Java AES giving BadPaddingException

Question

我正在尝试用Java为我的程序编写一个简单的加密和解密方法。它应该使用另一个字符串作为密钥来加密和解密一个字符串。

在测试时，发生了BadPaddingException。

我目前的加密方法：

public String encrypt(String strToEncrypt, String secretKey) {
try {
SecretKeyFactory factory = SecretKeyFactory.getInstance("PBKDF2WithHmacSHA1");
byte[] salt = new Hash().hashString(secretKey).getBytes();
KeySpec spec = new PBEKeySpec(secretKey.toCharArray(), salt, 65536, 256);
SecretKey tmp = factory.generateSecret(spec);
SecretKey secret = new SecretKeySpec(tmp.getEncoded(), "AES");
Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
byte[] iv = cipher.getParameters().getParameterSpec(IvParameterSpec.class).getIV();
IvParameterSpec ivspec = new IvParameterSpec(iv);
cipher.init(Cipher.ENCRYPT_MODE, secret, ivspec);
byte[] ciphertext = cipher.doFinal(strToEncrypt.getBytes("UTF-8"));
System.out.println("Finished encryption");
return new Base64().encodeToString(ciphertext);
} catch (Exception e) {
e.printStackTrace();
return null;
}
}

我目前的解密方法：

public String decrypt(String strToDecrypt, String secretKey) {  
try {
SecretKeyFactory factory = SecretKeyFactory.getInstance("PBKDF2WithHmacSHA1");
byte[] salt = new Hash().hashString(secretKey).getBytes();
KeySpec spec = new PBEKeySpec(secretKey.toCharArray(), salt, 65536, 256);
SecretKey tmp = factory.generateSecret(spec);
SecretKey secret = new SecretKeySpec(tmp.getEncoded(), "AES");
Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
byte[] iv = cipher.getParameters().getParameterSpec(IvParameterSpec.class).getIV();
IvParameterSpec ivspec = new IvParameterSpec(iv);
cipher.init(Cipher.DECRYPT_MODE, secret, ivspec);

byte[] decodedPlaintext = new Base64().decode(strToDecrypt);
byte[] plaintext = cipher.doFinal(decodedPlaintext);
System.out.println("Finished decryption");
return new Base64().encodeToString(plaintext);
} catch (Exception e) {
e.printStackTrace();
return null;
}
}

我收到以下异常：

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:975)
at java.base/com.sun.crypto.provider.CipherCore.fillOutputBuffer(CipherCore.java:1056)
at java.base/com.sun.crypto.provider.CipherCore.doFinal(CipherCore.java:853)
at java.base/com.sun.crypto.provider.AESCipher.engineDoFinal(AESCipher.java:446)
at java.base/javax.crypto.Cipher.doFinal(Cipher.java:2202)

Answer 1

在迈克尔和詹姆斯·K·波尔克总统的善意帮助下，我可以让en-和解密工作，并改善盐的生成。我的错误是，我没有使用相同的IvParameterSpec进行加密和解密。

我的加密方法：

public static String encrypt(String strToEncrypt, String secretKey) {
try {
SecretKeyFactory factory = SecretKeyFactory.getInstance("PBKDF2WithHmacSHA1");
byte[] salt = new byte[16];
SecureRandom.getInstanceStrong().nextBytes(salt);
KeySpec spec = new PBEKeySpec(secretKey.toCharArray(), salt, 65536, 256);
SecretKey tmp = factory.generateSecret(spec);
SecretKey secret = new SecretKeySpec(tmp.getEncoded(), "AES");
Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
byte[] iv = cipher.getParameters().getParameterSpec(IvParameterSpec.class).getIV();
IvParameterSpec ivspec = new IvParameterSpec(iv);
cipher.init(Cipher.ENCRYPT_MODE, secret, ivspec);
byte[] ivBytes = ivspec.getIV();
byte[] ciphertext = cipher.doFinal(strToEncrypt.getBytes("UTF-8"));
System.out.println("Finished encryption");
byte[] outputBytes = concat(concat(salt, ivBytes), ciphertext);
return new Base64().encodeToString(outputBytes);
} catch (Exception e) {
e.printStackTrace();
return null;
}
}

我的解密方法：

public static String decrypt(String strToDecrypt, String secretKey) {
try {
byte[] decodedCiphertext = new Base64().decode(strToDecrypt);
SecretKeyFactory factory = SecretKeyFactory.getInstance("PBKDF2WithHmacSHA1");
byte[] salt = Arrays.copyOfRange(decodedCiphertext, 0, 16);
KeySpec spec = new PBEKeySpec(secretKey.toCharArray(), salt, 65536, 256);
SecretKey tmp = factory.generateSecret(spec);
SecretKey secret = new SecretKeySpec(tmp.getEncoded(), "AES");
Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
byte[] iv = Arrays.copyOfRange(decodedCiphertext, 16, 32);
IvParameterSpec ivspec = new IvParameterSpec(iv);
cipher.init(Cipher.DECRYPT_MODE, secret, ivspec);

byte[] plaintext = cipher.doFinal(Arrays.copyOfRange(decodedCiphertext, 32, decodedCiphertext.length));
System.out.println("Finished decryption");
return new String(plaintext, "UTF-8");
} catch (Exception e) {
e.printStackTrace();
return null;
}
}