• Current Optics and Photonics
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• v.4 no.6
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• pp.483-499
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• 2020

In this paper, a novel analog signature scheme is proposed by modifying an RSA-based digital signature scheme with optical phase-shifting digital holography. The purpose of the proposed method is generating an analog signature to provide data confidentiality and security during the data transfer, compared to the digital signature. The holographic encryption technique applied to a hash value reveals an analog-type of pseudo-random pattern in the analog signature scheme. The public key and secret key needed to verify the analog signature are computed from public key ciphers which are generated by the same holographic encryption. The proposed analog signature scheme contains a kind of double encryption in the process of generating signature and key, which enhances security level more than the digital signature. The results of performance simulations show the feasibility of the highly secure signature scheme, and security analysis shows high robustness against known-message attacks and chosen-message attacks. In addition, the proposed method can apply to one-time signature schemes which can be used to sign only one message and it can also apply to authentication, e-mails, electronic banking and electronic data interchange.

• The Journal of the Korea Contents Association
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• v.5 no.1
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• pp.55-63
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• 2005

In undeniable digital signature scheme, the signature can not be verified without the signer's cooperation. The undeniable signature scheme can be used to computerize many applications which can not be done by a conventional digital signature scheme. In this study, we propose the undeniable digital multi-signature scheme which requires many signers and designated verifier The multi-signature can be verified only in cooperation with all signers. The proposed scheme satisfies undeniable property and it is secure against active attacks such as modification and denial of the multi-signature by signers. We also propose copyright protection method of co-authored digital contents as an application of the proposed scheme.

• Proceedings of the Korea Contents Association Conference
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• 2004.05a
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• pp.261-267
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• 2004

In undeniable digital signature scheme, the signature can not be verified without the signer's cooperation. The undeniable signature scheme can be used to computerize many applications which can not be done by a conventional digital signature scheme. In this study, we propose the undeniable digital multi-signature scheme which requires many signers and designated verifier. The multi-signature can be verified only in cooperation with all signers. The proposed scheme satisfies undeniable property and it is secure against active attacks such as modification and denial of the multi-signature by signers. We also discuss practical applications such as joint copyright protection on digital contents.

• Journal of Electrical Engineering and information Science
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• v.1 no.2
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• pp.87-95
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• 1996

This paper presents a (k,n) threshold digital signature scheme with no trusted dealer. Our idea is to use the EIGamal signature scheme modified for group use. Among many digital signature schemes, our modification has a nice property for our purpose. We also show a (k.n) threshold fail stop signature scheme and two (k.n) threshold undeniable signature schemes. We use [10] as the original fail stop signature scheme, and use [3] and [2] as the original undeniable signature schemes. Since all these schemes are based on the discrete log problem, we can use the same technique.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.2
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• pp.897-913
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• 2016

Threshold signature is very important in identity authentication and some other applications. In December 2010, Chinese Encryption Administration released the SM2 elliptic curve digital signature algorithm as the first standard of the digital signature algorithm in China. At present, the papers on the threshold signature scheme based on this algorithm are few. A SM2 elliptic curve threshold signature scheme without a trusted center is proposed according to the Joint-Shamir-RSS algorithm, the Joint-Shamir-ZSS algorithm, the sum or diff-SS algorithm, the Mul-SS algorithm, the Inv-SS algorithm and the PM-SS algorithm. The proposed scheme is analyzed from correctness, security and efficiency. The correctness analysis shows that the proposed scheme can realize the effective threshold signature. The security analysis shows that the proposed scheme can resist some kinds of common attacks. The efficiency analysis shows that if the same secret sharing algorithms are used to design the threshold signature schemes, the SM2 elliptic curve threshold signature scheme will be more efficient than the threshold signature scheme based on ECDSA.

• Journal of the Korea Society of Computer and Information
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• v.18 no.7
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• pp.85-92
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• 2013

In this paper, on the basis of Guilin Wang's proxy signature scheme and the Schnorr blind signature, we propose a secure proxy blind signature scheme. A proxy blind signature scheme is a digital signature scheme which combines the properties of a proxy signature and a blind signature scheme. Guilin Wang proposed a provably secure proxy signature scheme, which is based on a two-party Schnorr signature scheme. Also, using the proposed proxy blind signature scheme, we propose the proxy agent system for the electronic voting. We show the proposed scheme satisfies the security properties of both the blind signature and the proxy signature scheme and is efficient and optimal proxy blind signature scheme.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.12 no.6
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• pp.81-92
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• 2002

In some practical circumstances, the ability of a signer should be restricted. In group signature schemes, a group member of a group may be allowed to generate signatures up to a certain number of times according to his/her position in the group. In proxy signature schemes, an original signer may want to allow a proxy signer to generate a certain number of signatures on behalf of the original signer. In the paper, we present signature schemes, called c-times signature schemes, that restrict the signing ability of a signer up to c times for pre-defined value c at set-up. The notion of c-times signature schemes are formally defined, and generic transformation from a signature scheme to a c-times signature scheme is suggested. The proposed scheme has a self-enforcement property such that if a signer generates c+1 or more signatures, his/her signature is forged. As a specific example, we present a secure c-times signature scheme $^c$DSA based on the DSA (Digital Signature Algorithm) by using a threshold scheme. Our transformation can be applied to other ElGamal-like signature schemes as well.

• Journal of KIISE
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• v.44 no.4
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• pp.344-351
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• 2017

An attribute based signature system is a cryptographic system where users produce signatures based on some predicate of attributes, using keys issued by one or more attribute authorities. If a private key is leaked during signature generation, the signature can be forged. Therefore, signing operation computations should be performed using secure hardware, which is called tamper resistant hardware in this paper. However, since tamper resistant hardware does not provide high performance, it cannot perform many operations requiring attribute based signatures in a short time frame. This paper proposes a new attribute based signature system using high performance general hardware and low performance tamper resistant hardware. The proposed signature scheme consists of two signature schemes within a existing attribute based signature scheme and a digital signature scheme. In the proposed scheme, although the attribute based signature is performed in insecure environments, the digital signature scheme using tamper resistant hardware guarantees the security of the signature scheme. The proposed scheme improves the performance by 11 times compared to the traditional attribute based signature scheme on a system using only tamper resistant hardware.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.14 no.2
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• pp.69-74
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• 2004

Threshold digital signature is very useful for networks that have no infrastructure such as ad hoc network Up to date, research on threshold digital signature is mainly focused on RSA and DSA. Though Schnorr's digital signature scheme is very efficient in terms of both computation and communication. its hard structure using interactive proof prevents conversion to threshold version. This paper proposes an efficient threshold signature. scheme based on the Schnorr's signature. It has a desirable property of scalability and reduces runtime costs by precomputation.

• The Journal of Information Technology
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• v.4 no.4
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• pp.25-35
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• 2001

This paper presents a digital signature scheme for document image which directly embeds a signature onto the document. 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).