How Jax.Network foils single shard takeover attacks


A single shard takeover attack is a situation where a malicious attacker takes control of an entire node on a network and tries to alter the course of a transaction. For example, in a system consisting of 100 shards, only 51% of the network hash rate is needed to dominate the entire shard. 

A variation of this was seen in June 2018 when Bitcoin’s mempool was flooded with around 4500 dust transactions that Bitcoin did not confirm. The mempool size added up to 45 MB leading to an increase in transaction fee. Thus, it’s essential to study this attack.

Implementation of the single shard takeover attack

Consider a network divided into shards; a validator needs a certain amount of hash rate to mine the shards and validate transactions. One can compare this to a 51% attack that happens within a shard. The amount of hash rate required in this situation decreases by a considerable variable.

An attacker who uses his or her total hashing power on such a single shard can control it. With this, the hacker might become stronger and begin to manipulate transactions through the gained single shard. 

The attacker only needs to take over a majority of the collators present in the network to make a shard maleficent. After that, the hacker can easily submit invalid collations. Once the attacker can submit these invalid requests, he or she has achieved their purpose. 

Jax.Network has a way to counter this issue. It achieves this by varying the hash rate and merged mining.

How Jax.Network resolves the single-shard attack 

Jax.Network can eliminate the single-shard attack by leveraging merged mining. Merged mining is a process that involves mining two or more cryptocurrencies simultaneously without sacrificing the performance of the overall mining algorithm. In mining multiple shards, another shard can only exist when the nodes declare that they can sustain and validate the transactions that it represents. 

Adding a new shard involves a consensus among miners that the network is overloaded and needs new space. In such a situation, a new shard is created. That is how the network’s hash power is not concentrated to a single miner, preventing a single shard takeover attack. 

Working this way ensures that there is always a specific hash rate present that can save the shard from giving in to an attack attempt. There are two more factors to consider while safeguarding against single shard takeover attacks:

  • Security budget: 

To perform this attack, the attacker needs a considerable incentive. As such, Jax.Network places a substantial premium on miners’ profit when considering an annual security budget. This means that when an honest node mine and validates transactions, it is fairly compensated for its services—discouraging the attacking node since it has to provide a similar or larger counteroffer.

  • Security factor:

Security factor = security budget/capitalization

Taking security seriously means that the higher the security factor, the greater the security budget for a huge network that demands more transactions. Working in this manner keeps the gateway safe and prevents the network from delivering too many rewards to the miners.


A network must develop security against single-shard attacks. Jax.Network provides a competent and updated defense against single shard takeover attacks. 

Although the supply does not have a cap, the new ones are only released when the demand comes in. No attacker gets the chance to converge its hashing power on the network as it is not financially feasible because of the comparative investment in electricity and hardware. The security factors and security budget both are also very high.

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