• The KIPS Transactions:PartC
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• v.11C no.5
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• pp.683-688
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• 2004

NAT is a very useful IP address translation technique that allows two connected networks using different and incompatible IP address schemes. But it is impractical to use NAT for an application which uses the encrypted IP packet, embedding IP addresses inside of data payloads, to guarantee End-to-End Security such as IPSec. In addition to rewriting the source/destination IP addresses in the packet, NAT must modify IP checksum every time, which could lead to considerable performance decrease of the overall system in the process of the address translation. RSIP is an alternative to solve these disadvantages of NAT and the address shortage problems. Both NAT and RSIP divide networks into inside and outside addressing realms. NAT translates addresses between internal network and external network, but RSIP uses a borrowed external address for outside communications. RSIP server assigns a routable public address to a RSIP client temporarily to communicate with public net-work outside of the private network. In this paper, RSIP gateway for intranet environment is designed and its performance is evaluated. From the results of performance evaluation, we knew that RSIP is operated less sensitive to the data traffic. Also, the experiment shows that RSIP performs better than NAT when the transmission data grows larger.

• The Journal of the Korea institute of electronic communication sciences
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• v.13 no.2
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• pp.333-340
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• 2018

This paper introduces a BCH code decoder using parallel CRC(: Cyclic Redundancy Check) generation. Using a conventional parallel syndrome generator with a LFSR(: Linear Feedback Shift Register), it takes up a lot of space for a short code. The proposed decoder uses the parallel CRC method that is widely used to compute the checksum. This scheme optimizes the a syndrome generator in the decoder by eliminating redundant xor operation compared with the parallel LFSR and thus minimizes chip area and propagation delay. In simulation results, the proposed decoder has accomplished propagation delay reduction of 2.01 ns as compared to the conventional scheme. The proposed decoder has been designed and synthesized in $0.35-{\mu}m$ CMOS process.

• Korean Journal of Optics and Photonics
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• v.27 no.4
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• pp.133-142
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• 2016

This paper presents the design and simulation of a three-dimensional pixel-by-pixel scanning light detection and ranging (LIDAR) system with a microelectromechanical system (MEMS) scanning mirror and direct sequence optical code division multiple access (DS-OCDMA) techniques. It measures a frame with $848{\times}480$ pixels at a refresh rate of 60 fps. The emitted laser pulse waves of each pixel are coded with DS-OCDMA techniques. The coded laser pulse waves include the pixel's position in the frame, and a checksum. The LIDAR emits the coded laser pulse waves periodically, without idle listening time to receive returning light at the receiver. The MEMS scanning mirror is used to deflect and steer the coded laser pulse waves to a specific target point. When all the pixels in a frame have been processed, the travel time is used by the pixel-by-pixel scanning LIDAR to generate point cloud data as the measured result.

• Aerospace Engineering and Technology
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• v.7 no.1
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• pp.83-90
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• 2008

The next generation LID satellite has 64KB PROM which contains the boot loader and the monitor software, and two 4MB NVMEMs which are used for flight software storage. The boot loader has two operation modes which are the flight software mode and the monitor mode. In the flight software mode, it checks CRC checksum of selected NVMEM and copies flight software image from NVMEM to RAM And then it starts VxWorks RTOS in RAM, creates flight software tasks, and starts execution of flight software. In the monitor mode, it activates monitor software which performs NVMEM reprogramming and board-level testing on the ground. This paper is to present the design of Boot ROM software and verification method using simulator.

• Journal of the Korea Society of Computer and Information
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• v.14 no.10
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• pp.101-110
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• 2009

The 6LoWPAN(IPv6 Low-power Wireless Personal Area Network) performs IPv6 header compression, TCP/UDP/IGMP header compression, packet fragmentation and re-assemble to transmit IPv6 packet over IEEE 802,15.4 MAC/PHY. However, from the point of view of security. It has the existing security threats issued by IP packet fragmenting and reassembling, and new security threats issued by 6LoWPAN packet fragmenting and reassembling would be introduced additionally. If fragmented packets are retransmitted by replay attacks frequently, sensor nodes will be confronted with the communication disruption. This paper analysis security threats introduced by 6LoWPAN fragmenting and reassembling, and proposes a re-transmission mechanism that could minimize re-transmission to be issued by replay attacks. Re-transmission procedure and fragmented packet structure based on the 6LoWPAN standard(RFC4944) are designed. We estimate also re-transmission delay of the proposed mechanism. The mechanism utilizes timestamp, nonce, and checksum to protect replay attacks. It could minimize reassemble buffer overflow, waste of computing resource, node rebooting etc., by removing packet fragmentation and reassemble unnecessary.

• Journal of the Korea Computer Industry Society
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• v.5 no.1
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• pp.39-48
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• 2004

An IP address shortage problem is happening with a rapid propagation of the Internet and demands about a new IP address. Address translation technology as NAT is becoming use widely in order to solve these problems. NAT is an very useful If address translation technique that allows two connected networks to use different and incompatible IP address schemes. Rut it is difficult to use NAT particularly for applications that embeded IP addresses in data payloads or encrypted IP packet to guarantee End-to-End Security such as IPSec. In addition to rewiting the source/destination IP address in the packet, NAT must modify IP checksum every time, which could lead to considerablely performance decrease of the overall system in the process of address translation. RSIP is an alternative to solve these disadvantages and address shortage problems of NAT. Both NAT and RSIP divide networks into inside and outside addressing realms. NAT translates addresses between internal network and external network, but RSIP uses a borrowed external address for outside communications. RSIP server assigns a routable, public address to an RSIP client temporaily to communicate with public network outside the private network. In this paper, I will analyze NAT and RSIP gateway system, and then I will propose the Linux-based RSIP gateway for more efficient IP Address Translation in Intranet environments based on RSIP standard of IETF.

• KIPS Transactions on Computer and Communication Systems
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• v.12 no.9
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• pp.283-290
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• 2023

With the recent steady development of IoT technology, it is widely used in medical systems and smart TV watches. 66% of software development is developed through language C, which is vulnerable to memory attacks, and acts as a threat to IoT devices using language C. A stack-smashing overflow attack inserts a value larger than the user-defined buffer size, overwriting the area where the return address is stored, preventing the program from operating normally. IoT devices with low memory capacity are vulnerable to stack smashing overflow attacks. In addition, if the existing vaccine program is applied as it is, the IoT device will not operate normally. In order to defend against stack smashing overflow attacks on IoT devices, we used canaries among several detection methods to set conditions with random values, checksum, and DSLR (random storage locations), respectively. Two canaries were placed within the buffer, one in front of the return address, which is the end of the buffer, and the other was stored in a random location in-buffer. This makes it difficult for an attacker to guess the location of a canary stored in a fixed location by storing the canary in a random location because it is easy for an attacker to predict its location. After executing the detection program, after a stack smashing overflow attack occurs, if each condition is satisfied, the program is terminated. The set conditions were combined to create a number of eight cases and tested. Through this, it was found that it is more efficient to use a detection method using DSLR than a detection method using multiple conditions for IoT devices.