- Beta Releases
- Getting Started
- Known Issues
- Future Work
Zebra is the Zcash Foundation's independent, consensus-compatible implementation of a Zcash node, currently under development. It can be used to join the Zcash peer-to-peer network, which helps keeping Zcash working by validating and broadcasting transactions, and maintaining the Zcash blockchain state in a distributed manner. Please join us on Discord if you'd like to find out more or get involved!
Zcash is a cryptocurrency designed to preserve the user's privacy. Like most cryptocurrencies, it works by a collection of software nodes run by members of the Zcash community or any other interested parties. The nodes talk to each other in peer-to-peer fashion in order to maintain the state of the Zcash blockchain. They also communicate with miners who create new blocks. When a Zcash user sends Zcash, their wallet broadcasts transactions to these nodes which will eventually reach miners, and the mined transaction will then go through Zcash nodes until they reach the recipient's wallet which will report the received Zcash to the recipient.
The original Zcash node is named
zcashd and is developed by the Electric Coin
Company as a fork of the original Bitcoin node. Zebra, on the other hand, is
an independent Zcash node implementation developed from scratch. Since they
implement the same protocol,
zcashd and Zebra nodes can communicate with each
other and maintain the Zcash network interoperably.
If you just want to send and receive Zcash then you don't need to use Zebra directly. You can download a Zcash wallet application which will handle that for you. (Eventually, Zebra can be used by wallets to implement their functionality.) You would want to run Zebra if you want to contribute to the Zcash network: the more nodes are run, the more reliable the network will be in terms of speed and resistance to denial of service attacks, for example.
These are some of the advantages or benefits of Zebra:
- Better performance: since it was implemented from scratch in an async, parallelized way, Zebra
is currently faster than
- Better security: since it is developed in a memory-safe language (Rust), Zebra is less likely to be affected by memory-safety and correctness security bugs that could compromise the environment where it is run.
- Better governance: with a new node deployment, there will be more developers who can implement different features for the Zcash network.
- Dev accessibility: supports more developers, which gives new developers options for contributing to Zcash protocol development.
- Runtime safety: with an independent implementation, the detection of consensus bugs can happen quicker, reducing the risk of consensus splits.
- Spec safety: with several node implementations, it is much easier to notice bugs and ambiguity in protocol specification.
- User options: different nodes present different features and tradeoffs for users to decide on their preferred options.
- Additional contexts: wider target deployments for people to use a consensus node in more contexts e.g. mobile, wasm, etc.
Every few weeks, we release a new Zebra beta release.
Zebra's network stack is interoperable with
and Zebra implements all the features required to reach Zcash network consensus.
The goals of the beta release series are for Zebra to act as a fully validating Zcash node, for all active consensus rules as of NU5 activation.
Currently, Zebra does not validate the following Zcash consensus rules:
- Validation of Sprout JoinSplit-on-Groth16 proofs
- Validation of Sprout anchors (root of the Sprout note commitment tree)
- Undocumented rules derived from Bitcoin
- Undocumented network protocol requirements
zebrad is still under development, so there is no supported packaging or
install mechanism. To run
zebrad, follow the instructions to compile
for your platform:
- Install Zebra's build dependencies:
- libclang: the
llvm-devpackages, depending on your package manager
- clang or another C++ compiler:
- libclang: the
cargo install --locked --git https://github.com/ZcashFoundation/zebra --tag v1.0.0-beta.2 zebrad
zebrad start(see Running Zebra for more information)
If you're interested in testing out
zebrad please feel free, but keep in mind
that there is a lot of key functionality still missing.
For more detailed instructions, refer to the documentation.
The recommended requirements for compiling and running
- 4+ CPU cores
- 16+ GB RAM
- 50GB+ available disk space for finalized state
- 100+ Mbps network connections
We continuously test that our builds and tests pass on:
The latest GitHub Runners for:
- Windows Server
- Debian Buster
Zebra's tests can take over an hour, depending on your machine. We're working on making them faster.
zebrad might build and run fine on smaller and slower systems - we haven't
tested its exact limits yet.
For more detailed requirements, refer to the documentation.
If Zebra's build runs out of RAM, try setting:
If Zebra's tests timeout or run out of RAM, try running:
cargo test -- --test-threads=2
(cargo uses all the processor cores on your machine by default.)
Some of Zebra's tests deliberately cause errors that make Zebra panic. macOS records these panics as crash reports.
If you are seeing "Crash Reporter" dialogs during Zebra tests, you can disable them using this Terminal.app command:
defaults write com.apple.CrashReporter DialogType none
By default, Zebra uses the following inbound TCP listener ports:
- 8233 on Mainnet
- 18233 on Testnet
zebrad's typical network usage is:
- Initial sync: 30 GB download
- Ongoing updates: 10-50 MB upload and download per day, depending on peer requests
For more detailed information, refer to the documentation.
Some of Zebra's tests download Zcash blocks, so they might be unreliable depending on your network connection.
You can set
ZEBRA_SKIP_NETWORK_TESTS=1 to skip the network tests.
Zebra may be unreliable on Testnet, and under less-than-perfect network conditions. See our roadmap for details.
There are a few bugs in Zebra that we're still working on fixing:
- Zebra's address book can use all available memory #1873
- Zebra does not evict pre-upgrade peers from the peer set across a network upgrade #706
- Zebra accepts non-minimal height encodings #2226
- In rare cases, Zebra panics on shutdown #1678
- Interrupt handler does not work when a blocking task is running #1351
- Zebra should eventually exit once the task finishes. Or you can forcibly terminate the process.
Zebra's state commits changes using database transactions. If you forcibly terminate it, or it panics, any incomplete changes will be rolled back the next time it starts.
In 2021, we intend to finish NU5 validation, start adding RPC support and start adding wallet integrations. This phased approach allows us to test Zebra's independent implementation of the consensus rules, before asking users to entrust it with their funds.
- Full consensus rule validation
- Wallet functionality
- RPC functionality
Performance and Reliability:
- Reliable syncing on Testnet
- Reliable syncing under poor network conditions
- Batch verification
- Performance tuning
Currently, the following features are out of scope:
- Mining support
- Optional Zcash network protocol messages
- Consensus rules removed before Canopy activation (Zebra checkpoints on Canopy activation)
The Zebra website contains user documentation, such as how to run or configure Zebra, set up metrics integrations, etc., as well as developer documentation, such as design documents. We also render API documentation for the external API of our crates, as well as internal documentation for private APIs.
Zebra has a responsible disclosure policy, which we encourage security researchers to follow.
Zebra is distributed under the terms of both the MIT license and the Apache License (Version 2.0).