[英]Why does Json.NET fail to serialize a X509Certificate2?
每當我嘗試使用 Json.NET 序列化 X509Certificate2 實例時(不使用其 ISerializable 實現,但選擇忽略它),Json.NET 會引發異常。
異常消息是“'System.Security.Cryptography.X509Certificates.X509Certificate2'上已存在名為'CertContext'的成員。使用 JsonPropertyAttribute 指定另一個名稱。”
我寫了一個程序來重現它:
using System.Reflection;
using System.Security.Cryptography.X509Certificates;
using Newtonsoft.Json;
using Newtonsoft.Json.Serialization;
internal class Program
{
private static void Main(string[] args)
{
var resolver = new DefaultContractResolver
{
IgnoreSerializableInterface = true,
DefaultMembersSearchFlags =
BindingFlags.Instance | BindingFlags.NonPublic | BindingFlags.Public | BindingFlags.GetProperty
};
JsonConvert.SerializeObject(new X509Certificate2(), new JsonSerializerSettings {ContractResolver = resolver});
}
}
經過調查,我注意到 X509Certificate2 實現了一個名為“CertContext”的屬性,該屬性在其基類 X509Certificate 中隱藏了一個同名的方法。 我如何告訴 Json.NET 只采用派生程度最高的屬性,就像通常那樣?
我最近發現需要序列化X509Certificate2
實例,以便比較兩個行為不同的假定相同環境的差異。 我能夠通過以下JsonSerializerSettings
實現序列化:
new JsonSerializerSettings {
Error = (s, a) => a.ErrorContext.Handled = true,
ContractResolver = new DefaultContractResolver {
IgnoreSerializableInterface = true
}
}
這是一個完整的工作示例,它 JSON 序列化本地機器存儲中的第一個證書並打開它:
namespace ConsoleApp1
{
using System.Diagnostics;
using System.IO;
using System.Security.Cryptography.X509Certificates;
using Newtonsoft.Json;
using Newtonsoft.Json.Serialization;
class Program
{
static void Main(string[] args)
{
var store = new X509Store(StoreName.My, StoreLocation.LocalMachine);
try
{
store.Open(OpenFlags.ReadOnly);
var cert = store.Certificates[0];
var path = Path.GetTempFileName();
File.WriteAllText(
path,
JsonConvert.SerializeObject(
cert, new JsonSerializerSettings {
Formatting = Formatting.Indented,
// Ignore serializtion errors
Error = (s, a) => a.ErrorContext.Handled = true,
ContractResolver = new DefaultContractResolver {
// Ensures all properties are serialized
IgnoreSerializableInterface = true
}
}
)
);
Process.Start(path);
}
finally
{
store.Close();
}
}
}
}
為此,您可以使用轉換器:
public class X509Certificate2JsonConverter : JsonConverter
{
public override bool CanConvert(Type objectType)
{
return objectType == typeof(X509Certificate2);
}
public override object ReadJson(JsonReader reader,
Type objectType, object existingValue, JsonSerializer serializer)
{
var deserializedRaw = serializer.Deserialize<byte[]>(reader);
var deserialized = new X509Certificate2(deserializedRaw);
return deserialized;
}
public override void WriteJson(JsonWriter writer,
object value, JsonSerializer serializer)
{
byte[] certData = ((X509Certificate2)value).Export(X509ContentType.Pfx);
serializer.Serialize(writer, certData);
}
}
以及對它的測試:
public class CertificateHolder : IDisposable
{
[JsonConverter(typeof(X509Certificate2JsonConverter))]
public X509Certificate2 Certificate { get; set; }
public void Dispose() => Certificate?.Dispose();
public static X509Certificate2 CreateCertificate()
{
var ecdsa = ECDsa.Create();
var req = new CertificateRequest("cn=foobar", ecdsa, HashAlgorithmName.SHA256);
var c = req.CreateSelfSigned(DateTimeOffset.Now, DateTimeOffset.Now.AddYears(5));
return c;
}
}
[TestFixture]
class X509Certificate2JsonConverterTests
{
[Test]
public void Serialization()
{
var holder = new CertificateHolder();
holder.Certificate = CertificateHolder.CreateCertificate();
var str = JsonConvert.SerializeObject(holder);
var holderRestored = JsonConvert.DeserializeObject<CertificateHolder>(str);
var holderStr = holder.Certificate.ToString();
var holderRestoredStr = holderRestored.Certificate.ToString();
Assert.AreEqual(holderStr, holderRestoredStr);
holder.Dispose();
holderRestored.Dispose();
}
}
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