在 .NET Core 中加密字符串

Question

我想使用密钥加密 .NET Core 中的字符串。我有一个客户端/服务器场景，想在客户端加密一个字符串，将其发送到服务器并解密。

由于 .NET Core 仍处于早期阶段（例如，Rijndael 尚不可用），我有哪些选择？

Answer 1

您真的不应该在 .NET 中使用 Rijndael/RijndaelManaged。如果你使用它的 BlockSize 值为 128（这是默认值），那么你使用的是 AES，因为我 explained in a similar question。

.NET Core 中可用的对称加密选项有：

• AES (System.Security.Cryptography.Aes.Create())
• 3DES (System.Security.Cryptography.TripleDES.Create())

对于非对称加密

• RSA (System.Security.Cryptography.RSA.Create())

特别是在 .NET Core 上，工厂是最好的选择，因为它们会返回一个在当前执行的操作系统上工作的对象。例如，RSACng 是一种公共类型，但仅适用于 Windows；并且 RSAOpenSsl 是公共类型，但仅在 Linux 和 macOS 上受支持。

Answer 2

这个问题已经有了答案，但我认为我们可以提供一个更简单的解决方案。

如果你只是想保护你的数据，在 .NET Core 中有一个实现，它可以让你摆脱加密的烦恼； DataProtectionProvider.

在Startup.cs:

public void ConfigureServices(IServiceCollection services)
{
    services.AddDataProtection(); //Add this
    [..]
    services.AddMvc();
}

如果您愿意，可以指定用于加密和验证的算法（使用Microsoft.AspNetCore.DataProtection），如下所示：

services.AddDataProtection()
       .UseCryptographicAlgorithms(new AuthenticatedEncryptionSettings()
       {
           EncryptionAlgorithm = EncryptionAlgorithm.AES_256_GCM,
           ValidationAlgorithm = ValidationAlgorithm.HMACSHA256
       });

然后使用这样的服务加密/解密：

public class CipherService : ICipherService
{
    private readonly IDataProtectionProvider _dataProtectionProvider;
    private const string Key = "my-very-long-key-of-no-exact-size";

    public CipherService(IDataProtectionProvider dataProtectionProvider)
    {
        _dataProtectionProvider = dataProtectionProvider;
    }

    public string Encrypt(string input)
    {
        var protector = _dataProtectionProvider.CreateProtector(Key);
        return protector.Protect(input);
    }

    public string Decrypt(string cipherText)
    {
        var protector = _dataProtectionProvider.CreateProtector(Key);
        return protector.Unprotect(cipherText);
    }
}

编辑 正如下面的 cmets 中所提到的，了解像这样使用 DataProtectionProvider 只能在同一台机器上使用存储在本地磁盘上的密钥。

Answer 3

这是一个没有身份验证的简单示例：

var text = "Hello World";
var buffer = Encoding.UTF8.GetBytes(text);

var iv = GetRandomData(128);
var keyAes = GetRandomData(256);


byte[] result;
using (var aes = Aes.Create())
{
    aes.Key = keyAes;
    aes.IV = iv;

    using (var encryptor = aes.CreateEncryptor(aes.Key, aes.IV))
    using (var resultStream = new MemoryStream())
    {
        using (var aesStream = new CryptoStream(resultStream, encryptor, CryptoStreamMode.Write))
        using (var plainStream = new MemoryStream(buffer))
        {
            plainStream.CopyTo(aesStream);
        }

        result = resultStream.ToArray();
    }
}

对于密钥生成：

private static byte[] GetRandomData(int bits)
{
    var result = new byte[bits / 8];
    RandomNumberGenerator.Create().GetBytes(result);
    return result;
}

Answer 4

我有一个不同的方法，我想用一个密钥加密一个字符串，并得到一个可以再次用同一个密钥解密的加扰字符串。请参阅以下扩展方法：

    public static string Encrypt(this string text, string key)
    {
        if (string.IsNullOrEmpty(key))
            throw new ArgumentException("Key must have valid value.", nameof(key));
        if (string.IsNullOrEmpty(text))
            throw new ArgumentException("The text must have valid value.", nameof(text));

        var buffer = Encoding.UTF8.GetBytes(text);
        var hash = new SHA512CryptoServiceProvider();
        var aesKey = new byte[24];
        Buffer.BlockCopy(hash.ComputeHash(Encoding.UTF8.GetBytes(key)), 0, aesKey, 0, 24);

        using (var aes = Aes.Create())
        {
            if (aes == null)
                throw new ArgumentException("Parameter must not be null.", nameof(aes));

            aes.Key = aesKey;

            using (var encryptor = aes.CreateEncryptor(aes.Key, aes.IV))
            using (var resultStream = new MemoryStream())
            {
                using (var aesStream = new CryptoStream(resultStream, encryptor, CryptoStreamMode.Write))
                using (var plainStream = new MemoryStream(buffer))
                {
                    plainStream.CopyTo(aesStream);
                }

                var result = resultStream.ToArray();
                var combined = new byte[aes.IV.Length + result.Length];
                Array.ConstrainedCopy(aes.IV, 0, combined, 0, aes.IV.Length);
                Array.ConstrainedCopy(result, 0, combined, aes.IV.Length, result.Length);

                return Convert.ToBase64String(combined);
            }
        }
    }

    public static string Decrypt(this string encryptedText, string key)
    {
        if (string.IsNullOrEmpty(key))
            throw new ArgumentException("Key must have valid value.", nameof(key));
        if (string.IsNullOrEmpty(encryptedText))
            throw new ArgumentException("The encrypted text must have valid value.", nameof(encryptedText));

        var combined = Convert.FromBase64String(encryptedText);
        var buffer = new byte[combined.Length];
        var hash = new SHA512CryptoServiceProvider();
        var aesKey = new byte[24];
        Buffer.BlockCopy(hash.ComputeHash(Encoding.UTF8.GetBytes(key)), 0, aesKey, 0, 24);

        using (var aes = Aes.Create())
        {
            if (aes == null)
                throw new ArgumentException("Parameter must not be null.", nameof(aes));

            aes.Key = aesKey;

            var iv = new byte[aes.IV.Length];
            var ciphertext = new byte[buffer.Length - iv.Length];

            Array.ConstrainedCopy(combined, 0, iv, 0, iv.Length);
            Array.ConstrainedCopy(combined, iv.Length, ciphertext, 0, ciphertext.Length);

            aes.IV = iv;

            using (var decryptor = aes.CreateDecryptor(aes.Key, aes.IV))
            using (var resultStream = new MemoryStream())
            {
                using (var aesStream = new CryptoStream(resultStream, decryptor, CryptoStreamMode.Write))
                using (var plainStream = new MemoryStream(ciphertext))
                {
                    plainStream.CopyTo(aesStream);
                }

                return Encoding.UTF8.GetString(resultStream.ToArray());
            }
        }
    }

Answer 5

默认情况下，ASP.NET Core 应用程序启用数据保护系统。除非您想重新配置默认密钥存储位置或密钥的使用寿命，否则您甚至不需要在 StartUp 方法中执行任何操作。在这种情况下，您将在 ConfigureServices 方法中执行以下操作：

services.ConfigureDataProtection(dp =>
    {
        dp.PersistKeysToFileSystem(new DirectoryInfo(@"c:\keys"));
        dp.SetDefaultKeyLifetime(TimeSpan.FromDays(14));
    });

由于数据保护系统默认位于应用程序的服务集合中，因此可以通过依赖注入使其可用。以下是如何将 IDataProtectionProvider 注入控制器，然后使用它在控制器的构造函数中创建 IDataProtector 的实例：

public class HomeController : Controller
{
    IDataProtector _protector;

    public HomeController(IDataProtectionProvider provider)
    {
        _protector = provider.CreateProtector(GetType().FullName);
    }
}

然后您可以调用保护程序来加密内容，如下所示：

public IActionResult Index()
{
    var model = _service.GetAll().Select(c => new ContractViewModel {
        Id = _protector.Protect(c.Id.ToString()),
        Name = c.Name }).ToList();
    return View(model);
}

我希望这会有所帮助:)

Answer 6

您可以使用 System.Security.Cryptography 来做到这一点

string keyString = "encrypt123456789";
var key = Encoding.UTF8.GetBytes(keyString);//16 bit or 32 bit key string

using (var aesAlg = Aes.Create())
{
    using (var encryptor = aesAlg.CreateEncryptor(key, aesAlg.IV))
    {
        using (var msEncrypt = new MemoryStream())
        {
            using (var csEncrypt = new CryptoStream(msEncrypt, encryptor, CryptoStreamMode.Write))
            using (var swEncrypt = new StreamWriter(csEncrypt))
            {
                swEncrypt.Write(text);
            }

            var iv = aesAlg.IV;

            var decryptedContent = msEncrypt.ToArray();

            var result = new byte[iv.Length + decryptedContent.Length];

            Buffer.BlockCopy(iv, 0, result, 0, iv.Length);
            Buffer.BlockCopy(decryptedContent, 0, result, iv.Length, decryptedContent.Length);

            return Convert.ToBase64String(result);
        }
    }
}

用于解密

var fullCipher = Convert.FromBase64String(cipherText);

var iv = new byte[16];
var cipher = new byte[16];

Buffer.BlockCopy(fullCipher, 0, iv, 0, iv.Length);
Buffer.BlockCopy(fullCipher, iv.Length, cipher, 0, iv.Length);
var key = Encoding.UTF8.GetBytes(keyString);//same key string

using (var aesAlg = Aes.Create())
{
    using (var decryptor = aesAlg.CreateDecryptor(key, iv))
    {
        string result;
        using (var msDecrypt = new MemoryStream(cipher))
        {
            using (var csDecrypt = new CryptoStream(msDecrypt, decryptor, CryptoStreamMode.Read))
            {
                using (var srDecrypt = new StreamReader(csDecrypt))
                {
                    result = srDecrypt.ReadToEnd();
                }
            }
        }

        return result;
    }
}

Answer 7

对于那些使用@sundarraj 发布的上述解决方案并获得 System.Security.Cryptography.CryptographicException: 'Padding is invalid and cannot be removed。解密时出错使用这些代码行来修复解密：

var cipher = new byte[full.Length - iv.Length];

Buffer.BlockCopy(full, 0, iv, 0, iv.Length);
Buffer.BlockCopy(full, iv.Length, cipher, 0, cipher.Length);