• Journal of Industrial Convergence
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• v.18 no.5
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• pp.23-29
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• 2020

The Internet of things (IoT) is the extension of Internet connectivity into various devices and everyday objects. Embedded with electronics, Internet connectivity and other forms of hardware. The IoT poses significant risk to the entire digital ecosystem. This is because so many of these devices are designed without a built-in security system to keep them from being hijacked by hackers. This paper proposed a mutual authentication protocol for IoT Devices using symmetric-key algorithm. The proposed protocol use symmetric key cryptographic algorithm to securely encrypt data on radio channel. In addition, the secret key used for encryption is random number of devices that improves security by using variable secret keys. The proposed protocol blocked attacker and enabled legal deives to communicate because only authenticated devices transmit data by a mutual authentication protocol. Finally, our scheme is safe for attacks such as eavesdropping attack, location tracking, replay attack, spoofing attack and denial of service attack and we confirmed the safety by attack scenario.

• Journal of the Institute of Convergence Signal Processing
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• v.10 no.4
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• pp.256-261
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• 2009

While .NET and J2EE bisects recent distributed environment, .NET displays "Remoting" as a technology to call remote object. Remoting is frequently used as a protocol in OLTP's WEB program development in form of RPC that exchange data in XML form under HTTP environment. Purpose of this research is to draw problems when applying security to .NET remoting technology that is recently used in web programming, and to find effective application plan by implementing. The main discussion is following. First, network layer security should be replaced to application layer security for better performance and flexibility. Second, the serialization procedure that is repeated in both remoting and encryption module should take place once. Lastly, implementation of "Surrogate" and "Compress" will be discussed that enables to eliminate unnecessary data(table relations, keys, etc) that is used in dataset object of .NET in order to reduce the size of data. It is possible to achieve improvement in speed by two times through immediate implementation in these cases. In order for easier use, component based framework should be supplied hereafter.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.2
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• pp.1020-1042
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• 2019

Reversible data hiding in encrypted images (RDHEI) provides some real-time cloud applications; i.e. the cloud, acting as a data-hider, automatically embeds timestamp in the encrypted image uploaded by a content owner. Many existing methods of RDHEI only satisfy user privacy in which the data-hider does not know the original image, but leaks owner privacy in which the receiver can obtains the original image by decryption and extraction. In the literature, the method of Zhang et al. is the one providing weak content-owner privacy in which the content-owner and data-hider have to share a data-hiding key. In this paper, we take care of the stronger notion, called strong content-owner privacy, and achieve it by presenting a new reversible data hiding in encrypted images. In the proposed method, image decryption and message extraction are separately controlled by different types of keys, and thus such functionalities are decoupled to solve the privacy problem. At the technique level, the original image is segmented along a Hilbert filling curve. To keep image privacy, segments are transformed into an encrypted image by using random permutation. The encrypted image does not reveal significant information about the original one. Data embedment can be realized by using pixel histogram-style hiding, since this property, can be preserved before or after encryption. The proposed method is a modular method to compile some specific reversible data hiding to those in encrypted image with content owner privacy. Finally, our experimental results show that the image quality is 50.85dB when the averaged payload is 0.12bpp.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.14 no.5
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• pp.37-47
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• 2004

The security of personal informations has been an important issue since the field of smart card applications has been expanded explosively. The security of smart card is based on cryptographic algorithms, which are highly required to be implemented into hardware for higher speed and stronger security. In this paper, a SEED cryptographic processor is designed by employing one round key generation block which generates 16 round keys without key registers and one round function block which is used iteratively. Both the round key generation block and the F function are using only one G function block with one 5${\times}$l MUX sequentially instead of 5 G function blocks. The proposed SEED processor has been implemented such that each round operation is divided into seven sub-rounds and each sub-round is executed per clock. Functional simulation of the proposed cryptographic processor has been executed using the test vectors which are offered by Korea Information Security Agency. In addition, we have evaluated the proposed SEED processor by executing VHDL synthesis and FPGA board test. The die area of the proposed SEED processor decreases up to approximately 40% compared with the conventional processor.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.15 no.1
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• pp.87-97
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• 2005

A secure index search protocol let us search the index of encrypted documents using the trapdoor for a keyword. It enables an untrusted server to learn nothing more than the search result about the documents without revealing the keyword. A lot of secure search protocols have been suggested but they only considered the search between a single-user and a server. In real organizations such as government offices or enterprises where exist many hierarchical departments, the search system for groups is arisen more often. In this paper, we construct secure index search protocols for hierarchical group settings without re-encryption of the old encrypted documents when group keys are re-keyed newly.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.32 no.5
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• pp.765-777
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• 2022

The SABER algorithm, a PKE/KEM algorithm presented in NIST PQC Standardization Round 3, is an algorithm based on the Module-LWR problem among lattice-based problems and has a Meta-PKE structure. At this time, the secret information used in the encryption process is called a ephemeral key, and in this paper, the ephemeral key reuse attack using the Meta-PKE structure is described. For each parameter satisfying the security strengths required by NIST, we present a detailed analysis of the previous studies attacked using 4, 6, and 6 queries, and improve them, using only 3, 4, and 4 queries. In addition, we introduce how to reduce the computational complexity of recovering ephemeral keys with a single query from the brute-force complexity on the n-dimension lattice, 2^7.91×n, 2^10.51×n, 2^12.22×n to 2^4.91×n, 2^6.5×n, 2^6.22×n, for each parameter, and present the results and limitations.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.34 no.3
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• pp.365-378
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• 2024

The operating system (OS) of mobiles or embedded devices is based on the Linux kernel. These OSs request random numbers from the Linux kernel for system operation, such as encryption keys and security features. To provide random numbers reliably, the Linux kernel has a dedicated random number generator (Linux Pseudo Random Number Generator, LPRNG). Recently, LPRNG has undergone a major structural changes. However, despite the major changes, no security analysis has been published on the structure of the new LPRNG. Therefore, we analyze these structural changes as a preliminary study to utilize the security analysis of the new LPRNG. Furthermore, the differences between before and after the changes are divided into cryptographic and performance perspectives to identify elements that require security analysis. This result will help us understand the new LPRNG and serve as a base for security analysis.

• The KIPS Transactions:PartC
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• v.13C no.5 s.108
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• pp.541-548
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• 2006

Sensor network is a network for realizing the ubiquitous computing circumstances, which aggregates data by means of observation or detection deployed at the inaccessible places with the capacities of sensing and communication. To realize this circumstance, data which sensor nodes gathered from sensor networks are delivered to users, in which it is required to encrypt the data for the guarantee of secure communications. Therefore, it is needed to design key management scheme for encoding appropriate to the sensor nodes which feature continual data transfer, limited capacity of computation and storage and battery usage. We propose a key management scheme which is appropriate to sensor networks organizing hierarchical architecture. Because sensor nodes send data to their parent node, we can reduce routing energy. We assume that sensor nodes have different security levels by their levels in hierarchy. Our key management scheme provides different key establishment protocols according to the security levels of the sensor nodes. We reduce the number of sensor nodes which share the same key for encryption so that we reduce the damage by key exposure. Also, we propose key update protocols which take different terms for each level to update established keys efficiently for secure data encoding.

• The KIPS Transactions:PartC
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• v.14C no.6
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• pp.463-470
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• 2007

Revocation is one of the main difficulties faced in implementing Public Key Infrastructures(PHs). Boneh, Ding and Tsudik first introduced a mediated cryptography for obtaining immediate revocation of RSA keys used in PKIs. Their method is based on the idea that each user's private key can be split into two random shares, one of which is given to the user and the other to an online security mediator(SEM). Thus any signature or decryption must be performed as a cooperation between a user and his/her associated SEM and revocation is achieved by instructing the mediator SEM to stop cooperating the user. Recently, Libert and Quisquater showed that the fast revocation method using a SEcurity Mediator(SEM) in a mRSA can be applied to the Boneh-Franklin identify based encryption and GDH signature schemes. In this paper we propose a mediated identity based signature(mIBS) with batch verification which apply the SEM architecture to an identity based signature. Libert's GDH siganture scheme is not forward secure even though forward security is an important and desirable feature for signature schemes. We propose an efficient key udating mediated signature scheme, mKUS based on mIBS and analyze its security and efficiency.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.28 no.5
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• pp.1099-1112
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• 2018

The field of post-quantum cryptography (PQC) is an active area of research as cryptographers look for public-key cryptosystems that can resist quantum adversaries. Among those categories in PQC, code-based cryptosystem provides high security along with efficiency. Recent works on code-based cryptosystems focus on the side-channel resistant implementation since previous works have indicated the possible side-channel vulnerabilities on existing algorithms. In this paper, we recovered the secret key in HyMES(Hybrid McEliece Scheme) using a single power consumption trace. HyMES is a variant of McEliece cryptosystem that provides smaller keys and faster encryption and decryption speed. During the decryption, the algorithm computes the parity-check matrix which is required when computing the syndrome. We analyzed HyMES using the fact that the joint distributions of nonlinear functions used in this process depend on the secret key. To the best of our knowledge, we were the first to propose the side-channel analysis based on joint distributions of leakages on public-key cryptosystem.