java加密-解密小结

package basic.security;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

import org.apache.commons.codec.binary.Hex;

public class EncrypMD5 {
	
	public byte[] eccrypt(String info) throws NoSuchAlgorithmException{
		//���MD5�㷨���MessageDigest����
		MessageDigest md5 = MessageDigest.getInstance("MD5"); 
		byte[] srcBytes = info.getBytes();
		//ʹ��srcBytes����ժҪ
		md5.update(srcBytes);
		//��ɹ�ϣ���㣬�õ�result
		byte[] resultBytes = md5.digest();
		return resultBytes;
	}
	
	public static void main(String args[]) throws NoSuchAlgorithmException{
		String msg = "aaa";
		EncrypMD5 md5 = new EncrypMD5();
		byte[] b = md5.eccrypt(msg);
		//System.out.println(((b)));
		//System.out.println(new String((b)));
		//System.out.println((new Hex().encode(b))); //[B@58ea58e3： byte[]没法直接显示成string
		
		// 将byte[]组装string ？
		// 1 借助 Hex
		System.out.println(new String(new Hex().encode(b)));
		
		
		// 2 自己组装
		int i;
		StringBuffer buf = new StringBuffer(); 
	    for (int offset = 0; offset < b.length; offset++) {
	    	i = b[offset];
	    	if (i < 0) {
	    		i += 256;
	    	}
	    	if (i < 16) {
	    		buf.append("0");
	    	}
	    	// 将整型 十进制 i 转换为16位，用十六进制参数表示的无符号整数值的字符串表示形式。
	    	buf.append(Integer.toHexString(i)); 
	    }
	    
	    // 32位的加密
	    String md5Str = buf.toString();
	     System.out.println(""+ md5Str);
	    // 16位的加密
	     md5Str = buf.toString().substring(8,24); 
		System.out.println(""+ md5Str);
		
	}

}

package basic.security;

import java.io.IOException;

import sun.misc.BASE64Decoder;
import sun.misc.BASE64Encoder;


public class Base64Test {

	public String encode(String toEncodeContent){
		if(toEncodeContent == null){
			return null;
		}
		BASE64Encoder encoder = new BASE64Encoder();
//		BASE32Encoder encoder32 = new BASE32Encoder();
		return encoder.encode(toEncodeContent.getBytes());
	}
	
	public String decode(String toDecodeContent){
		if(toDecodeContent == null) {
			return null;
		}
		byte[] buf = null;
		try {
			buf = new BASE64Decoder().decodeBuffer(toDecodeContent);
		} catch(IOException e){
			e.printStackTrace();
		} finally {
		}
		return new String(buf);
	}
	
	public static void main(String[] args) throws Exception {
		Base64Test test = new Base64Test();
		String toEncodeContent = "I12313";
		String encodeRet = test.encode(toEncodeContent);
		System.out.println(encodeRet);
		System.out.println(test.decode(encodeRet));
	}
}

package basic.security;

import java.security.InvalidKeyException;
import java.security.NoSuchAlgorithmException;
import java.security.Security;

import javax.crypto.BadPaddingException;
import javax.crypto.Cipher;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.KeyGenerator;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.SecretKey;

public class EncrypDES {
	
	//KeyGenerator 提供对称密钥生成器的功能，支持各种算法
	private KeyGenerator keygen;
	//SecretKey 负责保存对称密钥
	private SecretKey deskey;
	//Cipher负责完成加密或解密工作
	private Cipher c;
	//该字节数组负责保存加密的结果
	private byte[] cipherByte;
	
	public EncrypDES() throws NoSuchAlgorithmException, NoSuchPaddingException{
		Security.addProvider(new com.sun.crypto.provider.SunJCE());
		//实例化支持DES算法的密钥生成器(算法名称命名需按规定，否则抛出异常)
		keygen = KeyGenerator.getInstance("DES");
		//生成密钥
		deskey = keygen.generateKey();
		//生成Cipher对象,指定其支持的DES算法
		c = Cipher.getInstance("DES");
	}
	
	/**
	 * 对字符串加密
	 * 
	 * @param str
	 * @return
	 * @throws InvalidKeyException
	 * @throws IllegalBlockSizeException
	 * @throws BadPaddingException
	 */
	public byte[] Encrytor(String str) throws InvalidKeyException,
			IllegalBlockSizeException, BadPaddingException {
		// 根据密钥，对Cipher对象进行初始化，ENCRYPT_MODE表示加密模式
		c.init(Cipher.ENCRYPT_MODE, deskey);
		byte[] src = str.getBytes();
		// 加密，结果保存进cipherByte
		cipherByte = c.doFinal(src);
		return cipherByte;
	}

	/**
	 * 对字符串解密
	 * 
	 * @param buff
	 * @return
	 * @throws InvalidKeyException
	 * @throws IllegalBlockSizeException
	 * @throws BadPaddingException
	 */
	public byte[] Decryptor(byte[] buff) throws InvalidKeyException,
			IllegalBlockSizeException, BadPaddingException {
		// 根据密钥，对Cipher对象进行初始化，DECRYPT_MODE表示加密模式
		c.init(Cipher.DECRYPT_MODE, deskey);
		cipherByte = c.doFinal(buff);
		return cipherByte;
	}

	/**
	 * @param args
	 * @throws NoSuchPaddingException 
	 * @throws NoSuchAlgorithmException 
	 * @throws BadPaddingException 
	 * @throws IllegalBlockSizeException 
	 * @throws InvalidKeyException 
	 */
	public static void main(String[] args) throws Exception {
		EncrypDES de1 = new EncrypDES();
		String msg ="lkasddad艾弗森的";
		byte[] encontent = de1.Encrytor(msg);
		byte[] decontent = de1.Decryptor(encontent);
		System.out.println("明文是:" + msg);
		System.out.println("加密后:" + new String(encontent));
		System.out.println("解密后:" + new String(decontent));
	}

}

初始化：   
 KeyPairGenerator keyPairGen = KeyPairGenerator.getInstance("RSA");
		//初始化密钥对生成器，密钥大小为1024位
		keyPairGen.initialize(1024);
		//生成一个密钥对，保存在keyPair中
		KeyPair keyPair = keyPairGen.generateKeyPair();
		//得到私钥
		RSAPrivateKey privateKey = (RSAPrivateKey)keyPair.getPrivate();				
		//得到公钥
		RSAPublicKey publicKey = (RSAPublicKey)keyPair.getPublic();       

 加密：
//Cipher负责完成加密或解密工作，基于RSA
			Cipher cipher = Cipher.getInstance("RSA");
			//根据公钥，对Cipher对象进行初始化
			cipher.init(Cipher.ENCRYPT_MODE, publicKey); // 采用加密模式ENCRYPT_MODE

byte[] resultBytes = cipher.doFinal(srcBytes); 

解密 
//Cipher负责完成加密或解密工作，基于RSA 
Cipher cipher = Cipher.getInstance("RSA");
 //根据公钥，对Cipher对象进行初始化 
cipher.init(Cipher.DECRYPT_MODE, privateKey);// 采用解密模式DECRYPT_MODE
byte[] resultBytes = cipher.doFinal(srcBytes);