java - 在 Android 中解密 Rijndael

Question

我基本上需要解密从用 Rijndael 加密的服务器检索到的密码，我以前从未使用过加密/解密，我完全迷失了。我在这个网络的某个地方发现Java有一些不需要外部库就能实现的方法，但我没有得到它。我唯一需要的是解密，因为无论如何我都不会写回服务器。

知道如何执行此操作或在哪里可以找到相关文档吗？

我不知道这段代码是否取自答案 here是我正在寻找的东西，我不太了解它，正如我所说，我以前从未使用过此类东西:

byte[] sessionKey = null; //Where you get this from is beyond the scope of this post
byte[] iv = null ; //Ditto
byte[] plaintext = null; //Whatever you want to encrypt/decrypt
Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
//You can use ENCRYPT_MODE or DECRYPT_MODE
cipher.calling init(Cipher.ENCRYPT_MODE, new SecretKeySpec(sessionKey, "AES"), new IvParameterSpec(iv));
byte[] ciphertext = cipher.doFinal(plaintext);

提前致谢。

Answer 1

这是一个简单的加密实用程序类，可能对您有帮助。它基于 ferenc.hechler 编写的代码，发布在以下网址: http://www.androidsnippets.com/encryptdecrypt-strings 我对其进行了一些更改以满足我的需要。

import java.math.BigInteger;
import java.security.InvalidKeyException;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;

import javax.crypto.BadPaddingException;
import javax.crypto.Cipher;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.KeyGenerator;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;

public class SimpleCrypto {

    private static final int KEY_SIZE = 128;

    public static String encrypt(String seed, String cleartext) throws NoSuchAlgorithmException, InvalidKeyException, NoSuchPaddingException, IllegalBlockSizeException, BadPaddingException {
        final byte[] rawKey = getRawKey(seed.getBytes());
        final byte[] result = encrypt(rawKey, cleartext.getBytes());
        return bin2hex(result);
    }

    public static String decrypt(String seed, String encrypted) throws NoSuchAlgorithmException, InvalidKeyException, IllegalBlockSizeException, BadPaddingException, NoSuchPaddingException {
        final byte[] rawKey = getRawKey(seed.getBytes());
        final byte[] enc = toByte(encrypted);
        final byte[] result = decrypt(rawKey, enc);
        return new String(result);
    }

    public static String decrypt(String seed, byte[] encrypted) throws NoSuchAlgorithmException, InvalidKeyException, IllegalBlockSizeException, BadPaddingException, NoSuchPaddingException {
        final byte[] rawKey = getRawKey(seed.getBytes());
        final byte[] result = decrypt(rawKey, encrypted);
        return new String(result);
    }

    private static byte[] getRawKey(byte[] seed) throws NoSuchAlgorithmException {
        final KeyGenerator kgen = KeyGenerator.getInstance("AES");
        final SecureRandom sr = SecureRandom.getInstance("SHA1PRNG");
        sr.setSeed(seed);
        kgen.init(KEY_SIZE, sr); // 192 and 256 bits may not be available
        final SecretKey skey = kgen.generateKey();
        byte[] raw = skey.getEncoded();
        return raw;
    }

    public static byte[] encrypt(byte[] raw, byte[] clear) throws NoSuchAlgorithmException, NoSuchPaddingException, InvalidKeyException, IllegalBlockSizeException, BadPaddingException {
        final SecretKeySpec skeySpec = new SecretKeySpec(raw, "AES");
        final Cipher cipher = Cipher.getInstance("AES");
        cipher.init(Cipher.ENCRYPT_MODE, skeySpec);
        final byte[] encrypted = cipher.doFinal(clear);
        return encrypted;
    }

    public static byte[] decrypt(byte[] raw, byte[] encrypted) throws IllegalBlockSizeException, BadPaddingException, NoSuchAlgorithmException, NoSuchPaddingException, InvalidKeyException {
        final SecretKeySpec skeySpec = new SecretKeySpec(raw, "AES");
        final Cipher cipher = Cipher.getInstance("AES");
        cipher.init(Cipher.DECRYPT_MODE, skeySpec);
        final byte[] decrypted = cipher.doFinal(encrypted);
        return decrypted;
    }

    public static String toHex(String txt) {
        return bin2hex(txt.getBytes());
    }

    public static String fromHex(String hex) {
        return new String(toByte(hex));
    }

    public static byte[] toByte(String hexString) {
        final int len = hexString.length() / 2;
        final byte[] result = new byte[len];
        for (int i = 0; i < len; i++) {
            result[i] = Integer.valueOf(hexString.substring(2 * i, 2 * i + 2), 16).byteValue();
        }
        return result;
    }

    public static byte[] getHash(String str) {
        MessageDigest digest = null;
        try {
            digest = MessageDigest.getInstance("SHA-256");
        } catch (NoSuchAlgorithmException ex) {
            ex.printStackTrace();
        }
        digest.reset();
        return digest.digest(str.getBytes());
    }

    static String bin2hex(byte[] data) {
        return String.format("%0" + (data.length * 2) + "X", new BigInteger(1, data));
    }
}

以下是如何使用它来解密内容:

    final String ssid = "MY_WIFI_SSID";
    final String encWifiKey = "myEncryptedWifiKeyString";

    String wifiKey = "";
    try {
        wifiKey = new String(SimpleCrypto.decrypt(SimpleCrypto.getHash(ssid), Base64.decode(encWifiKey, Base64.DEFAULT)));
    } catch (InvalidKeyException e) {
        e.printStackTrace();
    } catch (IllegalBlockSizeException e) {
        e.printStackTrace();
    } catch (BadPaddingException e) {
        e.printStackTrace();
    } catch (NoSuchAlgorithmException e) {
        e.printStackTrace();
    } catch (NoSuchPaddingException e) {
        e.printStackTrace();
    }