如何加密/解密 XML 文件？

我正在尝试加密/解密 XML 文件。我找到了这个加密示例，但我不知道如何解密？任何想法？谢谢！

        // Load this XML file
        System.Xml.XmlDocument myDoc = new System.Xml.XmlDocument();
        myDoc.Load(@"c:\persons.xml");
        // Get a specified element to be encrypted
        System.Xml.XmlElement element = myDoc.GetElementsByTagName("Persons")[0] as System.Xml.XmlElement;

        // Create a new TripleDES key. 
        System.Security.Cryptography.TripleDESCryptoServiceProvider tDESkey = new System.Security.Cryptography.TripleDESCryptoServiceProvider();

        // Form a Encrypted XML with the Key
        System.Security.Cryptography.Xml.EncryptedXml encr = new System.Security.Cryptography.Xml.EncryptedXml();
        encr.AddKeyNameMapping("Deskey", tDESkey);

        // Encrypt the element data
        System.Security.Cryptography.Xml.EncryptedData ed = encr.Encrypt(element, "Deskey");

        // Replace the existing data with the encrypted data
        System.Security.Cryptography.Xml.EncryptedXml.ReplaceElement(element, ed, false);

        // saves the xml file with encrypted data
        myDoc.Save(@"c:\encryptedpersons.xml");

但我不知道如何解密？有任何想法吗？谢谢！

像这样的事情：

public static class Encryption
{
    private const string InitVector = "T=A4rAzu94ez-dra";
    private const int KeySize = 256;
    private const int PasswordIterations = 1000; //2;
    private const string SaltValue = "d=?ustAF=UstenAr3B@pRu8=ner5sW&h59_Xe9P2za-eFr2fa&ePHE@ras!a+uc@";

    public static string Decrypt(string encryptedText, string passPhrase)
    {
        byte[] encryptedTextBytes = Convert.FromBase64String(encryptedText);
        byte[] initVectorBytes = Encoding.UTF8.GetBytes(InitVector);
        byte[] passwordBytes = Encoding.UTF8.GetBytes(passPhrase);
        string plainText;
        byte[] saltValueBytes = Encoding.UTF8.GetBytes(SaltValue);

        Rfc2898DeriveBytes password = new Rfc2898DeriveBytes(passwordBytes, saltValueBytes, PasswordIterations);
        byte[] keyBytes = password.GetBytes(KeySize / 8);

        RijndaelManaged rijndaelManaged = new RijndaelManaged { Mode = CipherMode.CBC };

        try
        {
            using (ICryptoTransform decryptor = rijndaelManaged.CreateDecryptor(keyBytes, initVectorBytes))
            {
                using (MemoryStream memoryStream = new MemoryStream(encryptedTextBytes))
                {
                    using (CryptoStream cryptoStream = new CryptoStream(memoryStream, decryptor, CryptoStreamMode.Read))
                    {
                        //TODO: Need to look into this more. Assuming encrypted text is longer than plain but there is probably a better way
                        byte[] plainTextBytes = new byte[encryptedTextBytes.Length];

                        int decryptedByteCount = cryptoStream.Read(plainTextBytes, 0, plainTextBytes.Length);
                        plainText = Encoding.UTF8.GetString(plainTextBytes, 0, decryptedByteCount);
                    }
                }
            }
        }
        catch (CryptographicException)
        {
            plainText = string.Empty; // Assume the error is caused by an invalid password
        }

        return plainText;
    }

    public static string Encrypt(string plainText, string passPhrase)
    {
        string encryptedText;
        byte[] initVectorBytes = Encoding.UTF8.GetBytes(InitVector);
        byte[] passwordBytes = Encoding.UTF8.GetBytes(passPhrase);
        byte[] plainTextBytes = Encoding.UTF8.GetBytes(plainText);
        byte[] saltValueBytes = Encoding.UTF8.GetBytes(SaltValue);

        Rfc2898DeriveBytes password = new Rfc2898DeriveBytes(passwordBytes, saltValueBytes, PasswordIterations);
        byte[] keyBytes = password.GetBytes(KeySize / 8);

        RijndaelManaged rijndaelManaged = new RijndaelManaged {Mode = CipherMode.CBC};

        using (ICryptoTransform encryptor = rijndaelManaged.CreateEncryptor(keyBytes, initVectorBytes))
        {
            using (MemoryStream memoryStream = new MemoryStream())
            {
                using (CryptoStream cryptoStream = new CryptoStream(memoryStream, encryptor, CryptoStreamMode.Write))
                {
                    cryptoStream.Write(plainTextBytes, 0, plainTextBytes.Length);
                    cryptoStream.FlushFinalBlock();

                    byte[] cipherTextBytes = memoryStream.ToArray();
                    encryptedText = Convert.ToBase64String(cipherTextBytes);
                }
            }
        }

        return encryptedText;
    }
}

Edit:

Sani Huttunen 指出，如果您将使用相同的密码加密多条数据，我上面的静态实现会出现严重的性能问题。你可以在这里读更多关于它的内容：http://jmpstart.wordpress.com/2009/09/29/proper-use-of-rfc2898derivebytes/ http://jmpstart.wordpress.com/2009/09/29/proper-use-of-rfc2898derivebytes/

Edit:如果您需要使用相同的密码执行多次加密/解密（原始密码约 32 毫秒，新密码约 1 毫秒），则非静态实现的效率要高得多。

public class SimpleEncryption
{
    #region Constructor
    public SimpleEncryption(string password)
    {
        byte[] passwordBytes = Encoding.UTF8.GetBytes(password);
        byte[] saltValueBytes = Encoding.UTF8.GetBytes(SaltValue);

        _DeriveBytes = new Rfc2898DeriveBytes(passwordBytes, saltValueBytes, PasswordIterations);
        _InitVectorBytes = Encoding.UTF8.GetBytes(InitVector);
        _KeyBytes = _DeriveBytes.GetBytes(32);
    }
    #endregion

    #region Private Fields
    private readonly Rfc2898DeriveBytes _DeriveBytes;
    private readonly byte[] _InitVectorBytes;
    private readonly byte[] _KeyBytes;
    #endregion

    private const string InitVector = "T=A4rAzu94ez-dra";
    private const int PasswordIterations = 1000; //2;
    private const string SaltValue = "d=?ustAF=UstenAr3B@pRu8=ner5sW&h59_Xe9P2za-eFr2fa&ePHE@ras!a+uc@";

    public string Decrypt(string encryptedText)
    {
        byte[] encryptedTextBytes = Convert.FromBase64String(encryptedText);
        string plainText;

        RijndaelManaged rijndaelManaged = new RijndaelManaged { Mode = CipherMode.CBC };

        try
        {
            using (ICryptoTransform decryptor = rijndaelManaged.CreateDecryptor(_KeyBytes, _InitVectorBytes))
            {
                using (MemoryStream memoryStream = new MemoryStream(encryptedTextBytes))
                {
                    using (CryptoStream cryptoStream = new CryptoStream(memoryStream, decryptor, CryptoStreamMode.Read))
                    {
                        //TODO: Need to look into this more. Assuming encrypted text is longer than plain but there is probably a better way
                        byte[] plainTextBytes = new byte[encryptedTextBytes.Length];

                        int decryptedByteCount = cryptoStream.Read(plainTextBytes, 0, plainTextBytes.Length);
                        plainText = Encoding.UTF8.GetString(plainTextBytes, 0, decryptedByteCount);
                    }
                }
            }
        }
        catch (CryptographicException exception)
        {
            plainText = string.Empty; // Assume the error is caused by an invalid password
        }

        return plainText;
    }

    public string Encrypt(string plainText)
    {
        string encryptedText;
        byte[] plainTextBytes = Encoding.UTF8.GetBytes(plainText);

        RijndaelManaged rijndaelManaged = new RijndaelManaged {Mode = CipherMode.CBC};

        using (ICryptoTransform encryptor = rijndaelManaged.CreateEncryptor(_KeyBytes, _InitVectorBytes))
        {
            using (MemoryStream memoryStream = new MemoryStream())
            {
                using (CryptoStream cryptoStream = new CryptoStream(memoryStream, encryptor, CryptoStreamMode.Write))
                {
                    cryptoStream.Write(plainTextBytes, 0, plainTextBytes.Length);
                    cryptoStream.FlushFinalBlock();

                    byte[] cipherTextBytes = memoryStream.ToArray();
                    encryptedText = Convert.ToBase64String(cipherTextBytes);
                }
            }
        }

        return encryptedText;
    }
}