How do I implement JWT validation in ASP.NET Core?

How do I implement JWT validation in ASP.NET Core?

To implement JWT validation in ASP.NET Core, you need to configure the authentication middleware in your Startup.cs file.

What packages do I need to install for JWT validation?

You need to install the Microsoft.AspNetCore.Authentication.JwtBearer package to handle JWT authentication.

Can you show me a code example for setting it up?

Sure! Here's a basic example:

public void ConfigureServices(IServiceCollection services) {
    services.AddAuthentication(options => {
        options.DefaultAuthenticateScheme = JwtBearerDefaults.AuthenticationScheme;
        options.DefaultChallengeScheme = JwtBearerDefaults.AuthenticationScheme;
    })
    .AddJwtBearer(options => {
        options.TokenValidationParameters = new TokenValidationParameters {
            ValidateIssuer = true,
            ValidateAudience = true,
            ValidateLifetime = true,
            ValidateIssuerSigningKey = true,
            ValidIssuer = "yourIssuer",
            ValidAudience = "yourAudience",
            IssuerSigningKey = new SymmetricSecurityKey(Encoding.UTF8.GetBytes("yourSecretKey"))
        };
    });
} 

What should I do if I get a 401 Unauthorized error?

A 401 Unauthorized error usually indicates that the token is missing or invalid. Ensure that the token is included in the Authorization header and is correctly signed.