javax.crypto.IllegalBlockSizeException: Input length must be multiple of 16 when decrypting with padded cipher

原文地址：http://songjianyong.iteye.com/blog/1571029

/**
 * AESHelper.java
 * cn.com.songjy.test
 *
 * Function： TODO 
 *
 *   ver     date              author
 * ──────────────────────────────────
 *            2012-6-29         songjianyong
 *
 * Copyright (c) 2012, TNT All Rights Reserved.
*/

package cn.com.songjy.test;

import java.io.UnsupportedEncodingException;
import java.security.InvalidKeyException;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;

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

/**
 * ClassName:AESHelper
 *
 * @author   songjianyong
 * @version  1.0
 * @since    v1.0
 * @Date     2012-6-29 下午2:06:07 
 */
public class AESHelper {

    /**
     * @method main
     * @param args
     * @throws 
     * @since v1.0
     */

    public static void main(String[] args) {

        String content = "宋建勇";
        String password = "12345678";
        byte[] encryptResult = encrypt(content, password);//加密
        byte[] decryptResult = decrypt(encryptResult,password);//解密
        System.out.println("解密后：" + new String(decryptResult));
        
        /*容易出错的地方，请看下面代码*/
        System.out.println("***********************************************");
        try {
            String encryptResultStr = new String(encryptResult,"utf-8");
            decryptResult = decrypt(encryptResultStr.getBytes("utf-8"),password);
            System.out.println("解密后：" + new String(decryptResult));
        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
        } catch (Exception e) {
            // TODO: handle exception
        }
        /*则，系统会报出如下异常：javax.crypto.IllegalBlockSizeException: Input length must be multiple of 16 when decrypting with padded cipher
    at com.sun.crypto.provider.SunJCE_f.b(DashoA13*..)
    at com.sun.crypto.provider.SunJCE_f.b(DashoA13*..)
    at com.sun.crypto.provider.AESCipher.engineDoFinal(DashoA13*..)
    at javax.crypto.Cipher.doFinal(DashoA13*..)
    at cn.com.songjy.test.ASCHelper.decrypt(ASCHelper.java:131)
    at cn.com.songjy.test.ASCHelper.main(ASCHelper.java:58)
         * */
        /*这主要是因为加密后的byte数组是不能强制转换成字符串的, 换言之,字符串和byte数组在这种情况下不是互逆的,
         * 要避免这种情况，我们需要做一些修订，可以考虑将二进制数据转换成十六进制表示,
         * 主要有两个方法:将二进制转换成16进制(见方法parseByte2HexStr)或是将16进制转换为二进制(见方法parseHexStr2Byte)*/
        
        /*然后，我们再修订以上测试代码*/
        System.out.println("***********************************************");
        String encryptResultStr = parseByte2HexStr(encryptResult);
        System.out.println("加密后：" + encryptResultStr);
        byte[] decryptFrom = parseHexStr2Byte(encryptResultStr);
        decryptResult = decrypt(decryptFrom,password);//解码
        System.out.println("解密后：" + new String(decryptResult));
    }

    /**
     * 加密
     * @method encrypt
     * @param content    需要加密的内容
     * @param password    加密密码
     * @return
     * @throws 
     * @since v1.0
     */
    public static byte[] encrypt(String content, String password){
        try {
            KeyGenerator kgen = KeyGenerator.getInstance("AES");
            kgen.init(128, new SecureRandom(password.getBytes()));
            SecretKey secretKey = kgen.generateKey();
            byte[] enCodeFormat = secretKey.getEncoded();
            SecretKeySpec key = new SecretKeySpec(enCodeFormat, "AES");
            Cipher cipher = Cipher.getInstance("AES");// 创建密码器
            byte[] byteContent = content.getBytes("utf-8");
            cipher.init(Cipher.ENCRYPT_MODE, key);// 初始化
            byte[] result = cipher.doFinal(byteContent);
            return result; // 加密
        } catch (NoSuchAlgorithmException e) {
            e.printStackTrace();
        }catch (NoSuchPaddingException e) {
            e.printStackTrace();
        }catch (UnsupportedEncodingException e) {
            e.printStackTrace();
        }catch (InvalidKeyException e) {
            e.printStackTrace();
        }catch (IllegalBlockSizeException e) {
            e.printStackTrace();
        }catch (BadPaddingException e) {
            e.printStackTrace();
        }
        return null;
    }
    
    /**
     * 解密
     * @method decrypt
     * @param content    待解密内容
     * @param password    解密密钥
     * @return
     * @throws 
     * @since v1.0
     */
    public static byte[] decrypt(byte[] content, String password){
        try {
            KeyGenerator kgen = KeyGenerator.getInstance("AES");
            kgen.init(128, new SecureRandom(password.getBytes()));
            SecretKey secretKey = kgen.generateKey();
            byte[] enCodeFormat = secretKey.getEncoded();
            SecretKeySpec key = new SecretKeySpec(enCodeFormat, "AES");
            Cipher cipher = Cipher.getInstance("AES");// 创建密码器
            cipher.init(Cipher.DECRYPT_MODE, key);// 初始化
            byte[] result = cipher.doFinal(content);
            return result; // 解密
        } 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 null;
    }
    
    /**
     * 将二进制转换成16进制
     * @method parseByte2HexStr
     * @param buf
     * @return
     * @throws 
     * @since v1.0
     */
    public static String parseByte2HexStr(byte buf[]){
        StringBuffer sb = new StringBuffer();
        for(int i = 0; i < buf.length; i++){
            String hex = Integer.toHexString(buf[i] & 0xFF);
            if (hex.length() == 1) {
                hex = '0' + hex;
            }
            sb.append(hex.toUpperCase());
        }
        return sb.toString();
    }
    
    /**
     * 将16进制转换为二进制
     * @method parseHexStr2Byte
     * @param hexStr
     * @return
     * @throws 
     * @since v1.0
     */
    public static byte[] parseHexStr2Byte(String hexStr){
        if(hexStr.length() < 1)
            return null;
        byte[] result = new byte[hexStr.length()/2];
        for (int i = 0;i< hexStr.length()/2; i++) {
            int high = Integer.parseInt(hexStr.substring(i*2, i*2+1), 16);
            int low = Integer.parseInt(hexStr.substring(i*2+1, i*2+2), 16);
            result[i] = (byte) (high * 16 + low);
        }
        return result;
    }
    
    /**
     * 另外一种加密方式--这种加密方式有两种限制
     * 1、密钥必须是16位的
     * 2、待加密内容的长度必须是16的倍数，如果不是16的倍数，就会出如下异常
     * javax.crypto.IllegalBlockSizeException: Input length not multiple of 16 bytes
        at com.sun.crypto.provider.SunJCE_f.a(DashoA13*..)
        at com.sun.crypto.provider.SunJCE_f.b(DashoA13*..)
        at com.sun.crypto.provider.SunJCE_f.b(DashoA13*..)
        at com.sun.crypto.provider.AESCipher.engineDoFinal(DashoA13*..)
        at javax.crypto.Cipher.doFinal(DashoA13*..)
        要解决如上异常，可以通过补全传入加密内容等方式进行避免。
     * @method encrypt2
     * @param content    需要加密的内容
     * @param password    加密密码
     * @return
     * @throws 
     * @since v1.0
     */
    public static byte[] encrypt2(String content, String password){
        try {
            SecretKeySpec key = new SecretKeySpec(password.getBytes(), "AES");
            Cipher cipher = Cipher.getInstance("AES/ECB/NoPadding");
            byte[] byteContent = content.getBytes("utf-8");
            cipher.init(Cipher.ENCRYPT_MODE, key);// 初始化
            byte[] result = cipher.doFinal(byteContent);
            return result; // 加密
        } catch (NoSuchAlgorithmException e) {
            e.printStackTrace();
        } catch (NoSuchPaddingException e) {
            e.printStackTrace();
        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
        } catch (InvalidKeyException e) {
            e.printStackTrace();
        } catch (IllegalBlockSizeException e) {
            e.printStackTrace();
        } catch (BadPaddingException e) {
            e.printStackTrace();
        }
        return null;
    }
    
    
}

测试效果： 

解密后：宋建勇 
*********************************************** 
javax.crypto.IllegalBlockSizeException: Input length must be multiple of 16 when decrypting with padded cipher
at com.sun.crypto.provider.SunJCE_f.b(DashoA13*..) 
at com.sun.crypto.provider.SunJCE_f.b(DashoA13*..) 
at com.sun.crypto.provider.AESCipher.engineDoFinal(DashoA13*..) 
at javax.crypto.Cipher.doFinal(DashoA13*..) 
at cn.com.songjy.test.ASCHelper.decrypt(ASCHelper.java:141) 
at cn.com.songjy.test.ASCHelper.main(ASCHelper.java:58) 
java.lang.NullPointerException 
at java.lang.String.<init>(String.java:594) 
at cn.com.songjy.test.ASCHelper.main(ASCHelper.java:59) 
*********************************************** 
加密后：961000B09BDDA1F81E81EF3EFDC3A926 
解密后：宋建勇