一個DESKeySpec對象
        DESKeySpec desKey = new DESKeySpec(password.getBytes());
        // 建立一個密匙工廠
        SecretKeyFactory keyFactory = SecretKeyFactory.getInstance("DES");
        // 將DESKeySpec對象轉換成SecretKey對象
        SecretKey securekey = keyFactory.generateSecret(desKey);
        // Cipher對象實際完成解密操做
        Cipher cipher = Cipher.getInstance("DES");
        // 用密匙初始化Cipher對象
        cipher.init(Cipher.DECRYPT_MODE, securekey, random);
        // 真正開始解密操做
        return cipher.doFinal(src);
    }

}

測試類：DesTest.javaapp

package com.kale.des;

public class DesTest {

    /**
     * @param args
     */
    public static void main(String[] args) {
        // TODO 自動生成的方法存根
        //待加密內容
        String str = "kale123456789";
        //密碼，長度要是8的倍數
        String password = "12345678";
        byte[] result = null;
        try{
            result = DES.desLock(str.getBytes(),password);
            System.out.println("加密後內容爲："+new String(result));
        }
        catch(Exception e){
            System.out.println("加密失敗！");
        }
        
        //解密
        try {
            byte[] unLockResult = DES.desUnclock(result, password);
            System.out.println("解密後內容爲："+new String(unLockResult));
        } 
        catch (Exception e1) {
            //e1.printStackTrace();
            System.out.println("密鑰錯誤，沒法解密！");
        }
    }

}

結果：dom

加密後內容爲：S��:�3@d!�A��.
解密後內容爲：kale123456789測試

2、MD5加密

實現類：MD5.javaspa

package com.kale.md5;

import java.io.UnsupportedEncodingException;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;


public class MD5 {  
    /*
       * MD5加密
       */
      public static String getMD5Str(String str) {     
          MessageDigest messageDigest = null;     
       
          try {     
              messageDigest = MessageDigest.getInstance("MD5");     
       
              messageDigest.reset();     
       
              messageDigest.update(str.getBytes("UTF-8"));     
          } catch (NoSuchAlgorithmException e) {     
              System.out.println("NoSuchAlgorithmException caught!");     
              System.exit(-1);     
          } catch (UnsupportedEncodingException e) {     
              e.printStackTrace();     
          }     
       
          byte[] byteArray = messageDigest.digest();     
       
          StringBuffer md5StrBuff = new StringBuffer();     
          
          for (int i = 0; i < byteArray.length; i++) {                 
              if (Integer.toHexString(0xFF & byteArray[i]).length() == 1)     
                  md5StrBuff.append("0").append(Integer.toHexString(0xFF & byteArray[i]));     
              else     
                  md5StrBuff.append(Integer.toHexString(0xFF & byteArray[i]));     
          }     
          //16位加密，從第9位到25位
          return md5StrBuff.substring(8, 24).toString().toUpperCase();    
      }  
}

測試類：Md5Test.java.net

package com.kale.md5;

public class Md5Test {

    /**
     * @param args
     */
    public static void main(String[] args) {
        String password = "123456789";
        String result = MD5.getMD5Str(password);
        System.out.println(result.toLowerCase());
    }

}

結果：323b453885f5181fcode

3、RSA

實現類：RSA.java

package com.kale.rsa;

import java.math.BigInteger;
import java.security.KeyFactory;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.NoSuchAlgorithmException;
import java.security.interfaces.RSAPrivateKey;
import java.security.interfaces.RSAPublicKey;
import java.security.spec.RSAPrivateKeySpec;
import java.security.spec.RSAPublicKeySpec;
import java.util.HashMap;

import javax.crypto.Cipher;

public class RSA{

    /**
     * 生成公鑰和私鑰
     * @throws NoSuchAlgorithmException 
     *
     */
    public static HashMap<String, Object> getKeys() throws NoSuchAlgorithmException{
        HashMap<String, Object> map = new HashMap<String, Object>();
        KeyPairGenerator keyPairGen = KeyPairGenerator.getInstance("RSA");
        keyPairGen.initialize(1024);
        KeyPair keyPair = keyPairGen.generateKeyPair();
        RSAPublicKey publicKey = (RSAPublicKey) keyPair.getPublic();
        RSAPrivateKey privateKey = (RSAPrivateKey) keyPair.getPrivate();
        map.put("public", publicKey);
        map.put("private", privateKey);
        return map;
    }
    /**
     * 使用模和指數生成RSA公鑰
     * 注意：【此代碼用了默認補位方式，爲RSA/None/PKCS1Padding，不一樣JDK默認的補位方式可能不一樣，如Android默認是RSA
     * /None/NoPadding】
     * 
     * @param modulus
     *            模
     * @param exponent
     *            指數
     * @return
     */
    public static RSAPublicKey getPublicKey(String modulus, String exponent) {
        try {
            BigInteger b1 = new BigInteger(modulus);
            BigInteger b2 = new BigInteger(exponent);
            KeyFactory keyFactory = KeyFactory.getInstance("RSA");
            RSAPublicKeySpec keySpec = new RSAPublicKeySpec(b1, b2);
            return (RSAPublicKey) keyFactory.generatePublic(keySpec);
        } catch (Exception e) {
            e.printStackTrace();
            return null;
        }
    }

    /**
     * 使用模和指數生成RSA私鑰
     * 注意：【此代碼用了默認補位方式，爲RSA/None/PKCS1Padding，不一樣JDK默認的補位方式可能不一樣，如Android默認是RSA
     * /None/NoPadding】
     * 
     * @param modulus
     *            模
     * @param exponent
     *            指數
     * @return
     */
    public static RSAPrivateKey getPrivateKey(String modulus, String exponent) {
        try {
            BigInteger b1 = new BigInteger(modulus);
            BigInteger b2 = new BigInteger(exponent);
            KeyFactory keyFactory = KeyFactory.getInstance("RSA");
            RSAPrivateKeySpec keySpec = new RSAPrivateKeySpec(b1, b2);
            return (RSAPrivateKey) keyFactory.generatePrivate(keySpec);
        } catch (Exception e) {
            e.printStackTrace();
            return null;
        }
    }

    /**
     * 公鑰加密
     * 
     * @param data
     * @param publicKey
     * @return
     * @throws Exception
     */
    public static String encryptByPublicKey(String data, RSAPublicKey publicKey)
            throws Exception {
        Cipher cipher = Cipher.getInstance("RSA");
        cipher.init(Cipher.ENCRYPT_MODE, publicKey);
        // 模長
        int key_len = publicKey.getModulus().bitLength() / 8;
        // 加密數據長度 <= 模長-11
        String[] datas = splitString(data, key_len - 11);
        String mi = "";
        //若是明文長度大於模長-11則要分組加密
        for (String s : datas) {
            mi += bcd2Str(cipher.doFinal(s.getBytes()));
        }
        return mi;
    }

    /**
     * 私鑰解密
     * 
     * @param data
     * @param privateKey
     * @return
     * @throws Exception
     */
    public static String decryptByPrivateKey(String data, RSAPrivateKey privateKey)
            throws Exception {
        Cipher cipher = Cipher.getInstance("RSA");
        cipher.init(Cipher.DECRYPT_MODE, privateKey);
        //模長
        int key_len = privateKey.getModulus().bitLength() / 8;
        byte[] bytes = data.getBytes();
        byte[] bcd = ASCII_To_BCD(bytes, bytes.length);
        System.err.println(bcd.length);
        //若是密文長度大於模長則要分組解密
        String ming = "";
        byte[][] arrays = splitArray(bcd, key_len);
        for(byte[] arr : arrays){
            ming += new String(cipher.doFinal(arr));
        }
        return ming;
    }
    /**
     * ASCII碼轉BCD碼
     * 
     */
    public static byte[] ASCII_To_BCD(byte[] ascii, int asc_len) {
        byte[] bcd = new byte[asc_len / 2];
        int j = 0;
        for (int i = 0; i < (asc_len + 1) / 2; i++) {
            bcd[i] = asc_to_bcd(ascii[j++]);
            bcd[i] = (byte) (((j >= asc_len) ? 0x00 : asc_to_bcd(ascii[j++])) + (bcd[i] << 4));
        }
        return bcd;
    }
    public static byte asc_to_bcd(byte asc) {
        byte bcd;

        if ((asc >= '0') && (asc <= '9'))
            bcd = (byte) (asc - '0');
        else if ((asc >= 'A') && (asc <= 'F'))
            bcd = (byte) (asc - 'A' + 10);
        else if ((asc >= 'a') && (asc <= 'f'))
            bcd = (byte) (asc - 'a' + 10);
        else
            bcd = (byte) (asc - 48);
        return bcd;
    }
    /**
     * BCD轉字符串
     */
    public static String bcd2Str(byte[] bytes) {
        char temp[] = new char[bytes.length * 2], val;

        for (int i = 0; i < bytes.length; i++) {
            val = (char) (((bytes[i] & 0xf0) >> 4) & 0x0f);
            temp[i * 2] = (char) (val > 9 ? val + 'A' - 10 : val + '0');

            val = (char) (bytes[i] & 0x0f);
            temp[i * 2 + 1] = (char) (val > 9 ? val + 'A' - 10 : val + '0');
        }
        return new String(temp);
    }
    /**
     * 拆分字符串
     */
    public static String[] splitString(String string, int len) {
        int x = string.length() / len;
        int y = string.length() % len;
        int z = 0;
        if (y != 0) {
            z = 1;
        }
        String[] strings = new String[x + z];
        String str = "";
        for (int i=0; i<x+z; i++) {
            if (i==x+z-1 && y!=0) {
                str = string.substring(i*len, i*len+y);
            }else{
                str = string.substring(i*len, i*len+len);
            }
            strings[i] = str;
        }
        return strings;
    }
    /**
     *拆分數組 
     */
    public static byte[][] splitArray(byte[] data,int len){
        int x = data.length / len;
        int y = data.length % len;
        int z = 0;
        if(y!=0){
            z = 1;
        }
        byte[][] arrays = new byte[x+z][];
        byte[] arr;
        for(int i=0; i<x+z; i++){
            arr = new byte[len];
            if(i==x+z-1 && y!=0){
                System.arraycopy(data, i*len, arr, 0, y);
            }else{
                System.arraycopy(data, i*len, arr, 0, len);
            }
            arrays[i] = arr;
        }
        return arrays;
    }
}

測試類：RsaTest.java

package com.kale.rsa;

import java.security.interfaces.RSAPrivateKey;
import java.security.interfaces.RSAPublicKey;
import java.util.HashMap;

public class RsaTest {

    public static void main(String[] args) throws Exception {
        // TODO Auto-generated method stub
        HashMap<String, Object> map = RSA.getKeys();
        //生成公鑰和私鑰
        RSAPublicKey publicKey = (RSAPublicKey) map.get("public");
        RSAPrivateKey privateKey = (RSAPrivateKey) map.get("private");
        
        //模
        String modulus = publicKey.getModulus().toString();
        //公鑰指數
        String public_exponent = publicKey.getPublicExponent().toString();
        //私鑰指數
        String private_exponent = privateKey.getPrivateExponent().toString();
        //明文
        String ming = "kale123456789";
        //使用模和指數生成公鑰和私鑰
        RSAPublicKey pubKey = RSA.getPublicKey(modulus, public_exponent);
        RSAPrivateKey priKey = RSA.getPrivateKey(modulus, private_exponent);
        //加密後的密文
        String mi = RSA.encryptByPublicKey(ming, pubKey);
        System.out.println(mi);
        //解密後的明文
        ming = RSA.decryptByPrivateKey(mi, priKey);
        System.out.println(ming);
    }
}

結果：

81169AA3AF3CEC80AAA685B0500A2BF058AB13BDEBA62A3D38AD382C444F66EC3DCA3C7E0225DF73C529EB94DDB978B761A87FB26518DEAC7FF85678BFB2B117B765E32E8E7A23864D2D69E9E351AA8FAA26F02F9964DA6275744833D7C8ABF2552DA83DBE66E682CE0592D3595220FAD9E4D56D849867135DE0CD3BDDFDCAF2
128
kale123456789

源碼下載：http://download.csdn.net/detail/shark0017/8075485

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