I have tried to implement JWT token authorisation into my system but it’s not working. I’m new to ASP.net so please go easy on me.

I can login fine and i do get the token as expected. But when I try to use the token as a Bearer token to access an [Authorize] protected End point I get 401 error.

In postman I get Bearer error="invalid_token" in header

I tried to acces my /api/Blogs endpoint which is protected using [Authorize]. I entered “Bearer token” in Swagger and also Authorization > Bearer Token in Postman. Both didn’t work and gave me 401 error.

Here’s my program.cs

//Identity
builder.Services.AddIdentity<ApplicationUser, IdentityRole>()
    .AddEntityFrameworkStores<AppDbContext>()
    .AddDefaultTokenProviders();

// JWT
var key = Encoding.UTF8.GetBytes(builder.Configuration["JWT:AccessTokenKey"]);
builder.Services.AddAuthentication(auth =>
{
    auth.DefaultAuthenticateScheme = JwtBearerDefaults.AuthenticationScheme;
    auth.DefaultChallengeScheme = JwtBearerDefaults.AuthenticationScheme;
    auth.DefaultScheme = JwtBearerDefaults.AuthenticationScheme;

})
.AddJwtBearer(options => {
     options.SaveToken = true;
     options.RequireHttpsMetadata = false;
     options.TokenValidationParameters = new TokenValidationParameters()
     {
         ValidateIssuer = true,
         ValidateAudience = true,   
         ValidateIssuerSigningKey = true,
         ValidateLifetime = true,
         ValidIssuer = builder.Configuration["JWT:Issuer"],
         ValidAudience = builder.Configuration["JWT:Audience"],
         IssuerSigningKey = new SymmetricSecurityKey(key)
     };
     });

builder.Services.AddSwaggerGen(options =>
{
    options.AddSecurityDefinition("oauth2", new OpenApiSecurityScheme
    {
        In = ParameterLocation.Header,
        Name = "Authorization",
        Type = SecuritySchemeType.ApiKey,
    });
    options.OperationFilter<SecurityRequirementsOperationFilter>();
});

builder.Services.AddScoped<IAuthenticationService, AuthenticationService>();
builder.Services.AddScoped<ITokenService, TokenService>();
builder.Services.AddScoped<IEmailService, EmailService>();
builder.Services.AddScoped<IGmailEmailProvider, GmailEmailProvider>();
builder.Services.AddScoped<IBlogService, BlogService>();

builder.Services.AddControllers();
// Learn more about configuring Swagger/OpenAPI at https://aka.ms/aspnetcore/swashbuckle
builder.Services.AddEndpointsApiExplorer();

var app = builder.Build();

app.UseCors(policy =>
    policy.WithOrigins("http://localhost:3000/", "https://localhost:3001")
        .AllowAnyMethod()
        .WithHeaders(HeaderNames.ContentType)
);

// Configure the HTTP request pipeline.
if (app.Environment.IsDevelopment())
{
    app.UseSwagger();
    app.UseSwaggerUI();
}

app.UseHttpsRedirection();
app.UseAuthentication();
app.UseAuthorization();
app.MapControllers();
app.Run();

Controller

[HttpGet]
        [Authorize]
        public async Task<IActionResult> GetAllBlogsAsync()
        {
            var result = await _blogService.GetAllBlogsAsync();
            return Ok(result);
        }

TokenService

public class TokenService : ITokenService
    {
        private readonly string _key;
        private readonly string _issuer;
        private readonly string _audience;
        public TokenService(IConfiguration configuration)
        {
            _key = configuration.GetSection("JWT:AccessTokenKey").Value!;
            _issuer = configuration.GetSection("JWT:Issuer").Value!;
            _audience = configuration.GetSection("JWT:Audience").Value!;
        }
        public string GenerateToken(ApplicationUser user, IList<string> userRoles)
        {
            var tokenHandler = new JwtSecurityTokenHandler();
            var key = Encoding.UTF8.GetBytes(_key);
            
            var authClaims = new List<Claim>
            {
                new Claim(ClaimTypes.Name, user.UserName),
                new Claim(JwtRegisteredClaimNames.Jti, Guid.NewGuid().ToString()),
            };

            foreach (var userRole in userRoles)
            {
                authClaims.Add(new Claim(ClaimTypes.Role, userRole));
            }


            var token = new JwtSecurityToken(
                issuer: _issuer,
                audience: _audience,
                claims: authClaims,
                expires: DateTime.Now.AddDays(1),
                signingCredentials: new SigningCredentials(new SymmetricSecurityKey(key), SecurityAlgorithms.HmacSha256)
            );
            return new JwtSecurityTokenHandler().WriteToken(token);
        }

    }

Thank you for the help