Question

我正在使用JSON在我的应用程序中存储某些设置。某些设置包含敏感信息（例如密码），而其他设置不敏感。理想情况下，我希望能够序列化我的对象，其中敏感属性自动加密，同时保持非敏感设置可读。有没有办法使用Json.Net做到这一点？我没有看到任何与加密相关的设置。

Answer 1

Json.Net没有内置加密功能。如果您希望能够在序列化过程中加密和解密，则需要编写一些自定义代码。一种方法是将自定义IContractResolver与IValueProvider结合使用。值提供程序为您提供了一个钩子，您可以在其中转换序列化过程中的值，而合同解析程序可让您控制值提供程序的应用时间和位置。他们可以一起为您提供所需的解决方案。

以下是您需要的代码示例。首先，您会注意到我已经定义了一个新的[JsonEncrypt]属性;这将用于指示您要加密的属性。 EncryptedStringPropertyResolver类扩展了Json.Net提供的DefaultContractResolver。我重写了CreateProperties()方法，以便检查基本解析程序创建的JsonProperty对象，并将自定义EncryptedStringValueProvider的实例附加到任何具有{{1}的字符串属性已应用的属性。 [JsonEncrypt]稍后通过相应的EncryptedStringValueProvider和GetValue()方法处理目标字符串属性的实际加密/解密。

SetValue()

准备好解析器之后，下一步是将自定义using System; using System.Collections.Generic; using System.IO; using System.Linq; using System.Reflection; using System.Security.Cryptography; using System.Text; using Newtonsoft.Json; using Newtonsoft.Json.Serialization; [AttributeUsage(AttributeTargets.Property)] public class JsonEncryptAttribute : Attribute { } public class EncryptedStringPropertyResolver : DefaultContractResolver { private byte[] encryptionKeyBytes; public EncryptedStringPropertyResolver(string encryptionKey) { if (encryptionKey == null) throw new ArgumentNullException("encryptionKey"); // Hash the key to ensure it is exactly 256 bits long, as required by AES-256 using (SHA256Managed sha = new SHA256Managed()) { this.encryptionKeyBytes = sha.ComputeHash(Encoding.UTF8.GetBytes(encryptionKey)); } } protected override IList<JsonProperty> CreateProperties(Type type, MemberSerialization memberSerialization) { IList<JsonProperty> props = base.CreateProperties(type, memberSerialization); // Find all string properties that have a [JsonEncrypt] attribute applied // and attach an EncryptedStringValueProvider instance to them foreach (JsonProperty prop in props.Where(p => p.PropertyType == typeof(string))) { PropertyInfo pi = type.GetProperty(prop.UnderlyingName); if (pi != null && pi.GetCustomAttribute(typeof(JsonEncryptAttribute), true) != null) { prop.ValueProvider = new EncryptedStringValueProvider(pi, encryptionKeyBytes); } } return props; } class EncryptedStringValueProvider : IValueProvider { PropertyInfo targetProperty; private byte[] encryptionKey; public EncryptedStringValueProvider(PropertyInfo targetProperty, byte[] encryptionKey) { this.targetProperty = targetProperty; this.encryptionKey = encryptionKey; } // GetValue is called by Json.Net during serialization. // The target parameter has the object from which to read the unencrypted string; // the return value is an encrypted string that gets written to the JSON public object GetValue(object target) { string value = (string)targetProperty.GetValue(target); byte[] buffer = Encoding.UTF8.GetBytes(value); using (MemoryStream inputStream = new MemoryStream(buffer, false)) using (MemoryStream outputStream = new MemoryStream()) using (AesManaged aes = new AesManaged { Key = encryptionKey }) { byte[] iv = aes.IV; // first access generates a new IV outputStream.Write(iv, 0, iv.Length); outputStream.Flush(); ICryptoTransform encryptor = aes.CreateEncryptor(encryptionKey, iv); using (CryptoStream cryptoStream = new CryptoStream(outputStream, encryptor, CryptoStreamMode.Write)) { inputStream.CopyTo(cryptoStream); } return Convert.ToBase64String(outputStream.ToArray()); } } // SetValue gets called by Json.Net during deserialization. // The value parameter has the encrypted value read from the JSON; // target is the object on which to set the decrypted value. public void SetValue(object target, object value) { byte[] buffer = Convert.FromBase64String((string)value); using (MemoryStream inputStream = new MemoryStream(buffer, false)) using (MemoryStream outputStream = new MemoryStream()) using (AesManaged aes = new AesManaged { Key = encryptionKey }) { byte[] iv = new byte[16]; int bytesRead = inputStream.Read(iv, 0, 16); if (bytesRead < 16) { throw new CryptographicException("IV is missing or invalid."); } ICryptoTransform decryptor = aes.CreateDecryptor(encryptionKey, iv); using (CryptoStream cryptoStream = new CryptoStream(inputStream, decryptor, CryptoStreamMode.Read)) { cryptoStream.CopyTo(outputStream); } string decryptedValue = Encoding.UTF8.GetString(outputStream.ToArray()); targetProperty.SetValue(target, decryptedValue); } } } }属性应用于您希望在序列化期间加密的类中的字符串属性。例如，这是一个可能代表用户的设计类：

[JsonEncrypt]

最后一步是将自定义解析器注入序列化过程。为此，请创建一个新的public class UserInfo { public string UserName { get; set; } [JsonEncrypt] public string UserPassword { get; set; } public string FavoriteColor { get; set; } [JsonEncrypt] public string CreditCardNumber { get; set; } }实例，然后将JsonSerializerSettings属性设置为自定义解析程序的新实例。将设置传递给ContractResolver或JsonConvert.SerializeObject()方法，一切正常。

这是一个往返演示：

DeserializeObject()

输出：

public class Program
{
    public static void Main(string[] args)
    {
        try
        {
            UserInfo user = new UserInfo
            {
                UserName = "jschmoe",
                UserPassword = "Hunter2",
                FavoriteColor = "atomic tangerine",
                CreditCardNumber = "1234567898765432",
            };

            // Note: in production code you should not hardcode the encryption
            // key into the application-- instead, consider using the Data Protection 
            // API (DPAPI) to store the key.  .Net provides access to this API via
            // the ProtectedData class.

            JsonSerializerSettings settings = new JsonSerializerSettings();
            settings.Formatting = Formatting.Indented;
            settings.ContractResolver = new EncryptedStringPropertyResolver("My-Sup3r-Secr3t-Key");

            Console.WriteLine("----- Serialize -----");
            string json = JsonConvert.SerializeObject(user, settings);
            Console.WriteLine(json);
            Console.WriteLine();

            Console.WriteLine("----- Deserialize -----");
            UserInfo user2 = JsonConvert.DeserializeObject<UserInfo>(json, settings);

            Console.WriteLine("UserName: " + user2.UserName);
            Console.WriteLine("UserPassword: " + user2.UserPassword);
            Console.WriteLine("FavoriteColor: " + user2.FavoriteColor);
            Console.WriteLine("CreditCardNumber: " + user2.CreditCardNumber);
        }
        catch (Exception ex)
        {
            Console.WriteLine(ex.GetType().Name + ": " + ex.Message);
        }
    }
}

小提琴：https://dotnetfiddle.net/trsiQc

Answer 2

虽然@Brian的解决方案非常聪明，但我不喜欢自定义ContractResolver的复杂性。我将Brian的代码转换为JsonConverter，因此您的代码将变为

public class UserInfo
{
    public string UserName { get; set; }

    [JsonConverter(typeof(EncryptingJsonConverter), "My-Sup3r-Secr3t-Key")]
    public string UserPassword { get; set; }

    public string FavoriteColor { get; set; }

    [JsonConverter(typeof(EncryptingJsonConverter), "My-Sup3r-Secr3t-Key")]
    public string CreditCardNumber { get; set; }
}

我发布了（相当冗长的）EncryptingJsonConverter作为Gist以及blogged about it。

Answer 3

我的解决方案：

    public string PasswordEncrypted { get; set; }

    [JsonIgnore]
    public string Password
    {
        get
        {
            var encrypted = Convert.FromBase64String(PasswordEncrypted);
            var data = ProtectedData.Unprotect(encrypted, AdditionalEntropy, DataProtectionScope.LocalMachine);
            var res = Encoding.UTF8.GetString(data);
            return res;
        }
        set
        {
            var data = Encoding.UTF8.GetBytes(value);
            var encrypted = ProtectedData.Protect(data, AdditionalEntropy, DataProtectionScope.LocalMachine);
            PasswordEncrypted = Convert.ToBase64String(encrypted);
        }

（可以减少冗长）

如何在序列化对象时加密选定的属性？

3 个答案: