Fork-free Red Belly Blockchain cuts double spend danger

University of Sydney launch quicker, safer blockchain aimed at consortiums



A new blockchain system developed by researchers at the University of Sydney may help cure the scale and speed issues that affect the technology.

The Red Belly Blockchain, removes the risks of double spending and is much faster than existing systems such as Bitcoin, researchers say.

Most blockchain systems are ‘forkable’ in that they require participants to agree on a chain out of multiple possible branches of blocks.

Blockchain systems are distributed chains of blocks. Each node in the system can create a new block of transactions and append the block to its view of the chain. Since the system is distributed, multiple nodes may add different blocks at the same point in the chain, before learning of the presence of other blocks.

This results in a forked chain or tree. For nodes to then agree on a single, true state of the system, different strategies are applied. Bitcoin, for example, selects the longest branch and 'wastes' all blocks not present in it.

"If an attacker can solve crypto-puzzles fast enough to grow a local branch of the blockchain faster than the rest of the system, then it will eventually impose its own branch to all participants," wrote university researcher Christopher Natoli in a previous paper.

The attacker "does not even need a large fraction of the computational power to exceed the length of the chain, allowing her to double spend in new transactions the coins that she already spent in earlier transactions".

No forks given

The Red Belly Blockchain by comparison “enforces integrity initially rather than recovering from inconsistencies” said Dr Gramoli, head of the university’s Concurrent Systems Research Group.

“As opposed to mainstream public blockchains, ours is not subject to double spending – when an individual successfully spends their money more than once – because its chain of blocks never forks. The absence of forks means there is no need for any number of confirmations. A transaction in a block is there for good,” he said.

Targetted at consortium blockchains – a model somewhere between public and fully private blockchains, where only a pre-selected set of nodes can participate in verification, but where the blockchain could potentially be accessed by anyone – Red Belly applies “a new multivalued Byzantine consensus algorithm”.

“The algorithm preserves integrity in a public consortium regardless of failures and attacks,” Gramoli added.

The benefits of Red Belly – the mechanics of which are outlined in the paper (Leader, Randomization, Signature)-free Byzantine Consensus for Consortium Blockchains – include much higher throughput and less risk.

The number of transactions blockchain systems like Bitcoin and Ethereum can process per second is currently around 7,000. The Visa payments network at peak capacity, can process around 56,000 transactions per second.

“In recent testing, our blockchain achieved the best performance we have seen so far – with more than 440,000 transactions per second on 100 machines,” Gramoli explained. “As opposed to consortium blockchains, it can treat hundreds of thousands of transactions per second coming from a potentially unbounded number of clients. It offers a performance that scales horizontally, which ensures the security of transactions.”

Researchers will now develop a recommendation system to automate the selection of the participants of a consensus instance.

“We will soon release wallets to help the end-users issue transactions and read the balance of their account from anywhere,” Gramoli added.

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