为什么试图加密字符串时，我得到BadPaddingException？

问题描述

我创建一个加密类在我的Andr​​oid项目encryt /解密的二进制数据，通过这种link.

I create an Encryption class to encryt/decrypt binary data in my Android project, by this link.

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));
    }
}

然后我运行的主要活动code：

Then I run the code in main activity:

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

然后我得到一个 BadPaddingException 时，在执行以下code测试（）：

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

有趣的是，我比创建Android项目以外的Java项目。而code运行得很好，没有任何例外。

The funny thing is that I created a Java project other than Android project. And the code is running just fine without any exception.

这有什么错我的code？

What's wrong with my code?

推荐答案

SHA1PRNG是的不的密钥导出功能，并实施可跨供应商有所不同。请使用正确的KDF如PBKDF2的密码。 这是一个关键的是的不的一个关键，它是一个字符串。

"SHA1PRNG" is not a key derivation function, and the implementation may differ across providers. Please use a correct KDF such as PBKDF2 for passwords. "This is a key" is not a key, it is a string.

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