dcrdex

README

Bison Wallet and DCRDEX development

This is the repository for development of Bison Wallet, DCRDEX, and Tatanka Mesh.

What is DCRDEX?

The Decred Decentralized Exchange (DEX) is a system that enables trustless exchange of different types of blockchain assets via a familiar market-based API. DEX is a non-custodial solution for cross-chain exchange based on atomic swap technology. DEX matches trading parties and facilitates price discovery and the communication of swap details.

Matching is performed through a familiar exchange interface, with market and limit orders and an order book. Settlement occurs on-chain. DEX's epoch-based matching algorithm and rules of community conduct ensure that the order book action you see is real and not an army of bots.

Trades are performed directly between users through on-chain contracts with no actual reliance on DEX, though swap details must be reported both as a courtesy and to prove compliance with trading rules. Trades are settled with pure 4-transaction atomic swaps and nothing else. Because DEX collects no trading fees, there's no intermediary token and no fee transactions.

Although trading fees are not collected, DEX does require a one-time registration fee to be paid on-chain. Atomic swap technology secures all trades, but client software must still adhere to a set of policies to ensure orderly settlement of matches. The maximum penalty imposable by DEX is loss of trading privileges and forfeiture of registration fee.

What is Bison Wallet

Bison Wallet is a multi-wallet developed in concert with DCRDEX and Tatanka Mesh. Bison Wallet leverages state-of-the-art blockchain technology to bring more features and more privacy for your favorite assets. DCRDEX is built-in, as well as advanced trading features like market-making and arbitrage, directly from your wallet.

Our goal is to find a balance of convenience and privacy that works for you, while giving you access to advanced features most wallets ignore. For many assets, we can cut out the middleman altogether and allow you to interact directly with the blockchain network. This type of wallet is highly-resilient to data collection and censorship.

We also focus on bringing advanced, asset-specific features for out wallets. With Decred, you can use StakeShuffle to further anonymize your funds, or stake your DCR and earn some block rewards. The Zcash wallet exposes unified addresses and shielded pools, and operates on a shielded-first principle that makes privacy effortless. Keep an eye on development here. We are dedicated to exposing these technologies to the communities that want them.

What is Tatanka Mesh

Tatanka Mesh (Tatanka, the mesh) is the evolution of DCRDEX. Where DCRDEX relies on a central server for maintaining order books and policing trades, Tatanka is a decentralized P2P protocol that enables a network of subscribers to collectively perform these tasks. Here are the three critical services that Tatanka Mesh provides.

• Enhance the ability for users to connect and to share data both publicly and privately
• Aggregate reputation data and monitor fidelity bonds. Tatanka can limit access to users who earn a bad reputation
• Oracle services for fiat exchange rates and blockchain transaction fee rates

The mesh collects no fees for its services. Trades are performed using trustless atomic swaps that exchange funds directly between wallets.

Going P2P empowers our users to trade directly, enhancing security, censorship-resistance, privacy. and self-sovereignty.

Contents

• Getting Started
• Important Stuff to Know
• Fees
• DEX Specification
• Contribute
• Source

Getting Started

To trade on DCRDEX, you can use Bison Wallet. There are a few simple options for obtaining Bison Wallet. The standalone wallet is strongly recommended as it is the easiest to setup and generally has the most up-to-date downloads. Pick just one method:

1. From version 1.0, installers are available for all major operating systems
2. Download standalone Bison Wallet for your operating system for the latest release on GitHub.
3. Use your operating system's package manager. See OS Packages for more info.
4. Use Decrediton, the official graphical Decred wallet, which integrates Bison Wallet, and go to the DEX tab.
5. Build the standalone client from source.

See the Client Installation and Configuration page on the wiki for more information and a detailed walk-through of the initial setup.

Almost everyone will just want the client to trade on existing markets, but if you want to set up a new DEX server and host markets of your choice, see Server Installation.

OS Packages

We are in the process of adding the application to various OS package managers:

• Arch Linux (AUR). e.g. $ yay dcrdex. Accessible to Arch-based distros like Manjaro.
• MacOS. Homebrew cask coming soon.
• Windows. winget package coming soon.
• Debian/Fedora. apt repository coming soon.

Important Stuff to Know

Trades settle on-chain and require block confirmations. Trades do not settle instantly. In some cases, they may take hours to settle. The client software should not be shut down until you are absolutely certain that your trades have settled.

The client has to stay connected for the full duration of trade settlement. Losses of connectivity of a couple minutes are fine, but don't push it. A loss of internet connectivity for more than 20 hours during trade settlement has the potential to result in lost funds. Simply losing your connection to the DEX server does not put funds at risk. You would have to lose connection to an entire blockchain network.

There are initially limits on the amount of ordering you can do. We'll get these limits displayed somewhere soon, but in the meantime, start with some smaller orders to build up your reputation. As you complete orders, your limit will go up.

If you fail to complete swaps when your orders are matched, your account will accumulate strikes that may lead to your account becoming automatically suspended. These situations are not always intentional (e.g. prolonged loss of internet access, crashed computer, etc.), so for technical assistance, please reach out on Matrix.

Fees

DEX does not collect any fees on the trades, but since all swap transactions occur on-chain and are created directly by the users, they will pay network transaction fees. Transaction fees vary based on how orders are matched. Fee estimates are shown during order creation, and the realized fees are displayed on the order details page.

To ensure that on-chain transaction fees do not eat a significant portion of the order quantity, orders must be specified in increments of a minimum lot size. To illustrate, if on-chain transaction fees worked out to $5, and a user was able to place an order to trade $10, they would lose half of their trade to transaction fees. For chains with single-match fees of $5, if the operator wanted to limit possible fees to under 1% of the trade, the minimum lot size would need to be set to about $500.

The scenario with the lowest fees is for an entire order to be consumed by a single match. If this happens, the user pays the fees for two transactions: one on the chain of the asset the user is selling and one on the chain of the asset the user is buying. The worst case is for the order to be filled in multiple matches each of one lot in amount, potentially requiring as many swaps as lots in the order. Check the dex specification for more details about how atomic swaps work.

DEX Specification

The DEX specification details the messaging and trading protocols required to use the Market API. Not only is the code in the decred/dcrdex repository open-source, but the entire protocol is open-source. So anyone can, in principle, write their own client or server based on the specification. Such an endeavor would be ill-advised in these early stages, while the protocols are undergoing constant change.

Contribute

Looking to contribute? We need your help to make DEX #1.

Nearly all development is done in Go and JavaScript. Work is coordinated through the repo issues, so that's the best place to start. Before beginning work, chat with us in the DEX Development room. The pace of development is pretty fast right now, so you'll be expected to keep your pull requests moving through the review process.

Check out these wiki pages for more information.

• Getting Started Contributing
• Backend Development
• Run dcrdex and bisonw on simnet. Recommended for development.
• Run bisonw on testnet. Recommended for poking around.
• Run the test app server. Useful for GUI development, or just to try everything out without needing to create wallets or connect to a dcrdex server.

Source

The DEX specification was drafted following stakeholder approval of the specification proposal.

The source code for the DEX server and client are being developed according to the specification. This undertaking was approved via a second DEX development proposal.

FAQS

• How can I integrate new assets? To add new assets, follow the instructions here and see existing implementations here.