AES错误：给定最后块未正确填充 [英] AES Error: Given final block not properly padded

问题描述

我需要帮助这个错误：给定最后块未正确填充。

I need help with this error: Given final block not properly padded. As you can see from the title, I am working with AES.

这里是代码行在哪里是错误：

Here is the code of line where is error:

 byte[] decrypted = cipher.doFinal(bytes);

以下是完整代码：

public class AESCrypt {
private final Cipher cipher;
private final SecretKeySpec key;
private String encryptedText, decryptedText;

public AESCrypt(String password) throws Exception {
    // hash password with SHA-256 and crop the output to 128-bit for key
    MessageDigest digest = MessageDigest.getInstance("SHA-256");
    digest.update(password.getBytes("UTF-8"));
    byte[] keyBytes = new byte[16];
    System.arraycopy(digest.digest(), 0, keyBytes, 0, keyBytes.length);

    cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
    key = new SecretKeySpec(keyBytes, "AES");
}

public String encrypt(String plainText) throws Exception {
    byte[] iv = new byte[cipher.getBlockSize()];
    new SecureRandom().nextBytes(iv);
    AlgorithmParameterSpec spec = new IvParameterSpec(iv);
    cipher.init(Cipher.ENCRYPT_MODE, key, spec);
    byte[] encrypted = cipher.doFinal(plainText.getBytes());
    encryptedText = asHex(encrypted);
    return encryptedText;
}

public String decrypt(String cryptedText) throws Exception {
    byte[] iv = new byte[cipher.getBlockSize()];
    AlgorithmParameterSpec spec = new IvParameterSpec(iv);
    cipher.init(Cipher.DECRYPT_MODE, key, spec);
    // decrypt the message
    byte[] bytes = cryptedText.getBytes("UTF-8");
    byte[] decrypted = cipher.doFinal(bytes);
    decryptedText = asHex(decrypted);
    System.out.println("Desifrovani tekst: " + decryptedText + "\n");

    return decryptedText;
}

public static String asHex(byte buf[]) {
    StringBuilder strbuf = new StringBuilder(buf.length * 2);
    int i;
    for (i = 0; i < buf.length; i++) {
        if (((int) buf[i] & 0xff) < 0x10) {
            strbuf.append("0");
        }
        strbuf.append(Long.toString((int) buf[i] & 0xff, 16));
    }
    return strbuf.toString();
}

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

    System.out.print("....AES....\n");

    String message = "MESSAGE";
    String password = "PASSWORD";

    System.out.println("MSG:" + message);

    AESCrypt aes = new AESCrypt(password);
    String encryptedText = aes.encrypt(message).toString();
    System.out.println("SIFROVANA PORUKA: " + encryptedText);
    String decryptedText = aes.decrypt(encryptedText).toString();       
    System.out.print("DESIFROVANA PORUKA: " + decryptedText);
}

}

推荐答案

根据你的评论，你很接近加密工作。

Per your comment, you are pretty close to getting the crypto working.

您需要将IV代码从加密/解密方法移动到其他位置，例如

You need to move the IV generation code from your encryption/decryption methods to somewhere else, like so

public AlgorithmParameterSpec getIV() {
AlgorithmParameterSpec ivspec;
byte[] iv = new byte[cipher.getBlockSize()];
new SecureRandom().nextBytes(iv);
ivspec = new IvParameterSpec(iv);
}

然后将ivspec传递到加密和解密方法 encrypt（String，AlgorithmParameterSpec）），因此您对加密和解密都有相同的iv。

then pass that ivspec into both the encrypt and decrypt methods (making them look like encrypt(String,AlgorithmParameterSpec)), so that you have the same iv for both encryption and decryption.

，不要在decryptptedByteArray上调用 printBase64Binary ，而是调用 new String（decryptedByteArray，UTF-8）

Also, don't call printBase64Binary on the decryptedByteArray, instead call new String(decryptedByteArray, "UTF-8")

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