用下面这种方式解密的数据，能不能得到它的加密方式？

        static string Password = "XXXXX";

        public static string Decrypt(string source)
        {
            string s;

            if (String.IsNullOrEmpty(source))
                throw new ArgumentException("No data given");
            byte[] inputData = Convert.FromBase64String(source);
            if (inputData.Length < 8)
                throw new ArgumentException("Invalid input data");

            byte[] salt = new byte[8];
            for (int i = 0; i < salt.Length; i++)
            {
                salt[i] = inputData[i];
            }

            Rfc2898DeriveBytes rfc2898DeriveBytes = new Rfc2898DeriveBytes(Password, salt);
            Rijndael rijndael = Rijndael.Create();
            rijndael.Padding = PaddingMode.ISO10126;
            rijndael.IV = rfc2898DeriveBytes.GetBytes(rijndael.BlockSize / 8);
            rijndael.Key = rfc2898DeriveBytes.GetBytes(rijndael.KeySize / 8);
            using (MemoryStream memoryStream = new MemoryStream())
            using (
                CryptoStream cryptoStream =
                    new CryptoStream(memoryStream, rijndael.CreateDecryptor(), CryptoStreamMode.Write))
            {
                cryptoStream.Write(inputData, 8, inputData.Length - 8);
                cryptoStream.Close();
                byte[] bytes = memoryStream.ToArray();
                s = Encoding.Unicode.GetString(bytes);
            }
            return s;
        }

对加密解密这块不熟，请有经验的朋友解答，谢谢。
如果需要，我有几个样例数据与加密后的结果。

posted on 2007-05-06 00:01 deerchao 阅读(298) 评论(6) 编辑收藏网摘

#1楼  2007-05-06 10:51 Edwin Liu

加密字串的前8个字节就是salt,后面的就是加密数据,使用的是对称加密,由Salt与Password就能得到rfc2898DeriveBytes,后面的就可以解密了。

一般来说，对于对称加密，只要得到加密的源码，一定就能解密回复引用查看

#2楼 [楼主] 2007-05-06 14:42 deerchao

@Edwin Liu
谢谢，已经搞定。

public static string Encrypt(string param)
{
byte[] salt = new byte[] { (byte)'a', (byte)'b', (byte)'c', (byte)'d', (byte)'e', (byte)'f', (byte)'g', (byte)'h' };
byte[] bytes = Encoding.Unicode.GetBytes(param);

Rfc2898DeriveBytes deriveBytes = new Rfc2898DeriveBytes(Password, salt);
Rijndael rijndael = Rijndael.Create();
byte[] iv = deriveBytes.GetBytes(rijndael.BlockSize / 8);
byte[] key = deriveBytes.GetBytes(rijndael.KeySize / 8);
rijndael.Padding = PaddingMode.ISO10126;
rijndael.IV = iv;
rijndael.Key = key;

using (MemoryStream memStream = new MemoryStream())
using (CryptoStream cryptoStream = new CryptoStream(memStream, rijndael.CreateEncryptor(), CryptoStreamMode.Write))
{
cryptoStream.Write(bytes, 0, bytes.Length);
cryptoStream.Close();
byte[] outputData = memStream.ToArray();
byte[] result = new byte[outputData.Length + 8];

Array.Copy(salt,result,8);
Array.Copy(outputData, 0, result, 8, outputData.Length);
return Convert.ToBase64String(result);
}
}
回复引用查看

#3楼  2007-05-07 10:29 Edwin Liu

salt一般都不是常量,否则也不称之为Salt了.可由.Net的加密类获取随机码.

另一种更安全的做法是:文件=Salt长度(8字节)+Salt+数据,而[Salt长度]指示了数据的起始位置,Salt由数据的簦名得到(解密时可验证该簦名,以决断数据是否被更改过),[Salt长度]可以是明文也可以是内定的一种对称加密方式加密的数据.

如果要求不是很严格,可以只对[Salt长度]加密而不对[数据]加密,这样速度要快很多,特别是处理大数据的情况. 回复引用查看