Ironwood migration

Zcash is going through a network upgrade called Ironwood (also known as NU6.3). It adds a new shielded pool — the encrypted part of the Zcash blockchain where your private balance is held — and closes the older Orchard pool. Once Ironwood activates, the Zcash network itself will no longer allow Orchard funds to be spent: they have to be moved into Ironwood first. This is a network rule that applies to every Zcash wallet, not a Cake Wallet restriction.

Because Cake Wallet automatically shields your Zcash, almost every Cake Wallet user with a Zcash balance will go through this migration.

Cake Wallet does the move for you, automatically, in a privacy-preserving way. There is no setting to turn on, no button to press, and nothing to sign up for. You do not need to do anything except open your wallet and leave the app running for a while.

What you need to do

1. Open your Zcash wallet in Cake Wallet.

2. Let it finish syncing. When syncing has finished, the sync area at the top of the screen is empty — no status text and no dot.

3. Leave the app open until migration finishes.

You'll know it has finished when the migrating to Ironwood row under your balance disappears, your Available Balance is back to its normal amount, and no new Migration transactions appear in your history.

When it happens

Ironwood activates at Zcash block height 3,428,143 (defined in ZIP 258). Nothing happens in your wallet before then.

After activation, migration starts on its own the first time you open a synced Zcash wallet that still holds an Orchard balance.

Why this is happening

A cryptographic bug was found in the Orchard shielded pool that could, in theory, have allowed counterfeit ZEC to be created. Ironwood adds a supply-verification step — a "turnstile", meaning funds have to be moved across into the new pool in order to be counted — so the network can prove the total ZEC supply is correct.

Every Zcash wallet has to move its users' funds across that turnstile. Cake Wallet does it for you.

What you'll see

• A “Zcash Network Upgrade” notice. The first time migration starts, Cake Wallet shows a notice explaining the upgrade and how much of your balance is being migrated. Tap Continue to dismiss it — you can reopen it any time by tapping the migrating to Ironwood row under your balance.

• Transactions labelled Migration. Your Orchard balance is split into standard, round-number amounts, and each of those is moved in its own transaction, so you will see a number of these rows. They appear as outgoing transactions with an amount next to them, which can look alarming — but they are your own funds moving between your own pools inside your own wallet. Nothing is being sent to anyone else.

• Part of your balance shown as migrating. While migration is running, the portion still sitting in Orchard is counted with your confirming balance rather than your Available Balance, and the row under your balance reads migrating to Ironwood, so your available figure is lower than your full balance until migration finishes. See Why part of your balance isn't spendable yet, below.

• The same receive address as before. Orchard and Ironwood share one address. Your address and QR code do not change, and there is nothing to re-share with anyone who pays you.

• A slightly lower total. Each migrated amount pays a small network fee — on the order of 0.0002 ZEC — so your total balance dips a little. It is proportionally more noticeable on very small balances.

• One label change on the Receive screen. The Shielded address option's subtitle changes from Default (Orchard) to Default (Ironwood).

Is my privacy retained?

While the turnstile necessarily means that all amounts in migration transactions are temporarily exposed, Cake Wallet has built out the migration process in a way that is as privacy-preserving as possible. We do this by:

• Splitting your Zcash coins into standard denominations (i.e. 10 ZEC, 1 ZEC, 0.1 ZEC, etc.) to blend in with other user's migration transactions.

• Spacing out migration transactions instead of sending them all at once.

• Ensuring that all Cake Wallet users use this privacy-preserving path so no one stands out on chain.

While this is the best approach for your privacy, it does mean that it will take slightly longer than the less privacy-preserving approaches some other Zcash wallets may take.

To us, your privacy is worth it.

Is my money safe?

Yes. Your ZEC is safe for the whole process. Migration moves it between two shielded pools inside your own wallet — it never sends anything to anyone else, and your seed and keys are unchanged throughout. Nothing can be lost by waiting, and nothing can be lost by closing the app.

What does change is timing: each portion of your balance becomes spendable again only once it has been migrated. Your funds are not at risk, they are just temporarily not available to send.

Why part of your balance isn't spendable yet

Once Ironwood activates, the Zcash network no longer allows funds to be spent out of the old Orchard pool. Any of your ZEC still sitting in Orchard therefore cannot be sent until the wallet has moved it into Ironwood. This is a rule of the upgrade itself, not something Cake Wallet chose.

Cake Wallet shows this by counting the not-yet-migrated portion with your confirming balance rather than your Available Balance, labelled migrating to Ironwood under your balance. As each amount is migrated, it moves back into your available balance, and once migration has finished your full balance is spendable again.

For more on the difference between available and full balances, see Why is my Available Balance 0?.

How long it takes

Migration is paced deliberately — roughly one transaction per Zcash block, about 75 seconds apart. That spreads the work out and keeps your transfers from standing out on-chain. It does mean the whole thing can take a while.

What happens if you close the app

Nothing breaks. Closing Cake Wallet just pauses migration. The next time you open the wallet and it syncs, migration continues on its own from where it stopped — the wallet works out what is left to move each time, so nothing is lost and nothing has to be started over. The only consequence of closing the app is that the remaining part of your balance stays unspendable for longer, so it's worth coming back and letting it finish.

Autoshielding

While only Orchard funds are migrated, your transparent balance and any Legacy Shielded (Sapling) funds will be automatically shielded into the Ironwood pool as well due to our core autoshielding function.

Autoshielding also keeps working as normal, and after activation it shields incoming transparent funds straight into Ironwood, so those never need migrating at all. See Zcash for how addresses and autoshielding work.

Still have questions?

If something about your Zcash balance still doesn't look right after migration has finished, start with Why are my funds not appearing? — and if that doesn't resolve it, contact our support team at support@cakewallet.com.