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How Epic Cash works

Both wallets take part​

Epic Cash uses Mimblewimble. Instead of writing an address and an amount on the blockchain, the two wallets build each transaction together, like a handshake:

  1. The sender's wallet starts it and locks the outputs being sent.
  2. The receiver's wallet adds its part and signs.
  3. The sender's wallet signs too, finishes the transaction and posts it to the network.

Something has to carry the messages between the two wallets: Epicbox holds each message while the other wallet is offline; Link · HTTP and Link · Tor go straight to the other wallet while it is open; Direct · File Transfer and Direct · QR Payment are the manual ways. See Payment methods.

Confirmations​

When the network accepts a transaction, a miner puts it in a block. The block that holds the transaction is the first confirmation, and every block after it adds one more and makes the transaction harder to undo.

The wallet treats a transaction as final after a set number of confirmations, 6 by default (a setting in Advanced, from 1 to 30). Until then it shows as Confirming, and received outputs cannot be spent yet. The wallet sees new blocks only through its node: if confirmations do not move, check that the node is synced.

Outputs and change​

The balance is a set of outputs, like notes in a wallet. To send 3 EPIC from a 5 EPIC output, the wallet spends the whole output: 3 EPIC go to the recipient, a small fee goes to the miners, and the rest comes back as a new output, the change.

That is why part of the balance can be unavailable for a while after a send:

  • Locked: outputs in a send that is not finished yet. They are unlocked if the send is cancelled.
  • Awaiting finalization: a transaction still waiting for the other wallet.
  • Confirming: outputs in a block with fewer confirmations than the setting, including the change.

With Outputs on in Advanced, the outputs are listed under Outputs.

Smallest or All​

Which outputs a send spends:

  • Smallest (the default) takes the smallest spendable outputs until the amount and fee are covered. Only those are locked while the send confirms; the rest can be sent right away.
  • All spends every spendable output and returns one change output. Everything is locked until it confirms, and the fee is a little higher because each input costs. Sending the whole balance always uses All.

Split and consolidate​

Both are network transactions from this wallet to itself, and both lock every spendable output until they confirm.

  • Split makes 2 to 10 outputs of nearly equal value, so sends can follow each other.
  • Consolidate merges every spendable output into one.
  • Split change (on by default) does the same inside an ordinary send when few outputs would be left, for 0.004 EPIC per extra output.

Both are under Outputs › Manage outputs. Activity shows each as two entries, a send and a receive, both with this wallet.

Fees​

Every transaction pays a small network fee, shown as Network fee before sending. It goes to the miners. The fee depends on how many outputs the transaction spends and creates, not on the amount. All, next to the amount, fills in the whole spendable balance minus the exact fee, so no change is left.

More detail for developers is on the Epic Cash Developer Hub.