• Journal of Communications and Networks
• /
• v.15 no.5
• /
• pp.464-468
• /
• 2013

The widespread use of cryptographic technologies is complicated by inconsistencies and duplication in the key management systems supporting their applications. The proliferation of key management systems or protocols also results in higher operational and infrastructure costs, and fails in interoperability. Thus, it is essential to realize key management interoperability between different and heterogeneous cryptosystems. This paper presents a practical and separable key management system for heterogeneous public-key cryptosystems. We achieve the interoperability between different cryptosystems via cryptography approaches rather than communication protocols. With our scheme, each client can freely use any kind of cryptosystemthat it likes. The proposed scheme has two advantages over the key management interoperability protocol introduced by the organization for the advancement of structured information standards. One is that all the related operations do not involve the communication protocol and thus no special restrictions are taken on the client devices. The other is that the proposed scheme does not suffer from single-point fault and bottleneck problems.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.11 no.4
• /
• pp.2254-2275
• /
• 2017

In this paper, we present an IND-CCA2 secure certificateless proxy re-encryption scheme in the random oracle model. A certificateless public key cryptography simplifies the certificate management in a traditional public key infrastructure and the built-in key escrow feature in an identity-based public key cryptography. Our scheme shares the merits of certificateless public key encryption cryptosystems and proxy re-encryption cryptosystems. Our certificateless proxy re-encryption scheme has several practical and useful properties - namely, multi-use, unidirectionality, non-interactivity, non-transitivity and so on. The security of our scheme bases on the standard bilinear Diffie-Hellman and the decisional Bilinear Diffie-Hellman assumptions.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.21 no.11
• /
• pp.878-883
• /
• 2020

Cryptographic algorithms are used to prevent the illegal manipulation of data. They are divided into public-key cryptosystems and symmetric-key cryptosystems. Public-key cryptosystems require considerable time for encryption and decryption compared to symmetric-key cryptosystem. On the other hand, key management, and delivery are easier for public-key cryptosystems than symmetric-key cryptosystems because different keys are used for encryption and decryption. Furthermore, hash functions are being used very effectively to verify the integrity of the digital content, as they always generate output with a fixed size using the data of various sizes as input. This paper proposes a method using RSA public-key cryptography and a hash function to determine if a digital image is deformed or not and to detect the manipulated location. In the proposed method, the entire image is divided into several blocks, 64×64 in size. The watermark is then allocated to each block to verify the deformation of the data. When deformation occurs, the manipulated pixel will be divided into smaller 4×4 sub-blocks, and each block will have a watermark to detect the location. The safety of the proposed method depends on the security of the cryptographic algorithm and the hash function.

• Review of KIISC
• /
• v.1 no.1
• /
• pp.94-99
• /
• 1991

공개 키암호 시스템(public key dcytosystem)의 각종 방식을 설명하고 심도있는 이 론적 해석과 예제를 통한 각 암호 시스템의 타당성을 입증한다. 또한, 대칭암호 시스템 (private-key cipher systems)과 비대칭암호시스템(public-key cryptosystems)별로 나누어 인 증(authentication) 및 디지탈 서명(digital signature)에 관한 문제들을 다음 목차에 따라 연재 로 자세히 기술하고자 한다.

• Journal for History of Mathematics
• /
• v.11 no.2
• /
• pp.8-16
• /
• 1998

We survey the development of cryptography from the ancient to the present as a mathematical point of view, and recent results of public key cryptosystems.

• ETRI Journal
• /
• v.38 no.4
• /
• pp.724-734
• /
• 2016

To achieve confidentiality, integrity, authentication, and non-repudiation simultaneously, the concept of signcryption was introduced by combining encryption and a signature in a single scheme. Certificate-based encryption schemes are designed to resolve the key escrow problem of identity-based encryption, as well as to simplify the certificate management problem in traditional public key cryptosystems. In this paper, we propose a new certificate-based signcryption scheme that has been proved to be secure against adaptive chosen ciphertext attacks and existentially unforgeable against chosen-message attacks in the random oracle model. Our scheme is not based on pairing and thus is efficient and practical. Furthermore, it allows a signcrypted message to be immediately verified by the public key of the sender. This means that verification and decryption of the signcrypted message are decoupled. To the best of our knowledge, this is the first signcryption scheme without pairing to have this feature.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.14 no.2
• /
• pp.738-756
• /
• 2020

The modular multiplication is the key module of public-key cryptosystems such as RSA (Rivest-Shamir-Adleman) and ECC (Elliptic Curve Cryptography). However, the efficiency of the modular multiplication, especially the modular square, is very low. In order to reduce their operation cycles and power consumption, and improve the efficiency of the public-key cryptosystems, a dual-field efficient FIPS (Finely Integrated Product Scanning) modular multiplication algorithm is proposed. The algorithm makes a full use of the correlation of the data in the case of equal operands so as to avoid some redundant operations. The experimental results show that the operation speed of the modular square is increased by 23.8% compared to the traditional algorithm after the multiplication and addition operations are reduced about (s² - s) / 2, and the read operations are reduced about s² - s, where s = n / 32 for n-bit operands. In addition, since the algorithm supports the length scalable and dual-field modular multiplication, distinct applications focused on performance or cost could be satisfied by adjusting the relevant parameters.

• Journal of KIISE:Computer Systems and Theory
• /
• v.31 no.1_2
• /
• pp.51-58
• /
• 2004

Most of pubic-key cryptosystems are built on the basis of arithmetic operations defined over the finite field GF$GF(2^m)$ .The other operations of finite fields except addition can be computed by repeated multiplications. Therefore, it is very important to implement the multiplication operation efficiently in public-key cryptosystems. We propose an efficient bit-parallel normal basis multiplier for$GF(2^m)$ fields defined by All-One Polynomials. The gate count and time complexities of our proposed multiplier are lower than or equal to those of the previously proposed multipliers of the same class. Also, since the architecture of our multiplier is regular, it is suitable for VLSI implementation.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.4 no.4
• /
• pp.270-273
• /
• 2009

In 1988, Buchmann et al. proposed a public key cryptosystem making use of ideals of the maximal orders in quadra tic fields which may pave the way for a public key cryptosystem using imaginary quadratic non-invertible ideals as generators. Next year, H$\ddot{u}$hnlein, Tagaki et al. published the cryptosystem with trapdoor and conductor prime p over non-maximal orders. On the other hand Kim and Moon proposed a public key cryptosystrem and a key distribution cry ptotsystem over class semigroup in 2003. We, in this paper, introduce and analyze the cryptotsystems mentioned above.

• Journal of Korea Multimedia Society
• /
• v.8 no.7
• /
• pp.974-987
• /
• 2005

As the ad hoc networks have been received a great deal of attention to not only the military but also the industry applications, some security mechanisms are required for implementing a practical ad hoc application. In this paper, we propose a security architecture in ad hoc networks for the purpose of supporting ID-based public key cryptosystems because of the advantage that ID-based schemes require less complex infrastructure compared with the traditional public key cryptosystems. We assume a trusted key generation center which only issues a private key derived from IDs of every nodes in the system setup phase, and use NIL(Node ID List) and NRL(Node Revocation List) in order to distribute the information about IDs used as public keys in our system. Furthermore, we propose a collaborative status checking mechanism that is performed by nodes themselves not by a central server in ad-hoc network to check the validity of the IDs.