Multi-client functional encryption (MCFE) is an extension of functional encryption (FE) in which the decryption procedure involves ciphertexts from multiple parties. In this paper, we consider MCFE schemes supporting encryption labels, which allow the encryptor to limit the amount of possible mix-and-match that can take place during the decryption. This...
In the recent years, many research lines on Functional Encryption (FE) have been suggested and studied regarding the functionality, security, or efficiency. These studies include quadratic FE, multi-client FE, function-hiding FE, dynamic FE and much more. Nevertheless, an open problem on a basic functionality, the single-input inner-product (IPFE), remains: can...
A double-authentication preventing signature(DAPS)scheme is a digital signature scheme equipped with a self-enforcement mechanism. Messages consist of an address and a payload component, and a signer is penalized if she signs two messages with the same addresses but different payloads. The penalty is the disclosure of the signer’s signing key....
Tokenomics is an international forum for theory, design, analysis, implementation and applications of blockchains and smart contracts. The goal of the conference is to bring together economists, computer science researchers and practitioners working on blockchains in a unique program featuring outstanding invited talks and academic presentations.
The nascent economic crisis is highlighting the need to rely on creative policy responses. Helicopter money appears to be one of the few untried monetary tool. Central Bank Digital Currencies (CBDCs) based on Distributed Ledger Technologies (DLTs) would provide the optimal infrastructure to implement such stimulus policy.
In a recent work by Augot et al. (2017), a scheme is proposed to build an identity system on top of the Bitcoin network. However, this proposal incurs very high costs since Bitcoin transactions require heavy fees. The current work introduces modifications to their scheme to make it more cost...
We propose a model which uses the exchange rate of Bitcoin against the US dollar to predict the computing power of Bitcoin network. We show that free entry places an upper-bound on mining revenues and we devise a structural framework to measure its value. Calibrating the model’s parameters allows us...
We analyze a two-country economy with complete markets, featuring two national currencies as well as a global (crypto)currency. If the global currency is used in both countries, the national nominal interest rates must be equal and the exchange rate between the national currencies is a risk-adjusted martingale. We call the...
In a novel model of an endowment economy, we analyze coexistence and competition between traditional fiat money (Dollar) and another intrinsically worthless medium of exchange, not controlled by a central bank, such as Bitcoin. Agents can trade consumption goods in either currency or hold on to currency for speculative purposes....
The introduction of a central bank digital currency (CBDC) allows the central bank to engage in large-scale intermediation by competing with private financial intermediaries for deposits. Yet, since a central bank is not an investment expert, it cannot invest in long-term projects itself, but relies on investment banks to do...