EIPs/EIPS/eip-2031.md

---
eip: 2031
title: State Rent B - Net transaction counter
author: Alexey Akhunov (@AlexeyAkhunov)
discussions-to: https://ethereum-magicians.org/t/eip-2031-net-transaction-counter-change-b-from-state-rent-v3-proposal/3283
status: Draft
type: Standards Track
category: Core
created: 2019-05-15
requires: 2029
---

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## Simple Summary
<!--"If you can't explain it simply, you don't understand it well enough." Provide a simplified and layman-accessible explanation of the EIP.-->
Ethereum starts to track the number of transactions inside its state (for now, only number of transactions after this change is introduced, therefore
it is called *Net* transaction count).
It is done by incrementing a storage slot in the special contract, called *State counter contract* ([EIP-2029](https://eips.ethereum.org/EIPS/eip-2029)).

## Abstract
<!--A short (~200 word) description of the technical issue being addressed.-->
It is part of the State Rent roadmap. This particular change makes any Ethereum transaction increment the transaction counter, which is a special storage slot
in the *State counter contract*. This counter will be used to populate the nonces of newly created
non-contract accounts. This way of populating nonce ensures replay protection for accounts that were evicted and then brought back by sending ether to them.

## Motivation
<!--The motivation is critical for EIPs that want to change the Ethereum protocol. It should clearly explain why the existing protocol specification is inadequate to address the problem that the EIP solves. EIP submissions without sufficient motivation may be rejected outright.-->
Ethereum currently does not have a special place in the state for tracking number of transactions.

## Specification
<!--The technical specification should describe the syntax and semantics of any new feature. The specification should be detailed enough to allow competing, interoperable implementations for any of the current Ethereum platforms (go-ethereum, parity, cpp-ethereum, ethereumj, ethereumjs, and [others](https://github.com/ethereum/wiki/wiki/Clients)).-->
A new field, with the location 0 (that means it resides in the storage slot 0 in the state counter contract, and can
be read by calling that contract with argument being 32 zero bytes), is added to the state counter contract. It will eventually contain `txCount`, the total number of transactions processed up until that point.
On an after block B, or after the deployment of the state counter contract (which comes first), the field `txCount` is incremented after each transaction. Updating `txCount` means updating the storage of state counter contract at the location 0. These changes are never reverted.

## Rationale
<!--The rationale fleshes out the specification by describing what motivated the design and why particular design decisions were made. It should describe alternate designs that were considered and related work, e.g. how the feature is supported in other languages. The rationale may also provide evidence of consensus within the community, and should discuss important objections or concerns raised during discussion.-->
Two main alternatives were proposed for the replay protection of the accounts that were evicted by subsequently brought back by sending ether to them:
1. Temporal replay protection. The nonce of the new accounts (and those brought back) is still zero, but a new `valid-until` field is introduced, making
transactions invalid for inclusion after the time specified in this field. This, however, has unwanted side effected related to the fact that account
nonces are not only used for replay protection, but also for computing the addresses of the deployed contracts (except those created by `CREATE2`).
2. Setting nonce of new accounts (and those brought back) to something depending on the current block number. This approach requires coming up with
an arbitrary parameter, which is the maximum number of transaction in the block, so that the new nonces never clash with the existing nonces.
This is mostly a concern for private networks at the moment, because they will potentially have significantly more transactions in a block.

## Backwards Compatibility
<!--All EIPs that introduce backwards incompatibilities must include a section describing these incompatibilities and their severity. The EIP must explain how the author proposes to deal with these incompatibilities. EIP submissions without a sufficient backwards compatibility treatise may be rejected outright.-->
This change is not backwards compatible and requires hard fork to be activated.

## Test Cases
<!--Test cases for an implementation are mandatory for EIPs that are affecting consensus changes. Other EIPs can choose to include links to test cases if applicable.-->
Tests cases will be generated out of a reference implementation.

## Implementation
<!--The implementations must be completed before any EIP is given status "Final", but it need not be completed before the EIP is accepted. While there is merit to the approach of reaching consensus on the specification and rationale before writing code, the principle of "rough consensus and running code" is still useful when it comes to resolving many discussions of API details.-->
There will be proof of concept implementation to refine and clarify the specification.

## Copyright
Copyright and related rights waived via [CC0](https://creativecommons.org/publicdomain/zero/1.0/).