Android和C之间的加密兼容#

得到了我的一些帮助 http://oogifu.blogspot.com/2009/01/aes-in-java-and-c.html

这是我的Java类:

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;
    }
}

我曾经 http://iharder.sourceforge.net/current/java/base64/

这是我的课程:

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);
        }
    }
}

我真的希望这能帮助别人!

在提供的c#源代码示例中,请注意这一行:

Encoding.ASCII.GetString(newClearData);

UTF-8是Android的默认编码,因此加密字符串(特别是非ASCII字符,如中文)将传递给C#,假设为UTF-8。如果使用ASCII编码解码回字符串,文本将被置乱。这是一个更好的,

Encoding.UTF8.GetString(newClearData);

谢谢

是的,它应该是好的,只要我们的密钥大小是相同的-128位AES和正确的分组密码模式(CBC)。您可能会遇到填充问题,但这应该很容易解决。我最近在Java和Python中遇到了这些问题,但最终一切正常。用于编码的Base64在HTTP上应该可以使用。祝你好运

您链接到的Android示例似乎使用ECB模式,因此不安全。理解所选块模式的含义至关重要。在这个级别上,加密很容易出错,导致系统不如您想象的那么安全。

你可以从这个开始 wikipedia article Practical Cryptography' 对于任何实现加密安全的人来说都是非常有价值的。

至于对字符串进行编码,如果必须将字符串转换为ASCII文本Base64,这是一种很好的方法,但我建议您研究使用HTTP PUT或POST来节省这一额外步骤。

internet上的大多数示例都是AES的弱实现。为了使实现强大,应该始终使用random IV,并对密钥进行散列。

有关AES更安全(随机IV+散列密钥)的跨平台(android、ios、c#)实现,请参见我的答案- https://stackoverflow.com/a/24561148/2480840