Java DES文件加密解密 javax.crypto.BadPaddingException: Given final block not properly padded

Posted on 2012-05-19 13:19 IceWee 阅读(30856) 评论(3) 编辑收藏所属分类: Java 、加解密

本工具类经过测试可用，之前写的没有使用CipherInputStream和CipherOutputStream，生成的加密文件与源文件大小不一致，加密时没有问题，解密时总是抛出如下异常：

Exception in thread "main" javax.crypto.BadPaddingException: Given final block not properly padded

at com.sun.crypto.provider.SunJCE_f.b(DashoA13*..)

at com.sun.crypto.provider.AESCipher.engineDoFinal(DashoA13*..)

at javax.crypto.Cipher.doFinal(DashoA13*..)

其中BASE64底层依赖库没有使用SUN的，而是下载的“javabase64-1.3.1.jar”

DESUtils.java

package demo.security;

import java.io.File;

import java.io.FileInputStream;

import java.io.FileOutputStream;

import java.io.InputStream;

import java.io.OutputStream;

import java.security.Key;

import java.security.SecureRandom;

import javax.crypto.Cipher;

import javax.crypto.CipherInputStream;

import javax.crypto.CipherOutputStream;

import javax.crypto.KeyGenerator;

import javax.crypto.SecretKey;

import javax.crypto.SecretKeyFactory;

import javax.crypto.spec.DESKeySpec;

/**

*

* DES加密解密工具包

*

* @author IceWee

* @date 2012-5-19

* @version 1.0

public class DESUtils {

private static final String ALGORITHM = "DES";

private static final int CACHE_SIZE = 1024;

/**

*

* 生成随机密钥

*

* @return

* @throws Exception

public static String getSecretKey() throws Exception {

return getSecretKey(null);

}

/**

*

* 生成密钥

*

* @param seed 密钥种子

* @return

* @throws Exception

public static String getSecretKey(String seed) throws Exception {

SecureRandom secureRandom;

if (seed != null && !"".equals(seed))

secureRandom = new SecureRandom(seed.getBytes());

else

secureRandom = new SecureRandom();

KeyGenerator keyGenerator = KeyGenerator.getInstance(ALGORITHM);

keyGenerator.init(secureRandom);

SecretKey secretKey = keyGenerator.generateKey();

return Base64Utils.encode(secretKey.getEncoded());

}

/**

*

* 加密

*

* @param data

* @param key

* @return

* @throws Exception

public static byte[] encrypt(byte[] data, String key) throws Exception {

Key k = toKey(Base64Utils.decode(key));

Cipher cipher = Cipher.getInstance(ALGORITHM);

cipher.init(Cipher.ENCRYPT_MODE, k);

return cipher.doFinal(data);

}

/**

*

* 文件加密

*

* @param key

* @param sourceFilePath

* @param destFilePath

* @throws Exception

public static void encryptFile(String key, String sourceFilePath, String destFilePath) throws Exception {

File sourceFile = new File(sourceFilePath);

File destFile = new File(destFilePath);

if (sourceFile.exists() && sourceFile.isFile()) {

if (!destFile.getParentFile().exists()) {

destFile.getParentFile().mkdirs();

}

destFile.createNewFile();

InputStream in = new FileInputStream(sourceFile);

OutputStream out = new FileOutputStream(destFile);

Key k = toKey(Base64Utils.decode(key));

Cipher cipher = Cipher.getInstance(ALGORITHM);

cipher.init(Cipher.ENCRYPT_MODE, k);

CipherInputStream cin = new CipherInputStream(in, cipher);

byte[] cache = new byte[CACHE_SIZE];

int nRead = 0;

while ((nRead = cin.read(cache)) != -1) {

out.write(cache, 0, nRead);

out.flush();

}

out.close();

cin.close();

in.close();

}

/**

*

* 解密

*

* @param data

* @param key

* @return

* @throws Exception

public static byte[] decrypt(byte[] data, String key) throws Exception {

Key k = toKey(Base64Utils.decode(key));

Cipher cipher = Cipher.getInstance(ALGORITHM);

cipher.init(Cipher.DECRYPT_MODE, k);

return cipher.doFinal(data);

}

/**

*

* 文件解密

*

* @param key

* @param sourceFilePath

* @param destFilePath

* @throws Exception

public static void decryptFile(String key, String sourceFilePath, String destFilePath) throws Exception {

File sourceFile = new File(sourceFilePath);

File destFile = new File(destFilePath);

if (sourceFile.exists() && sourceFile.isFile()) {

if (!destFile.getParentFile().exists()) {

destFile.getParentFile().mkdirs();

}

destFile.createNewFile();

InputStream in = new FileInputStream(sourceFile);

OutputStream out = new FileOutputStream(destFile);

Key k = toKey(Base64Utils.decode(key));

Cipher cipher = Cipher.getInstance(ALGORITHM);

cipher.init(Cipher.DECRYPT_MODE, k);

CipherOutputStream cout = new CipherOutputStream(out, cipher);

byte[] cache = new byte[CACHE_SIZE];

int nRead = 0;

while ((nRead = in.read(cache)) != -1) {

cout.write(cache, 0, nRead);

cout.flush();

}

cout.close();

out.close();

in.close();

}

/**

*

* 转换密钥

*

* @param key

* @return

* @throws Exception

private static Key toKey(byte[] key) throws Exception {

DESKeySpec dks = new DESKeySpec(key);

SecretKeyFactory keyFactory = SecretKeyFactory.getInstance(ALGORITHM);

SecretKey secretKey = keyFactory.generateSecret(dks);

return secretKey;

}

Base64Utils.java

package demo.security;

import java.io.ByteArrayInputStream;

import java.io.ByteArrayOutputStream;

import java.io.File;

import java.io.FileInputStream;

import java.io.FileOutputStream;

import java.io.InputStream;

import java.io.OutputStream;

import it.sauronsoftware.base64.Base64;

/**

*

* BASE64编码解码工具包

*

*

* 依赖javabase64-1.3.1.jar

*

* @author IceWee

* @date 2012-5-19

* @version 1.0

public class Base64Utils {

/**

* 文件读取缓冲区大小

private static final int CACHE_SIZE = 1024;

/**

*

* BASE64字符串解码为二进制数据

*

* @param base64

* @return

* @throws Exception

public static byte[] decode(String base64) throws Exception {

return Base64.decode(base64.getBytes());

}

/**

*

* 二进制数据编码为BASE64字符串

*

* @param bytes

* @return

* @throws Exception

public static String encode(byte[] bytes) throws Exception {

return new String(Base64.encode(bytes));

}

/**

*

* 将文件编码为BASE64字符串

*

*

* 大文件慎用，可能会导致内存溢出

*

* @param filePath 文件绝对路径

* @return

* @throws Exception

public static String encodeFile(String filePath) throws Exception {

byte[] bytes = fileToByte(filePath);

return encode(bytes);

}

/**

*

* BASE64字符串转回文件

*

* @param filePath 文件绝对路径

* @param base64 编码字符串

* @throws Exception

public static void decodeToFile(String filePath, String base64) throws Exception {

byte[] bytes = decode(base64);

byteArrayToFile(bytes, filePath);

}

/**

*

* 文件转换为二进制数组

*

* @param filePath 文件路径

* @return

* @throws Exception

public static byte[] fileToByte(String filePath) throws Exception {

byte[] data = new byte[0];

File file = new File(filePath);

if (file.exists()) {

FileInputStream in = new FileInputStream(file);

ByteArrayOutputStream out = new ByteArrayOutputStream(2048);

byte[] cache = new byte[CACHE_SIZE];

int nRead = 0;

while ((nRead = in.read(cache)) != -1) {

out.write(cache, 0, nRead);

out.flush();

}

out.close();

in.close();

data = out.toByteArray();

}

return data;

}

/**

*

* 二进制数据写文件

*

* @param bytes 二进制数据

* @param filePath 文件生成目录

public static void byteArrayToFile(byte[] bytes, String filePath) throws Exception {

InputStream in = new ByteArrayInputStream(bytes);

File destFile = new File(filePath);

if (!destFile.getParentFile().exists()) {

destFile.getParentFile().mkdirs();

}

destFile.createNewFile();

OutputStream out = new FileOutputStream(destFile);

byte[] cache = new byte[CACHE_SIZE];

int nRead = 0;

while ((nRead = in.read(cache)) != -1) {

out.write(cache, 0, nRead);

out.flush();

}

out.close();

in.close();

}

DESTester.java

package demo.security;

public class DESTester {

static String key;

static {

try {

key = DESUtils.getSecretKey();

} catch (Exception e) {

e.printStackTrace();

}

public static void main(String[] args) throws Exception {

long begin = System.currentTimeMillis();

encryptFile();

decryptFile();

test();

long end = System.currentTimeMillis();

System.err.println("耗时：" + (end-begin)/1000 + "秒

");

}

static void encryptFile() throws Exception {

String sourceFilePath = "D:/demo.mp4";

String destFilePath = "D:/demo_encrypted.mp4";

DESUtils.encryptFile(key, sourceFilePath, destFilePath);

}

static void decryptFile() throws Exception {

String sourceFilePath = "D:/demo_encrypted.mp4";

String destFilePath = "D:/demo_decrypted.mp4";

DESUtils.decryptFile(key, sourceFilePath, destFilePath);

}

static void test() throws Exception {

String source = "这是一行测试DES加密/解密的文字，你看完也等于没看，是不是啊？！";

System.err.println("原文:\t" + source);

byte[] inputData = source.getBytes();

inputData = DESUtils.encrypt(inputData, key);

System.err.println("加密后:\t" + Base64Utils.encode(inputData));

byte[] outputData = DESUtils.decrypt(inputData, key);

String outputStr = new String(outputData);

System.err.println("解密后:\t" + outputStr);

}

Feedback

# re: Java DES文件加密解密 javax.crypto.BadPaddingException: Given final block not properly padded 回复 更多评论

2012-09-04 22:09 by yaray

str.getBytes();
调用此方法时，凡是未指定具体字符编码的程序，均依赖于JRE所在操作系统的默认编码类型，因此类似的加解密程序均是不完全可靠的。解决办法：调用此方法时指定为 UTF-8 编码，即：str.getBytes("UTF-8");

# re: Java DES文件加密解密 javax.crypto.BadPaddingException: Given final block not properly padded 回复 更多评论

2012-09-05 09:07 by IceWee

@yaray
感谢回复，可能我系统上的文字都用的UTF-8编码吧，Eclipse的编码也用的UTF-8，所以没有测试到这个bug。

# re: Java DES文件加密解密 javax.crypto.BadPaddingException: Given final block not properly padded 回复 更多评论

2013-01-10 20:34 by free4wp

SecureRandom 实现完全随操作系统本身的內部状态，除非调用方在调用 getInstance 方法之后又调用了 setSeed 方法；该实现在 windows 上每次生成的 key 都相同，但是在 solaris 或部分 linux 系统上则不同。
正确的解决方法：
http://free4wp.com/%e8%a7%a3%e5%86%b3linux%e6%93%8d%e4%bd%9c%e7%b3%bb%e7%bb%9f%e4%b8%8baes%e8%a7%a3%e5%af%86%e5%a4%b1%e8%b4%a5%e7%9a%84%e9%97%ae%e9%a2%98.html

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