This book is the first to present the state of the art and provide technical focus on the latest advances in the foundations of blockchain systems. It is a collaborative work between specialists in cryptography, distributed systems, formal languages, and economics, and addresses hot topics in blockchains from a theoretical...
We propose a model that uses the exchange rate of Bitcoin against the US dollar to predict the computing power of Bitcoin’s network. We show that free entry places an upper bound on mining revenues and explain how it can be identified. Calibrating the model’s parameters allows us to accurately...
It is widely believed that financial markets cannot be liquid without centralised processes to manage counterparty risk. We propose an alternative method for liquidity based on reversible and composable contracts run atop a blockchain. Novel instruments for zero-collateral intermediation can be defined.
We propose a framework for the fundamental valuation of utility tokens. Our model endogenizes the velocity of circulation of tokens and yields a pricing formula that is fully microfounded. According to our model, tokens are valuable because they have to be immediately accessible when the services are needed, a requirement...
2-Step Multi-Client Quadratic Functional Encryption from Decentralized Function-Hiding Inner-Product
In this paper, we present a multi-client quadratic functional encryption (MCQFE) scheme from function-hiding inner-product (FHIP). The main challenge in such construction is that all the clients require the access to the master secret key of the underlying FHIP scheme, which clearly breaches the security. To overcome this challenge, we...
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.
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...