Json Web Token (JWT) / JWS Implementation for .NET Core

This library supports generating and decoding JSON Web Tokens.

Features

• Support .NET Core / (ASP.NET Core).
• Two Extention Methods for Converting Unix Timestamp between .NET DateTime.
• Simple usage.

Installation

At first, You need to install Newtonsoft.Json. FYI.
and, Please download and compile JwtCore yourself or Install by NuGet,

PM> Install-Package JwtCore

NuGet repo is here.

Usage

Creating Tokens

var payload = new Dictionary<string, object>()
{
    { "claim1", 0 },
    { "claim2", "claim2-value" }
};
var secretKey = "GQDstcKsx0NHjPOuXOYg5MbeJ1XT0uFiwDVvVBrk";
string token = JwtCore.JsonWebToken.Encode(payload, secretKey, JwtCore.JwtHashAlgorithm.HS256);
Console.WriteLine(token);

Output will be: eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzI1NiJ9.eyJjbGFpbTEiOjAsImNsYWltMiI6ImNsYWltMi12YWx1ZSJ9.8pwBI_HtXqI3UgQHQ_rDRnSQRxFL1SR8fbQoS-5kM5s

Verifying and Decoding Tokens

var token = "eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzI1NiJ9.eyJjbGFpbTEiOjAsImNsYWltMiI6ImNsYWltMi12YWx1ZSJ9.8pwBI_HtXqI3UgQHQ_rDRnSQRxFL1SR8fbQoS-5kM5s";
var secretKey = "GQDstcKsx0NHjPOuXOYg5MbeJ1XT0uFiwDVvVBrk";
try
{
    string jsonPayload = JwtCore.JsonWebToken.Decode(token, secretKey);
    Console.WriteLine(jsonPayload);
}
catch (JwtCore.SignatureVerificationException)
{
    Console.WriteLine("Invalid token!");
}

Output will be:

{"claim1":0,"claim2":"claim2-value"}

You can also deserialize the JSON payload directly to a .Net object with DecodeToObject:

var payload = JwtCore.JsonWebToken.DecodeToObject(token, secretKey) as IDictionary<string, object>;
Console.WriteLine(payload["claim2"]);

which will output:

claim2-value

exp claim

As described in the JWT RFC the exp "claim identifies the expiration time on or after which the JWT MUST NOT be accepted for processing." If an exp claim is present and is prior to the current time the token will fail verification. The exp (expiry) value must be specified as the number of seconds since 1/1/1970 UTC.

var now = DateTime.UtcNow.ToUnixTimeSeconds();
var payload = new Dictionary<string, object>()
{
    { "exp", now }
};
var secretKey = "GQDstcKsx0NHjPOuXOYg5MbeJ1XT0uFiwDVvVBrk";
string token = JwtCore.JsonWebToken.Encode(payload, secretKey, JwtCore.JwtHashAlgorithm.HS256);
string jsonPayload = JwtCore.JsonWebToken.Decode(token, secretKey);

if you will decode json that has invalid Unix Timestamp, you'll get some exception.

string jsonPayload = JwtCore.JsonWebToken.Decode(token, secretKey); // JwtCore.SignatureVerificationException!

Configure JSON Serialization

By default JSON Serialization is done by Newtonsoft.Json. To configure a different one first implement the IJsonSerializer interface.

public class CustomJsonSerializer : IJsonSerializer
{
    public string Serialize(object obj)
    {
        // Implement using favorite JSON Serializer
    }

    public T Deserialize<T>(string json)
    {
        // Implement using favorite JSON Serializer
    }
}

Next configure this serializer as the JsonSerializer.

JsonWebToken.JsonSerializer = new CustomJsonSerializer();