加密Android和C＃之间的兼容 [英] Encryption compatible between Android and C#

问题描述

我发现大量的例子怎么办加密在C＃中，和一对夫妇为Android，但我特别寻找一种方式来处理加密（使用类似AES，TripleDES的，等等）Android和最终风被解密在C＃。我发现了一个例如在Android和<一个编码AES href="http://stackoverflow.com/questions/273452/c-implementations-of-aes-encryption">encoding/decoding AES 在C＃中，但我不知道这是兼容的（C＃需要一个IV，没有什么是在Android例如规定了这一点）。此外，在编码加密的字符串进行传输通过HTTP的好方法推荐的（Base64？）将是有益的。谢谢你。

I've found plenty of examples how to do encryption in C#, and a couple for Android, but I'm particularly looking for a way to handle encrypting (using something like AES, TripleDES, etc.) from Android, and eventually wind up being decrypted in C#. I found an example for encoding AES in Android and encoding/decoding AES in C# but am not sure if these are compatible (C# requires an IV, nothing is specified for this in the Android example). Also, a recommendation on a good way of encoding the encrypted string for transmission over HTTP (Base64?) would be helpful. Thanks.

推荐答案

得到<一一些帮助href="http://oogifu.blogspot.com/2009/01/aes-in-java-and-c.html">http://oogifu.blogspot.com/2009/01/aes-in-java-and-c.html.

下面是我的Java类：

Here is my Java class:

package com.neocodenetworks.smsfwd;

import java.security.*;
import javax.crypto.*;
import javax.crypto.spec.*;
import android.util.Log;

public class Crypto {
    public static final String TAG = "smsfwd";

    private static Cipher aesCipher;
    private static SecretKey secretKey;
    private static IvParameterSpec ivParameterSpec;

    private static String CIPHER_TRANSFORMATION = "AES/CBC/PKCS5Padding";
    private static String CIPHER_ALGORITHM = "AES";
    // Replace me with a 16-byte key, share between Java and C#
    private static byte[] rawSecretKey = {0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
                                          0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00};

    private static String MESSAGEDIGEST_ALGORITHM = "MD5";

    public Crypto(String passphrase) {
        byte[] passwordKey = encodeDigest(passphrase);

        try {
            aesCipher = Cipher.getInstance(CIPHER_TRANSFORMATION);
        } catch (NoSuchAlgorithmException e) {
            Log.e(TAG, "No such algorithm " + CIPHER_ALGORITHM, e);
        } catch (NoSuchPaddingException e) {
            Log.e(TAG, "No such padding PKCS5", e);
        }

        secretKey = new SecretKeySpec(passwordKey, CIPHER_ALGORITHM);
        ivParameterSpec = new IvParameterSpec(rawSecretKey);
    }

    public String encryptAsBase64(byte[] clearData) {
        byte[] encryptedData = encrypt(clearData);
        return net.iharder.base64.Base64.encodeBytes(encryptedData);
    }

    public byte[] encrypt(byte[] clearData) {
        try {
            aesCipher.init(Cipher.ENCRYPT_MODE, secretKey, ivParameterSpec);
        } catch (InvalidKeyException e) {
            Log.e(TAG, "Invalid key", e);
            return null;
        } catch (InvalidAlgorithmParameterException e) {
            Log.e(TAG, "Invalid algorithm " + CIPHER_ALGORITHM, e);
            return null;
        }

        byte[] encryptedData;
        try {
            encryptedData = aesCipher.doFinal(clearData);
        } catch (IllegalBlockSizeException e) {
            Log.e(TAG, "Illegal block size", e);
            return null;
        } catch (BadPaddingException e) {
            Log.e(TAG, "Bad padding", e);
            return null;
        }
        return encryptedData;
    }

    private byte[] encodeDigest(String text) {
        MessageDigest digest;
        try {
            digest = MessageDigest.getInstance(MESSAGEDIGEST_ALGORITHM);
            return digest.digest(text.getBytes());
        } catch (NoSuchAlgorithmException e) {
            Log.e(TAG, "No such algorithm " + MESSAGEDIGEST_ALGORITHM, e);
        }

        return null;
    }
}

我用<一个href="http://iharder.sourceforge.net/current/java/base64/">http://iharder.sourceforge.net/current/java/base64/为base64编码。

I used http://iharder.sourceforge.net/current/java/base64/ for the base64 encoding.

下面是我的C＃类：

using System;
using System.Text;
using System.Security.Cryptography;

namespace smsfwdClient
{
    public class Crypto
    {
        private ICryptoTransform rijndaelDecryptor;
        // Replace me with a 16-byte key, share between Java and C#
        private static byte[] rawSecretKey = {0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
                                              0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00};

        public Crypto(string passphrase)
        {
            byte[] passwordKey = encodeDigest(passphrase);
            RijndaelManaged rijndael = new RijndaelManaged();
            rijndaelDecryptor = rijndael.CreateDecryptor(passwordKey, rawSecretKey);
        }

        public string Decrypt(byte[] encryptedData)
        {
            byte[] newClearData = rijndaelDecryptor.TransformFinalBlock(encryptedData, 0, encryptedData.Length);
            return Encoding.ASCII.GetString(newClearData);
        }

        public string DecryptFromBase64(string encryptedBase64)
        {
            return Decrypt(Convert.FromBase64String(encryptedBase64));
        }

        private byte[] encodeDigest(string text)
        {
            MD5CryptoServiceProvider x = new System.Security.Cryptography.MD5CryptoServiceProvider();
            byte[] data = Encoding.ASCII.GetBytes(text);
            return x.ComputeHash(data);
        }
    }
}

我真的希望这可以帮助别人！

I really hope this helps someone else!

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