Skip to main content

Nonce Types in EVVM

The EVVM system implements two distinct nonce mechanisms for payment functions: sync and async. Understanding these nonce types is essential for developers interfacing with the EVVM contract, as they serve different purposes and behave in significantly different ways.

Sync Nonce​

Definition and Behavior​

The sync nonce is a consecutive counter that increments sequentially by one each time a payment transaction is executed. This mechanism closely resembles the standard nonce implementation used in Ethereum transactions.

Key Characteristics:​

  • Sequential Incrementing: Each successful transaction increases the nonce value by exactly one unit.
  • Transaction Ordering: Ensures transactions are processed in the order they were issued.
  • Replay Protection: Prevents transaction replay attacks by requiring each transaction to have a unique nonce value.
  • Predictability: The next valid nonce is always the current nonce value plus one.

Use Cases:​

  • Standard payment operations where transaction order matters
  • Operations that require deterministic processing sequence
  • Situations where transaction dependencies exist
  • Services that rely on deterministic payment processing

Sync Nonce

Async Nonce​

Definition and Behavior​

The async nonce is a non-consecutive number that is user-generated and transaction-specific. Unlike the sync nonce, async nonces do not follow a predetermined sequence and can be any valid number chosen by the user.

Key Characteristics:​

  • Non-sequential: Numbers don't need to follow any particular order or sequence.
  • Uniqueness Per Address: Each async nonce can only be used once per address.
  • User-defined: Users can generate their own nonce values, providing flexibility in transaction preparation.
  • Parallelism: Multiple transactions can be prepared independently without knowledge of other pending transactions.

Use Cases:​

  • Parallel transaction processing
  • Delayed execution scenarios
  • Batch transaction preparation without dependency on execution order
  • Systems where transaction preparation and submission might happen on different timelines

Async Nonce