c# - 加密和解密查询字符串导致附加未知文本

Question

Net 应用程序与 .Net 框架 4.0。要加密和解密查询字符串，我使用下面的代码块。有趣的是当我尝试解密一个字符串时

string a = "username=testuser&email=testmail@yahoo.com"

解密后

string b = "username=testuser&email=testmail@yahoo.com\0\0\0\0\0\0\0\0\0\0\0"

我不确定为什么“\0”附加到我的解密值。

我怎样才能避免这种情况？

我用于加密和解密的代码块是 -

public string EncryptQueryString(string inputText, string key, string salt)
        {
            byte[] plainText = Encoding.UTF8.GetBytes(inputText);

            using (RijndaelManaged rijndaelCipher = new RijndaelManaged())
            {
                PasswordDeriveBytes secretKey = new PasswordDeriveBytes(Encoding.ASCII.GetBytes(key), Encoding.ASCII.GetBytes(salt));
                using (ICryptoTransform encryptor = rijndaelCipher.CreateEncryptor(secretKey.GetBytes(32), secretKey.GetBytes(16)))
                {
                    using (MemoryStream memoryStream = new MemoryStream())
                    {
                        using (CryptoStream cryptoStream = new CryptoStream(memoryStream, encryptor, CryptoStreamMode.Write))
                        {
                            cryptoStream.Write(plainText, 0, plainText.Length);
                            cryptoStream.FlushFinalBlock();
                            string base64 = Convert.ToBase64String(memoryStream.ToArray());

                            // Generate a string that won't get screwed up when passed as a query string.
                            string urlEncoded = HttpUtility.UrlEncode(base64);
                            return urlEncoded;
                        }
                    }
                }
            }
        }

        public string DecryptQueryString(string inputText, string key, string salt)
        {
            byte[] encryptedData = Convert.FromBase64String(inputText);
            PasswordDeriveBytes secretKey = new PasswordDeriveBytes(Encoding.ASCII.GetBytes(key), Encoding.ASCII.GetBytes(salt));

            using (RijndaelManaged rijndaelCipher = new RijndaelManaged())
            {
                using (ICryptoTransform decryptor = rijndaelCipher.CreateDecryptor(secretKey.GetBytes(32), secretKey.GetBytes(16)))
                {
                    using (MemoryStream memoryStream = new MemoryStream(encryptedData))
                    {
                        using (CryptoStream cryptoStream = new CryptoStream(memoryStream, decryptor, CryptoStreamMode.Read))
                        {
                            byte[] plainText = new byte[encryptedData.Length];
                            cryptoStream.Read(plainText, 0, plainText.Length);
                            string utf8 = Encoding.UTF8.GetString(plainText);
                            return utf8;
                        }
                    }
                }
            }
        }

Answer 1

更改以下行:

cryptoStream.Read(plainText, 0, plainText.Length);
string utf8 = Encoding.UTF8.GetString(plainText);
return utf8;

到

StringBuilder outputValue = new StringBuilder();

byte[] buffer = new byte[1024];
int readCount = cryptoStream.Read(buffer, 0, buffer.Length);
while (readCount > 0) {
    outputValue.Append(Encoding.UTF8.GetString(buffer, 0, readCount));
    readCount = cryptoStream.Read(buffer, 0, buffer.Length);
}

return outputValue.ToString();

上面的另一个版本:

String outputValue = String.Empty;
using ( MemoryStream outputStream = new MemoryStream() ) {
    byte[] buffer = new byte[1024];
    int readCount = 0;
    while ((readCount = cryptoStream.Read(buffer, 0, buffer.Length)) > 0) {
        outputStream.Write(buffer, 0, readCount);
    }

    return Encoding.Unicode.GetString(outputStream.ToArray());

}

本质上，Read 是附加空字符来填充字符串。通过将其限制为解密字符的实际数量，您将获得唯一的原始字符串。

以上考虑到 cryptoStream.Read 可能无法一次读取整个字符串。我还没有对此进行测试(今天晚些时候)，但它看起来不错。