在 .NET Core 中加密字符串

Question

我想使用密钥在 .NET Core 中加密字符串。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。如果您使用的 BlockSize 值为 128（默认值），那么您使用的是 AES，就像我 explained in a similar question.

.NET Core 中可用的对称加密选项是：

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

以及非对称加密

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

特别是在 .NET Core 上，工厂是最好的方式，因为它们会返回一个在当前正在执行的操作系统上工作的对象。例如，RSACng 是 public 类型，但仅适用于 Windows； RSAOpenSsl 是 public 类型，但仅在 Linux 和 macOS 上受支持。

Answer 2

这是一个简单的示例没有身份验证：

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 3

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。

如果您只是想保护您的数据，.NET Core 中有一个实现可以让您摆脱加密的烦恼； DataProtectionProvider.

在Startup.cs中：

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encrypt/decrypt使用这样的服务：

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);
    }
}

编辑正如下面评论中提到的，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可能是个好主意。

Answer 4

ASP.NET 核心应用程序默认启用数据保护系统。您甚至不需要在 StartUp 方法中执行任何操作，除非您想重新配置默认密钥存储位置或密钥的生命周期。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。下面介绍如何将 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);
    }
}

然后您可以像这样调用保护器来加密内容：

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

希望对您有所帮助:)

Answer 5

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我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 6

您可以使用 System.Security.Cryptography

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);
        }
    }
}

解密用

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

对于使用@sundarraj 发布的上述解决方案并在解密时出现 System.Security.Cryptography.CryptographicException: 'Padding is invalid and cannot be removed.' 错误的用户，请使用以下代码行修复解密：

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);

在 .NET Core 中加密字符串

Encrypt String in .NET Core

c#

encryption

.net-core