1个块(16字节)的Java AES-128加密返回2个块(32字节)作为输出

Question

我使用以下代码进行AES-128加密,以编码16字节的单个块,但编码值的长度为2个32字节的块.我错过了什么吗？

    plainEnc = AES.encrypt("thisisapassword!");

    import java.security.*;
    import java.security.spec.InvalidKeySpecException;
    import javax.crypto.*;
    import sun.misc.*;

    public class AES {

         private static final String ALGO = "AES";
         private static final byte[] keyValue = 
            new byte[] { 'T', 'h', 'e', 'B', 'e', 's', 't',
    'S', 'e', 'c', 'r','e', 't', 'K', 'e', 'y' };

    public static String encrypt(String Data) throws Exception {
            System.out.println("string length: " + (Data.getBytes()).length); //length = 16
            Key key = generateKey();
            Cipher chiper = Cipher.getInstance(ALGO);
            chiper.init(Cipher.ENCRYPT_MODE, key);
            byte[] encVal = chiper.doFinal(Data.getBytes());
            System.out.println("output length: " + encVal.length); //length = 32
            String encryptedValue = new BASE64Encoder().encode(encVal);
            return encryptedValue;
        }

        public static String decrypt(String encryptedData) throws Exception {
            Key key = generateKey();
            Cipher chiper = Cipher.getInstance(ALGO);
            chiper.init(Cipher.DECRYPT_MODE, key);
            byte[] decordedValue = new BASE64Decoder().decodeBuffer(encryptedData);
            byte[] decValue = chiper.doFinal(decordedValue);
            String decryptedValue = new String(decValue);
            return decryptedValue;
        }
        private static Key generateKey() throws Exception {
            Key key = new SecretKeySpec(keyValue, ALGO);
            return key;
    }

}

Answer 1

Cipher.getInstance("AES")返回使用PKCS#5填充的密码.在所有情况下都添加了此填充 - 当明文已经是块大小的倍数时,将添加整个填充块.

在Cipher.getInstance()调用中明确指定您的意图,以避免依赖于默认值并可能导致混淆:

Cipher.getInstance("AES/ECB/NoPadding");

您还将看到您正在使用ECB模式,这在几乎任何情况下都是一个糟糕的选择.