Browsing by Author "Lin, Han-Yu"

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A DL Based Short Strong Designated Verifier Signature Scheme with Low Computation
(2011-03-01)
Lin, Han-Yu
;
Wu, Tzong-Sun
;
Yeh, Yi-Shiung
;
資訊工程學系
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Department of Computer Science
A designated verifier signature (DVS) scheme is a special type of digital signature scheme without the property of non-repudiation. Such schemes only allow the designated verifier to validate the signer's signature. Meanwhile, the designated verifier is not able to convince any third party of the signature's actual signer, since he can also generate a computationally indistinguishable one compared to the received signature. A strong designated verifier signature (SDVS) scheme further prohibits anyone except for the intended verifier from validating the signature as it requires the designated verifier's private key to finish the verification process. In this paper, we propose an efficient short SDVS scheme with low computation costs. Unlike many SDVS schemes primarily implemented on pairing-based cryptosystems, we focus on the discrete logarithms (DL) based system. Compared with those DL based SDVS schemes, ours provides better functionalities and efficiency and hence benefits the practical applications. In addition, the security requirement of unforgeability against existential forgery on adaptive chosen-message attacks (EU-CMA) is proved in the random oracle model.
A GROUP-ORIENTED PROXY CMAE SCHEME WITH COMPUTATIONAL SECRECY
(2008-11-01)
Wu, Tzong-Sun
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Lin, Han-Yu
;
資訊工程學系
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Department of Computer Science
This paper presents a group-oriented proxy convertible multi-authenticated encryption (CMAE) scheme for strengthening the gradually wide applications which have to simultaneously fulfill the security requirements of integrity, authentication, confidentiality and non-repudiation. The proposed scheme allows a group of original signers to delegate their signing power to an authorized person called proxy signer, such that the proxy signer can generate an authenticated ciphertext on behalf of the original group. Instead of anyone else, only a designated recipient can decrypt the ciphertext and verify its corresponding signature for the purpose of confidentiality. In case of a later dispute over repudiation, the designated recipient also has the ability to convert the multi-signature into an ordinary one for convincing anyone of the signer's dishonesty. Moreover, the computational secrecy ensures that the produced ciphertext is computationally indistinguishable with respect to two candidate messages.
An Efficient Strong Designated Verifier Proxy Signature Scheme for Electronic Commerce
(2012-07-01)
Lin, Han-Yu
;
Wu, Tzong-Sun
;
Huang, Shih-Kun
;
資訊工程學系
;
Department of Computer Science
"A strong designated verifier signature (SDVS) scheme only allows a designated verifier to validate signer's signatures for ensuring confidentiality. At the same time, the designated verifier can not transfer the signature to any third party, since he can also generate another computationally indistinguishable SDVS, which is referred to as non-transferability. A proxy signature scheme is a special type of digital signature schemes, which enables an authorized proxy signer to create a valid proxy signature on behalf of the original one. The resulted proxy signature is publicly verifiable by anyone. In this paper, we elaborate on the merits of SDVS schemes and proxy signature schemes to propose an efficient strong designated verifier proxy signature (SDVPS) scheme in which only a designated verifier can be convinced of the proxy signer's identity. The proposed scheme has crucial benefits in organizational operations and electronic commerce. Compared with related schemes, ours has not only shorter signature length, but also lower computational costs. Moreover, the security requirement of unforgeability against existential forgery under adaptive chosen-message attacks (EF-CMA) is proved in the random oracle model."
Audio watermarking scheme with dynamic adjustment in mute period
(2011-06-01)
Wu, Tzong-Sun
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Lin, Han-Yu
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Hu, Wang-Chieh
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Chen, Yih-Sen
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資訊工程學系
Watermark is some imperceptible information embedded into the work for later verification and thus it can be used to prove the originality or to protect the work from being illegally copied or modified. Kaabneh and Youssef (2001) proposed a muteness-based watermarking method for audio file. Their method can successfully embed watermarking information into audio file such that the human ears cannot distinguish the covered work from the original one. To improve the efficiency, we proposed a watermarking method for audio files in this paper. By adjusting the length of mute period dynamically, the proposed method can achieve the goal of watermark embedding with little variation of the original work. Experiment has shown that our method has the advantages of efficiency and fidelity as compared with theirs. Furthermore, it does not require the original audio file to derive the embedded watermark. (C) 2010 Elsevier Ltd. All rights reserved.
Certificate-Based Secure Three-Party Signcryption Scheme With Low Costs
(2012-07-01)
Lin, Han-Yu
;
Wu, Tzong-Sun
;
Huang, Shih-Kun
;
資訊工程學系
;
Department of Computer Science
"A signcryption scheme combining public key encryptions and digital signatures can simultaneously satisfy the security requirements of confidentiality, integrity, authenticity and non-repudiation. In a three-party communication environment, a message signcrypted by one party might have to be securely delivered to the other two and they usually independently decrypt the ciphertext and verify recovered signature. Consequently, traditional signcryption schemes of single-recipient setting are not applicable. In this paper, we elaborate on the certificate-based cryptosystem to propose a provably secure three-party signcryption scheme from bilinear pairings. The security requirement of confidentiality against indistinguishability under adaptive chosen-ciphertext attacks (IND-CCA2) and that of unforgeability against existential forgery under adaptive chosen-message attacks (EF-CMA) are proved in the random oracle model. Moreover, our scheme enables each recipient to solely reveal the signer's original signature for public verification without extra computational efforts when the case of a later dispute over repudiation occurs. To the best of our knowledge, the proposed scheme is the first provably secure signcryption considering three-party communication environments."
EFFICIENT CONVERTIBLE MULTI-AUTHENTICATED ENCRYPTION SCHEME WITHOUT MESSAGE REDUNDANCY OR ONE-WAY HASH FUNCTION
(2010-09-01)
Tsai, Jia-Lun
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Wu, Tzong-Sun
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Lin, Han-Yu
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Lee, Jong-Eao
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應用數學系
A convertible multi-authenticated encryption (CMAE) scheme providing confidentiality, authenticity and non-repudiation properties allows a designated recipient to recover and verify an authenticated message which is signed by multiple signers. The recipient has the ability to further prove the dishonesty of signers to any third party if they repudiate their signature latter. In 2008, Wu et al. first proposed a CMAE scheme based on. discrete logarithms, but the computational complexity of their scheme is rather high and the message redundancy is required. To improve the performance and remove the message redundancy, Tsai adopted one-way hash functions (such as MD5) to propose a new scheme. In 2005, however, MD5 was cracked by Wang and Yu, which indicates that the schemes using one-way hash functions might turn out to be vulnerable to such an attack. This paper proposes a new efficient CMAE scheme. Neither the one-way hash, function nor the message redundancy is employed in the proposed scheme. The scheme not only preserves the advantages of Wu et al. 's, but also outperforms their scheme. With low computational cost, our proposed scheme can be practically implemented.
Efficient proxy signcryption scheme with provable CCA and CMA security
(2010-10-01)
Lin, Han-Yu
;
Wu, Tzong-Sun
;
Huang, Shih-Kun
;
Yeh, Yi-Shiung
;
資訊工程學系
For facilitating the confidential transaction with delegation such as on-line proxy auction and business contract signing by an authorized proxy, we propose an efficient proxy signcryption scheme from pairings. Our scheme allows an original signer to delegate his signing power to a proxy one such that the latter can signcrypt a plaintext on behalf of the former. The signcrypted message can only be decrypted by a designated recipient who is also responsible for verifying the recovered proxy signature. To deal with a later dispute over repudiation, the designated recipient can easily announce the ordinary proxy signature for public verification without extra computational efforts. To guarantee the realistic applicability, we demonstrate that our scheme outperforms previous works in terms of functionalities and computational efficiency. Moreover, the security requirement of confidentiality against indistinguishability under adaptive chosen-ciphertext attacks (IND-CCA2) and that of unforgeability against existential forgery under adaptive chosen-message attacks (EF-CMA) are proved in random oracle models. (C) 2010 Elsevier Ltd. All rights reserved.
Efficient proxy signcryption scheme with provable CCA and CMA security
(2010-10-01)
Lin, Han-Yu
;
Wu, Tzong-Sun
;
Huang, Shih-Kun
;
Yeh, Yi-Shiung
;
資訊工程學系
For facilitating the confidential transaction with delegation such as on-line proxy auction and business contract signing by an authorized proxy, we propose an efficient proxy signcryption scheme from pairings. Our scheme allows an original signer to delegate his signing power to a proxy one such that the latter can signcrypt a plaintext on behalf of the former. The signcrypted message can only be decrypted by a designated recipient who is also responsible for verifying the recovered proxy signature. To deal with a later dispute over repudiation, the designated recipient can easily announce the ordinary proxy signature for public verification without extra computational efforts. To guarantee the realistic applicability, we demonstrate that our scheme outperforms previous works in terms of functionalities and computational efficiency. Moreover, the security requirement of confidentiality against indistinguishability under adaptive chosen-ciphertext attacks (IND-CCA2) and that of unforgeability against existential forgery under adaptive chosen-message attacks (EF-CMA) are proved in random oracle models. (C) 2010 Elsevier Ltd. All rights reserved.
Efficient self-certified proxy CAE scheme and its variants
(2009-06-01)
Wu, Tzong-Sun
;
Lin, Han-Yu
;
資訊工程學系
;
Department of Computer Science
Elaborating on the merits of proxy signature schemes and convertible authenticated encryption (CAE) schemes, we adopt self-certified public key systems to construct efficient proxy CAE schemes enabling an authorized proxy signer to generate an authenticated ciphertext on behalf of the original signer. To satisfy the requirement of confidentiality, only the designated recipient is capable of decrypting the ciphertext and verifying the proxy signature. A significant advantage of the proposed schemes is that the proxy signature conversion process takes no extra cost, i.e., when the case of a later dispute over repudiation occurs, the designated recipient can easily reveal the ordinary proxy signature for the public arbitration. If needed, the designated recipient can also convince anyone that he is the real recipient. In addition, integrating with self-certified public key systems, our schemes can earn more computational efficiency, since authenticating the public key and verifying the proxy signature can be simultaneously carried out within one-step. (c) 2009 Elsevier Inc. All rights reserved.
EFFICIENT VERIFIER-BASED AUTHENTICATED KEY AGREEMENT PROTOCOL FOR THREE PARTIES
(2010-02-01)
Wu, Tzong-Sun
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Lin, Han-Yu
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Hsu, Chien-Lung
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Chang, Kuo-Yi
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資訊工程學系
Authenticated key agreement protocols for three parties enable two clients to establish a secure communication channel through an authentication server. Generally speaking, there are two approaches to achieve this purpose. One is to issue a common session key for both clients by the key distribution center (KDC). The other is to use public key cryptosystems and the encrypted key exchange (EKE) protocol to encrypt the transmitted messages and then further derive a common session key. Recently, lots of researches on authenticated key agreement protocol for three parties use the servers public key to ensure the security of transmitted messages. Yet, the approach obviously has some drawbacks, such as increasing the cost of key management for each client. Hence, the demand for secure protocols without the server's public key comes out. In this paper, we propose an efficient verifier-based authenticated key agreement for three parties. The proposed protocol can resist the password guessing attack and other existential attacks. Moreover, compared with previous works, the proposed one also has lower computational costs.
Improved convertible authenticated encryption scheme with provable security
(2011-07-01)
Lin, Han-Yu
;
Hsu, Chien-Lung
;
Huang, Shih-Kun
;
資訊工程學系
;
Department of Computer Science
Convertible authenticated encryption (CAE) schemes allow a signer to produce an authenticated ciphertext such that only a designated recipient can decrypt it and verify the recovered signature. The conversion property further enables the designated recipient to reveal an ordinary signature for dealing with a later dispute over repudiation. Based on the EIGamal cryptosystem, in 2009, Lee et al. proposed a CAE scheme with only heuristic security analyses. In this paper, we will demonstrate that their scheme is vulnerable to the chosen-plaintext attack and then further propose an improved variant. Additionally, in the random oracle model, we prove that the improved scheme achieves confidentiality against indistinguishability under adaptive chosen-ciphertext attacks (IND-CCA2) and unforgeability against existential forgery under adaptive chosen-message attacks (EF-CMA). (C) 2011 Elsevier B.V. All rights reserved.
Pairings Based Designated Verifier Signature Scheme for Three-Party Communication Environment
(2009)
Lin, Han-Yu
;
Wu, Tzong-Sun
;
資訊工程學系
;
Department of Computer Science
A designated verifier signature (DVS) scheme has the property that only the designated verifier specified by the signer can check the validity of the signature instead of anyone else. Meanwhile, the designated verifier can not use this proof to convince any third party that a signature is generated by the claimed signer. Consider the application of three-party communication environment. One party may has to generate a signature such that only the other two is capable of verifying it solely. In this paper, we propose a novel DVS scheme for three-party communication environment from pairings. The proposed scheme has the following advantages: (i) Each of the two designated verifiers can independently check the validity of the signature without cooperating with the other; (ii) The proposed scheme is efficient in terms of the executed pairings, since it only needs one pairing computation to generate a DVS for two designated verifiers; (iii) The proposed scheme satisfies the security requirements of unforgeability, non-transferability and source hiding.
Self-Certified Proxy Convertible Authenticated Encryption Scheme
(2008)
Lin, Han-Yu
;
Wu, Tzong-Sun
;
Huan, Ting-Yu
;
Yeh, Yi-Shiung
;
資訊工程學系
A proxy convertible authenticated encryption (CAE) scheme allows an original signer to delegate his signing power to a proxy signer such that the proxy signer can generate an authenticated ciphertext on behalf of the original signer The generated authenticated ciphertext can only be decrypted and verified by the specific recipient instead of everyone else for the purpose of confidentiality. Integrating with self-certified public key systems, the proposed scheme can save more communication overheads and computation efforts, since it is not necessary to transmit and verify the public key certificate. That is, authenticating the public key can be combined with subsequent cryptographic operations such as the signature verification. In case of a later repudiation, the specific recipient has the ability to convert the signature into an ordinary one for convincing anyone of the signer dishonesty.
Structural Binary CBC Encryption Mode
(2009-05-01)
Yeh, Yi-Shiung
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Huang, Ting-Yu
;
Lin, Han-Yu
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資訊工程學系
;
Department of Computer Science
A block cipher is a kind of symmetric encryption algorithm that operates on blocks of fixed length, often 64 or 128 bits. It transforms blocks of plaintext into blocks of ciphertext of the same length under the provided secret key. A common characteristic of currently Widely used modes of operation such as CBC, CFB and OFB is the sequential procedure. i.e., the encryption/decryption algorithm can not start to process until the previous operation finished, which is considered to be inefficient in multi-processor structures. In this paper, we combine CBC mode of operation and the binary free data structure to propose a new structural binary CBC encryption mode allowing parallelized computing. A significant property of the proposed mode of operation is independent branch operations. When applied in multi-processor structures, different branch operations can make effective use of CPUs to perform in parallel, which will lead to shorter computing time and greatly improve the overall performance.