Utreexo: A dynamic hash-based accumulator optimized for the Bitcoin UTXO set
It wasn't me! Repudiability and (Un)claimability of Ring Signatures
by Thaddeus Dryja (MIT’s Digital Currency Initiative)
Abstract: In the Bitcoin consensus network, all nodes come to agreement on the set of Unspent Transaction Outputs (The “UTXO” set). The size of this shared state is a scalability constraint for the network, as the size of the set expands as more users join the system, increasing resource requirements of all nodes. Decoupling the network’s state size from the storage requirements of individual machines would reduce hardware requirements of validating nodes. We introduce a hash based accumulator to locally represent the UTXO set, which is logarithmic in the size of the full set. Nodes attach and propagate inclusion proofs to the inputs of transactions, which along with the accumulator state, give all the information needed to validate a transaction. While the size of the inclusion proofs results in an increase in network traffic, these proofs can be discarded after verification, and aggregation methods can reduce their size to a manageable level of overhead. In our simulations of downloading Bitcoin’s blockchain up to early 2019 with 500MB of RAM allocated for caching, the proofs only add approximately 25% to the amount otherwise downloaded.
DCI's Neha Narula Interviewed by Anderson Cooper on '60 Minutes' - 'Bitcoin's Wild Ride'
by Sunoo Park (MIT Media Lab) and Adam Sealfon (MIT CSAIL)
To appear in the International Cryptology Conference (CRYPTO 2019).
Podcast: DCI's Neha Narula interviewed by Hari Sreenivasan for CNN's Amanpour
“Ten years ago, a mysterious computer programmer invented a new type of money that wasn't backed by any government or kept in any bank. There were no coins or bills, just long strings of letters and numbers stored inside a network of computers that anybody could be a part of by downloading some free software over the Internet. Today that computerized currency, bitcoin, is well-known, though little understood, and bitcoin's popularity has inspired the creation of thousands of other types of digital money, known as "cryptocurrency." Over the last decade, you could have made a five million percent profit by investing in cryptocurrency. Or you could have lost everything. It has been a wild ride, and few people have experienced the highs and lows…” Cooper. A (2019, May 19) Bitcoin’s Wild Ride.
DCI's Tadge Dryja interviewed by WHAT BITCOIN DID for a podcast on 'The Limitations of Lightning'
“Republican Senator Mitt Romney and Democratic Senator Chris Murphy join Christiane Amanpour from Washington D.C. to discuss their bipartisan trip to the Middle East and the growing tensions between the U.S. and Iran. Bill Weld, the only Republican challenging President Trump in the 2020 election talks about why he decided to run. Our Hari Sreenivasan talks to Neha Narula, the Director of the Digital Currency Initiative at the MIT Media Lab, about the future of cryptocurrencies.” Amanpour Podcast
DCI's Madars Virza presents: zk-SHARKs: Combining Succinct Verification and Public Coin Setup at ZKPROOF Workshop
In this episode for Lightning Month, I talk with Tadge Dryja, the co-author of the Lightning Network whitepaper. We discuss the limitations of the lightning network, why Bitcoin might not be for everyone, alternative scaling ideas, fees and inflation.
Cryptanalysis of Curl-P and Other Attacks on the IOTA Cryptocurrency
‘zk-SHARKs: Combining Succinct Verification and Public Coin Setup’ by Madars Virza (MIT DCI)
Madars presents at ZKPROOF Workshop on his project zk-SHARKS.
DCI Mentioned in BBC's 'Should Google, Amazon and Facebook fear this woman?'
By Ethan Heilman (Boston Uni), Neha Narula (MIT Media Lab), Garrett Tanzer (Harvard), James Lovejoy (MIT Media Lab), Michael Colavita (Harvard), Madars Virza (MIT Media Lab), and Tadge Dryja (MIT Media Lab)
We present attacks on the cryptography formerly used in the IOTA blockchain, including under certain conditions the ability to forge signatures. We developed practical attacks on IOTA’s cryptographic hash function Curl-P-27, allowing us to quickly generate short colliding messages. These collisions work even for messages of the same length. Exploiting these weaknesses in Curl-P-27, we broke the EU-CMA security of the former IOTA Signature Scheme (ISS). Finally, we show that in a chosen-message setting we could forge signatures and multi-signatures of valid spending transactions (called bundles in IOTA).
Blockchain and the Value of Operational Transparency for Supply Chain Finance
US presidential hopeful Elizabeth Warren says she'd consider dismantling the tech giants should she ever get the top job. But is this really necessary or even possible?
Read full article here
Knowledge @ Wharton's 'How a New Technology Can Disrupt the Global Supply Chain'
by Jiri Chod (BU), Nikolaos Trikakis (MIT), Gerry Tsoukalas (Upenn Wharton), Henry Aspegren (MIT), and Mark Weber (MIT). Nominated for an award in the Journal of Management Science. Sept 15th, 2018
In this paper, we develop a new theory that shows signaling a firm's fundamental quality (e.g., its operational capabilities) to lenders through inventory transactions to be more efficient --- it leads to less costly operational distortions --- than signaling through loan requests, and we characterize how the efficiency gains depend on firm operational characteristics such as operating costs, market size, inventory salvage value and failure probability.
MIT Technology Review and MIT Media Lab Digital Currency Initiative Announce 2019 Business of Blockchain Conference on May 2
An interdisciplinary team from MIT, Wharton and Boston College has created a new blockchain-based system that has the potential to disrupt the global supply chain. Called ‘b_verify,’ the system is designed to help small and medium-size enterprises — especially those in developing nations — get financing from lenders at potentially better terms while mitigating warehouse deposit fraud. The system brings greater transparency to a key part of the supply chain, which can have a big impact on global trade financing. Bverify introduces a series of blockchain technology innovations tailored to facilitate supply chain finance and operations management.
Read the article here
How to Subvert Backdoored Encryption: Security Against Adversaries that Decrypt.
Today, MIT Technology Review announced the third annual Business of Blockchain event, which will take place on May 2, 2019 at the MIT Media Lab. The event is held in collaboration with the Digital Currency Initiative, an MIT Media Lab research group focusing on cryptocurrencies and their underlying technology, and brings together industry leaders and pioneers in this emerging field to examine the technology, ethics, and impact of blockchains.
Read the Article here
Compelled Decryption and the Fifth Amendment: Exploring the Technical Boundaries
By Thibaut Horel, Sunoo Park, Silas Richelson, and Vinod Vaikuntanathan. Published in the Innovations in Theoretical Computer Science conference (ITCS 2019).
Practical Accountability of Secret Processes
By Aloni Cohen and Sunoo Park. Published in the Harvard Journal of Law and Technology (JOLT), Fall 2018 issue.
SpaceMint: A Cryptocurrency Based on Proofs of Space
By Jonathan Frankle, Sunoo Park, Daniel Shaar, Shafi Goldwasser, and Daniel J. Weitzner. Published in the 27th USENIX Security Symposium (USENIX Security 2018).
DCI's Director interviewed for Fortune's latest article: 'Zcash Discloses Vulnerability That Could Have Allowed 'Infinite Counterfeit' Cryptocurrency'
By Sunoo Park, Albert Kwon, Georg Fuchsbauer, Peter Gaži, Joël Alwen, and Krzysztof Pietrzak. Published in the 22nd International Conference on Financial Cryptography and Data Security (Financial Crypto 2018)
"DCI Working Groups: the blockchain sandbox at MIT" On Medium by DCI's Alin Dragos
On March 1 of last year, Ariel Gabizon was tidying up a presentation he was preparing to deliver the following day at a financial cryptography conference on the Caribbean island of Curaçao when he spotted a seemingly small mathematical mistake that could, he realized, jeopardize billions of dollars in capital.
Read the full article here
Coin Rivet's 'Single Lightning Network node routes record number of Satoshis in a day'
Our MIT motto, mens et manus, is a call-to-action to be more than mere technologists and to learn (by doing!) how to be thoughtful makers of a better world. The Digital Currency Initiative (DCI) Working Group Program creates a sandbox for interdisciplinary teams of students to hack on pressing topics in cryptocurrency and blockchain technology. Students from the Blockchain Lab will collaborate with instructors, companies and DCI to investigate uses of blockchain technology and how to integrate it into viable business models.
Read the full post on Medium
Coindesk's 'This Scaling Tech Could Let You Sync Bitcoin Straight From Your Phone' using UTreeXO created by Tadge Dryja
A Lightning Network node hosted by Satoshi Labs successfully routed one Bitcoin worth of Lightning transactions in a 24-hour period
Read the full article and watch the video here
“Maybe we don’t have to store everything ourselves.”
That’s Tadge Dryja, cryptocurrency research scientist at the MIT Digital Currency Initiative, explaining the concept behind his bitcoin scaling solution, “utreexo.”
Based on an idea that has been pursued by developers for many years, utreexo seeks to streamline an aspect of bitcoin’s code that leads to heavy storage requirements over time.
Read the original article here