Android--DES加密解密

版權聲明：本文為部落客原創文章，轉載請标明出處。 https://blog.csdn.net/chaoyu168/article/details/78739623

概念就不介紹了，自己百度，主要就是三步：建立Cipher對象，初始化Cipher，加密解密

調用DES加密算法包最精要的就是下面兩句話：

Cipher cipher = Cipher.getInstance("DES/CBC/PKCS5Padding");

cipher.init(Cipher.ENCRYPT_MODE, key, zeroIv);

CBC是工作模式，DES一共有電子密碼本模式（

ECB ）、加密分組連結模式（ CBC ）、加密回報模式（ CFB ）和輸出回報模式（ OFB

）四種模式，

PKCS5Padding是填充模式，還有其它的填充模式：

然後，cipher.init（)一共有三個參數：Cipher.ENCRYPT_MODE, key, zeroIv，zeroIv就是初始化向量，一個8為字元數組。

工作模式、填充模式、初始化向量這三種因素一個都不能少。否則，如果你不指定的話，那麼就要程式就要調用預設實作。

DES加密類：

public class DES {  
    private static byte[] iv = {1,2,3,4,5,6,7,8};  
    public static String encryptDES(String encryptString, String encryptKey) throws Exception {  
//      IvParameterSpec zeroIv = new IvParameterSpec(new byte[8]);  
        IvParameterSpec zeroIv = new IvParameterSpec(iv);  
        SecretKeySpec key = new SecretKeySpec(encryptKey.getBytes(), "DES");  
        Cipher cipher = Cipher.getInstance("DES/CBC/PKCS5Padding");  
        cipher.init(Cipher.ENCRYPT_MODE, key, zeroIv);  
        byte[] encryptedData = cipher.doFinal(encryptString.getBytes());  
       
        return Base64.encode(encryptedData);  
    }  
    public static String decryptDES(String decryptString, String decryptKey) throws Exception {  
        byte[] byteMi = new Base64().decode(decryptString);  
        IvParameterSpec zeroIv = new IvParameterSpec(iv);  
//      IvParameterSpec zeroIv = new IvParameterSpec(new byte[8]);  
        SecretKeySpec key = new SecretKeySpec(decryptKey.getBytes(), "DES");  
        Cipher cipher = Cipher.getInstance("DES/CBC/PKCS5Padding");  
        cipher.init(Cipher.DECRYPT_MODE, key, zeroIv);  
        byte decryptedData[] = cipher.doFinal(byteMi);  
       
        return new String(decryptedData);  
    }  
}             

BASE64工具類：

import java.io.ByteArrayOutputStream;  
import java.io.IOException;  
import java.io.OutputStream;  
  
  
  
public class Base64 {  
    private static final char[] legalChars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/".toCharArray();  
    /** 
     * data[]進行編碼 
     * @param data 
     * @return 
     */  
        public static String encode(byte[] data) {  
            int start = 0;  
            int len = data.length;  
            StringBuffer buf = new StringBuffer(data.length * 3 / 2);  
  
            int end = len - 3;  
            int i = start;  
            int n = 0;  
  
            while (i <= end) {  
                int d = ((((int) data[i]) & 0x0ff) << 16)  
                        | ((((int) data[i + 1]) & 0x0ff) << 8)  
                        | (((int) data[i + 2]) & 0x0ff);  
  
                buf.append(legalChars[(d >> 18) & 63]);  
                buf.append(legalChars[(d >> 12) & 63]);  
                buf.append(legalChars[(d >> 6) & 63]);  
                buf.append(legalChars[d & 63]);  
  
                i += 3;  
  
                if (n++ >= 14) {  
                    n = 0;  
                    buf.append(" ");  
                }  
            }  
  
            if (i == start + len - 2) {  
                int d = ((((int) data[i]) & 0x0ff) << 16)  
                        | ((((int) data[i + 1]) & 255) << 8);  
  
                buf.append(legalChars[(d >> 18) & 63]);  
                buf.append(legalChars[(d >> 12) & 63]);  
                buf.append(legalChars[(d >> 6) & 63]);  
                buf.append("=");  
            } else if (i == start + len - 1) {  
                int d = (((int) data[i]) & 0x0ff) << 16;  
  
                buf.append(legalChars[(d >> 18) & 63]);  
                buf.append(legalChars[(d >> 12) & 63]);  
                buf.append("==");  
            }  
  
            return buf.toString();  
        }  
  
        private static int decode(char c) {  
            if (c >= 'A' && c <= 'Z')  
                return ((int) c) - 65;  
            else if (c >= 'a' && c <= 'z')  
                return ((int) c) - 97 + 26;  
            else if (c >= '0' && c <= '9')  
                return ((int) c) - 48 + 26 + 26;  
            else  
                switch (c) {  
                case '+':  
                    return 62;  
                case '/':  
                    return 63;  
                case '=':  
                    return 0;  
                default:  
                    throw new RuntimeException("unexpected code: " + c);  
                }  
        }  
  
        /** 
         * Decodes the given Base64 encoded String to a new byte array. The byte 
         * array holding the decoded data is returned. 
         */  
  
        public static byte[] decode(String s) {  
  
            ByteArrayOutputStream bos = new ByteArrayOutputStream();  
            try {  
                decode(s, bos);  
            } catch (IOException e) {  
                throw new RuntimeException();  
            }  
            byte[] decodedBytes = bos.toByteArray();  
            try {  
                bos.close();  
                bos = null;  
            } catch (IOException ex) {  
                System.err.println("Error while decoding BASE64: " + ex.toString());  
            }  
            return decodedBytes;  
        }  
  
        private static void decode(String s, OutputStream os) throws IOException {  
            int i = 0;  
  
            int len = s.length();  
  
            while (true) {  
                while (i < len && s.charAt(i) <= ' ')  
                    i++;  
  
                if (i == len)  
                    break;  
  
                int tri = (decode(s.charAt(i)) << 18)  
                        + (decode(s.charAt(i + 1)) << 12)  
                        + (decode(s.charAt(i + 2)) << 6)  
                        + (decode(s.charAt(i + 3)));  
  
                os.write((tri >> 16) & 255);  
                if (s.charAt(i + 2) == '=')  
                    break;  
                os.write((tri >> 8) & 255);  
                if (s.charAt(i + 3) == '=')  
                    break;  
                os.write(tri & 255);  
  
                i += 4;  
            }  
        }  
          
}             

主函數：

public class main extends Activity {  
    /** Called when the activity is first created. */  
    @Override  
    public void onCreate(Bundle savedInstanceState) {  
        super.onCreate(savedInstanceState);  
        setContentView(R.layout.main);  
         
        String key = "12345678";  
        String text = "hello des";  
          
          
        try {  
            String result1 = DES.encryptDES(text,key);  
            String result2 = DES.decryptDES(result1, key);  
            Log.i("DES encode text is ", result1);  
            Log.i("DES encode text is ", result2);  
        } catch (Exception e) {  
            // TODO Auto-generated catch block  
            e.printStackTrace();  
        }      
    }  
}