NextKey

Storage Plain v361 → current

The ML-KEM-768 public key that will become CurrentKey in the following block .

Queried by: developerswalletsstakers

The Big Picture

When you want MEV protection for your transaction, you encrypt with NextKey. This key was announced by the upcoming block's author BEFORE they can see your encrypted submission. This ordering prevents them from choosing a key that only decrypts transactions they want to include.

Why This Matters

This is THE key you use for MEV protection. Fetch it, encrypt your transaction with it, then submit via submit_encrypted. The next block author will decrypt and execute your transaction.

Example Scenario

You want to stake 1000 TAO with MEV protection. Step 1: Query NextKey. Step 2: Encrypt your add_stake transaction with this key using ML-KEM + XChaCha20. Step 3: Call submit_encrypted with the ciphertext. Your stake is now MEV-protected.

Common Questions

Why not use CurrentKey?: CurrentKey is for the block being built NOW. Your submission goes into the NEXT block. Using CurrentKey would fail because that block author can't decrypt it (different key epoch).
What if NextKey changes while I'm encrypting?: Race condition - your encryption might use an old key. Always fetch NextKey immediately before encryption and submit quickly. If you see KeyExpired error, refetch and retry.
How often does NextKey change?: Every block. Each new block author announces their key for the following block. So NextKey updates roughly every 12 seconds (Bittensor block time).

Use Cases

Encrypt transactions for MEV protection
Build real-time MEV protection interfaces
Monitor key rotation for MEV protection availability

From Chain Metadata

Next ML‑KEM‑768 public key bytes, announced by the block author.

Purpose & Usage

Purpose

Provides the encryption key users should use for new encrypted submissions.

Common Query Patterns

Query to get next block's encryption key
Fetch before encrypting new submissions

Notes

ML-KEM-768 public key bytes
Announced by next block's author via announce_next_key
None if no key announced yet for next block
Fetch fresh before each encryption to avoid KeyExpired errors

Part of: MEV Shield

Stored Value

BoundedVec

value (BoundedVec)

Relationships

Modified By

announce_next_key

Code Examples

import { ApiPromise, WsProvider } from "@polkadot/api";
import { stringCamelCase } from "@polkadot/util";

const provider = new WsProvider("wss://entrypoint-finney.opentensor.ai:443");
const api = await ApiPromise.create({ provider });

// Query NextKey storage (no keys - plain value)
const result = await api.query
  [stringCamelCase("MevShield")]
  [stringCamelCase("NextKey")]();
console.log("NextKey:", result.toHuman());

On-Chain Activity

Write Frequency

●●●●○○ Medium 100K–1M est. writes

100K–1M estimated writes

#41 most written storage item

Write Source User Extrinsics

Modified via user-submitted extrinsics

As of block 7,429,232

Runtime Info

View Source

Pallet: MevShield
Storage Kind: Plain
First Version: v361
Current Version: v393

Back to MevShield Storage