Generating and validating JWT tokens using JWTSecurityTokenHandler

gistfile1.cs

        [Fact]
        public void First()
        {
            var tokenHandler = new JWTSecurityTokenHandler();
            var symmetricKey = GetRandomBytes(256/8);

            var now = DateTime.UtcNow;
            var tokenDescriptor = new SecurityTokenDescriptor
                {
                    Subject = new ClaimsIdentity(new Claim[]
                        {
                            new Claim(ClaimTypes.Name, "Pedro"),
                            new Claim(ClaimTypes.Role, "Author"), 
                        }),
                    TokenIssuerName = "self",
                    AppliesToAddress = "http://www.example.com",
                    Lifetime = new Lifetime(now, now.AddMinutes(2)),
                    SigningCredentials = new SigningCredentials(
                        new InMemorySymmetricSecurityKey(symmetricKey),
                        "http://www.w3.org/2001/04/xmldsig-more#hmac-sha256", 
                        "http://www.w3.org/2001/04/xmlenc#sha256"),


                };
            var token = tokenHandler.CreateToken(tokenDescriptor);
            
            var tokenString = tokenHandler.WriteToken(token);
            Console.WriteLine(tokenString);
            
            var validationParameters = new TokenValidationParameters()
                {
                    AllowedAudience = "http://www.example.com",
                    SigningToken = new BinarySecretSecurityToken(symmetricKey),
                    ValidIssuer = "self"
                };
            var principal = tokenHandler.ValidateToken(tokenString, validationParameters);
            Assert.True(principal.Identities.First().Claims
                .Any(c => c.Type == ClaimTypes.Name && c.Value == "Pedro"));
            Assert.True(principal.Identities.First().Claims
                .Any(c => c.Type == ClaimTypes.Role && c.Value == "Author"));
        }
    }        

please do this: var symmetricKey = (byte[]) GetRandomBytes(256 / 8);