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July 31, 2021 Eleftherios Kokoris-Kogias, Enis Ceyhun Alp, Linus Gasser, Philipp Jovanovic, Ewa Syta, Bryan Ford
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CALYPSO: Private Data Management for Decentralized Ledgers

This work enhances permissioned and permissionless blockchains with the ability to manage confidential data without forfeiting availability or decentralization.
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July 17, 2021 Itamar Zimerman, Eliya Nachmani, Lior Wolf
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Recovering AES Keys with a Deep Cold Boot Attack

In this work, we combine a novel cryptographic variant of a deep error correcting code technique with a modified SAT solver scheme to apply the attack on AES keys.
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July 16, 2021 Konstantinos (Kostas) Chalkias, Shir Cohen, Kevin Lewi, Fredric Moezinia, Yolan Romailler
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HashWires: Hyperefficient Credential-Based Range Proofs

This paper presents HashWires, a hash-based range proof protocol that is applicable in settings for which there is a trusted third party (typically a credential issuer) that can generate commitments. We refer to these as “credential-based” range proofs (CBRPs). HashWires improves upon hashchain solutions that are typically restricted to micro-payments for small interval ranges, achieving an exponential speedup in proof generation and verification time.
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May 12, 2021 Sam Blackshear, Konstantinos (Kostas) Chalkias, Panagiotis Chatzigiannis, Riyaz Faizullabhoy, Irakliy Khaburzaniya, Lefteris Kokoris Kogias, Joshua Lind, David Wong, Tim Zakian
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Reactive Key-Loss Protection in Blockchains

We present a novel approach for blockchain asset owners to reclaim their funds in case of accidental private-key loss or transfer to a mistyped address. Our solution can be deployed upon failure or absence of proactively implemented backup mechanisms, such as secret sharing and cold storage.
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November 3, 2020 Lefteris Kokoris Kogias, Dahlia Malkhi, Alexander Spiegelman
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Asynchronous Distributed Key Generation for Computationally Secure Randomness, Consensus, and Threshold Signatures

In this paper, we present the first Asynchronous Distributed Key Generation (ADKG) algorithm which is also the first distributed key generation algorithm that can generate cryptographic keys with a dual (𝑓, 2𝑓 + 1)−threshold (where 𝑓 is the number of faulty parties).
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November 1, 2020 Mathieu Baudet, George Danezis, Alberto Sonnino
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FastPay: High-Performance Byzantine Fault Tolerant Settlement

FastPay allows a set of distributed authorities, some of which are Byzantine, to maintain a high-integrity and availability settlement system for pre-funded payments. It can be used to settle payments in a native unit of value (crypto-currency), or as a financial side-infrastructure to support retail payments in fiat currencies. FastPay is based on Byzantine Consistent Broadcast as its core primitive, foregoing the expenses of full atomic commit channels (consensus).
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October 23, 2020 Sarah Azouvi, George Danezis, Valeria Nikolaenko
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Winkle: Foiling Long-Range Attacks in Proof-of-Stake Systems

Winkle protects any validator-based byzantine fault tolerant consensus mechanisms, such as those used in modern Proof-of-Stake blockchains, against long-range attacks where old validators’ signature keys get compromised. Winkle is a decentralized secondary layer of client-based validation, where a client includes a single additional field into a transaction that they sign: a hash of the previously sequenced block.
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October 22, 2020 Konstantinos (Kostas) Chalkias, François Garillot, Valeria Nikolaenko
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Taming the many EdDSAs

This paper analyses security of concrete instantiations of EdDSA by identifying exploitable inconsistencies between standardization recommendations and Ed25519 implementations. We mainly focus on current ambiguity regarding signature verification equations, binding and malleability guarantees, and incompatibilities between randomized batch and single verification.
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October 21, 2020 Emma Zhong, Kevin Cheang, Shaz Qadeer, Wolfgang Grieskamp, Sam Blackshear, Junkil Park, Yoni Zohar, Clark Barrett, David Dill
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The Move Prover

The Libra blockchain is designed to store billions of dollars in assets, so the security of code that executes transactions is important. The Libra blockchain has a new language for implementing transactions, called “Move.” This paper describes the Move Prover, an automatic formal verification system for Move.
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September 15, 2020 Ankush Das, Shaz Qadeer
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Exact and Linear-Time Gas-Cost Analysis

Blockchains support execution of smart contracts: programs encoding complex transaction protocols between distrusting parties. Due to their distributed nature, blockchains rely on third-party miners to execute and validate transactions. Miners are compensated by charging users with gas based on the execution cost of the transaction. To compute the exact gas cost, blockchains track gas cost dynamically creating its own overhead. This paper presents a static exact gas-cost analysis technique that can be employed to eliminate dynamic gas tracking.
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