Naoya Kitagawa

Design of real-time advanced lens free imager

A Lens Free Imager (LFI) is one of promising candidates for massive visual inspection systems in biology and medical science. In a practical application, millions of samples need to be inspected in a short period of time, which a single Lens Free Imager (LFI) system cannot accomplish. Therefore, we propose a high performance parallel LFI system called RALFIE (Real-time Advanced LFI Evaluation system). In this paper, we introduce the concept and detail of the design of RALFIE and a target application.

An anti-spam method via real-time retransmission detection

Tempfailing is widely used in many organizations as anti-spam technology. However, this technology causes a serious problem: it imposes long delays in mail delivery. To solve this problem, another technique called 5-Way Handshake was proposed, but its conventional implementation has a serious drawback. Based on the MX fallback mechanism defined by RFC5321, a legitimate sender must access MX hosts in order of their preferences. By making communication between primary and secondary MXs, the method examines whether a mail delivery follows the mechanism. This causes heavy communication overhead. In this paper, therefore, we propose modified mechanism of 5-Way Handshake for an anti-spam system in order to detect MX fallback in real-time.

A Spoofed E-Mail Countermeasure Method by Scoring the Reliability of DKIM Signature Using Communication Data

Recently, spoofed e-mails become sophisticated and the messages that cannot be identified by visual confirmation have been increasing. DKIM is one of the most famous methods as countermeasure of spoofed e-mail. However, since DKIM allows a signature by third party domains, a recipient server can be unable to determine whether the attached signature is the legitimate. To solve the problem, although a method using data of DKIM signature domain passed DKIM verification is proposed, this method only verifies the existence of the past deliveries, therefore it has an issue in reliability. To overcome the issue, in this paper, we propose a method to score the reliability of combinations of senders Header-From domain and DKIM signature domain by analyzing fluctuation of the existence of e-mail delivery obtained from the past communication data. By utilizing this method, the recipients can obtain the reliability score for each message including spoofed e-mail which was uniformly verified successfully in the ordinary DKIM verification, and can utilize our mechanism to spoofed e-mails countermeasure system.

Cache Function Activation on a Client Based DNSSEC Validation and Alert System by Multithreading

Domain Name System (DNS) is one of the most important services of the Internet since most communications normally begin with domain name resolutions provided by DNS. However, DNS has vulnerability against some kind of attacks such as DNS spoofing, DNS cache poisoning, and so on. DNSSEC is an security extension of DNS to provide secure name resolution services by using digital signature based on public key cryptography. However, there are several problems with DNSSEC such as failing resolution in case of validation failure, increasing the load of DNS full resolver, and so on. To mitigate these problems, we proposed a Client Based DNSSEC Validation System. This system performs DNSSEC validation on the client, and in case of validation failure, it forwards the failed response and alerts the user to the fact. However, this system has a problem that it inactivates the cache function of validation library so that it always performs DNSSEC validation even for the same query. In this paper, we report how to solve this problem by multithreading of DNSSEC validation system.

Throughput improvement of MPTCP communication by bicasting on multihomed network

With the spread of mobile devices, demands for high speed and stable communication have been growing. However wireless communication has a feature that is susceptible to the surrounding environment. For instance, many packet losses occur caused by the radio wave interference or attenuation. Recent many mobile devices have multiple wireless network interfaces. Multihoming improves throughput by connecting a host to more than one network using multiple network interfaces simultaneously. Although the previous studies of the bicasting on multihomed network indicate throughput improvement using Multihomed Mobile IP or SCTP, these protocols are not widely used. To solve the problem, we focused on Multipath TCP that is one of the transport layer protocols supporting the multihoming. In this paper, we implemented a system that emulates various actual environments of wireless communication and experimented the throughput and the influence effect using the several bicasting methods. As the result, we confirmed that the selective bicasting is the most suitable for throughput improvement in the actual network environments.