javax.crypto.BadPaddingException: Given final block not properly padded. Such issues can arise if a

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文章目录

一、发现问题
二、分析问题
三、解决问题
- 3.1 方法一：不要用openjdk
- 3.2 方法二：修改KeyGenerator.init
四、全部源码

一、发现问题

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javax.crypto.BadPaddingException: Given final block not properly padded. Such issues can arise if a bad key is used during decryption.at java.base/com.sun.crypto.provider.CipherCore.unpad(CipherCore.java:977)at java.base/com.sun.crypto.provider.CipherCore.fillOutputBuffer(CipherCore.java:1058)at java.base/com.sun.crypto.provider.CipherCore.doFinal(CipherCore.java:855)at java.base/com.sun.crypto.provider.DESCipher.engineDoFinal(DESCipher.java:314)at java.base/javax.crypto.Cipher.doFinal(Cipher.java:2207)

二、分析问题

这是一个des解密的代码，在执行cipher.doFinal()的时候报错：BadPaddingException

public static String decrypt(String keyStr,String content){try {Key key = loadKey(keyStr);Cipher cipher = Cipher.getInstance("DES");cipher.init(Cipher.DECRYPT_MODE,key);byte[] source =Base64.getDecoder().decode(content.getBytes(StandardCharsets.UTF_8));return new String(cipher.doFinal(source),StandardCharsets.UTF_8);}catch (Exception e){e.printStackTrace();return null;}
}

三、解决问题

这边有两个方法，两个方法都能解决问题，二选一即可。

3.1 方法一：不要用openjdk

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3.2 方法二：修改KeyGenerator.init

generator.init(new SecureRandom(keyStr.getBytes(StandardCharsets.UTF_8)));

修改成

SecureRandom secureRandom = SecureRandom.getInstance("SHA1PRNG");
secureRandom.setSeed(keyStr.getBytes());
generator.init(secureRandom);

四、全部源码

    private static Key loadKey(String keyStr){Key key = null;try {KeyGenerator generator = KeyGenerator.getInstance("DES");
//            generator.init(new SecureRandom(keyStr.getBytes(StandardCharsets.UTF_8)));SecureRandom secureRandom = SecureRandom.getInstance("SHA1PRNG");secureRandom.setSeed(keyStr.getBytes());generator.init(secureRandom);key = generator.generateKey();}catch (Exception e){e.printStackTrace();}return key;}public static String encrypt(String keyStr,String content){try {Key key = loadKey(keyStr);Cipher cipher = Cipher.getInstance("DES");cipher.init(Cipher.ENCRYPT_MODE,key);byte[] source = cipher.doFinal(content.getBytes(StandardCharsets.UTF_8));return new String(Base64.getEncoder().encode(source),StandardCharsets.UTF_8);}catch (Exception e){e.printStackTrace();return null;}}public static String decrypt(String keyStr,String content){try {Key key = loadKey(keyStr);Cipher cipher = Cipher.getInstance("DES");cipher.init(Cipher.DECRYPT_MODE,key);byte[] source =Base64.getDecoder().decode(content.getBytes(StandardCharsets.UTF_8));return new String(cipher.doFinal(source),StandardCharsets.UTF_8);}catch (Exception e){e.printStackTrace();return null;}}