JWT token provider

public class JwtTokenProvider
{
    public static string CreateToken(string secureKey, int expiration, string subject = null, string role = null)
    {
        // Get secret key bytes
        var tokenKey = Encoding.UTF8.GetBytes(secureKey);

        // Create a token descriptor (represents a token, kind of a "template" for token)
        var tokenDescriptor = new SecurityTokenDescriptor
        {
            Expires = DateTime.UtcNow.AddMinutes(expiration),
            SigningCredentials = new SigningCredentials(
                new SymmetricSecurityKey(tokenKey),
                SecurityAlgorithms.HmacSha256Signature)
        };

        if (!string.IsNullOrEmpty(subject))
        {
            tokenDescriptor.Subject = new ClaimsIdentity(new System.Security.Claims.Claim[]
            {
                new System.Security.Claims.Claim(ClaimTypes.Name, subject),
                new System.Security.Claims.Claim(JwtRegisteredClaimNames.Sub, subject),
                new System.Security.Claims.Claim(ClaimTypes.Role, role),
            });
        }

        // Create token using that descriptor, serialize it and return it
        var tokenHandler = new JwtSecurityTokenHandler();
        var token = tokenHandler.CreateToken(tokenDescriptor);
        var serializedToken = tokenHandler.WriteToken(token);

        return serializedToken;
    }
}