JAVA中的加密算法之单向加密

幽鸿

发布于 2020-04-02 17:44:20

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发布于 2020-04-02 17:44:20

JAVA中的加密算法之单向加密

作者:幽鸿 Apr 16, 2016 12:15:24 AM

Java一般需要获取对象MessageDigest来实现单向加密(信息摘要)。 1. MD5 即Message-Digest Algorithm 5（信息-摘要算法 5），用于确保信息传输完整一致。是计算机广泛使用的杂凑算法之一（又译摘要算法、哈希算法），主流编程语言普遍已有MD5实现。将数据（如汉字）运算为另一固定长度值，是杂凑算法的基础原理，MD5的前身有MD2、MD3和MD4。MD5的作用是让大容量信息在用数字签名软件签署私人密钥前被"压缩"成一种保密的格式（就是把一个任意长度的字节串变换成一定长的十六进制数字串）。除了MD5以外，其中比较有名的还有sha-1、RIPEMD以及Haval等

Java代码

import java.security.MessageDigest;   

    import java.security.NoSuchAlgorithmException;   
      
    public class EncrypMD5 {   
           
        public byte[] eccrypt(String info) throws NoSuchAlgorithmException{   
            //根据MD5算法生成MessageDigest对象   
            MessageDigest md5 = MessageDigest.getInstance("MD5");   
            byte[] srcBytes = info.getBytes();   
            //使用srcBytes更新摘要   
            md5.update(srcBytes);   
            //完成哈希计算，得到result   
            byte[] resultBytes = md5.digest();   
            return resultBytes;   
        }   
           
           
        public static void main(String args[]) throws NoSuchAlgorithmException{   
            String msg = "郭XX-精品相声技术";   
            EncrypMD5 md5 = new EncrypMD5();   
            byte[] resultBytes = md5.eccrypt(msg);   
               
            System.out.println("密文是：" + new String(resultBytes));   
            System.out.println("明文是：" + msg);   
        }   
      
    }  

import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
public class EncrypMD5 {
    public byte[] eccrypt(String info) throws NoSuchAlgorithmException{
    //根据MD5算法生成MessageDigest对象
    MessageDigest md5 = MessageDigest.getInstance("MD5");
    byte[] srcBytes = info.getBytes();
    //使用srcBytes更新摘要
    md5.update(srcBytes);
    //完成哈希计算，得到
    resultbyte[] resultBytes = md5.digest();
    return resultBytes;
 }
 
 public static void main(String args[]) throws NoSuchAlgorithmException{
      String msg = "郭XX-精品相声技术";
      EncrypMD5 md5 = new EncrypMD5();
      byte[] resultBytes = md5.eccrypt(msg);
      System.out.println("密文是：" + new String(resultBytes));
      System.out.println("明文是：" + msg);
 }}

2. SHA 是一种数据加密算法，该算法经过加密专家多年来的发展和改进已日益完善，现在已成为公认的最安全的散列算法之一，并被广泛使用。该算法的思想是接收一段明文，然后以一种不可逆的方式将它转换成一段（通常更小）密文，也可以简单的理解为取一串输入码（称为预映射或信息），并把它们转化为长度较短、位数固定的输出序列即散列值（也称为信息摘要或信息认证代码）的过程。散列函数值可以说时对明文的一种“指纹”或是“摘要”所以对散列值的数字签名就可以视为对此明文的数字签名。

Java代码

附件中是以上几种的源代码，附带额外的两种使用方式。

增加一种关于文件的哈希算法源代码：

Java代码

import java.io.FileInputStream;
import java.io.InputStream;
import java.security.MessageDigest;
public class FileHashUtil {
public static final char[] hexChar = {
'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f' };
public static final String[] hashTypes = new String[] { "MD2", "MD5", "SHA1", "SHA-256", "SHA-384", "SHA-512" };
public void MD5File(String fileNam

import java.security.MessageDigest;    
import java.security.NoSuchAlgorithmException;       
public class EncrypSHA {                
public byte[] eccrypt(String info) throws NoSuchAlgorithmException{
            MessageDigest md5 = 
            MessageDigest.getInstance("SHA");            
            byte[] srcBytes = info.getBytes();            
            //使用srcBytes更新摘要            
            md5.update(srcBytes);            
            //完成哈希计算，得到result            
            byte[] resultBytes = md5.digest();            
            return resultBytes;        
}           
/**        
* @param args        
* @throws NoSuchAlgorithmException         
*/       
public static void main(String[] args) throws NoSuchAlgorithmException {
            String msg = "郭XX-精品相声技术";            
            EncrypSHA sha = new EncrypSHA();            
            byte[] resultBytes = sha.eccrypt(msg);            
            System.out.println("明文是：" + msg);            
            System.out.println("密文是：" + new String(resultBytes));
                              
    }       
}   
import java.security.MessageDigest; 
import java.security.NoSuchAlgorithmException; 
public class EncrypSHA {
     public byte[] eccrypt(String info) throws NoSuchAlgorithmException{         
     MessageDigest md5 = MessageDigest.getInstance("SHA");         
     byte[] srcBytes = info.getBytes();//使用srcBytes更新摘要         
     md5.update(srcBytes);//完成哈希计算，得到result         
     byte[] resultBytes = md5.digest();         
     return resultBytes;
          
  }      
  
  /** *
      @param args *          
      @throws NoSuchAlgorithmException  */     
   public static void main(String[] args) throws NoSuchAlgorithmException {       
     String msg = "郭XX-精品相声技术";         
     EncrypSHA sha = new EncrypSHA();         
     byte[] resultBytes = sha.eccrypt(msg);         
     System.out.println("明文是：" + msg);         
     System.out.println("密文是：" + new String(resultBytes));     
 }}    e) throws Exception{           
      //String fileName = args[0];                
      System.out.println("需要获取hash的文件为：　" + fileName);                
      java.util.List mds = new java.util.ArrayList();             
         for (String hashType : hashTypes) {                    
            MessageDigest md = MessageDigest.getInstance(hashType);                    
            mds.add(md);                
         }                
         InputStream fis = null;                
         try {                  
           fis = new FileInputStream(fileName);                    
           byte[] buffer = new byte[1024];                    
           int numRead = 0;                    
           while ((numRead = fis.read(buffer)) > 0) {                     
              for (MessageDigest md : mds) {                        
                  md.update(buffer, 0, numRead);                        
              }                   
           }                
       } catch (Exception ex) {                 
          ex.printStackTrace();                
       } finally {                 
          if (fis != null) {                    
              fis.close();                   
          }               
       }                
       for (MessageDigest md : mds) {                  
           System.out.println(md.getAlgorithm() + " == " + toHexString(md.digest()));                
       }           
   }           
             
                 
   public static void main(String[] args) throws Exception {              
      String[] fileName = new String[] {"D:/hapfish/ShellFolder.java","D:/hapfish/ShellFolder - 副本.java",                          
                "E:/ShellFolder - 副本.java","E:/ShellFolder.txt","D:/hapfish/ShellFolder.jpg",                          
                "E:/ShellFolder增加字符.txt","D:/hapfish/birosoft.jar"};                
      FileHashUtil files  = new FileHashUtil();                
      for(int i=0;i               
        files.MD5File(fileName[i]);                
      }        
      
                                                                                
    }                
    
    public static String toHexString(byte[] b) {                
        StringBuilder sb = new StringBuilder(b.length * 2);                
        for (int i = 0; i < b.length; i++) {                
            sb.append(hexChar[(b[i] & 0xf0) >>> 4]);               
            sb.append(hexChar[b[i] & 0x0f]);                
        }                
        return sb.toString();        
    }    
           
 }    
 
import java.io.FileInputStream; 
import java.io.InputStream; 
import java.security.MessageDigest; 
public class FileHashUtil {  
   public static final char[] hexChar = {     '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f' };     
   public static final String[] hashTypes = new String[] { "MD2", "MD5", "SHA1", "SHA-256", "SHA-384", "SHA-512" };     
   public void MD5File(String fileName) throws Exception{       
       //String fileName = args[0];           
       System.out.println("需要获取hash的文件为：　" + fileName);           
       java.util.List mds = new java.util.ArrayList();           
       for (String hashType : hashTypes) {              
       MessageDigest md = MessageDigest.getInstance(hashType);              
       mds.add(md);}InputStream fis = null;              
       try {                
           fis = new FileInputStream(fileName);                   
           byte[] buffer = new byte[1024];                   
           int numRead = 0;                   
           while ((numRead = fis.read(buffer)) > 0) {                    
                 for (MessageDigest md : mds) {                        
                     md.update(buffer, 0, numRead);                       
                 }              
            }            
        } catch (Exception ex) {                
             ex.printStackTrace();              
        } finally {                
            if (fis != null) {fis.close();              
        }           
     }           
     for (MessageDigest md : mds) {              
          System.out.println(md.getAlgorithm() + " == " + toHexString(md.digest()));           
     }       
 }       
 public static void main(String[] args) throws Exception {         
      String[] fileName = new String[] {"D:/hapfish/ShellFolder.java","D:/hapfish/ShellFolder - 副本.java",   
      "E:/ShellFolder - 副本.java","E:/ShellFolder.txt","D:/hapfish/ShellFolder.jpg",   
      "E:/ShellFolder增加字符.txt","D:/hapfish/birosoft.jar"};
                FileHashUtil files  = new FileHashUtil();               
                for(int i=0;i>> 4]);            
                sb.append(hexChar[b[i] & 0x0f]);      
          }         
                return sb.toString();
}}

运行说明

说明代码

"D:/hapfish/ShellFolder.java",
"D:/hapfish/ShellFolder - 副本.java",
"E:/ShellFolder - 副本.java",
"E:/ShellFolder.txt",
"D:/hapfish/ShellFolder.jpg",
以上五个文件是同一文件经过复制、改扩展名的，最后计算哈希结果是一致的。
"E:/ShellFolder增加字符.txt" 增加了几个字符串，就不一样了
"D:/hapfish/birosoft.jar" 完全不相关的另外一个文件

"D:/hapfish/ShellFolder.java","D:/hapfish/ShellFolder - 副本.java", "E:/ShellFolder - 副本.java","E:/ShellFolder.txt","D:/hapfish/ShellFolder.jpg",以上五个文件是同一文件经过复制、改扩展名的，最后计算哈希结果是一致的。"E:/ShellFolder增加字符.txt" 增加了几个字符串，就不一样了"D:/hapfish/birosoft.jar" 完全不相关的另外一个文件

运行结果：

Java代码

需要获取hash的文件为：　D:/hapfish/ShellFolder.java
MD2 == 3a755a99c5e407005cd45ebd856b4649
MD5 == 5d08d440fa911d1e418c69a90b83cd86
SHA1 == 522c8c4f4ff1dd669e251c2ab854c3033a51ca63
SHA-256 == d1feb0c73c10a759e88bd240cb9d56d0598b4ff83a0704c6679f7ba12f6c4d99
SHA-384 == 8f8c9da4cd7241c58af3c52b49199033f2dcf3d67f421753999f87511618d9ea2d738e8c16b9b68a7572d06108ff10f6
SHA-512 == 4711579daee3ddacbaea189310348956cb43bcaaf0099f3be047b06f16c1a20a6b71ee3a4ee018128d647e9f2ef0d64474767
2238e49a8da3d0cd26dfe597458
需要获取hash的文件为：　D:/hapfish/ShellFolder - 副本.java
MD2 == 3a755a99c5e407005cd45ebd856b4649
MD5 == 5d08d440fa911d1e418c69a90b83cd86
SHA1 == 522c8c4f4ff1dd669e251c2ab854c3033a51ca63
SHA-256 == d1feb0c73c10a759e88bd240cb9d56d0598b4ff83a0704c6679f7ba12f6c4d99
SHA-384 == 8f8c9da4cd7241c58af3c52b49199033f2dcf3d67f421753999f87511618d9ea2d738e8c16b9b68a7572d06108ff10f6
SHA-512 == 4711579daee3ddacbaea189310348956cb43bcaaf0099f3be047b06f16c1a20a6b71ee3a4ee018128d647e9f2ef0d64474767
2238e49a8da3d0cd26dfe597458
需要获取hash的文件为：　E:/ShellFolder - 副本.java
MD2 == 3a755a99c5e407005cd45ebd856b4649
MD5 == 5d08d440fa911d1e418c69a90b83cd86
SHA1 == 522c8c4f4ff1dd669e251c2ab854c3033a51ca63
SHA-256 == d1feb0c73c10a759e88bd240cb9d56d0598b4ff83a0704c6679f7ba12f6c4d99
SHA-384 == 8f8c9da4cd7241c58af3c52b49199033f2dcf3d67f421753999f87511618d9ea2d738e8c16b9b68a7572d06108ff10f6
SHA-512 == 4711579daee3ddacbaea189310348956cb43bcaaf0099f3be047b06f16c1a20a6b71ee3a4ee018128d647e9f2ef0d64474767
2238e49a8da3d0cd26dfe597458
需要获取hash的文件为：　E:/ShellFolder.txt
MD2 == 3a755a99c5e407005cd45ebd856b4649
MD5 == 5d08d440fa911d1e418c69a90b83cd86
SHA1 == 522c8c4f4ff1dd669e251c2ab854c3033a51ca63
SHA-256 == d1feb0c73c10a759e88bd240cb9d56d0598b4ff83a0704c6679f7ba12f6c4d99
SHA-384 == 8f8c9da4cd7241c58af3c52b49199033f2dcf3d67f421753999f87511618d9ea2d738e8c16b9b68a7572d06108ff10f6
SHA-512 == 4711579daee3ddacbaea189310348956cb43bcaaf0099f3be047b06f16c1a20a6b71ee3a4ee018128d647e9f2ef0d64474767
2238e49a8da3d0cd26dfe597458
需要获取hash的文件为：　D:/hapfish/ShellFolder.jpg
MD2 == 3a755a99c5e407005cd45ebd856b4649
MD5 == 5d08d440fa911d1e418c69a90b83cd86
SHA1 == 522c8c4f4ff1dd669e251c2ab854c3033a51ca63
SHA-256 == d1feb0c73c10a759e88bd240cb9d56d0598b4ff83a0704c6679f7ba12f6c4d99
SHA-384 == 8f8c9da4cd7241c58af3c52b49199033f2dcf3d67f421753999f87511618d9ea2d738e8c16b9b68a7572d06108ff10f6
SHA-512 == 4711579daee3ddacbaea189310348956cb43bcaaf0099f3be047b06f16c1a20a6b71ee3a4ee018128d647e9f2ef0d64474767
2238e49a8da3d0cd26dfe597458
需要获取hash的文件为：　E:/ShellFolder增加字符.txt
MD2 == f2717c24c6c0e110457bd17221c9ca6c
MD5 == c49e353a7c4c26bd7ccb5e90917c230f
SHA1 == 477c8a9e465bfaa4be42d35c032a17f7e6b42b97
SHA-256 == 9fa18adaf242ebcdc6563922d84c2a163c82e1a24db2eb2b73978ed1f354a8a3
SHA-384 == 4eee8f8e6d64d21c15dc01fa049f4d12a3b8e1d94d87763fe0bea75ab5ea8432fa8251289ece45ee39fe3d36b3c3020c
SHA-512 == e852ec0ff77250be497389d2f5a1818c18bb66106b9905c4ee26fe0d256eb3b77e0ce9a28a84e4b67e4332ba37ec3aa75181
48e3a682318c0fc34c391f45c201
需要获取hash的文件为：　D:/hapfish/birosoft.jar
MD2 == 38c5e1404718916dec59c33cafc909b3
MD5 == dc3e2cc4fb3949cf3660e0f5f8c3fba3
SHA1 == cde3dc25498afc5a563af0bb0eb54dc45f71bb28
SHA-256 == adf6a961c70c6ea677dff066fc5d896fb0beb4dd442ca0eb619ae1d1b04291e5
SHA-384 == fe7c6b754893c53ebd82bb53703fb5cc32115c9a38f98072f73def90729b271ee3c5c78e258bd9ff5ee5476193c2178b
SHA-512 == a15376f327256a6e049dfbdc5c2ad3a98bffccc6fa92ee01ff53db6b04471ca0f45ca28f76ff4a6911b57825afa046671299141f2
499d71f1dac618c92385491

需要获取hash的文件为：　

D:/hapfish/ShellFolder.java
MD2 == 3a755a99c5e407005cd45ebd856b4649MD5 == 5d08d440fa911d1e418c69a90b83cd86SHA1 == 522c8c4f4ff1dd669e251c2ab854c3033a51ca63SHA-256 == d1feb0c73c10a759e88bd240cb9d56d0598b4ff83a0704c6679f7ba12f6c4d99SHA-384 == 8f8c9da4cd7241c58af3c52b49199033f2dcf3d67f421753999f87511618d9ea2d738e8c16b9b68a7572d06108ff10f6SHA-512 == 4711579daee3ddacbaea189310348956cb43bcaaf0099f3be047b06f16c1a20a6b71ee3a4ee018128d647e9f2ef0d644747672238e49a8da3d0cd26dfe597458

需要获取hash的文件为：　
D:/hapfish/ShellFolder - 副本.java
MD2 == 3a755a99c5e407005cd45ebd856b4649MD5 == 5d08d440fa911d1e418c69a90b83cd86SHA1 == 522c8c4f4ff1dd669e251c2ab854c3033a51ca63SHA-256 == d1feb0c73c10a759e88bd240cb9d56d0598b4ff83a0704c6679f7ba12f6c4d99SHA-384 == 
8f8c9da4cd7241c58af3c52b49199033f2dcf3d67f421753999f87511618d9ea2d738e8c16b9b68a7572d06108ff10f6
SHA-512 == 4711579daee3ddacbaea189310348956cb43bcaaf0099f3be047b06f16c1a20a6b71ee3a4ee018128d647e9f2ef0d644747672238e49a8da3d0cd26dfe597458

需要获取hash的文件为：　
E:/ShellFolder - 副本.javaMD2 == 3a755a99c5e407005cd45ebd856b4649MD5 == 5d08d440fa911d1e418c69a90b83cd86SHA1 == 522c8c4f4ff1dd669e251c2ab854c3033a51ca63SHA-256 == 
d1feb0c73c10a759e88bd240cb9d56d0598b4ff83a0704c6679f7ba12f6c4d99SHA-384 == 8f8c9da4cd7241c58af3c52b49199033f2dcf3d67f421753999f87511618d9ea2d738e8c16b9b68a7572d06108ff10f6SHA-512 == 4711579daee3ddacbaea189310348956cb43bcaaf0099f3be047b06f16c1a20a6b71ee3a4ee018128d647e9f2ef0d644747672238e49a8da3d0cd26dfe597458

需要获取hash的文件为：　
E:/ShellFolder.txtMD2 == 3a755a99c5e407005cd45ebd856b4649MD5 == 5d08d440fa911d1e418c69a90b83cd86SHA1 == 522c8c4f4ff1dd669e251c2ab854c3033a51ca63SHA-256 == d1feb0c73c10a759e88bd240cb9d56d0598b4ff83a0704c6679f7ba12f6c4d99SHA-384 == 8f8c9da4cd7241c58af3c52b49199033f2dcf3d67f421753999f87511618d9ea2d738e8c16b9b68a7572d06108ff10f6SHA-512 == 4711579daee3ddacbaea189310348956cb43bcaaf0099f3be047b06f16c1a20a6b71ee3a4ee018128d647e9f2ef0d644
747672238e49a8da3d0cd26dfe597458

需要获取hash的文件为：　
D:/hapfish/ShellFolder.jpgMD2 == 
3a755a99c5e407005cd45ebd856b4649MD5 == 5d08d440fa911d1e418c69a90b83cd86SHA1 == 
522c8c4f4ff1dd669e251c2ab854c3033a51ca63SHA-256 == d1feb0c73c10a759e88bd240cb9d56d0598b4ff83a0704c6679f7ba12f6c4d99SHA-384 == 8f8c9da4cd7241c58af3c52b49199033f2dcf3d67f421753999f87511618d9ea2d738e8c16b9b68a7572d06108ff10f6

SHA-512 == 4711579daee3ddacbaea189310348956cb43bcaaf0099f3be047b06f16c1a20a6b71ee3a4ee018128d647e9f2ef0d644747672238e49a8da3d0cd26dfe597458

需要获取hash的文件为：　
E:/ShellFolder增加字符.txtMD2 == f2717c24c6c0e110457bd17221c9ca6cMD5 == c49e353a7c4c26bd7ccb5e90917c230fSHA1 == 477c8a9e465bfaa4be42d35c032a17f7e6b42b97SHA-256 == 9fa18adaf242ebcdc6563922d84c2a163c82e1a24db2eb2b73978ed1f354a8a3SHA-384 == 4eee8f8e6d64d21c15dc01fa049f4d12a3b8e1d94d87763fe0bea75ab5ea8432fa8251289ece45ee39fe3d36b3c3020c

SHA-512 == e852ec0ff77250be497389d2f5a1818c18bb66106b9905c4ee26fe0d256eb3b77e0ce9a28a84e4b67e4332ba37ec3aa7
518148e3a682318c0fc34c391f45c201

需要获取hash的文件为：　
D:/hapfish/birosoft.jarMD2 == 38c5e1404718916dec59c33cafc909b3MD5 == dc3e2cc4fb3949cf3660e0f5f8c3fba3SHA1 == cde3dc25498afc5a563af0bb0eb54dc45f71bb28SHA-256 == adf6a961c70c6ea677dff066fc5d896fb0beb4dd442ca0eb619ae1d1b04291e5SHA-384 == fe7c6b754893c53ebd82bb53703fb5cc32115c9a38f98072f73def90729b271ee3c5c78e258bd9ff5ee5476193c2178b

SHA-512 == a15376f327256a6e049dfbdc5c2ad3a98bffccc6fa92ee01ff53db6b04471ca0f45ca28f76ff4a6911b57825afa04667
1299141f2499d71f1dac618c92385491

最后，把运行结果贴出来有点占空间，主要为了说明表述自己的猜想。一般来说同一哈希算法对同一文件(镜像、扩展名被修改)所产生的结果应该是一致的。

因此有个猜想，在baidu文库、腾讯的群共享上传时，先会判断是否有相同文件，从某种可能上来说也采用了对文件的哈希算法，毕竟从本地运算
一个哈希算法后获得的数值要比把整个文件传过去比较实惠得多。而且字符串的比较也是很方便的。

对于某一种哈希算法，存在一种可能：就是两个不同的文件，计算出来的哈希值可能是一样的。当然为了保险，可以用两种甚至更多的哈希算法，
只有在每种算法获得的哈希值都相同时，才能判断是同一个文件。
如果我们也对用户上传的文件进行哈希计算的话，就可以节省资源，同样的文件按理说可以减少上传次数……

说明：此种加密方法当加密内容超过118byte时，会抛出异常： Data must not be longer than 117 bytes

解决办法：采用分段加密与解密

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