• Journal of the Korea Institute of Information Security & Cryptology
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• v.16 no.6
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• pp.3-13
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• 2006

Internet mail has become a common communication method to send and receive an amount of data due to the tremendous high speed Internet service increment. But in other respect, the risk and damage of Junk mail is growing rapidly and nowadays Junk mail delivery problem is becoming more serious, because this is used for an attack or propagation scheme of malicious code. It's a most dangerous dominant cause for computer system accident. This paper shows the Junk mail characteristic which is based on the analysis of mail log in reality and then shows the implementation of the FQDN (Fully Qualified Domain Name) check and Personalized classification system and evaluates its performance.

• Journal of Advanced Navigation Technology
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• v.18 no.6
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• pp.588-593
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• 2014

Recently, the smart devices has been possessed by a large majority of the adult, and offered various personalization services. This paper proposed the lightweight Intelligent Image Security System that notice the existence of any intruder in real time at the place of requiring the security by using smart device. The proposed image security system recognized whether or not intruder exists using the difference frame on the basis of Integral Image and the dynamic background updating algorithms. The intrusion notification is achieved by using the GCM push server that send massages in the application unit of user mobile device, and the SMTP mail server which is use of e-mail standard protocol. In case of the occurrence of intruder, GCM push server send an push-massage by the private mobile device, and SMTP mail server send the intruder's photograph and intrusion time. By the convergence of the various image processing algorithms and the performance of smart device, The proposed image security system can be applied to the various Intelligent Image Security field.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2022.05a
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• pp.243-245
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• 2022

In this paper, a policy to manage e-mail system with respect to the increase in cyber threats through e-mail will be proposed but only from the perspective of security. After covering recent trends on cyber threats through e-mail, security measures including technical, administrative and operational will be encountered in order to finalize the policy proposal.

• The KIPS Transactions:PartD
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• v.13D no.3 s.106
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• pp.437-444
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• 2006

A chaos cipher system that focuses on the stream cipher system has a demerit that the longer the text is, the slower the speed of the encryption and description and the transmission and reception. On this study, we designed the cipher web mail system showing much better capabilities than the existing web mail system as the text is longer. In the embodiment of the cipher web mail system, we developed the key stream, the encryption and description of the text and the inside and outside mail viewer and so on. After the efficiency test, it was valued high in the respect of the speed of the encryption and description and the transmission and reception. And it made up for the defect of the stream cipher system. We expect that we can use it through the persistent applied study in the server system security, the file security, the security of the internet information, the protection of the e-commerce system information and other fields based on the cipher technique as the wide use cipher system that can replace the block cipher system.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.20 no.3
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• pp.189-194
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• 2020

Most cyber breaches are caused by APT attacks using malware. Hackers use the email system as a medium to penetrate the target. It uses e-mail as a method to access internally, destroys databases using long-term collected vulnerabilities, and illegally acquires personal information through system operation and ransomware. As such, the e-mail system is the most friendly and convenient, but at the same time operates in a blind spot of security. As a result, personal information leakage accidents can cause great damage to the company and society as a whole. This study intends to suggest an effective methodology to securely manage the APT attack by strengthening the security configuration of the e-mail system operating in the enterprise.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.25 no.1
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• pp.107-122
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• 2015

Many defensive mechanisms have been evolved as new attack methods are developed. However, APT attacks using e-mail are still hard to detect and prevent. Recently, many organizations in the government sector or private sector have been hacked by malicious e-mail based APT attacks. In this paper, first, we built hacking e-mail database based on the real e-mail data which were used in attacks on the Korean government organizations in recent years. Then, we extracted features from the hacking e-mails for profiling them. We design a case vector that can describe the specific characteristics of hacking e-mails well. Finally, based on case based reasoning, we made an algorithm for retrieving the most similar case from the hacking e-mail database when a new hacking e-mail is found. As a result, hacking e-mails have common characteristics in several features such as geo-location information, and these features can be used for classifying benign e-mails and malicious e-mails. Furthermore, this proposed case based reasoning algorithm can be useful for making a decision to analyze suspicious e-mails.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.19 no.1
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• pp.93-101
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• 2009

This paper proposes the detection method of spreading mails which hacker injects malicious codes to steal the information. And I developed the 'Analysis model' which is decoding traffics when hacker's encoding them to steal the information. I researched 'Methodology of intrusion detection techniques' in the computer network monitoring. As a result of this simulation, I developed more efficient rules to detect the PCs which are infected malicious codes in the hacking mail. By proposing this security policy which can be applicable in the computer network environment including every government or company, I want to be helpful to minimize the damage by hacking mail with malicious codes.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.15 no.6
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• pp.37-47
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• 2005

Recently, the malicious e-mail worm-viruses have been widely spreaded over the Internet. If the recipient opens the e-mail attachment or an e-mail itself that contains the worm-virus, the worm-virus can be activated and then cause a tremendous damage to the system by propagating itself to everyone on the mailing list in the user's e-mail package. In this paper, we have designed and implemented two methods blocking e-mail worm-viruses. In the fist method, each e-mail is transmitted only by sender activity such as the click of button on a mail client application. In the second one, we insert the two modules into the sender side, where the one module transforms a recipient's address depending on a predefined rule only in time of pushing button and the other converts the address reversely with the former module whenever an e-mail is sent. The lader method also supports a polymorphism model in order to cope with the new types of e-mail worm-virus attacks. The two methods are designed not to work for the e-mail viruses. There is no additional fraction on the receiver's side of the e-mail system. Experimental results show that the proposed methods can screen the e-mail worm-viruses efficiently with a low overhead.

• Journal of Digital Contents Society
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• v.18 no.7
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• pp.1403-1409
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• 2017

As the Internet evolves, security becomes more important. Especially, e-mail has become one of the most important services that companies and ordinary users use on the Internet. However, security vulnerabilities such as sniffing attacks, IDs, and password spoofs are causing many problems. This paper introduces an example of implementation of encrypted mailing program with which the secured mail is encrypted by symmetric key methode and the encrypted message can not be read without proper decryption. In order to use the current mailing systems, we keep the rules related to SMTP and POP3, and only the encrypted message is stored in the mail server system and the message can be decrypted only at the terminals of the senders and the receivers with the key which is shared in advanced by independent route between them. This implementation scheme can provide an efficiency that it does not request any change of current mailing system, which can be an additional security protection.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.14 no.2
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• pp.23-33
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• 2004

Because of a rapid growth of internet environment, it is also fast increasing to exchange message using e-mail. But, despite the convenience of e-mail, it is rising a currently bi9 issue to waste their time and cost due to the spam mail in an individual or enterprise. Many kinds of solutions have been studied to solve harmful effects of spam mail. Such typical methods are as follows; pattern matching using the keyword with representative method and method using the probability like Naive Bayesian. In this paper, we propose a classification method of spam mails from normal mails using Support Vector Machine, which has excellent performance in pattern classification problems, to compensate for the problems of existing research. Especially, the proposed method practices efficiently a teaming procedure with a word dictionary including a generated index by the n-Gram. In the conclusion, we verified the proposed method through the accuracy comparison of spm mail separation between an existing research and proposed scheme.