Android--DES加密解密

概念就不介绍了，自己百度，主要就是三步：创建Cipher对象，初始化Cipher，加密解密

调用DES加密算法包最精要的就是下面两句话：

Cipher cipher = Cipher.getInstance("DES/CBC/PKCS5Padding");
cipher.init(Cipher.ENCRYPT_MODE, key, zeroIv);

CBC是工作模式，DES一共有电子密码本模式（ECB）、加密分组链接模式（CBC）、加密反馈模式（CFB）和输出反馈模式（OFB）四种模式，

PKCS5Padding是填充模式，还有其它的填充模式：

然后，cipher.init（)一共有三个参数：Cipher.ENCRYPT_MODE, key, zeroIv，zeroIv就是初始化向量，一个8为字符数组。

工作模式、填充模式、初始化向量这三种因素一个都不能少。否则，如果你不指定的话，那么就要程序就要调用默认实现。

DES加密类：

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工具类：

import java.io.ByteArrayOutputStream;  import java.io.IOException;  import java.io.OutputStream;        public class Base64 {      private static final char[] legalChars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/".toCharArray();      /**      * data[]进行编码      * @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;              }          }            }  

主函数：

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();          }          }  }