Blockstream dreams of a whole new type of multi-signature called ROAST.


The research division of Blockstream, a blockchain technology company focused on Bitcoin (BTC), Strong asynchronous Schnorr threshold signatures (roast).

We want to avoid the problem of transaction failures due to missing or malicious signers and to be able to operate at scale.

The term multisignature or multisignature refers to a transactional method in which more than one signature must be signed before it can be executed. This standard is widely adopted in cryptocurrencies.

According to the blog on May 25th post In Blockstream research, the basic idea behind ROAST is to make transactions between the Bitcoin network and Blockstream’s sidechain Liquid more efficient, automated, secure and private.

In particular, ROAST has established itself as a signature standard that can work with and improve threshold signature schemes such as Flexible Round-Optimized Schnorr Threshold Signatures (FROST).

“ROAST is a simple wrapper around a threshold signature scheme like FROST. This ensures that an honest quorum of signers (i.e. Liquid employees) will always get valid signatures, even if there are signers in the way when the network connection has arbitrarily high latency.”

The researchers emphasized that while FROST could be an effective way to sign BTC transactions, the structure of coordinators and signers is designed to abort transactions when no signers are present, making them secure, but not suitable for “auto-signing software”.

To address this problem, the researchers say ROAST can guarantee enough trusted signers for each transaction to avoid failures, and can perform at a much larger scale than the 11/15 multi-signature standard used primarily by Blockstream.

“Our empirical performance evaluation shows that ROAST can scale to large groups of signers, such as a 67 out of 100 setup with coordinators and signers from different continents,” the Post added.

“Even if 33 malicious signers try to block signature attempts (eg send a bad response or no response at all), 67 honest signers can successfully generate a signature in seconds.”

To provide a brief explanation of how ROAST works, the team used the analogy of the Democratic Congress in charge of the “Frostland” legislation.

In essence, it is argued that it can be complex to approve signed legislation (transactions) in Frostland. This is because there are numerous factors that can lead to the sudden absence or absence of a large number of council members.

The process for responding (ROAST) is to collect and maintain a sufficient list of council members (signers) to ensure that the council secretary always has enough members to get the law passed.

“If at least seven members actually support the bill and act honestly, he knows that these seven members will eventually sign the currently assigned copies and be added back to the secretary’s list.”

“So the secretary can always be sure that the seven members will be back on his list at some point in the future, so the signing process won’t be interrupted,” the Post added.

Relevant: ‘DeFi is not decentralized at all,’ said a former Blockstream executive.

ROAST is part of a collaboration between Blockstream researchers Tim Ruffing and Elliott Jin, Viktoria Ronge and Dominique Schröder of the University of Erlangen-Nuremberg, and Jonas Schneider-Bensch of the CISPA Helmholtz Center for Information Security.

Along with the blog post, the researchers linked to the study on page 13. paper Gives a detailed explanation of ROAST.

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