To date, current ideas to address Ethereum’s scalability issue include:
L2 roll-ups: Optimistic (proof of fraud - e.g. Optimism, Arbitrum), Zero-Knowledge (“ZK”; zero-knowledge proof - Starkware, Immutable X, LoopRing, zkSync).
L2 sidechains: Polygon (uses Plasma as well as Optimistic and ZK roll-ups, but technically works in parallel with the main network and has its own consensus mechanism, and the security structure is independent of L1, therefore different from the aforementioned L2 roll-ups) .
ETH 2.0: expected network scaling due to sharding. The Ethereum consensus mechanism will also change from Proof-of-Work to PoS.
There is still no clear understanding of which of the above will determine the future of Ethereum. For example, if Ethereum is roll-up oriented, then L1 will be used only for data availability and security, while transactions will be carried out using L2 protocols. Ethereum’s scaling issue has led to the emergence of alternative L1 blockchains. And Aptos is the newest company to enter this market.
Aptos is a L1 Proof-of-Stake (PoS) blockchain developed by the creators, engineers and designers of the Meta* (Facebook*) Diem blockchain. But, although Aptos is being worked on by people from Diem, the project has nothing to do with either Diem or Meta*.
Aptos aims to solve the trilemma (decentralization, security, scalability) capable of mass adoption, including for companies and enterprises. Diem was originally designed to serve Meta*'s over 2 billion user base. Aptos will scale beyond the Meta* network. The modernity of the Aptos technology stack includes the latest developments in consensus mechanisms built on a flexible, security-oriented programming language - Move (explained below).
The Move programming language is purpose-built for secure resource management and modularity (also used to develop Diem). Move Benefits:
Easy property setting for assets that allows assets to be passed through smart contracts as arguments and returned as functions. Solidity is less dynamic as it stores assets in hashmaps that are permanently locked into the contract;
Referential transparency for immutable links. Solidity has no built-in access control and is immutable, which makes it relatively difficult to fix bugs and vulnerabilities once smart contracts are deployed;
Memory safety by preventing dead links and memory leaks. Move also offers a formal “Move Prover” tool that allows developers to quickly check and verify that their code is running as intended;
Secure storage of important information (tokens, smart contracts) using a native “resources” data type. Resources have a high status in the Move code architecture, which prevents them from being copied or accidentally destroyed.
Multi-chain deployment of dApps by design. Pontem has developed a fork of the Move Virtual Machine (“VM”) that can be easily deployed on other networks: Avalanche, Cosmos, Polkadot, etc. Its roadmap includes a potential Ethereum VM that will be compatible with the Move VM to facilitate deployment, interoperability and migration of dApps across multiple ecosystems.
In addition, Solidity is susceptible to reentry and other vulnerabilities. As a language that enhances DX, it is based on legacy blockchain languages (Solidity) in terms of security and flexibility. It is believed that the efficiency of Move programming is comparable to Rust.
In addition to Move’s security features, Aptos’ other security components are found in its consensus mechanism as well as user account protection.
Consensus mechanism: The Aptos Byzantine Fault Tolerance (“BFT”) protocol (“AptosBFT” v4) is a modern low-latency derivative of HotStuff (similar to Tendermint BFT from Cosmos Hub). Key features include:
AptosBFT is designed to provide network continuity and has no downtime when updating. Its consensus mechanism provides fault tolerance for up to one-third of malicious inspection nodes before the network is compromised. State synchronization allows validators that have fallen or fallen behind to quickly catch up. Low entry barriers, diversification and decentralization of validators increase the security of Aptos;
The protocol separates liveness from security so that the network will not fork as long as AptosBFT’s integrity guarantees are maintained - even if the network fails. The security of AptosBFT has been verified and officially confirmed ;
Block validation is done with a reputation system that analyzes the state of the network and automatically changes leading nodes to accommodate non-responsive validators. Because validator governance and configuration are managed by on-chain metrics, updates can be voted on by the community and implemented transparently and efficiently.
Transaction execution is deterministic, hermetic and measured. As Aptos stated, deterministic and hermetic means that the outcome of a transaction is predictable and based on two things:
on the information contained in the transaction;
on the current state of the registry.
This is a common attribute of L1 blockchains, except for Ethereum, Avalanche. Measurement is an important defense against denial-of-service attacks at the transaction execution level.
Account protection. Users (including validators) can rotate their private (consensus) keys to prevent theft. Key recovery methods are currently being developed that will be integrated into the blockchain account model to avoid loss of access due to loss of keys. This is a new feature not yet available on other blockchains.
Based on testnet activity to date, Aptos outperforms its competitors in two key areas - time to completion (TTF) and throughput. The blockchain is capable of achieving a TTF of less than 1 second with a maximum throughput of 160k transactions per second (TPS). Although the testnet results are from a controlled environment and tend to inflate performance, they are the only data available for Aptos to date. But, nevertheless, these indicators give an understanding of the capabilities of Aptos in the main network. Below is a comparison of Aptos with other L1 blockchains.
Risks and reasoning.
Potential network outages. A notable risk inherent in all blockchains is network outages. They affect UX and DX, and Solana is a prime example of this . As for Aptos, the team continues to improve and modernize its technology stack, including “AptosBFT” v4. In the event of an attack or periods of failure, the network reputation system automatically minimizes the negative impact of disabled validators.
Ecosystem organic scaling. Aptos is still in its early stages of development. Since it is a L1 blockchain built from the ground up, the key to the growth of the ecosystem depends on its ability to attract developers. Move’s state-of-the-art security and flexibility features are expected to drive DX and create the ideal development environment to attract developer activity.