Blockchain-Grundlagen
Transaction nonces
A nonce prevents replay in a defined account context.
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A counter attached to the account
An Ethereum account nonce is part of the rules that determine which transactions can be executed. For an ordinary transaction sent by an externally owned account, it identifies the next position in that account’s transaction sequence. This stops a signed transaction from being replayed indefinitely on the same chain. The nonce is not the wallet’s balance, a transaction’s block number or a measure of its importance. Ethereum account fields.
An example of a transaction queue
Suppose an account’s next transaction nonce is 12. The user signs a transfer with nonce 12 and another operation with nonce 13. If the first transaction has not been included, the second cannot simply occupy its place. A wallet can show both as pending even though the later transaction depends on the earlier position being filled.
Now suppose the user signs a different transaction with nonce 12. The two transactions compete for the same position. Under one accepted history, both cannot execute as successive transactions from that account with that same nonce. Which one gets included is not decided by the order of cards in a wallet’s activity screen. Network propagation, fee conditions and what a block producer includes matter.
This is why a transaction labelled “cancel” in a wallet is usually an attempt to replace an unconfirmed transaction, rather than a command that erases an already confirmed transfer. A replacement can lose the race. The receipt and accepted chain history must be checked before telling someone that the original operation was cancelled. Ethereum transaction lifecycle.
Different protocols can use different nonces
A signed token permit, an order and an account transaction can each have their own anti-replay mechanism. A signature containing a field called nonce is not necessarily bound to the account’s transaction counter. The contract checking that signature determines what the field means. Replacing a pending ETH transfer does not automatically revoke every order or permit the owner previously signed.
Ethereum’s EIP-7702 adds another important case: processing a valid delegation authorisation checks and increments the authorising account’s nonce. A modern investigation should not assume that every nonce change is explained solely by ordinary outgoing transactions visible in a wallet’s default list. The authorisation record and applicable protocol rules also need examination. EIP-7702 authorisation processing.
Reconstruct the sequence without inventing intent
Imagine a victim reporting that their wallet displayed “cancelled”, but the assets moved. Preserve the competing transaction hashes, their nonces, the receipt of the included transaction and the time each record was collected. Compare the destinations and calldata. This can establish which signed instruction executed. It cannot, by itself, show who operated the device or what a deceptive website displayed when the instruction was signed.
Keep those questions separate in the report. A nonce conflict is a technical explanation of transaction ordering; attributing the signature to a person requires additional evidence. Likewise, a gap in a block explorer’s presentation should prompt further inspection, not an immediate claim that the network created an unauthorised transaction.
Related entries explain signed permits, EOA delegation and preserving evidence after an incident.