Velocity, for cryptocurrencies

spend cryptocurrency inputs in chains to simulate cash velocity

DISCLAIMER

I TAKE NO RESPONSIBILITY FOR ANY PAIN/SUFFERING/MISFORTUNE CAUSED BY THE MISUSE OF MY TOOL

THIS TOOL DOES NOT WORK WITH ETHEREUM; ONLY BITCOIN DERIVATIVES SUCH AS BITCOIN CASH, LITECOIN, DASH, ZCASH, DIGIBYTE, SMARTCASH, ZCOIN, ETC. (i.e. anything forked from a recent Bitcoin Core codebase supported by EasyBitcoin-PHP). ENDEAVORS TO RUN THIS SCRIPT AS-IS ON ETH/ETC/ELLA/ETC. NETWORKS WILL LIKELY END IN DISASTER

Elevator Pitch

Velocity is a PHP script written as a tool to test the resiliency of cryptocurrency networks under heavy transaction loads. It connects via RPC to the daemon of choice to gather and spend each unspent input individually to a single address, thereby creating the first link in a transaction chain. Each chain is extended with new links as runtime continues. Inputs are never merged, or spent together; each chain remains independent from one another as links are added to them. Chains are discarded as new blocks are found; each new block starts a new round where new chains are built from fresh, confirmed inputs.

Features

• Fully automated - Velocity keeps a connection to the coin daemon and internally keeps track of all chains created, handles all states, and sends all money until it can no longer do so, then it dumps the remaining balance into the configured dust collector address
• Fast - Simple 1-to-1 transactions and use of an address pool (1000 by default) mean that Velocity moves money very quickly
• Widely compatible - Velocity will work with any Bitcoin Core full-node derivative that supports these common JSON-RPC calls: createrawtransaction, signrawtransaction, getrawtransaction, decoderawtransaction, sendrawtransaction, getnewaddress, getblockcount, getmempoolinfo, getaddressesbyaccount, getbestblockhash, and listunspent

Setup

1. As of v0.1, Velocity requires an RPC connection to a fully-validating daemon (with a host:port) to function. This may change in the future as the project matures. Refer to the developer's website of any particular coin if you wish to run their fully-validating daemon with Velocity.
2. Once you finish setting up the daemon, be sure that you allow the daemon to fully synchronize with the blockchain. Transactions crafted by Velocity will be rejected by the daemon if it knows that it is not fully sync'd with the network. Some daemons take days to sync depending on the hardware you are using; please be patient.
3. Also be sure that the RPC configuration you created for your daemon is reflected in your copy of the velocity script. Please only edit the $config options near the top.
4. The script was written and tested in PHP 7.0.30 on the Ubuntu 16.04.5 operating system. Theoretically, the PHP script will work on Windows. I do not plan on providing support for the Windows platform, so if any functions do not work on Windows, feel free to make a pull request. :)
5. I recommend Ubuntu as the OS base. You will need a copy of the php7.0 and php7.0-cli packages; install them via apt install php7.0 php7.0-cli. If you don't use Ubuntu or another Debian derivative with the apt package management system, please refer to your ditribution's package manager documentation on how to install the required php7.0 packages.

Running velocity

I recommend a 132x43 terminal window size for running Velocity.

I recommend running the fully-validating daemon in the background, not in its graphical QT form; QT will greatly reduce transaction throughput!

Assuming all above is already completed, your fully-validating daemon is running, and you are at a terminal in the directory in which you've downloaded and modified the velocity script per your configuration, you are ready run Velocity.

In your terminal, run the following command: ./velocity

• If you receive the error ./velocity: Permission denied you will need to chmod +x ./velocity first before running ./velocity

Velocity will immediately begin polling your coin daemon via RPC to check for unspent inputs and begin creating transaction chains.

What you will see

• If for any reason the daemon connection fails, you will see an [error] stating so and the reason why. Please verify your Velocity and crypto daemon config and try again.
• If the connection is successful, the following is an example of what you will see:

	Velocity, for cryptocurrencies (v0.4.7)
	running "/BUCash:1.5.0.2(EB32; AD12)/" since 12/15/2018 23:00:24

[main] runtime:	{ round:8  block:561026(!) }
[main] stats:	{ chains:7  links:7  links-confirmed:12,762  %-tx-count:3.33% }
[main] mempool:	{ tx-count:210  total-size:40,802 bytes  ram:192,016 bytes }
[main] pool:	{ deposit:1HAYihtzYaJCwRjd4WMNm2CC5oFNQh7mYP  total-bal:0.01764128 }
[main] dust:	{ collector:1PdiCq9dFU81Pi6suHtwr1QVMPBXx5d9oo  total-bal:0.00134695 }

• round:1 begins the first set of chains by creating links that spend transaction inputs. As blocks are found on the network, Velocity moves to the next round, and the number of total links (out of all chains) created for the round are then added to the links-confirmed stat (this stat, effectively, is the total number of transactions that Velocity has broadcasted to the network).
• Chains are emptied after each round because inputs are "fresh" to start brand new chains having received their first confirmation; as an example, some mempool restrictions, e.g. the 25-descendant limit, are reset for inputs once they are confirmed.
• mempool conveniently displays important stats gauged when stressing a cryptocurrency network: number of unconfirmed transactions in the mempool, aggregate size of unconfirmed transactions in bytes, and total RAM usage by the mempool
• pool displays a deposit address as well as the total-bal (total balance) available to all addresses within the address pool. (NOTE: Velocity creates a vpool account in your wallet to house all of the addresses used during runtime)
• If any chain runs into error during operation (i.e. receives an error from the RPC daemon) then the chain will be disabled and its tip will not be extended until the next round begins.
• When a new block is found, the (!) indicator will be displayed to the right of the block number for a short period of time (currently 5% of the avg block time; for BTC/BCH this is 30s)
• If the average block time for the coin passes and a block hasn't been found, the (?) indicator will be displayed to the right of the block number

Stopping Velocity

If you wish to shut down Velocity, all you need to do is close the terminal window in which it is running, or send a SIGINT signal (i.e. CTRL+C) to the process.