android中的加密传输

找到两种加密算法，一种MD5加密，适用于密码加密，因为这种算法不可逆；还有一种是RSA加密，这种加密是可逆的:
 
一、MD5加密
 

import java.security.MessageDigest; 
  
 
public class MD5 { 
  
        private final static String[] hexDigits = { "0", "1", "2", "3", "4", "5", 
  
                        "6", "7", "8", "9", "a", "b", "c", "d", "e", "f" }; 
  
 
        /**
 
         * 转换字节数组为16进制字串
 
         * 
         * @param b
 
         *            字节数组
 
         * @return 16进制字串
 
         */ 
  
        public static String byteArrayToHexString(byte[] b) { 
  
                StringBuffer resultSb = new StringBuffer(); 
  
                for (int i = 0; i < b.length; i++) { 
  
                        resultSb.append(byteToHexString(b[i])); 
  
                } 
  
                return resultSb.toString(); 
  
        } 
  
 
        private static String byteToHexString(byte b) { 
  
                int n = b; 
  
                if (n < 0) 
  
                        n = 256 + n; 
  
                int d1 = n / 16; 
  
                int d2 = n % 16; 
  
                return hexDigits[d1] + hexDigits[d2]; 
  
        } 
  
 
        public static String MD5Encode(String origin) {  
  
                String resultString = null; 
  
 
                try { 
  
                        resultString = new String(origin); 
  
                        MessageDigest md = MessageDigest.getInstance("MD5"); 
  
                        resultString = byteArrayToHexString(md.digest(resultString 
  
                                        .getBytes())); 
  
                } catch (Exception ex) { 
  
 
                } 
  
                return resultString; 
  
        } 
  
} 
 
 
二、RSA加密
 

import java.security.KeyPair; 
  
import java.security.KeyPairGenerator; 
  
import java.security.inte易做图ces.RSAPrivateKey; 
  
import java.security.inte易做图ces.RSAPublicKey; 
  
 
import javax.crypto.Cipher; 
  
 
/**
 
* RSAEncrypt
 
*
 
* @author chen
 
* @see
 
*/ 
  
public class Rsaencrype { 
  
 
   /**
 
     * Main method for RSAEncrypt.
 
     * @param args
 
     */ 
  
    public static void main(String[] args) { 
  
        try { 
  
            Rsaencrype encrypt = new Rsaencrype(); 
  
             
  
            String encryptText = "encryptText"; 
  
            KeyPairGenerator keyPairGen = KeyPairGenerator.getInstance("RSA"); 
  
            keyPairGen.initialize(1024); 
  
            KeyPair keyPair = keyPairGen.generateKeyPair(); 
  
            // Generate keys 
  
            RSAPrivateKey privateKey = (RSAPrivateKey) keyPair.getPrivate(); 
  
            RSAPublicKey publicKey = (RSAPublicKey) keyPair.getPublic(); 
  
             
  
            byte[] e = encrypt.e

补充：移动开发 , Android ,