c# - 如何使用 AES 在一个程序中加密，在另一个程序中解密

Question

有人告诉我not to use RSA 加密简单文本但使用 AES。我找到了一段简单的代码来实现 AES:

public static class Crypto
    {
        #region Settings

        private static int _iterations = 2;
        private static int _keySize = 256;

        private static string _hash = "SHA1";
        private static string _salt = "aselrias38490a32"; // Random
        private static string _vector = "8947az34awl34kjq"; // Random

        #endregion

        public static string Encrypt(string value, string password)
        {
            return Encrypt<AesManaged>(value, password);
        }

        public static string Encrypt<T>(string value, string password)
            where T : SymmetricAlgorithm, new()
        {

            byte[] vectorBytes = Encoding.ASCII.GetBytes(_vector);
            byte[] saltBytes = Encoding.ASCII.GetBytes(_salt);
            byte[] valueBytes = Encoding.UTF8.GetBytes(value);

            byte[] encrypted;
            using (T cipher = new T())
            {
                PasswordDeriveBytes _passwordBytes =
                    new PasswordDeriveBytes(password, saltBytes, _hash, _iterations);
                byte[] keyBytes = _passwordBytes.GetBytes(_keySize/8);

                cipher.Mode = CipherMode.CBC;

                using (ICryptoTransform encryptor = cipher.CreateEncryptor(keyBytes, vectorBytes))
                {
                    using (MemoryStream to = new MemoryStream())
                    {
                        using (CryptoStream writer = new CryptoStream(to, encryptor, CryptoStreamMode.Write))
                        {
                            writer.Write(valueBytes, 0, valueBytes.Length);
                            writer.FlushFinalBlock();
                            encrypted = to.ToArray();
                        }
                    }
                }
                cipher.Clear();
            }
            return Convert.ToBase64String(encrypted);
        }

        public static string Decrypt(string value, string password)
        {
            return Decrypt<AesManaged>(value, password);
        }

        public static string Decrypt<T>(string value, string password) where T : SymmetricAlgorithm, new()
        {
            byte[] vectorBytes = Encoding.ASCII.GetBytes(_vector);
            byte[] saltBytes = Encoding.ASCII.GetBytes(_salt);
            byte[] valueBytes = Convert.FromBase64String(value);

            byte[] decrypted;
            int decryptedByteCount = 0;

            using (T cipher = new T())
            {
                PasswordDeriveBytes _passwordBytes = new PasswordDeriveBytes(password, saltBytes, _hash, _iterations);
                byte[] keyBytes = _passwordBytes.GetBytes(_keySize/8);

                cipher.Mode = CipherMode.CBC;

                try
                {
                    using (ICryptoTransform decryptor = cipher.CreateDecryptor(keyBytes, vectorBytes))
                    {
                        using (MemoryStream from = new MemoryStream(valueBytes))
                        {
                            using (CryptoStream reader = new CryptoStream(from, decryptor, CryptoStreamMode.Read))
                            {
                                decrypted = new byte[valueBytes.Length];
                                decryptedByteCount = reader.Read(decrypted, 0, decrypted.Length);
                            }
                        }
                    }
                }
                catch (Exception ex)
                {
                    return String.Empty;
                }

                cipher.Clear();
            }
            return Encoding.UTF8.GetString(decrypted, 0, decryptedByteCount);
        }

    }

但是，这是基于返回的字符串，然后用于在同一程序中解密。我需要在 WinForms 程序中加密以下数据，并在整个单独的 Windows 服务程序中解密:

string fileName = System.IO.Path.Combine(Application.StartupPath, "alphaService.xml");
                XDocument doc = new XDocument();
                XElement xml = new XElement("Info",
                    new XElement("DatabaseServerName", txtServerName.Text),
                    new XElement("DatabaseUserName", txtDatabaseUserName.Text),
                    new XElement("DatabasePassword", txtDatabasePassword.Text),
                    new XElement("ServiceAccount", txtAccount.Text),
                    new XElement("ServicePassword", txtServicePassword.Text),
                    new XElement("RegistrationCode", txtRegistrationCode.Text));

                doc.Add(xml);
                doc.Save(fileName);

                // Convert XML doc to byte stream
                XmlDocument xmlDoc = new XmlDocument();
                xmlDoc.Load(fileName);

                // byte[] fileBytes = Encoding.Default.GetBytes(xmlDoc.OuterXml);

                string encrypted = Crypto.Encrypt(xmlDoc.OuterXml, "testpass");

我该怎么做？请显示示例代码。

编辑:凯文，我已经实现了你的算法，但问题是我想生成一次 key 并将其保存以供其他程序解密使用，但我需要将 byte[] 传递给加密函数。所以我尝试使用 System.Text.Encoding.ASCII.GetBytes(key); 进行转换而且它做得不正确。我的 key byte[] 的字节数错误。

string fileName = System.IO.Path.Combine(Application.StartupPath, "alphaService.xml");
                XDocument doc = new XDocument();
                XElement xml = new XElement("Info",
                    new XElement("DatabaseServerName", txtServerName.Text),
                    new XElement("DatabaseUserName", txtDatabaseUserName.Text),
                    new XElement("DatabasePassword", txtDatabasePassword.Text),
                    new XElement("ServiceAccount", txtAccount.Text),
                    new XElement("ServicePassword", txtServicePassword.Text),
                    new XElement("RegistrationCode", txtRegistrationCode.Text));

                doc.Add(xml);
                doc.Save(fileName);

                // Read file to a string
                string contents = File.ReadAllText(fileName);

                string key = String.Empty;
                byte[] aesKey;
                using (var aes = Aes.Create())
                {
                    // aesKey = aes.Key;
                    key = Convert.ToBase64String(aes.Key);
                }

                string sKey = "LvtZELDrB394hbSOi3SurLWAvC8adNpZiJmQDJHdfJU=";
                aesKey = System.Text.Encoding.UTF8.GetBytes(sKey);

                string encyptedText = EncryptDecrpt.EncryptStringToBase64String(contents, aesKey);
                File.WriteAllText(fileName, encyptedText);

EDIT2:这是现在的两个部分。加密端:

private void SaveForm()
        {
            try
            {
                string fileName = System.IO.Path.Combine(Application.StartupPath, "alphaService.xml");
                XDocument doc = new XDocument();
                XElement xml = new XElement("Info",
                    new XElement("DatabaseServerName", txtServerName.Text),
                    new XElement("DatabaseUserName", txtDatabaseUserName.Text),
                    new XElement("DatabasePassword", txtDatabasePassword.Text),
                    new XElement("ServiceAccount", txtAccount.Text),
                    new XElement("ServicePassword", txtServicePassword.Text),
                    new XElement("RegistrationCode", txtRegistrationCode.Text));

                doc.Add(xml);
                // doc.Save(fileName);

                // Read file to a string
                // string contents = File.ReadAllText(fileName);

                string key = String.Empty;
                byte[] aesKey;
                //using (var aes = Aes.Create())
                //{
                //    aesKey = aes.Key;
                //    key = Convert.ToBase64String(aes.Key);
                //}

                string sKey = "LvtZELDrB394hbSOi3SurLWAvC8adNpZiJmQDJHdfJU=";
                aesKey = Convert.FromBase64String(sKey);

                string encyptedText = EncryptDecrpt.EncryptStringToBase64String(doc.ToString(), aesKey);
                File.WriteAllText(fileName, encyptedText);
                //doc.Save(fileName);

尝试解密的 Windows 服务端:

try
        {
            string path = AppDomain.CurrentDomain.BaseDirectory;
            eventLog1.WriteEntry(path);
            string fileName = System.IO.Path.Combine(path, "alphaService.xml");

            string sKey = "LvtZELDrB394hbSOi3SurLWAvC8adNpZiJmQDJHdfJU=";
            Byte[] keyBytes = Convert.FromBase64String(sKey);

            var encryptedText = File.ReadAllText(fileName, new ASCIIEncoding());
            string xmlStr = DecryptStringFromBase64String(encryptedText, keyBytes);

            eventLog1.WriteEntry(xmlStr);

            using (XmlReader reader = XmlReader.Create(new StringReader(xmlStr)))
            {
                reader.ReadToFollowing("DatabaseServerName");
                DatabaseServerName = reader.ReadElementContentAsString();
                reader.ReadToFollowing("DatabaseUserName");
                DatabaseUserName = reader.ReadElementContentAsString();
                reader.ReadToFollowing("DatabasePassword");
                DatabasePassword = reader.ReadElementContentAsString();
                reader.ReadToFollowing("RegistrationCode");
                RegistrationCode = reader.ReadElementContentAsString();
            }
            eventLog1.WriteEntry("Configuration data loaded successfully");
        }
        catch (Exception ex)
        {
            eventLog1.WriteEntry("Unable to load configuration data.  " + ex.Message);
        }

Answer 1

我在下面编写的算法使用随机初始化向量，将其放在加密值的开头，这样您就可以对相同的值加密两次，而不会获得相同的加密输出。这是相当正常的，并且只允许您来回传递一个“ secret ”。

您将需要通过某些越界进程共享您的 key ，因为加密和解密都需要知道 key 。这是在其他地方记录的 key 交换的单独主题。 Here这是一个 SO 链接，如果您需要一些帮助，可以帮助您入门。

此外，如果您正在“编造”随机值，我建议您不要这样做。使用以下内容可以帮助您生成随机字节，然后将它们转换为 base64 字符串，这对于人类使用或某些类型的 key 交换来说更容易。请注意，这只是如何生成随 secret 钥的示例...实际上，这可能基于一些可重新创建的用户输入，或者您使用用户哈希值来查找您生成的随 secret 钥。无论如何，这里是 key 的代码...

byte[] key;
string base64Key;
using (var aes = Aes.Create())
{
    // key as byte[]
    key = aes.Key;  
    // key as base64string - which one you use depends on how you store your keys
    base64Key= Convert.ToBase64String(aes.Key);
}

使用方法如下...

    // you get the base64 encoded key from somewhere
    var base64Key = "+CffHxKmykUvCrrCILd4rZDBcrIoe3w89jnPNXYi0rU="; 
    // convert it to byte[] or alternatively you could store your key as a byte[] 
    //   but that depends on how you set things up.
    var key = Convert.FromBase64String(base64Key);
    var plainText = "EncryptThis";
    var encryptedText = EncryptStringToBase64String(plainText, key);
    var decryptedText = DecryptStringFromBase64String(encryptedText, key);

以下是加密方法...EncryptStringToBase64String 和 DecryptStringFromBase64String。

编辑:关于使用 Aes.BlockSize 作为 IV 大小的观点非常好。我还清理了争论检查。

    private const int KeySize = 256; // in bits
    static string EncryptStringToBase64String(string plainText, byte[] Key)
    {
        // Check arguments. 
        if (Key == null || Key.Length <= 0)
            throw new ArgumentNullException("Key");
        byte[] returnValue;
        using (var aes = Aes.Create())
        {
            aes.KeySize = KeySize;
            aes.GenerateIV();
            aes.Mode = CipherMode.CBC;
            var iv = aes.IV;
            if (string.IsNullOrEmpty(plainText))
                return Convert.ToBase64String(iv);
            var encryptor = aes.CreateEncryptor(Key, iv);

            // Create the streams used for encryption. 
            using (MemoryStream msEncrypt = new MemoryStream())
            {
                using (CryptoStream csEncrypt = new CryptoStream(msEncrypt, encryptor, CryptoStreamMode.Write))
                {
                    using (StreamWriter swEncrypt = new StreamWriter(csEncrypt))
                    {
                        //Write all data to the stream.
                        swEncrypt.Write(plainText);
                    }
                    // this is just our encrypted data
                    var encrypted = msEncrypt.ToArray();
                    returnValue = new byte[encrypted.Length + iv.Length];
                    // append our IV so our decrypt can get it
                    Array.Copy(iv, returnValue, iv.Length);
                    // append our encrypted data
                    Array.Copy(encrypted, 0, returnValue, iv.Length, encrypted.Length);
                }
            }
        }

        // return encrypted bytes converted to Base64String
        return Convert.ToBase64String(returnValue);
    }

    static string DecryptStringFromBase64String(string cipherText, byte[] Key)
    {
        // Check arguments. 
        if (string.IsNullOrEmpty(cipherText))
            return string.Empty;
        if (Key == null || Key.Length <= 0)
            throw new ArgumentNullException("Key");

        string plaintext = null;
        // this is all of the bytes
        var allBytes = Convert.FromBase64String(cipherText);

        using (var aes = Aes.Create())
        {
            aes.KeySize = KeySize;
            aes.Mode = CipherMode.CBC;

            // get our IV that we pre-pended to the data
            byte[] iv = new byte[aes.BlockSize/8];
            if (allBytes.Length < iv.Length)
                throw new ArgumentException("Message was less than IV size.");
            Array.Copy(allBytes, iv, iv.Length);
            // get the data we need to decrypt
            byte[] cipherBytes = new byte[allBytes.Length - iv.Length];
            Array.Copy(allBytes, iv.Length, cipherBytes, 0, cipherBytes.Length);

            // Create a decrytor to perform the stream transform.
            var decryptor = aes.CreateDecryptor(Key, iv);

            // Create the streams used for decryption. 
            using (MemoryStream msDecrypt = new MemoryStream(cipherBytes))
            {
                using (CryptoStream csDecrypt = new CryptoStream(msDecrypt, decryptor, CryptoStreamMode.Read))
                {
                    using (StreamReader srDecrypt = new StreamReader(csDecrypt))
                    {
                        // Read the decrypted bytes from the decrypting stream 
                        // and place them in a string.
                        plaintext = srDecrypt.ReadToEnd();
                    }
                }
            }
        }

        return plaintext;
    }

编辑 2:切勿使用 TextEncoding 将实际的二进制数据(如随 secret 钥)转换为字符串。如果数据以字符串形式开始，并且您使用编码将其转换为二进制，则且仅此您可以使用正确的编码将其从二进制转换为字符串吗？否则，您的代码将有时工作，这是折磨自己的良方。

        // This is base64 not UTF8, unicode, ASCII or anything else!!!
        string sKey = "LvtZELDrB394hbSOi3SurLWAvC8adNpZiJmQDJHdfJU=";
        aesKey = Convert.FromBase64String(sKey);

编辑3:

为什么写入文件时使用File.WriteAllText，而读取文件时却使用File.ReadAllBytes？您可以将其作为文本写入和读取，并使用 ASCII 编码，因为 base64 保证是 ASCII。 Decrypt 还会返回一个您未存储或使用的解密字符串。解密后的字符串是您需要解析的内容，因为它是您的 xml。

您可以使用它来保存文件...

    var encryptedText = File.ReadAllText(fileName, new ASCIIEncoding());

在解密中你应该这样做...

    var encryptedText = File.ReadAllText(fileName, new ASCIIEncoding());
    string xmlStr = DecryptStringFromBase64String(encryptedStr , keyBytes);

编辑4:我试图复制您的异常，但无法实现...这是我在控制台应用程序中运行的测试代码，它可以工作。

public static void EncryptMethod()
{
    var fileName = @"c:/text.xml";
    XDocument doc = new XDocument();
    XElement xml = new XElement("Info",
        new XElement("DatabaseServerName", "txtServerName.Text"),
        new XElement("DatabaseUserName", "txtDatabaseUserName.Text"),
        new XElement("DatabasePassword", "txtDatabasePassword.Text"),
        new XElement("ServiceAccount", "txtAccount.Text"),
        new XElement("ServicePassword", "txtServicePassword.Text"),
        new XElement("RegistrationCode", "txtRegistrationCode.Text"));
    doc.Add(xml);

    var sKey = "LvtZELDrB394hbSOi3SurLWAvC8adNpZiJmQDJHdfJU=";
    var aesKey = Convert.FromBase64String(sKey);

    string encyptedText = EncryptStringToBase64String(doc.ToString(), aesKey);
    File.WriteAllText(fileName, encyptedText);
}


public static void DecryptMethod()
{
    var fileName = @"c:/text.xml";
    string sKey = "LvtZELDrB394hbSOi3SurLWAvC8adNpZiJmQDJHdfJU=";
    Byte[] keyBytes = Convert.FromBase64String(sKey);

    var encryptedText = File.ReadAllText(fileName, new ASCIIEncoding());
    string xmlStr = DecryptStringFromBase64String(encryptedText, keyBytes);

    using (XmlReader reader = XmlReader.Create(new StringReader(xmlStr)))
    {
        reader.ReadToFollowing("DatabaseServerName");
        Console.WriteLine(reader.ReadElementContentAsString());
        reader.ReadToFollowing("DatabaseUserName");
        Console.WriteLine(reader.ReadElementContentAsString());
        reader.ReadToFollowing("DatabasePassword");
        Console.WriteLine(reader.ReadElementContentAsString());
        reader.ReadToFollowing("RegistrationCode");
        Console.WriteLine(reader.ReadElementContentAsString());
    }
}

从控制台应用程序的使用...

    EncryptMethod();
    DecryptMethod();