package org.javaniu.encryptanddecrypt;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.security.InvalidKeyException;
import java.security.KeyFactory;
import java.security.NoSuchAlgorithmException;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;

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

import org.apache.commons.lang.ArrayUtils;


/**
 * 加解密类
 * @author javaniu_飞翔
 */
public class EncryptorAndDecipher {

	public static void main(String[] args) {

		String test = "用户根据的服务商名称、接入服务商机房信息、审计记录时间段项、内容关键字四项查询条件，查询出相应的审计信息内容。";
		
		FileInputStream fisPub = null;
		FileInputStream fisPri = null;
		try {
			fisPub = new FileInputStream(new File("d://PublicKey"));
			fisPri = new FileInputStream(new File("d://PrivateKey"));
			
			byte[] pub = new byte[fisPub.available()];
			fisPub.read(pub);
			byte[] encript = encrypt(pub,test.getBytes());
			System.out.println(new String(encript));
			
			byte[] pri = new byte[fisPri.available()];
			fisPri.read(pri);
			byte[] decript = decipher(pri, encript);
			String str = new String(decript);
			System.out.println(str);
			
			
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		} finally {
			if(null != fisPub){
				try {
					fisPub.close();
				} catch (IOException e) {
					e.printStackTrace();
				}
			}
			
			if(null != fisPri){
				try {
					fisPri.close();
				} catch (IOException e) {
					e.printStackTrace();
				}
			}
				
		}
		
	}
	
	/**
	 * 对权限信息进行加密，加密失败时返回null
	 * @param publicKey - 1024rsa 公钥字节形式
	 * @param authority - 权限的明文字
	 * @return
	 */
	public static byte[] encrypt( byte[] publicKey, byte[] authority ){
		byte[] ciphertext = null;
		X509EncodedKeySpec pubKeySpec = new X509EncodedKeySpec( publicKey ); 
		KeyFactory keyFactory;
		try {
			keyFactory = KeyFactory.getInstance( "RSA" );
			PublicKey publicKey1 = keyFactory.generatePublic( pubKeySpec );
			
			ciphertext = encrypt( publicKey1, authority );
		} catch (Exception e) {
			e.printStackTrace();
		} 
		
		
		return ciphertext;
	}
	
	private static byte[] encrypt( PublicKey publicKey, byte[] authority ){
		byte[] ciphertext = new byte[]{};
		Cipher cipher = null;
		try {
			
			cipher = Cipher.getInstance( "RSA" );
			cipher.init(Cipher.ENCRYPT_MODE, publicKey);
			
			for (int i = 0; i < authority.length; i += 100) {
				byte[] subarray = ArrayUtils.subarray(authority, i, i + 100);
				byte[] doFinal = cipher.doFinal( subarray );
				ciphertext = ArrayUtils.addAll( ciphertext , doFinal);
			}
		} catch (NoSuchAlgorithmException e) {
			e.printStackTrace();
		} catch (NoSuchPaddingException e) {
			e.printStackTrace();
		} catch (InvalidKeyException e) {
			e.printStackTrace();
		} catch (IllegalBlockSizeException e) {
			e.printStackTrace();
		} catch (BadPaddingException e) {
			e.printStackTrace();
		}   
		
		return ciphertext;
	}

	/**
	 * 解密
	 * @param encodedKey
	 * @param ciphertext
	 * @return
	 */
	public static byte[] decipher( byte[] encodedKey, byte[] ciphertext ) {
		 
		byte[] authority = null;
		PKCS8EncodedKeySpec priKeySpec = new PKCS8EncodedKeySpec( encodedKey ); 
		KeyFactory keyFactory;
		try {
			keyFactory = KeyFactory.getInstance( "RSA" );
			PrivateKey privateKey = keyFactory.generatePrivate( priKeySpec );
			authority = decipher( privateKey, ciphertext );
			
		} catch (Exception e) {
			e.printStackTrace();
		} 
		return authority;
	}
	
	private static byte[] decipher( PrivateKey privateKey, byte[] ciphertext ){
		byte[] authority = new byte[]{};
		try {
			Cipher cipher = Cipher.getInstance( "RSA" );
			cipher.init(Cipher.DECRYPT_MODE, privateKey);
			
			for (int i = 0; i < ciphertext.length; i += 128) {
			   byte[] doFinal = cipher.doFinal( ArrayUtils.subarray(ciphertext, i, i + 128) );
			   authority = ArrayUtils.addAll( authority , doFinal);
			}
			
		} catch (Exception e) {
			e.printStackTrace();
		}
          
        return authority;   
	}
	
}