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Deepak Maram and Harjasleen Malvai

TL;DR Decentralized identity systems allow users to gather and manage their own credentials under the banner of self-created decentralized identifiers (DIDs). The key focus of DIDs is on shifting the control of a credential into users’ hands. Existing decentralized identity proposals, however, suffer from several problems. First and foremost, how do you bootstrap an ecosystem of credential issuers? It is unlikely that most existing legacy providers suddenly switch and issue such credentials. Second, like with cryptocurrencies, DID systems burden users with managing their own keys creating a significant risk of key loss. They also omit…


by Tyler Kell, Haaroon Yousaf, Sarah Allen, Sarah Meiklejohn, Ari Juels

Have you been offered the chance to earn unlimited passive income in cryptocurrency for life with no risks using a new technology called a smart contract? Congratulations! You may have just encountered a smart contract pyramid scheme.

Image from Wikimedia Commons

Pyramid schemes are not a new phenomenon, but they have found a new form in the nascent technology of smart contracts and decentralized, trustless programmable money. In this blog post we identify common characteristics of smart-contract based pyramid schemes that may serve as red flags for further study to determine if a smart-contract based project looks suspicious. Some of these characteristics may not be unique to pyramid schemes or smart-contract pyramid schemes, but some are.

According to the US SEC, “A pyramid scheme is an investment fraud in which…


by Jun-You Liu (Cornell, IC3), Surya Bakshi (UIUC, IC3), Shreyas Gandlur (Princeton), Ankush Das (CMU), and Andrew Miller (UIUC, IC3)

This research was done in collaboration with the UIUC Decentralized Systems Lab (DSL).

This post serves as the appendix to our post, “Using Universal Composability to Implement Off-Chain Payment Channels,” so please start there.

UC in somewhat more detail

In more detail,

Z is the environment, which is the distinguisher. Its goal is to distinguish the two worlds it’s talking to, which one is the ideal world and which one is the real world. F_spec is the ideal functionality in the ideal world. It is…


by Jun-You Liu (Cornell, IC3), Surya Bakshi (UIUC, IC3), Shreyas Gandlur (Princeton), Ankush Das (CMU), and Andrew Miller (UIUC, IC3)

This research was done in collaboration with the UIUC Decentralized Systems Lab (DSL).

Payment channels are one of the fundamental approaches for scaling cryptocurrency networks. In the academic cryptography literature on payment channels, it has been effective to use universal composability (UC) framework as a way of rigorously modeling and giving security definitions. However, there’s been a big gap between the UC model and the actual software implementations of payment channels that have been designed and maintained by cryptocurrency developers…

IC3

The Initiative for CryptoCurrencies and Contracts (IC3) is a blockchain research initiative based at Cornell. Find out more about IC3 research at initc3.org.

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