• Journal of the Korea Institute of Information Security & Cryptology
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• v.10 no.4
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• pp.107-112
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• 2000

In this paper, we study a security of HEA(Hangul Encryption Algorithm) against differential cryptanalysis. HEA, which is 1,024bits input/output and 56bits key size, has the same structure as DES(Data Encyption Standard) only for Korean characters to be produced in ciphertexts. An encryption algorithm should be developed to meet certain critria such as input/ouput dependencies, correlation, avalanche effects, etc. However HEA uses the same S-Boxes as DES does and just expands the plaintext/ciphertext sizes . We analysize HEA with a differential cryptanalysis and present two results. The number of rounds of HEA has not been determined in a concrete basis of cryptanalysis and we show a chosen plintext attack of 10 round reduced HEA with a diffe- rential cryptanalysis characteristic.

• International Journal of Computer Science & Network Security
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• v.22 no.8
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• pp.113-122
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• 2022

At the point when it is check out ourselves, it might track down various information in each turn or part of our lives. Truth be told, information is the new main thrust of our advanced civilization and in this every day, "information-driven" world, security is the significant angle to consider to guarantee dependability and accessibility of our organization frameworks. This paper includes a new cryptographic algorithm for safe route traversal for data of smart cities which is a contemporary, non-hash, non-straight, 3D encryption execution intended for having information securely scrambled in the interim having a subsequent theoretical layer of safety over it. Encryption generally takes an information string and creates encryption keys, which is the way to unscramble as well. In the interim in another strategy, on the off chance that one can sort out the encryption key, there are opportunities to unravel the information scrambled inside the information string. Be that as it may, in this encryption framework, the work over an encryption key (which is created naturally, henceforth no pre-assurance or uncertainty) just as the calculation produces a "state" in a way where characters are directed into the Rubik block design to disregard the information organization.

• Journal of Korea Multimedia Society
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• v.17 no.12
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• pp.1402-1411
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• 2014

Buyer-seller watermarking protocol is defined as the practice of imperceptible altering a digital content to embed a message using watermarking in the encryption domain. This protocol is acknowledged as one kind of copyright protection techniques in electronic commerce. Buyer-seller watermarking protocol is fundamentally based on public-key cryptosystem that is operating using the algebraic property of an integer. However, in general usage, digital contents which are handled in watermarking scheme mostly exist as real numbers in frequency domain through DCT, DFT, DWT, etc. Therefore, in order to use the watermarking scheme in a cryptographic protocol, digital contents that exist as real number must be transformed into integer type through preprocessing beforehand. In this paper, we presented a new watermarking scheme in an encrypted domain in an image that is based on the block-DCT framework and homomorphic encryption method for buyer-seller watermarking protocol. We applied integral-processing in order to modify the decimal layer. And we designed a direction-adaptive watermarking scheme by analyzing distribution property of the frequency coefficients in a block using JND threshold. From the experimental results, the proposed scheme was confirmed to have a good robustness and invisibility.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.24 no.4
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• pp.585-592
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• 2014

In this paper, we study the LEA[1] block cipher system in UICC-16bit only. Also, we explain a key-schedule function and encryption/decryption structures, propose an advanced modified key-scheduling, and perform LEA in UICC-16bit that we proposed advanced modified key-scheduling. Also, we compare LEA with ARIA that proposed domestic standard block cipher, and we evaluate the efficiency on the LEA algorithm.

• Journal of Multimedia Information System
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• v.7 no.2
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• pp.165-174
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• 2020

This document outlines a new color image encryption technology development. After splitting the original image into 240-bit blocks and modifying the first block by an initialization vector, an improved Feistel circuit is applied, sponsored by a genetic crossover operator and then strong chaining between the encrypted block and the next clear block is attached to set up the confusion-diffusion and heighten the avalanche effect, which protects the system from any known attack. Simulations carried out on a large database of color images of different sizes and formats prove the robustness of such a system.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.14 no.2
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• pp.724-737
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• 2020

Corrected Block TEA(or XXTEA) is a block cipher designed to correct security weakness in the original block TEA in 1998. In this paper, XXTEA cipher hardware which can encrypt or decrypt between 64-bit and 256-bit messages using 128-bit master key is implemented. Minimum message block size is 64-bit wide and maximal message block size is 256-bit wide. The designed XXTEA can encrypt and decrypt variable-length message blocks which are some arbitrary multiple of 32 bits in message block sizes. XXTEA core of this paper is described using Verilog-HDL and downloaded on Vertex4. The operation frequency is 177MHz. The maximum throughput for 64-bit message blocks is 174Mbps and that of 256-bit message blocks is 467Mbps. The cryptographic IP of this paper is applicable as security module of the mobile areas such as smart card, internet banking, e-commerce and IoT.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.3A
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• pp.399-405
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• 2000

In this paper, we deal with block cipher algorithm IDEA(international data encryption algorithm), previously known as typical block cipher system. first of all, analysing key scheduler we classify the key sequences with the used key bit and the unused key bits in each round. with this properties we propose the two method, which are differential analysis using differences of plaintext pairs and linear analysis using LSB bit of plaintexts and key sequences.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.10a
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• pp.653-656
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• 2013

TFTP(Trivial File Transfer Protocol)는 UDP(User Datagram Protocol) 기반의 파일 전송 프로토콜이다. TFTP는 프로토콜 구조가 단순하여 작은 크기의 데이터를 빠른 속도로 전송할 때 사용된다. 하지만 TFTP는 보안 기능을 지원하지 않기 때문에 데이터 노출의 위험이 있다. 본 논문에서는 Diffie-Hellman 키 교환 방식과 AES-CBC(Advanced Encryption Standard-Cipher Block Chaining) 암호화 방식을 이용하여 TFTP 프로토콜에 보안 기능을 추가하였다. Diffie-Hellman 키 교환 방식을 이용하여 두 사용자 간에 비밀 키를 공유하도록 하였고, AES-CBC 암호화를 지원하여 기밀성을 제공하도록 하였다. 수신된 데이터는 암호화 과정의 역으로 복호화를 수행하였다. WireShark 프로그램을 통하여 암호화된 데이터가 전송 되는 것을 확인하였다.

• Journal of information and communication convergence engineering
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• v.3 no.4
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• pp.201-204
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• 2005

Twofish is a 128-bit block cipher that accepts a variable-length key up to 256 bits. The cipher is a 16­round Feistel network with a bijective F function made up of four key-dependent 8-by-8-bit S-boxes, a fixed 4­by-4 maximum distance separable matrix over Galois Field$(GF (2^8)$, a pseudo-Hadamard transform, bitwise rotations, and a carefully designed key schedule. In this paper, the Twofish is modeled in VHDL and simulated. Hardware implementation gives much better performance than software-based approaches.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.9
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• pp.1703-1710
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• 2017

This paper propose a 3D point clouds (depth) security technique for digital holographic display service. Image contents encryption is a method to provide only authorized right owners with the original image information by encrypting the entire image or a part of the image. The proposed method detected an edge from a depth and performed quad tree decomposition, and then performed encryption. And encrypts the most significant block among the divided blocks. The encryption effect was evaluated numerically and visually. The experimental results showed that encrypting only 0.43% of the entire data was enough to hide the constants of the original depth. By analyzing the encryption amount and the visual characteristics, we verified a relationship between the threshold for detecting an edge-map. As the threshold for detecting an edge increased, the encryption ratio decreased with respect to the encryption amount.