• Journal of the Korea Institute of Information Security & Cryptology
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• v.11 no.3
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• pp.33-44
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• 2001

E-commerce has various advantages such as saving the cost and no constraint on time and space, unlike real-world commerce. On the other hand, e-commerce has some important issues to solve since the commerce is conducted on the cyberspace. The issues are a mutual confidence of parties participating in the commerce as well as a method of payments. On early days, electronic cash was designed using blind digital signature to protect the personal information from being exposed and to provide the perfect anonymity for user. In this paper, a new blind signature scheme based on Feige-Fiat-Shamir digital signature is proposed, which is very efficient compared with the other schemes in terms of the computational complexity. Also, a traceable Electronic Cash System which is based on the proposed blind digital signature is designed, which has a nice feature of identifying the spender in case of using the money illegally.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.4
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• pp.870-879
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• 1997

At crypto'89 meeting, D. chaum suggested an undeniable signature scheme. Undeniable signatures are verified via a protocol between the signer and verifier, so the cooperation of the signer is necessary. So far, ther have been several variants of undeniable signatures to obtain a signature scheme, which can control the abous of ordinary digital signatures. In this paper we integrate these variants into a generalized undeniable-type signature scheme. Also, it will be pointed out, that undeniable signature schemes but its first realization are vulnerable in full view of eavesdropping third party. Moreover, to solve this problem, we propose a new type of digital signature, called "result-indisting-uishable undeniable signature" and construct a practical protocol that implements it.

• The Transactions of the Korea Information Processing Society
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• v.5 no.4
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• pp.984-994
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• 1998

In the information society, all the information is transferred through the network, so it becomes an issue to protect the data on network. One of the fundamental cryptographic tools to protect the data on network, is digital signatures, and in many countries, cryptographers have been trying to make their own digital signature standard. Also, at Crypto'89 meeting, D.Chaum suggested an undeniable signature scheme. Undeniable signatures are verified via a protocol between the signer and the verifier, so the cooperation of the signer is necessary, So far, there have been several variants of undeniable signatures to obtain a signature scheme, which can control the abuse of ordinary digital signatures.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.7 no.2
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• pp.55-72
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• 1997

This paper presents a digital signature scheme for facsimile document which directly embeds a signature onto the document. We use multiple reference lines which have been scanned just before and modify each distance of changing pels both on the reference line specified by key and on the coding line with a single bit of the signature data. The time to take in signature is reduced by spreading of signature. Non-repudiation in origin, the 3rd condition of digital signature is realized by proposed digital signature scheme. The transmitter embeds the signature secretly and transfers it, and the receiver makes a check of any forgery on the signature and the document. This scheme is compatible with the ITU-T.4(CCITT G3 or G4 facsimile standards). The total amount of data transmitted and the image quality are about the same to that of the original document, and thus a third party notices that no signature is embedded on the document.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.22 no.5
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• pp.945-957
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• 2012

Electronic documents have characteristics that detecting whether an electronic document is modified or not is not an easy process. Thus verifying integrity of documents is very important for using electronic documents. To facilitate this process, various electronic document software provide digital signature capabilities on themselves. However, there were not much research on the security of digital signature function of software. Therefore, in this paper, we analyze the security of Adobe PDF, MS Word, Hancom Hangul, digital notary service and digital year-end-settlement service, and propose recommendations for implementation of digital signature funcion.

• Proceedings of the KIEE Conference
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• 2001.07d
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• pp.2193-2195
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• 2001

This paper proposes test strategy detecting the faulted digital device or the faulted digital circuit on the digital circuit board using signature analysis technique based on the polynoimal division theory. SSA(serial Signature Analysis) identifies the faults by comparing the reminder from good device and reminder from the tested device, which reminder is obtained by enforcing the data stream outputed from output pins of tested device on LFSR(Linear Feedback Shift Resister) representing the characteristic equation.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.3
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• pp.519-525
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• 2003

Technology that develop existent EDI according to electronic commerce environment by XML's entrance on the stage is XML/EDI. The DTD is meta data that define meaning of expressed data on XML document. Therefore, in case DTD information is damaged this information to base security of XML document dangerous. Not that attach digital signature on XML document for XML/EDI that is encoded in internet shopping mall in this research, proposed method to attach digital signature to DTD. When sign digital, problem that create entirely other digest cost because do not examine about order that change at message digest process is happened. This solved by method to create DTD's digital signature using DOM that can embody tree structure for standard structure and document.

• The Journal of the Korea institute of electronic communication sciences
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• v.16 no.4
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• pp.683-688
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• 2021

Digital signature algorithms such as RSA and ECDSA are threatened by the development of quantum computer technology, which is attracting attention as a future technology. Alternatively, various post-quantum algorithms such as grid-based, multivariate-based, code-based, and hash-based are being studied. Among them, the hash-based is a fast and quantitative security level that can be calculated and its safety has been proven. So it is receiving a lot of attention. In this paper, we examine various hash-based digital signature algorithms that have been proposed so far, and analyze their features and their strengths and weaknesses. In addition, we emphasize the importance of reducing the size of the signature in order for the hash-based signature algorithm to be practically used.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.27 no.4
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• pp.743-751
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• 2017

As smart phones are becoming popular, an operating system is being used at wearable devices, home appliances and smart TVs. A user is able to use various applications on devices with operating system, but there is an increased threat of hacker. Thus, the technology for detecting the forgery of applications is becoming more important on operating system. To detect the forgery of the application, a digital signature technology is used on the filed of application digital signature. According to W3C recommendation, the signing process of application digital signature must be performed at least twice, and the applications which are signed by the application digital signature have to be validated for all signature files when the application is installed in the operating system. Hence, the performance of the application digital signature validation system is closely related to the installer performance on the operating system. Existing validation system has performance degradation due to redundancy of integrity verification among application components. This research was conducted to improve the performance of the application digital signature validation system. The proposal of validation system which is applied proxy system shows a performance improvement compared to the existing verification system.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.13 no.5
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• pp.129-136
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• 2003

A representative payment broker system is SET and one of its signature shcemes is a dual digital signature scheme. A dual digital signature scheme expose neither user's payment information(credit card number etc.) to merchandiser, nor user's order information to bank So it keeps user's Privacy safe. The digital signature scheme like this is being necessary as E-commerce is revitalized. But a dual digital signature of SET is not appropriate for wireless environments because it needs so many computations and communications. In this paper, we propose a signcryption scheme that generates a polynomial using a payment information for merchandiser and an order information for bank in order to reduce communications. We analyze the problem of existing signcryption schemes and dual digital signature schemes. Also we analyze the security properties of the proposed scheme.