How to linearize your cluster

The exploration of a novel partitioning attack within network transactions reveals significant vulnerabilities and potential solutions. This attack involves an attacker creating multiple conflicting versions of a transaction, distributing them across the network to fragment the network nodes into isolated groups, each aware of only one version of the attacker's transaction. This fragmentation complicates the relay of honest transactions across these partitions, especially when these transactions require linearization information that is not universally recognized across the fragmented network.

The issue becomes particularly acute when honest transactions need to spend or attach to an attacker's transaction. Under current conditions, a mempool (memory pool) is unlikely to accept a transaction that attempts to spend another that it does not recognize due to conflict with its version of the attacker's transaction. This could potentially halt the propagation of honest transactions across the network. A proposed solution to this problem is package relay, which could facilitate the propagation of honest transactions by allowing for the relay of entire clusters of transactions, including those that are part of the attacker's scheme.

The discussion further delves into the implications of requiring nontrivial chunkings or linearizations to be forwarded across the network. The attacker could exploit this requirement by not only partitioning the network with single transactions but also with entire clusters that differ in ID or structure. This situation exacerbates the issue when there is a need to attach to an entire cluster, not just an attacker transaction, as propagation becomes impossible due to the inability to optimize linearization for unknown cluster versions. Again, package relay emerges as a potential remedy, allowing for the replacement of competing attacker clusters with a singular, optimized cluster, thereby mitigating the attack.

Moreover, the conversation highlights that while introducing requirements for linearizations could seemingly aggravate the attack—especially in scenarios not involving direct attachment to malleable attacker transactions—the merger of attacker and honest linearizations might offer an optimal solution. If such a merger can be proven effective, the necessity for linearizations may not necessarily worsen the situation.