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## What is cruzbit?
[cruzbit](https://cruzb.it) is a simple decentralized peer-to-peer ledger implementation. cruzbit is very similar to [Bitcoin](https://www.bitcoin.com/bitcoin.pdf) with the following notable differences:
* **Newer crypto** - The [Ed25519 signature system](https://ed25519.cr.yp.to/) is used for signing transactions. This system has a number of nice properties to protect users from security risks present with naive usage of ECDSA. The 256-bit version of the [SHA-3 hashing algorithm](https://en.wikipedia.org/wiki/SHA-3) is used for all hashing operations in the application, including the proof-of-work function but excluding hashing performed internally by the signature system. It's reported to be
[blazing fast](https://keccak.team/2017/is_sha3_slow.html) when implemented in hardware. [NaCl Secretbox](https://nacl.cr.yp.to/secretbox.html) is used to encrypt wallet private keys (not part of the protocol.)
* **Simplified transaction format** - No inputs and outputs. Just public key sender and receiver with a time, amount, explicit fee, memo field, pseudo-random nonce, series and signature. The series is incremented network-wide roughly once a week based on block height to allow for pruning transaction history. Also included are 2 optional fields for specifying maturity and expiration, both at a given block height.
* **No UTXO set** - This is a consequence of the second point. It considerably simplifies ledger construction and management as well as requires a wallet to know only about its public key balances and the current block height. It also allows the ledger to map more directly to the well-understood concept of a [double-entry bookkeeping system](https://en.wikipedia.org/wiki/Double-entry_bookkeeping_system). In cruzbit, the sum of all public key balances must equal the issuance at the current block height. This isn't the first ledger to get rid of the UTXO set model but I think we do it in a uniquely simple way.
* **No scripting** - This is another consequence of the second point. Signatures are simply signatures and not tiny scripts. It's a bit simpler and arguably safer. It does limit functionality, e.g. there is no native notion of a multi-signature transaction, however, depending on your needs, you can come _close_ to accomplishing that using [mechanisms external to cruzbit](https://en.wikipedia.org/wiki/Shamir%27s_Secret_Sharing).
* **No fixed block size limit** - Since transactions in cruzbit are more-or-less fixed size we cap blocks by transaction count instead, with the initial limit being 10,000 transactions. This per-block transaction limit increases with "piecewise-linear-between-doublings growth." This means the limit doubles roughly every 2 years by block height and increases linearly between doublings up until a hard limit of 2,147,483,647. This was directly inspired by [BIP 101](https://github.com/bitcoin/bips/blob/master/bip-0101.mediawiki). We use block height instead of time since another change in cruzbit is that all block headers contain the height (as well as the total cumulative chain work.)
* **[Reference implementation](https://github.com/cruzbit/cruzbit) is in [Go](https://golang.org/)** - Perhaps more accessible than C++. Hopefully it makes blockchain programming a bit easier to understand and attracts a wider variety of developer interest.
* **Web-friendly peer protocol** - Peer communication is via secure [WebSockets](https://developer.mozilla.org/en-US/docs/Web/API/WebSockets_API). And the peer protocol and all primitives are structured in [JSON](https://www.json.org/). This should make working with the protocol easy for just about every modern development environment.
## Getting started mining
If you missed out on the opportunity to mine other cryptocurrencies you could give cruzbit a try!
### 1. Rust needs to be installed
- MacOS / Linux (from https://www.rust-lang.org/learn/get-started)
* ```curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh```
- Windows:
- https://www.petergirnus.com/blog/how-to-install-rust-on-windows
- https://forge.rust-lang.org/infra/other-installation-methods.html
### 2. cmake needs to be installed
- macOS
- ```brew install cmake```
- Debian Linux:
- ```apt install cmake```
- Windows
- ```winget install Kitware.CMake```
### 3. Running the client
Note: --release flag is needed for compiler optimizations
### Mining
Like Bitcoin, any blocks you mine will need to have an additional 100 blocks mined on top of them prior to the new cruzbits being applied to your balance. This is to mitigate a potentially poor user experience in the case of honest blockchain reorganizations.
#### Mining with multiple keys
```cargo run --release -- --datadir datadir --numminers 1 --keyfile keys.txt```
Instead of mining with a single public key, you can use the wallet to generate many keys and dump the public keys to a text file which the client will accept as a `--keyfile` argument. The wallet commands to do this are `genkeys` and `dumpkeys`.
#### Mining with a single key
```cargo run --release -- --datadir datadir --numminers 1 --pubkey [pub key from wallet]```
#### GPU mining with OpenCL
```cargo run --release --features opencl -- --datadir datadir --numminers 1 --keyfile keys.txt```
#### GPU mining with Cuda
```cargo run --release --features cuda -- --datadir clientdata --numminers 1 --keyfile keys.txt```
#### Not interested in mining but want to play with cruzbit?
No problem! You can run the client with `--numminers 0` so that it can function as your wallet peer.
```cargo run --release -- --datadir datadir --numminers 0```
### 4. Running the wallet
```cargo run --release --bin wallet -- --walletdb walletdata```
## Database compatibility with golang cruzbit
- client db data is not compatible
- wallet db data is compatible
## License
cruzbit is released under the terms of the MIT license. See [LICENSE](https://github.com/christian-smith/cruzbit/blob/master/LICENSE) for more information or see https://opensource.org/licenses/MIT.
## Join us on Discord
**[Cruzbit Discord](https://discord.gg/MRrEHYw)** for general chat as well as updates, including development status.