What Is the Main Security Challenge Introduced by Sharding a Blockchain?
The main security challenge with sharding is the 'single-shard takeover' risk. By dividing the chain, the total security is also partitioned, meaning a malicious actor would only need to compromise a small fraction of the total network validators to control a single shard.
This allows them to validate invalid transactions on that shard. Solutions like random validator assignment and fraud proofs are implemented to mitigate this risk.
Glossar
Malicious Actor
Exploit ⎊ The term "Malicious Actor" within cryptocurrency, options trading, and financial derivatives denotes an individual, group, or automated system leveraging vulnerabilities or asymmetries within market structures, protocols, or participant behavior to generate illicit profit or inflict detrimental consequences.
Invalid Transactions
State Transition ⎊ Invalid Transactions are those that violate the protocol's rules, either syntactically or semantically, leading to their rejection by nodes or their inclusion in a block but without any state change, often resulting in wasted computational resources.
Random Validator Assignment
Security ⎊ Random validator assignment is a core security mechanism in sharded proof-of-stake blockchains, designed to prevent a single shard takeover by malicious actors.
Sharding
Fragmentation ⎊ Sharding, within cryptocurrency networks, represents a database partitioning technique designed to enhance transaction throughput and scalability by dividing the blockchain into smaller, more manageable segments known as shards.
Fraud Proofs
Concept ⎊ Fraud proof refers to a cryptographic mechanism that allows a network participant to prove that a specific block or transaction is invalid without re-executing the entire computation.