Question

我有一个简单的加密/解密例程，它在Windows窗体应用程序中像超级按钮一样工作，但似乎总是在asp.net应用程序中返回空字符串。

用于加密和解密的代码如下：

   /// <summary>
/// Encrypt a string using dual encryption method. Return a encrypted cipher Text
/// </summary>
/// <param name="toEncrypt">string to be encrypted</param>
/// <param name="useHashing">use hashing? send to for extra secirity</param>
/// <returns></returns>
public static string Encrypt(string toEncrypt, bool useHashing)
{
    byte[] keyArray;
    byte[] toEncryptArray = UTF8Encoding.UTF8.GetBytes(toEncrypt);

    System.Configuration.AppSettingsReader settingsReader = new AppSettingsReader();
    // Get the key from config file
    string key = (string)settingsReader.GetValue("SecurityKey", typeof(String));
    //System.Windows.Forms.MessageBox.Show(key);
    if(useHashing)
    {
        MD5CryptoServiceProvider hashmd5 = new MD5CryptoServiceProvider();
        keyArray = hashmd5.ComputeHash(UTF8Encoding.UTF8.GetBytes(key));
        hashmd5.Clear();
    }
    else
        keyArray = UTF8Encoding.UTF8.GetBytes(key);

    TripleDESCryptoServiceProvider tdes = new TripleDESCryptoServiceProvider
    {
        Key = keyArray,
        Mode = CipherMode.ECB,
        Padding = PaddingMode.PKCS7
    };

    ICryptoTransform cTransform = tdes.CreateEncryptor();
    byte[] resultArray = cTransform.TransformFinalBlock(toEncryptArray, 0, toEncryptArray.Length);
    tdes.Clear();
    return Convert.ToBase64String(resultArray, 0, resultArray.Length);
}

/// <summary>
/// DeCrypt a string using dual encryption method. Return a DeCrypted clear string
/// </summary>
/// <param name="cipherString">encrypted string</param>
/// <param name="useHashing">Did you use hashing to encrypt this data? pass true is yes</param>
/// <returns></returns>
public static string Decrypt(string cipherString, bool useHashing)
{
    byte[] keyArray;
    byte[] toEncryptArray = Convert.FromBase64String(cipherString);

    System.Configuration.AppSettingsReader settingsReader = new AppSettingsReader();
    //Get your key from config file to open the lock!
    string key = (string)settingsReader.GetValue("SecurityKey", typeof(String));

    if(useHashing)
    {
        MD5CryptoServiceProvider hashmd5 = new MD5CryptoServiceProvider();
        keyArray = hashmd5.ComputeHash(UTF8Encoding.UTF8.GetBytes(key));
        hashmd5.Clear();
    }
    else
        keyArray = UTF8Encoding.UTF8.GetBytes(key);

    TripleDESCryptoServiceProvider tdes = new TripleDESCryptoServiceProvider
    {
        Key = keyArray,
        Mode = CipherMode.ECB,
        Padding = PaddingMode.PKCS7
    };

    ICryptoTransform cTransform = tdes.CreateDecryptor();
    byte[] resultArray = cTransform.TransformFinalBlock(toEncryptArray, 0, toEncryptArray.Length);

    tdes.Clear();
    return UTF8Encoding.UTF8.GetString(resultArray);
}

我已经执行了解密代码，一切似乎都很好，直到我上线为止：

byte[] resultArray = cTransform.TransformFinalBlock(toEncryptArray, 0, toEncryptArray.Length);

toEncryptArray包含8个字节的值，但是当将其转换为resultArray时，它始终以零字节数组结尾吗？

我的课程顶部有以下用途：

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

在我的Web.config中，我在appSettings部分中显示以下行：

<add key="SecurityKey" value="SomeRandomTextToMakeAKey" />

谁能看到我所缺少的东西？

Graham Sivill

Answer 1

您仅加密了零字节。通过填充模式（PKCS＃7）可以将其扩展为八个字节，就像PKCS＃7总是填充一样。否则，它将无法区分以01结尾且具有7字节明文和填充字节的解密明文。

因此，如果在解密过程中将填充设置为无填充（PaddingMode.None），则可能会取回8个（填充）字节，其值为08。请注意，您需要将其视为十六进制，因为这些字节表示ASCII中的Backspace。

cTransform.TransformFinalBlock总是返回空字符串吗？

1 个答案: