How to Use EarthBucks Swap

This is the second post of three about EarthBucks Swap. The first post explains the contracts on the two blockchains. This post explains the app: how to trade, and the rules and limits of the room.

The room

Swap is one room, where users trade EBX for Bitcoin Cash (BCH). The room has three parts:

• The best prices. At the top, two tiles show the best card to buy EBX and the best card to sell EBX, with the spread between them.
• The feed. Messages, trade cards and the steps of each trade show in one list, in time order.
• The people. Each user shows with their name, their avatar, a badge if they are verified, and their trade record.

EBX is what you trade, and BCH is the money. Thus each price is the price of one EBX. The room shows prices in US dollars at the current BCH price from Coinbase. Dollars are only a view: each card locks exact amounts of EBX and BCH, and you sign those amounts.

Cards: asks and bids

A card is an offer at a fixed price. There are two kinds:

• An ask sells EBX for BCH. The user who posts it is the seller.
• A bid buys EBX with BCH. The user who posts it is the buyer.

The user who posts a card is the maker. The user who takes it is the taker. A take starts the trade at once. There is no second question to the maker: the maker agreed to the price when they posted the card.

Post a card

Select Sell EBX or Buy EBX. Type the amount, in EBX or in dollars, and the price of one EBX, in dollars or in BCH. Then select an expiry: 5 minutes, 15 minutes (the default), 1 hour or 4 hours. Then select No wait (the default) or Wait for BCH confirmations. Your wallet signs the card.

With No wait, the trade does not wait for a BCH block, and it can end in seconds. With Wait, the seller’s wallet waits for 1 BCH confirmation for each 1 BCH of the trade, up to 6. Choose Wait for a large trade. Each card shows its choice.

A card has a fixed price. If the price of BCH moves while your card is open, a taker can take your card at the old price. Thus the expiry is short. When your card expires, you can post a new one at a new price.

Take a card

Select Take on a card. Your wallet signs the take, and the trade starts.

If you sell EBX on a card with no wait, the app tells you the risk: a buyer who double-spends their BCH lock can take your EBX. Your wallet checks for a double-spend before it claims, but the check cannot stop every double-spend.

The best card of each side shows at the top. You can also take a card that is not at the best price. For example, you can take the card of a friend at a price that you agreed with them. The app warns you before you take such a card. This is an off-market take. It does not count in the index price or in the last-trade price.

You can take a card only when its maker is online in the room.

Joining and leaving the room

Anybody can read the room. To post or take a card, you join it. Your first post or take joins you, so you do not have to join first.

• One tab at a time. You can be in the room in one browser tab only. If you post or take in a different tab or on a different device, the app asks you first. A move to the new tab cancels the open cards of the old tab.
• Leaving cancels your open cards. When you leave the room, your open cards are cancelled. A card is an offer from a person who is there. If you are not there, nobody can take your card.
• Closing the tab is leaving. If your tab does not reach the server for 15 seconds, your session ends, and your open cards are cancelled.
• Leaving does not stop a trade. A trade in progress continues after you leave the room (see below).

The room shows each user as online, inactive (for 2 minutes after they leave) or offline.

Room size

The room holds up to 100 verified users and up to 100 unverified users at one time. The two groups are separate, so unverified users cannot fill the room and keep verified users out. If your group is full, the app tells you, and you can try again soon.

During a trade

After a take, the wallets of both users do the steps of the swap: the locks, the checks and the claims. You do not do these steps by hand. But your wallet does them in your browser, because only your browser has your keys.

Thus, keep an EarthBucks tab open until your wallet has done its last step. A bar at the top of each page shows while the tab is necessary. It can be any page of EarthBucks, not only Swap. The navigation bar shows your active trades and a link to Swap. If you close the tab, the trade waits, and it continues when you open EarthBucks again. But each step has a deadline, and if you are away too long, your wallet can miss it. The first post explains the deadlines.

A trade with no wait can end in seconds when both users are online. The seller’s claim stays in the BCH mempool until a block includes it. A trade that waits for confirmations takes at least one BCH block. A BCH block comes each 10 minutes on average, but some blocks take much longer. The feed shows each step, and the app plays a short chime when your card is taken and when your trade ends. You can mute the chime.

A trade ends in one of these ways:

• Settled: each user has the coins of the other user.
• Refunded: each user has their own coins back.
• Cancelled or expired: the trade stopped before both locks were in place. If one lock was made, its owner gets it back after its refund height.

Fees

• The taker pays 1%. The taker’s fee is 1% of the coin that the taker pays: BCH when you take an ask, and EBX when you take a bid. It rounds up to the smallest unit. The maker pays no fee.
• The fee is only for a trade that settles. The fee is in the taker’s lock, and only the claim of that lock pays it. A refunded trade pays no Swap fee.
• The BCH network fee. Each BCH transaction of a swap pays a network fee of 1,000 satoshis (0.00001 BCH). The buyer pays it on the BCH lock, and the seller pays it on the claim. The buyer’s wallet also pays the normal network fee of the payment that funds the lock.
• EBX transactions have no fee.

The take dialog shows the exact amounts that you will pay and get, with the fees.

Limits

These limits are for the launch. We will change them as we learn.

Limit	Value
Size of one trade	$1.00 to $100.00 of BCH
Lowest EBX price on a card	$0.10
Trades of one account in 24 hours	$1,000.00
Open cards and trades in progress, together	5
Smallest amount of EBX	0.01 EBX
Smallest taker’s fee in BCH	546 satoshis (the BCH dust limit)
Length of a message	500 characters
Messages of a verified user	10 in each 10 seconds
Messages of an unverified user	5 in each 10 seconds
Users in the room	100 verified and 100 unverified

Some notes:

• The size of a trade is the dollar value of its BCH at the current BCH price. The app checks it, and the $0.10 floor, when you post a card. A card stays valid while it is open, also when the BCH price moves.
• The $0.10 floor is a lowest price for the venue. It is not a statement about the value of EBX.
• The 24-hour limit counts your open cards and each trade that you made or took in the last 24 hours, whatever its result. Each card counts at its dollar value when it was posted.
• The 546-satoshi minimum applies to the taker’s fee of an ask, so a very small ask cannot be taken. A smaller BCH output does not go through the BCH network.
• Without a BCH price, nobody can post or take a card, because the app cannot check the limits.

Verified and unverified users

Every user can trade. Verified users get more:

• Verified users can send more messages. An unverified user can send 5 messages in each 10 seconds. A verified user can send 10. This keeps spam out of the room.
• Verified users have their own places in the room, as explained above.
• Verified users show a badge next to their name.
• Only trades between two verified users count in the index price.

The trade limits are the same for verified and unverified users.

The trade record

Next to each user, the room shows their trade record: the number of trades that they finished, and how many of them they backed out of. For example, “41 trades · 1 backed out (97%)”. The record does not block anybody. It helps you decide whose cards to take.

The EBX index price

The room shows an EBX price index, the price of EBX in dollars from real trades. Select the index to see how the app calculates it, and how close each minimum is.

The index is the median price of the trades of the last 24 hours, weighted by the dollar value of each trade. Only some trades count:

• The trade settled.
• Both users were verified when it settled.
• The trade was at the best price of its side when it was taken (not off-market).

There must be at least 3 such trades, between at least 3 accounts, for $10 or more in total. Otherwise the room shows “No index yet”.

The trades of one account count for at most 25% of the total value. Thus one person who trades with their own second account moves the index very little. And the app shows no dollar value from an index that is more than 10 minutes old.

Try it

1. Open Swap.
2. Select the Swap title for a short summary of how a swap works.
3. Take a card, or post a card with Sell EBX or Buy EBX.
4. Keep the tab open until the trade settles.

If you do not have BCH yet, deposit some on the Bitcoin Cash page of your wallet. If you do not have EBX, you can mine it, or buy it in Swap.

The third post tells how Bitcoin Cash came into EarthBucks, and what comes next.