Electroneum Virtual Machine (EVM)

The EVM’s physical instantiation can’t be described in the same way that one might point to a cloud or an ocean wave, but it does exist as one single entity maintained by thousands of connected computers running an Electroneum Smart Chain client.

The Electroneum protocol itself exists solely for the purpose of keeping the continuous, uninterrupted, and immutable operation of this special state machine. It’s the environment in which all Electroneum accounts and smart contracts live. At any given block in the chain, Electroneum Smart Chain has one and only one ‘canonical’ state, and the EVM is what defines the rules for computing a new valid state from block to block.

Prerequisites

Some basic familiarity with common terminology in computer science such as bytes↗, memory↗, and a stack↗ are necessary to understand the EVM. It would also be helpful to be comfortable with cryptography/blockchain concepts like hash functions↗ and the Merkle tree↗.

From ledger to state machine

The analogy of a ‘distributed ledger’ is often used to describe blockchains like Bitcoin, which enable a decentralized currency using fundamental tools of cryptography. The ledger maintains a record of activity which must adhere to a set of rules that govern what someone can and cannot do to modify the ledger. For example, a Bitcoin address cannot spend more Bitcoin than it has previously received. These rules underpin all transactions on Bitcoin and many other blockchains.

While Electroneum has its own native cryptocurrency (ETN) that follows almost exactly the same intuitive rules, it also enables a much more powerful function: smart contracts. For this more complex feature, a more sophisticated analogy is required. Instead of a distributed ledger, Electroneum Smart Chain is a distributed state machine↗. Electroneum Smart Chain’s state is a large data structure which holds not only all accounts and balances, but a machine state, which can change from block to block according to a pre-defined set of rules, and which can execute arbitrary machine code. The specific rules of changing state from block to block are defined by the EVM.

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