Plasma

2 min read

Pronunciation

[plaz-muh]

Analogy

Imagine the main as a central courthouse. Plasma creates many smaller, independent local courts (child chains) that handle most everyday cases (transactions) quickly and cheaply. Each local court periodically sends a summary (Merkle root) of its decisions to the central courthouse. If someone believes a local court made a mistake or acted fraudulently, they can appeal to the central courthouse (initiate an exit game) using evidence from these summaries.

Definition

A scaling framework that uses a system of 'child chains' (Plasma chains) anchored to a main (typically ). Plasma chains process transactions and periodically commit Merkle roots of their blocks to the , relying on fraud proofs and a 'Plasma exit' mechanism for security.

Key Points Intro

Plasma is a non-custodial scaling solution that involves child chains periodically committing to the main chain.

Key Points

Consists of child chains that are themselves smaller blockchains.

Child chains post block commitments (Merkle roots) to the Layer 1 chain.

Users can withdraw their assets from a Plasma chain back to Layer 1 through an 'exit game' if they suspect fraud or censorship.

Relies on fraud proofs to ensure the validity of Plasma chain operations.

Data is generally kept off the Layer 1 chain (unlike rollups), reducing L1 costs but creating data availability challenges.

Example

OMG Network (formerly OmiseGO) was one of the early projects to implement a Plasma-based solution for faster payments on .

Technical Deep Dive

Plasma chains are structured as trees of child chains rooted in the main . Each child chain has its own production mechanism. The security model relies on users monitoring the Plasma chain and initiating an exit if they detect malicious behavior by the Plasma operator. The exit game involves submitting evidence (Merkle proofs of inclusion for their transactions/UTXOs) to the . There's a challenge period during which others can contest an exit. Data availability is a key concern: if the Plasma operator withholds data, users might not be able to construct the proofs needed to exit or challenge fraud. Variants like 'Plasma Cash' tried to mitigate some data availability issues by assigning unique IDs to tokens.

Security Warning

Plasma chains require users to be vigilant and potentially participate in complex exit games to secure their funds. Data availability is a critical assumption; if the operator withholds data, it can be difficult or impossible to exit safely. Mass exit scenarios can also congest the chain.

Caveat

Plasma has seen less adoption compared to , partly due to the complexity of its exit games and data availability concerns. Many of its concepts have influenced other designs.

Related Terms

Blockchain & Cryptocurrency Glossary

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