为什么我得到BadPaddingException时，试图加密字符串

Question

我创建了一个Encryption类来加密/解密我的Android项目中的二进制数据，通过这个链接。

package com.my.package;
import java.security.SecureRandom;
import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;
// TODO Incomplete class
public class Encryption {
    private static final byte[] salt = { (byte) 0xA4, (byte) 0x0B, (byte) 0xC8,
            (byte) 0x34, (byte) 0xD6, (byte) 0x95, (byte) 0xF3, (byte) 0x13 };
    private static int BLOCKS = 128;
    private static byte[] encrypt(byte[] raw, byte[] clear) throws Exception {
        SecretKeySpec skeySpec = new SecretKeySpec(raw, "AES");
        Cipher cipher = Cipher.getInstance("AES");
        cipher.init(Cipher.ENCRYPT_MODE, skeySpec);
        byte[] encrypted = cipher.doFinal(clear);
        return encrypted;
    }
    private static byte[] decrypt(byte[] raw, byte[] encrypted)
            throws Exception {
        SecretKeySpec skeySpec = new SecretKeySpec(raw, "AES");
        Cipher cipher = Cipher.getInstance("AES");
        cipher.init(Cipher.DECRYPT_MODE, skeySpec);
        byte[] decrypted = cipher.doFinal(encrypted);
        return decrypted;
    }
    private static byte[] getKey() throws Exception {
        byte[] keyStart = "this is a key".getBytes();
        KeyGenerator kgen = KeyGenerator.getInstance("AES");
        SecureRandom sr = SecureRandom.getInstance("SHA1PRNG");
        sr.setSeed(keyStart);
        kgen.init(128, sr); // 192 and 256 bits may not be available
        SecretKey skey = kgen.generateKey();
        byte[] key = skey.getEncoded();
        return key;
    }
    public static void test() {
        String test = "My Name Is Dragon Warrior";
        byte[] e = null;
        try {
            e = encrypt(getKey(), test.getBytes());
        } catch (Exception e1) {
            // TODO Auto-generated catch block
            e1.printStackTrace();
        }
        byte[] d = null;
        try {
            d = decrypt(getKey(), e);
        } catch (Exception e1) {
            // TODO Auto-generated catch block
            e1.printStackTrace();
        }
        System.out.println(new String(d));
    }
}

然后在主活动中运行代码:

public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    // ...
    Encryption.test();
    // ...
}

当以下代码在test()中执行时，我得到一个BadPaddingException:

try {
    d = decrypt(getKey(), e);
} catch (Exception e1) {
    // TODO Auto-generated catch block
    e1.printStackTrace();
}

有趣的是，我创建了一个Java项目而不是Android项目。代码运行正常，没有任何异常。

我的代码有什么问题?

Answer 1

"SHA1PRNG" 不是密钥派生函数，不同的提供者的实现可能不同。请使用正确的KDF(例如PBKDF2)作为密码。"This is a key" 不是键，它是一个字符串。