我使用javax.crypto.cipher来加密和解密一些数据。 它运作良好。但有时候，解密会出现badPaddingException。如果我将一个成功的呼叫与一个故障呼叫进行比较，则给予密码的输入是相同的，并且密码以相同的方式初始化。
我如何实现我的密码
dcipher = Cipher.getInstance("PBEWithMD5AndDES");
KeySpec keySpec = new PBEKeySpec(passPhrase.toCharArray(), salt, iterationCount);
SecretKey key = SecretKeyFactory.getInstance("PBEWithMD5AndDES").generateSecret(keySpec);
dcipher.init(Cipher.DECRYPT_MODE, key, paramSpec);
我如何使用它
dec = Base64.decode(str) ;
byte[] utf8 = dcipher.doFinal(dec);
在doFinal上引发了异常。
有什么想法吗？
谢谢！
哦，顺便说一句，我使用bouncyCastle作为提供者，并将其添加到列表顶部
Security.insertProviderAt(new org.bouncycastle.jce.provider.BouncyCastleProvider(), 1);
为了完整性，并且因为问题仍然不时出现。这是完整的课程。
public class EncryptDecryptUtil {
/** Encryption Cipher */
private static Cipher ecipher;
/** Decription Cipher */
private static Cipher dcipher;
private static Logger logger = Logger.getLogger(EncryptDecryptUtil.class);
/**
* Constructor used to create this object. Responsible for setting and initializing this object's encrypter and
* decrypter Cipher instances given a Secret Key and algorithm.
*
* @param key Secret Key used to initialize both the encrypter and decrypter instances.
* @param algorithm Which algorithm to use for creating the encrypter and decrypter instances.
*/
public EncryptDecryptUtil(SecretKey key, String algorithm) {
Security.insertProviderAt(new org.bouncycastle.jce.provider.BouncyCastleProvider(), 1);
try {
ecipher = Cipher.getInstance(algorithm);
dcipher = Cipher.getInstance(algorithm);
ecipher.init(Cipher.ENCRYPT_MODE, key);
dcipher.init(Cipher.DECRYPT_MODE, key);
} catch (NoSuchPaddingException e) {
System.out.println("EXCEPTION: NoSuchPaddingException");
} catch (NoSuchAlgorithmException e) {
System.out.println("EXCEPTION: NoSuchAlgorithmException");
} catch (InvalidKeyException e) {
System.out.println("EXCEPTION: InvalidKeyException");
}
}
/**
* Constructor used to create this object. Responsible for setting and initializing this object's encrypter and
* decrypter Chipher instances given a Pass Phrase and algorithm.
*
* @param passPhrase Pass Phrase used to initialize both the encrypter and decrypter instances.
*/
public EncryptDecryptUtil(String passPhrase) {
Security.insertProviderAt(new org.bouncycastle.jce.provider.BouncyCastleProvider(), 1);
// 8-bytes Salt
byte[] salt = { (byte) 0xB9, (byte) 0x8B, (byte) 0xD8, (byte) 0x31, (byte) 0x55, (byte) 0x24, (byte) 0xF3, (byte) 0x13 };
// Iteration count
int iterationCount = 19;
try {
// Generate the secret key associated to the passphrase.
KeySpec keySpec = new PBEKeySpec(passPhrase.toCharArray(), salt, iterationCount);
SecretKey key = SecretKeyFactory.getInstance("PBEWithMD5AndDES").generateSecret(keySpec);
// Get instance of the cipher
ecipher = Cipher.getInstance("PBEWithMD5AndDES");
dcipher = Cipher.getInstance("PBEWithMD5AndDES");
// Prepare the parameters to the cipthers
AlgorithmParameterSpec paramSpec = new PBEParameterSpec(salt, iterationCount);
ecipher.init(Cipher.ENCRYPT_MODE, key, paramSpec);
dcipher.init(Cipher.DECRYPT_MODE, key, paramSpec);
} catch (InvalidAlgorithmParameterException e) {
logger.error("during encrypter instantiation",e);
} catch (InvalidKeySpecException e) {
logger.error("during encrypter instantiation",e);
} catch (NoSuchPaddingException e) {
logger.error("during encrypter instantiation",e);
} catch (NoSuchAlgorithmException e) {
logger.error("during encrypter instantiation",e);
} catch (InvalidKeyException e) {
logger.error("during encrypter instantiation",e);
}
}
/**
* Takes a single String as an argument and returns an Encrypted version of that String.
*
* @param str String to be encrypted
* @return <code>String</code> Encrypted version of the provided String
*/
public String encrypt(String str) {
try {
// Encode the string into bytes using utf-8
byte[] utf8 = str.getBytes("UTF8");
// Encrypt
byte[] enc = ecipher.doFinal(utf8);
// Encode bytes to base64 to get a string
return new String( Base64.encode(enc), "UTF8");
} catch (BadPaddingException e) {
logger.error("during encryption : ",e);
} catch (IllegalBlockSizeException e) {
logger.error("during encryption : ",e);
} catch (UnsupportedEncodingException e) {
logger.error("during encryption : ",e);
}
return new String();
}
/**
* Takes a encrypted String as an argument, decrypts and returns the decrypted String.
*
* @param str Encrypted String to be decrypted
* @return <code>String</code> Decrypted version of the provided String
*/
public String decrypt(String str) {
byte[] dec = new byte[0];
try {
// Decode base64 to get bytes. Not sure to understand why.
dec = Base64.decode(str) ;
// Decrypt
byte[] utf8 = dcipher.doFinal(dec);
// Decode using utf-8
return new String(utf8, "UTF8");
} catch (BadPaddingException e) {
logger.error("error during decryption. String to decode was : "+str + " byte array to decode was : "+ Arrays.toString(dec) ,e);
} catch (IllegalBlockSizeException e) {
logger.error("during decryption : ",e);
} catch (UnsupportedEncodingException e) {
logger.error("during decryption : ",e);
}
return new String();
}
}
修改： 我想强调这两点：
...
for( int i = 0 ; i<1000000000 ; i++){
EncryptDecryptUtil encryptDecript = new EncryptDecryptUtil("pass");
if ( !"YES".equals(encryptDecript.decrypt("Q3qWLKo6yJY="))){
System.out.println("Fail at call " + i);
throw new InvalidParameterException() ;
}
}
那么也许它可能来自我使用EncryptDecryptUtils类的方式？它是一个Spring bean的领域，曾经有过一次。
com.myStuff.dlm.cryptography.EncryptDecryptUtil error during decryption. String to decode was : Q3qWLKo6yJY= byte array to decode was : [114, 52, -52, -54, 82, 87, 124, 84]
javax.crypto.BadPaddingException: Given final block not properly padded
at com.sun.crypto.provider.SunJCE_f.b(DashoA13*..)
at com.sun.crypto.provider.SunJCE_f.b(DashoA13*..)
at com.sun.crypto.provider.SunJCE_ab.b(DashoA13*..)
at com.sun.crypto.provider.PBEWithMD5AndDESCipher.engineDoFinal(DashoA13*..)
at javax.crypto.Cipher.doFinal(DashoA13*..)
at com.dvidea.dlm.cryptography.EncryptDecryptUtil.decrypt(EncryptDecryptUtil.java:166)
答案 0 :(得分：3)
只是一个想法：也许你在不同的提供商（Sun / BC /等）中跳
问候。
答案 1 :(得分：2)
一些想法：
堆栈跟踪表明BouncyCastle提供程序可能未被提取。您可以尝试将提供程序显式传递给Cipher和KeyFactory。
您提供的代码是唯一正在运行的代码，对吧？这个过程中没有其他线程吗？
我想知道你是否可能通过在KeySpec和ParameterSpec上指定salt和iterationCount来混淆密码。我看到的示例（encrypt PBEWithMD5AndDES in j2me，http://cs.saddleback.edu/rwatkins/CS4B/Crypto/FileEncryptor.html）在创建KeySpec时未指定这些示例。
答案 2 :(得分：1)
可能与此错误有关：http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=4414138
底线：不要使用String来存储 加密文字！
也许这可以解决它：
dec = Base64.decode(str.getBytes("UTF-8"));
答案 3 :(得分：0)
在黑暗中这是一个镜头，但尝试实例化你的密码：
dcipher = Cipher.getInstance("PBEWithMD5AndDES/CBC/PKCS5Padding");
答案 4 :(得分：0)
badPaddingException通常表示密码错误。使用“wrong_password”作为密码会重新创建错误：
EncryptDecryptUtil encryptDecript = new EncryptDecryptUtil("wrong_password");
encryptDecript.decrypt("Q3qWLKo6yJY=");
结果：
error during decryption. String to decode was : Q3qWLKo6yJY=
byte array to decode was : [67, 122, -106, 44, -86, 58, -56, 106]
javax.crypto.BadPaddingException: Given final block not properly padded
答案 5 :(得分：0)
我要走出困境并建议这是一个线程安全问题。
尝试在synchronized调用周围添加ecipher/dcipher#doFinal块，您可以轻松地将关联的Cipher对象用作要与其同步的对象。
byte[] enc;
synchronized (ecipher) {
enc = ecipher.doFinal(utf8);
}