Timed-Release Encryption with Master Time Bound Key

Choi, Gwangbae; Vaudenay, Serge

doi:10.1007/978-3-030-39303-8_13

Cited by 3 publications

(2 citation statements)

References 17 publications

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“…In 1996, Rivest et al 4 first proposed two preliminary TRE construction schemes, the first is TLP scheme based on factorization problem, and the second is the sender issues time and message to the agent, which laid the theoretical foundation for the sustainable research of TRE. So far, the construction of TRE scheme includes TLP [5][6][7][8][9][10] , agents [11][12][13][14][15][16][17] and other methods [18][19][20][21][22][23] . In the TRE scheme constructed based on TLP, the decryption key is hidden in a mathematical formula.…”

Section: Introductionmentioning

confidence: 99%

Multiple Time Servers Timed-Release Encryption Based on Shamir Secret Sharing

Yuan

Cheng

Chen

et al. 2023

Preprint

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Timed-release encryption (TRE) is a cryptographic primitive that can realize the data be decrypted and accessed only at a specified time in the future preset by the data sender. Currently, most TRE schemes adopt noninteractive single time server mode. However, once the single time server is attacked or corrupted, it is prone to directly threaten the TRE security application. Although there are some TRE schemes that "distribute" the single time server into multiple ones, there is a problem that they cannot resist single-point failure. For this reason, a multi-time server TRE scheme based on Shamir secret sharing and its variant scheme are proposed. In our proposed schemes, the ciphertext can be decrypted when the number of time trapdoors obtained by the data receiver exceeds or equals to the threshold. It can not only guarantee the security of data sender's identity privacy information, but also greatly improve the reliability of TRE. Security analysis shows that our schemes have data confidentiality, verifiability, anti-advance decryption and multi-time trapdoor robust decryption. Efficiency analysis shows that when choosing a reasonable threshold, the computational efficiency of our schemes is slightly improved compared with the existing multiple time servers TRE schemes.

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Section: Introductionmentioning

confidence: 99%

Multiple Time Servers Timed-Release Encryption Based on Shamir Secret Sharing

Yuan

Cheng

Chen

et al. 2023

Preprint

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show abstract

“…Some encryption primitives have time-dependent decryption properties, and are therefore related to our work. Time-Release Encryption (TRE) [6,19] allows to produce ciphertexts that cannot be decrypted before a given date. Some schemes implement a pre-open mechanism that allows to decrypt the ciphertexts before the date [14].…”

Section: Introductionmentioning

confidence: 99%

CCA Secure A Posteriori Openable Encryption in the Standard Model

Bultel

2022

Topics in Cryptology – CT-RSA 2022

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A Posteriori Openable Public Key Encryptions (APOPKE) allow any user to generate a constant-size key that decrypts the messages they have sent over a chosen period of time. As an important feature, the period can be dynamically chosen after the messages have been sent. This primitive was introduced in 2016 by Bultel and Lafourcade. They also defined the Chosen-Plaintext Attack (CPA) security for APOPKE, and designed a scheme called GAPO, which is CPA secure in the random oracle model. In this paper, we formalize the Chosen-Ciphertext Attack (CCA) security for APOPKE, then we design a scheme called CHAPO (for CHosen-ciphetext attack resistant A Posteriori Openable encryption), and we prove its CCA security in the standard model. CHAPO is approximately twice as efficient as GAPO and is more generic. We also give news applications, and discuss the practical impact of its CCA security.

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Multiple time servers timed-release encryption based on Shamir secret sharing for EHR cloud system

Yuan,

Cheng,

Chen

et al. 2024

J Cloud Comp

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Electronic health record (EHR) cloud system, as a primary tool driving the informatization of medical data, have positively impacted both doctors and patients by providing accurate and complete patient information. However, ensuring the security of EHR cloud system remains a critical issue. Some patients require regular remote medical services, and controlling access to medical data involving patient privacy during specific times is essential. Timed-release encryption (TRE) technology enables the sender to preset a future time T at which the data can be decrypted and accessed. It is a cryptographic primitive with time-dependent properties. Currently, mainstream TRE schemes are based on non-interactive single time server methods. However, if the single time server is attacked or corrupted, it is easy to directly threaten the security applications of TRE. Although some research schemes “distribute” the single time server into multiple ones, they still cannot resist the single point of failure problem. To address this issue, we propose a multiple time servers TRE scheme based on Shamir secret sharing and another variant derived from it. In our proposed schemes, the data receiver does not need to interact with the time servers; instead, they only need to obtain the time trapdoors that exceed or equal the preset threshold value for decryption, which ensures the identity privacy of the data sender and tolerates partial downtime or other failures of some time servers, significantly improving TRE reliability. Security analysis indicates that our proposed schemes demonstrate data confidentiality, verifiability, anti-advance decryption, and robust decryption with multiple time trapdoors, making them more practical. Efficiency analysis indicates that although our schemes have slightly higher computational costs than most efficient existing TRE schemes, such differences are insignificant from a practical application perspective.

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Timed-Release Encryption with Master Time Bound Key

Cited by 3 publications

References 17 publications

Multiple Time Servers Timed-Release Encryption Based on Shamir Secret Sharing

Multiple Time Servers Timed-Release Encryption Based on Shamir Secret Sharing

CCA Secure A Posteriori Openable Encryption in the Standard Model

Multiple time servers timed-release encryption based on Shamir secret sharing for EHR cloud system

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