How to build time-lock encryption

Liu, Jia; Jager, Tibor; Kakvi, Saqib A.; Warinschi, Bogdan

doi:10.1007/s10623-018-0461-x

Cited by 60 publications

(14 citation statements)

References 55 publications

(151 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The recent emergence of blockchain technology [6] and smart contracts [4] have started the development of new decentralized approaches. One of the decentralized approaches [18], [19], [20] encloses private information with blockchain puzzles used in Proof-of-Work [6] and therefore minimizes the computational burden of the information senders as the blockchain puzzles are periodically solved by blockchain miners. However in such an approach, the involved heavy cryptographic primitives result in very high performance overhead [19], [21].…”

Section: A Sending Private Information To a Future Time Pointmentioning

confidence: 99%

SilentDelivery: Practical Timed-Delivery of Private Information Using Smart Contracts

Palanisamy

2022

IEEE Trans. Serv. Comput.

View full text Add to dashboard Cite

This paper proposes SilentDelivery, a secure, scalable and cost-efficient protocol for implementing timed-delivery of private information in a decentralized blockchain network. SilentDelivery employs a novel combination of threshold secret sharing and decentralized smart contracts. The protocol maintains shares of the decryption key of the private information of an information sender using a group of trustees recruited in a blockchain network before the specified future time-frame and restores the information to the information recipient at the required time-frame. To tackle the key challenges that limit the security and scalability of the protocol, SilentDelivery incorporates two novel countermeasure strategies. The first strategy, namely silent recruitment, enables a trustee to get recruited by a sender silently without the knowledge of any third party. The second strategy, namely dual-mode execution, makes the protocol run in a lightweight mode by default, where the cost of running smart contracts is reduced from O(n) to O(1). We implement the protocol over the Ethereum official test network. The results demonstrate that SilentDelivery is more secure and scalable compared to the state of the art and reduces the cost of running smart contracts by 85%.

show abstract

Section: A Sending Private Information To a Future Time Pointmentioning

confidence: 99%

SilentDelivery: Practical Timed-Delivery of Private Information Using Smart Contracts

Palanisamy

2022

IEEE Trans. Serv. Comput.

View full text Add to dashboard Cite

show abstract

“…Note that the distributed trust needed for fairness does not affect UP. Alternatively, Timelock encryption could be employed, allowing the encryption to be locked for a specific time-period, without the need for distributed key generation [35].…”

Section: E Fairnessmentioning

confidence: 99%

Æternum: A Decentralized Voting System with Unconditional Privacy

Killer

Knecht

Müller

et al. 2021

2021 IEEE International Conference on Blockchain and Cryptocurrency (ICBC)

View full text Add to dashboard Cite

is crucial to protect BP against present and future adversaries, thus, not relying on computational intractability.However, REV schemes often apply cryptographic protocols based on Mixnets or Homomorphic Encryption, which rely on hardness assumptions to achieve BP [27]. Thus, Unconditional BP (UP) does not assume computational intractability and eliminates the need for Trusted Third Parties (TTP) [36]. Minimizing trust assumptions and removing the reliance on TTPs for specific tasks within the voting process is a fundamental argument for decentralized voting systems, e.g., for voting in a consortium of industry participants. Instead of relying on TTPs, the UP-based REV system can be fully decentralized. Since most prior work on REV does not achieve UP, they rely on a TTP or base their privacy on a secret shared between multiple trusted entities [36].AEternum's voting scheme provides UP and does not rely on a single trusted authority [36]. In order to achieve UP, the deployment of a decentralized PBB is required. Distributed Ledgers (DL) offer a suitable approach to deploy a Decentralized PBB (DPBB) to achieve such a distribution of trust among authorities [29]. DLs are tamper-proof and immutable, replicate data securely, making them ideal for storing ballots that should not be manipulated by anyone [30].This paper proposes AEternum, the first DL-based REV system combining a voting scheme with UP and a public permissioned DL, which serves as a DPBB. AEternum's voting scheme is based on Non-Interactive Zero-Knowledge Proofs (NIZKP) [36]. UP holds under the assumption of the existence of a PBB and an anonymous channel [37]. Furthermore, the trust assumptions do not impact UP, but are fundamental for verifiability and correctness i.e., trusted authorities are required for fairness. For instance, homomorphic threshold encryption is used to disallow trend analysis during an open voting period. Computational intractability assumptions are only relevant during the voting period to prevent the creation of invalid votes [36].The remainder of the paper is organized as follows. While essential definitions are presented in Section II, Section III discusses AEternum's system design followed by the implementation details in Section IV. Section V renders the discussion, Section VI outlines the security analysis and VII the evaluation. Finally, Section IX draws conclusions and outlines future work.Abstract-Remote Electronic Voting (REV) systems allow voters to cast their votes in an uncontrolled, distributed environment. At the same time, the REV system must provide ballot privacy and verifiability of the final tally. Research has proposed REV schemes offering ballot privacy based on computational intractability assumptions, but only a few provide Unconditional Privacy (UP).Therefore, this work proposes AEternum, a REV system with a voting scheme providing UP. AEternum does not require trust in a central authority, nor does it assume computational intractability of an underlying mathematical problem to provide UP. To satisfy UP's...

show abstract

“…Recently, some efforts try to model the time by capturing "real-world-time". Liu et al [56] utilized a blockchain-based computing model to simulate real time, eliminating the role of a time server.…”

Section: Timed-release Encryptionmentioning

confidence: 99%

A Lightweight and Privacy-Preserving Answer Collection Scheme for Mobile Crowdsourcing

Dai¹,

Weng²,

Yang³

et al. 2021

KSII TIIS

View full text Add to dashboard Cite

Mobile Crowdsourcing (MCS) has become an emerging paradigm evolved from crowdsourcing by employing advanced features of mobile devices such as smartphones to perform more complicated, especially spatial tasks. One of the key procedures in MCS is to collect answers from mobile users (workers), which may face several security issues. First, authentication is required to ensure that answers are from authorized workers. In addition, MCS tasks are usually location-dependent, so the collected answers could disclose workers' location privacy, which may discourage workers to participate in the tasks. Finally, the overhead occurred by authentication and privacy protection should be minimized since mobile devices are resource-constrained. Considering all the above concerns, in this paper, we propose a lightweight and privacy-preserving answer collection scheme for MCS. In the proposed scheme, we achieve anonymous authentication based on traceable ring signature, which provides authentication, anonymity, as well as traceability by enabling malicious workers tracing. In order to balance user location privacy and data availability, we propose a new concept named current location privacy, which means the location of the worker cannot be disclosed to anyone until a specified time. Since the leakage of current location will Dai et al.: A Lightweight and Privacy-Preserving Answer Collection Scheme forMobile Crowdsourcing seriously threaten workers' personal safety, causing such as absence or presence disclosure attacks, it is necessary to pay attention to the current location privacy of workers in MCS.We encrypt the collected answers based on timed-release encryption, ensuring the secure transmission and high availability of data, as well as preserving the current location privacy of workers. Finally, we analyze the security and performance of the proposed scheme. The experimental results show that the computation costs of a worker depend on the number of ring signature members, which indicates the flexibility for a worker to choose an appropriate size of the group under considerations of privacy and efficiency.

show abstract

How to build time-lock encryption

Cited by 60 publications

References 55 publications

SilentDelivery: Practical Timed-Delivery of Private Information Using Smart Contracts

SilentDelivery: Practical Timed-Delivery of Private Information Using Smart Contracts

Æternum: A Decentralized Voting System with Unconditional Privacy

A Lightweight and Privacy-Preserving Answer Collection Scheme for Mobile Crowdsourcing

Contact Info

Product

Resources

About