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About 7,404 papers for “Ciphertext”

Chosen Ciphertext Security with Optimal Ciphertext Overhead

Masayuki Abe, Eike Kiltz, Tatsuaki Okamoto · IEICE Transactions on Fundamentals of Electronics Communications and Computer Sciences · 2010

Every public-key encryption scheme has to incorporate a certain amount of randomness into its ciphertexts to provide semantic security against chosen ciphertext attacks (IND-CCA). The difference between the length of a ciphertext and the embedded message is called the ciphertext overhead. While a generic brute-force adversary running in 2t steps gives a theoretical lower bound of t bits on the ciphertext overhead for IND-CPA security, the best known IND-CCA secure schemes demand roughly 2t bits even in the random oracle model. Is the t-bit gap essential for achieving IND-CCA security? We close the gap by proposing an IND-CCA secure scheme whose ciphertext overhead matches the generic lower bound up to a small constant. Our scheme uses a variation of a four-round Feistel network in the random oracle model and hence belongs to the family of OAEP-based schemes. Maybe of independent interest is a new efficient method to encrypt long messages exceeding the length of the permutation while retaining the minimal overhead.

Cited by 4

Corresponding Ciphertext.

John Kwao Dawson (14593666), Frimpong Twum (14593669), James Benjamin Hayfron Acquah (14593672) et al. · Figshare · 2023

Cited by 0Open access

of Ciphertext

Huo Lina, Li Deshunb, Tan Yinglub et al. · 2016

Abstract. Secure index is the core technology in the full-ciphertext retrieval. In order to appliance the efficient full-text retrieval in the ciphertext state, a streamline dynamic successive trees of ciphertext(SDSTC)index model is proposed. The SDSTC index model which supports queries of substring and dynamic updating of index, has a high recall and precision ratio in retrieval. Giving algorithms of model index creation, retrieval and ciphertext index updating and the analysis of its security and efficiency. Compared with other existing index models, experiments show that the SDSTC index model has good time efficiency and more suitable for areas of ciphertext security of full-text retrieval.

Cited by 0

Ciphertext size.

Sandro Amofa (18078398), Qi Xia (187080), Hu Xia (18078401) et al. · Figshare · 2024

<div><p>Modern healthcare has a sharp focus on data aggregation and processing technologies. Consequently, from a data perspective, a patient may be regarded as a timestamped list of medical conditions and their corresponding corrective interventions. Technologies to securely aggregate and access data for individual patients in the quest for precision medicine have led to the adoption of Digital Twins in healthcare. Digital Twins are used in manufacturing and engineering to produce digital models of physical objects that capture the essence of device operation to enable and drive optimization. Thus, a patient’s Digital Twin can significantly improve health data sharing. However, creating the Digital Twin from multiple data sources, such as the patient’s electronic medical records (EMR) and personal health records (PHR) from wearable devices, presents some risks to the security of the model and the patient. The constituent data for the Digital Twin should be accessible only with permission from relevant entities and thus requires authentication, privacy, and provable provenance. This paper proposes a blockchain-secure patient Digital Twin that relies on smart contracts to automate the updating and communication processes that maintain the Digital Twin. The smart contracts govern the response the Digital Twin provides when queried, based on policies created for each patient. We highlight four research points: access control, interaction, privacy, and security of the Digital Twin and we evaluate the Digital Twin in terms of latency in the network, smart contract execution times, and data storage costs.</p></div>

Cited by 0Open access

On Ciphertext Undetectability

2008

Abstract. We propose a novel security notion for public-key encryption schemes- ciphertext undetectability. Informally, an encryption scheme has the property of ciphertext undetectability, if the attacker is unable to distinguish between valid and invalid ciphertexts. We compare this notion with the established ones, such as indistinguishability of ciphertexts and plaintext awareness. We analyze the possibilities of constructing schemes with the property of ciphertext undetectability. Moreover, we prove that the Damg*ard ElGamal, the Cramer-Shoup scheme and its lite variant achieve ciphertext undetectability under standard assumptions.

Cited by 0

Black ciphertext image.

Abdulbasid Banga (21512013), Yasir Mahmood (21512016), Naif Al Mudawi (19262167) et al. · Figshare · 2025

<div> Substitution Box (S-Box) has had been a cardinal component of various cryptographic systems. In this paper, we introduce a novel S-Box design that merges octagonal geometry with chaotic dynamics to enhance the security effects of the cryptographic systems. In particular, the proposed method leverages the geometric properties of octagons and the unpredictability of chaotic maps to construct a novel S-Box with improved security features. The mathematical construct octagon carries out the necessary operation of confusion in the proposed S-Box. The centres of these octagons are hypothetically created within the confines of the matrix of numbers. Further, these octagons have different radii, locations, and the amounts with which the numbers lying on their boundaries have to be circularly shifted clockwise or anti-clockwise to create the confusion effects. In case, a portion of octagon goes past the edges of the matrix, the numbers lying on its boundary have been wrapped out. This process has been repeated numerous times to come up with a reliable and a secured S-Box. The comprehensive security analyses validate that the proposed S-Box is furnished with nice security effects and has the requisite resilience to defy the varied cryptanalytic threats. The results of non-linearity and differential probability are 105.625 and 0.0391 respectively which signals towards the inherent robustness of the suggested S-Box. </div>

Cited by 0Open access

Baboon ciphertext image.

Abdulbasid Banga (21512013), Yasir Mahmood (21512016), Naif Al Mudawi (19262167) et al. · Figshare · 2025

<div> Substitution Box (S-Box) has had been a cardinal component of various cryptographic systems. In this paper, we introduce a novel S-Box design that merges octagonal geometry with chaotic dynamics to enhance the security effects of the cryptographic systems. In particular, the proposed method leverages the geometric properties of octagons and the unpredictability of chaotic maps to construct a novel S-Box with improved security features. The mathematical construct octagon carries out the necessary operation of confusion in the proposed S-Box. The centres of these octagons are hypothetically created within the confines of the matrix of numbers. Further, these octagons have different radii, locations, and the amounts with which the numbers lying on their boundaries have to be circularly shifted clockwise or anti-clockwise to create the confusion effects. In case, a portion of octagon goes past the edges of the matrix, the numbers lying on its boundary have been wrapped out. This process has been repeated numerous times to come up with a reliable and a secured S-Box. The comprehensive security analyses validate that the proposed S-Box is furnished with nice security effects and has the requisite resilience to defy the varied cryptanalytic threats. The results of non-linearity and differential probability are 105.625 and 0.0391 respectively which signals towards the inherent robustness of the suggested S-Box. </div>

Cited by 0Open access

Obfuscated Ciphertext Mixing

Ben Adida, Douglas Wikström · 2005

Mixnets are a type of anonymous channel composed of a handful of trustees that, each in turn, shu#e and rerandomize a batch ciphertexts. For applications that require verifiability, each trustee provides a proof of correct mixing. Though mixnets have recently been made quite e#cient, they still require secret computation and proof generation after the mixing process.

Cited by 0

Bethencourt?????? Ciphertext Policy ???????????? ??????????????? ???????????? ????????? ?????? ??????

????????? · The Royal Society of Chemistry’s Journals, Books and Databases (The Royal Society of Chemistry) · 2010

??? ??????????????? Bethencourt?????? CP-ABE?????? ???????????? ????????? ?????? ????????? ?????? ????????????. ????????? ????????? ????????? ?????? ????????? ????????? KP-ABE??? ?????? ?????????, CP-ABE?????? ????????? ????????? ????????? ?????? ????????? ????????? ???????????? ????????? ????????? NOT????????? ????????? ????????? ???????????? ??????????????? ?????????. ?????? ?????? Bethencourt?????? CP-ABE??? ????????? ????????? ?????? ????????? ?????? ????????? ??? Bethencourt?????? CP-ABE?????? ???????????? ????????? ?????? ????????? ?????? ??????????????? ??????.

Cited by 0

On Ciphertext Undetectability

Martin Stanek · 2008

Abstract. We propose a novel security notion for public-key encryption schemes – ciphertext undetectability. Informally, an encryption scheme has the property of ciphertext undetectability, if the attacker is unable to distinguish between valid and invalid ciphertexts. We compare this notion with the established ones, such as indistinguishability of ciphertexts and plaintext awareness. We analyze the possibilities of constructing schemes with the property of ciphertext undetectability. Moreover, we prove that the Damg˚ard ElGamal, the Cramer-Shoup scheme and its lite variant achieve ciphertext undetectability under standard assumptions.

Cited by 0

White ciphertext image.

Abdulbasid Banga (21512013), Yasir Mahmood (21512016), Naif Al Mudawi (19262167) et al. · Figshare · 2025

<div> Substitution Box (S-Box) has had been a cardinal component of various cryptographic systems. In this paper, we introduce a novel S-Box design that merges octagonal geometry with chaotic dynamics to enhance the security effects of the cryptographic systems. In particular, the proposed method leverages the geometric properties of octagons and the unpredictability of chaotic maps to construct a novel S-Box with improved security features. The mathematical construct octagon carries out the necessary operation of confusion in the proposed S-Box. The centres of these octagons are hypothetically created within the confines of the matrix of numbers. Further, these octagons have different radii, locations, and the amounts with which the numbers lying on their boundaries have to be circularly shifted clockwise or anti-clockwise to create the confusion effects. In case, a portion of octagon goes past the edges of the matrix, the numbers lying on its boundary have been wrapped out. This process has been repeated numerous times to come up with a reliable and a secured S-Box. The comprehensive security analyses validate that the proposed S-Box is furnished with nice security effects and has the requisite resilience to defy the varied cryptanalytic threats. The results of non-linearity and differential probability are 105.625 and 0.0391 respectively which signals towards the inherent robustness of the suggested S-Box. </div>

Cited by 0Open access