Manage settings for your payout address

Authorize once with a BIP-322 signature from your payout address, then update every field on one screen: a coinbase OP_RETURN, a coinbase scriptSig tag, a starting or fixed difficulty, plus per-worker overrides. One save ends the session — no accounts, no email.

What each field does

OP_RETURN: up to 75 bytes of UTF-8 added as an additional output in the coinbase transaction of any block this pool mines under your address. Standard, indexed by every explorer, permanent.
scriptSig text: up to 64 bytes of UTF-8 spliced into the coinbase input's scriptSig after the pool's own tag. This is the "pool signature" slot — where AntPool prints "/AntPool/", you'd print yours.
Starting difficulty: the vardiff seed for every connection you open. Vardiff still adapts up/down from there. Useful if you know your rig's hashrate and want to skip the first minute of vardiff calibration.
Fixed difficulty: disables vardiff entirely for your connections and holds the diff constant. Useful for low-hashrate hobby rigs (Bitaxe, Nerdminer) where you want a specific submit rate.

Minimum accepted diff is 64. The floor exists to keep one low-hashrate connection from flooding the pool with shares. A 400 GH/s Bitaxe submits ~1 share/second at diff 64 — plenty for stats visibility.

Every field can be set as a per-address default (applies to all your workers) or overridden for a specific worker. Re-authorize anytime to change or clear anything. Empty text = clear that slot.

Message field content: UTF-8 printable text, spaces, punctuation, and emoji are fine. Control characters, bidi override marks, line separators, and the BOM are rejected — they would either break the on-chain byte stream or let a message reorder itself visually in explorers.

When your changes take effect

Message fields apply live. Difficulty fields apply on your next reconnect.

OP_RETURN and scriptSig text — ckpool re-reads your registration on every workbase refresh (~30 seconds). Register a new message and the very next block this pool finds under your address will carry it, even if your miner has been connected for hours.
Starting difficulty and fixed difficulty — these apply exactly once per Stratum session, at the mining.authorize step. An already-connected miner keeps its current diff until it reconnects. To force the change, restart your miner (or the miner's pool config) so it re-authorizes.

If you need to see a diff change immediately: on Antminer web UI, hit Miner Configuration → Save & Apply to trigger a re-connect. On cgminer, restart the process. On Bitaxe/Nerdminer, power-cycle.

Step 1 — Authorize this session

One signature opens a short-lived session (10 minutes). During the session you can update every field — the session closes when you hit Save.

Sign this exact text in your wallet

Copy the text below and sign it as a BIP-322 message. The signature must be over these bytes exactly — do not edit anything.

— bytes ·

How to sign with your wallet

Sparrow Desktop (recommended)

Install Sparrow from sparrowwallet.com and launch it in testnet4 mode (Preferences → Server → Bitcoin Core → Network → Testnet4, or start with sparrow --testnet4).
Open the wallet that holds your payout address.
Tools → Sign/Verify Message. Paste your address in the address field, the payload above in the message field.
Pick BIP-322 simple as the signature format (the default for segwit addresses in recent Sparrow versions).
Click Sign. Copy the base64 signature Sparrow shows.

Electrum

Start Electrum in testnet4 mode: electrum --testnet4.
Open the wallet that holds your payout address.
Tools → Sign/verify message. Paste your address, then the payload text.
Click Sign. Electrum ≥ 4.4 uses BIP-322 for segwit addresses automatically.

Verify a signature yourself before submitting

Paste the payload and signature into mempool.space's verify-message tool — if it reports valid there, this endpoint will accept it.

Step 2 — Update your settings

Session open for —. Valid until —. One save applies everything and ends the session.

Defaults for all workers

Applied to every share from this address unless a per-worker override below matches.

scriptSig text — up to 64 bytes UTF-8

0 / 64 bytes

OP_RETURN text — up to 75 bytes UTF-8

0 / 75 bytes

Starting difficulty — seeds vardiff on connect

Fixed difficulty — disables vardiff

If both are set, fixed wins. Applies on the miner's next reconnect.

Per-worker overrides

Each row overrides the defaults above for shares whose stratum workername matches. Ckpool matches the label exactly (case-sensitive) after the . or _ in your stratum username. Any worker without its own row falls back to the defaults.

Worker	scriptSig	`OP_RETURN`	Start diff	Fixed diff
No per-worker overrides.

Expires in (days)

All rows share the same expiry. Re-authorize to extend.

Constraints and limitations

75-byte cap on OP_RETURN, 64-byte cap on scriptSig text. Truncated on the server side rather than rejected, but pick something that fits.
BIP-322 signatures only — legacy Bitcoin Signed Message is not accepted (half the mining audience uses segwit; BIP-322 covers all address types).
Per-worker overrides are case-sensitive on the label. A row for bmm applies to tb1q….bmm shares, not tb1q….BMM. If a connecting worker has no row of its own, it inherits the defaults (wildcard) row.
Cold-storage addresses need the signing key online. If your payout address is on a Ledger or Trezor, use Sparrow (which can drive the hardware signer) to sign the session payload. Air-gapped setups will need to shuttle the payload to the offline machine, sign there, and shuttle the signature back.
Testnet4-only right now. The pool runs testnet4 during the ECX alphanet pruned-support wait. When we flip to alphanet, sessions here will need to be redone with alphanet-format addresses.

Prefer scripting? The CLI in scripts/register-message.py uses the one-shot /api/register-message endpoint and stays supported.