AES錯誤：鑑於最終塊未正確填充

Question

我需要此錯誤的幫助：給定最終塊未正確填充。從標題中可以看出，我正在與AES合作。

這裏是行的代碼，其中的錯誤：

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

下面是完整的代碼：

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); 
} 

}

Answer 1

根據你的評論，你很接近獲得加密工作。

你需要從你的加密/解密方法移動IV代碼到其他地方，像這樣

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

那麼ivspec傳遞到兩個加密和解密方法（使它們看起來像encrypt(String,AlgorithmParameterSpec)） ，這樣你的加密和解密都有相同的iv。

而且，不要對decryptedByteArray調用printBase64Binary，而是調用new String(decryptedByteArray, "UTF-8")

Answer 2

你有兩個問題，第一你編碼輸出到一個十六進制字符串，但不解碼解碼方法。其次，你生成一個隨機的IV，但不要再次使用它來解碼。

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

public String decrypt(byte[] 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[] decrypted = cipher.doFinal(cryptedText); 
    decryptedText = new String(decrypted, "UTF-8"); 
    return decryptedText; 
} 



String decryptedText = aes.decrypt(aes.encrypt(message)).toString();