Authentication - email validation

    // *** Request model ***
    public class ValidateEmailRequest
    {
        public string Username { get; set; }
        public string B64SecToken { get; set; }
    }

// *** Service (repository) method implementation ***
        public void ValidateEmail(ValidateEmailRequest request)
        {
            var target = _users.FirstOrDefault(x =>
                x.Username == request.Username && x.SecurityToken == request.B64SecToken);

            if (target == null)
                throw new InvalidOperationException("Authentication failed");

            target.IsConfirmed = true;
        }


// *** Validate email action implementation (return generated email validation token) ***
        [HttpPost("[action]")]
        public ActionResult ValidateEmail([FromBody] ValidateEmailRequest request)
        {
            try
            {
                _userRepository.ValidateEmail(request);
                return Ok();
            }
            catch (InvalidOperationException ex)
            {
                return BadRequest(ex.Message);
            }
        }