# Start Here

## Directory Structure

DarkFi broadly follows the standardized unix directory structure.

* All bundled applications are contained in `bin/` subdirectory.
* Random scripts and helpers such as build artifacts, node deployment
  or syntax highlighting is in `contrib/`.
* Documentation is in `doc/`.
* Example codes are in `example/`.
* Script utilities are in `script/`. See also the large `script/research/`
  subdir.
* All core code is contained in `src/`.
  See [Architecture Overview](arch/overview.md) for a detailed description.
    * The `src/sdk/` crate is used by WASM contracts and core code.
      It contains essential primitives and code shared between them.
    * `src/serial/` is a crate containing the binary serialization code,
      which is the same as used by Bitcoin.
    * `src/contract/` contains our native bundled contracts. It's worth
      looking at these to familiarize yourself with what contracts on DarkFi
      are like.

## Using DarkFi

Refer to the main [README](../index.html) file for instructions on how to
install Rust and necessary deps.

Then proceed to the [Running a Node](testnet/node.md) guide.

## Join the Community

Although we have a Telegram, we don't believe in centralized proprietary apps,
and our core community organizes through our own fully anonymous p2p chat system
which has support for Tor (and Nym waiting for 
[this feature request](https://github.com/nymtech/nym/issues/3610)).

Every Monday at 14:00 UTC (DST) or 15:00 UTC (ST) in #dev we have our main
project meeting.

See the guide on [darkirc](misc/darkirc/darkirc.md) for instructions on joining.

## Contributing as a Dev

Check out the [contributor's guide](dev/contrib/contrib.md) for where to find
tasks and submitting patches to the project.

If you're not a dev but wish to learn then take a look at the
[agorism hackers study guide](dev/learn.md).

Lastly familiarize yourself with the [project architecture](arch/arch.md).
The book also contains a cryptography section with a helpful
[ZK explainer](crypto/zk_explainer.md).

DarkFi also has a [project spec](spec/crypto-schemes.md) and
a [DEP](dep/0001.md) (Drk Enhancement Proposals) system.

## Detailed Overview

Source code is under `src/` subdirectory. Main interesting modules are:

* `net/` is our own p2p network. There are sessions such as incoming or outgoing that have channels (connections). Protocols are attached to channels depending on the session. The p2p network is also multi-transport with support for TCP (+TLS), Tor and Nym. So you can access the p2p fully anonymously (network level privacy).
* `event_graph/` which is a DAG sync protocol used for ensuring eventual consistency of data, such as with chat systems (you don't drop any messages).
* `runtime/` is the WASM smart contract engine. We separate computation into several stages which is checks-effects-interactions paradigm in solidity but enforced in the smart contract explicitly. For example in the `exec()` phase, you can only read, whereas writes must occur in the `apply(update)` phase.
* `blockchain/` and `validator/` is the blockchain and consensus algos.
* `zk/` is the ZK VM, which is simply loads bytecode which is used to build the circuits. It's a very simple model rather than the TinyRAM computation models. We opted for this because we prefer simplicity in systems design.
* `sdk/` contains a crypto SDK usable in smart contracts and applications. There are also Python bindings here, useful for making utilities or small apps.
* `serial/` contains our own serialization because we don't trust rust serialization libs like serde (recently confirmed when they start bundling binaries). We also have async serialization and deserialization which is good for network code.
* `tx/` is the tx we use. Note signatures are not in the calldata as having this outside it allows more efficient verification (since you can do it in parallel and so on).
    * All darkfi calls are precomputed ahead of time which is needed for ZK. Normally in eth or other smart contract chains, the calldata is calculated where the function is invoked. Whereas in darkfi the entire callgraph and calldata is bundled since ZK proofs must be computed ahead of time. This also improves things like static analysis and security (limiting call depth is easy to check before verification).
    * Verifying sigs or call depth ahead of time helps make the chain more attack resistant.
* `contract/` contains our native smart contracts. Namely:
    * `money`, which is multi-asset anonymous transfers, anonymous swaps and token issuance. The token issuance is programmatic. When creating a token, it commits to a smart contract which specifies how the token is allowed to be issued.
    * `deploy` for deploying smart contracts.
    * `dao`, which is a fully anonymous DAO. All the DAOs on chain are anonymous, including the amounts and activity of the treasury. All participants are anonymous, proposals are anonymous and votes are anonymous including the token weighted vote amount, and user identity. You cannot see who is in the DAO.

NOTE: we try to minimize external dependencies in our code as much as possible. We even try to limit dependencies within submodules.

Inside `bin/` contains utilities and applications:

* `darkfid/` is the daemon and `drk/` is the wallet. Currently being updated to the new testnet (if you see the commit log last few days).
* `dnet/` is a viewer to see the p2p traffic of nodes, and `deg/` is a viewer for the event graph data. We use these as debugging and monitoring tools.
* `dhtd/` is a distributed hash table, like IPFS, for transferring static data and large files around. Currently just a prototype but we'll use this later for images in the chat or other static content like seller pages on the marketplace.
* `tau/` is an anon p2p task manager which we use. We don't use github issues, and seek to minimize our dependence on centralized services. Eventually we want to be fully p2p and attack resistant.
* `darkirc/` is our main community chat. It uses [RLN](crypto/rln.md); you stake money and if you post twice in an epoch then you get slashed which prevents spam. There is a free tier. It uses the `event_graph` for synchronizing the history. You can attach any IRC frontend to use it rn. Later we'll make our own UI.
* `zkas/` is our ZK compiler.
* `zkrunner/` contains our ZK debugger (run `zkrunner` with `--trace`), and `zkrender` which renders a graphic of the circuit layout.
* `lilith/` is a universal seed node. Eventually we will add swarming support to our p2p network which is an easy addon.

Lastly worth taking a look is `script/research/` and `script/research/zk/` which contains impls of most major ZK algos. `bench/` contains benchmarks.
`script/escrow.sage` is a utility for doing escrow. We'll integrate it in the wallet later, but it works for now.

We could say more on our design philosophy of simplicity oriented approach to systems dev, but I'll drop these links here for now:

* [Suckless Philosophy: software that sucks less](https://suckless.org/philosophy/)
* [How to Design Perfect (Software) Products  by Pieter Hintjens](http://hintjens.com/blog:19/noredirect/true)

Recent crypto code audit: [ZK Security DarkFi Code Audit](https://dark.fi/zksecurity-audit-q124.pdf)

Useful link on [our ZK toolchain](zkas/writing-zk-proofs.md)

For proof files, see `proof/` and `src/contract/*/proof/` subdirs.
