NOTICE: It's an experiment and a very early draft! Please, feel free to submit your ideas or pull requests.

ZOLD is a crypto currency.

ZOLD is going to solve these problems:

• Blockchain is slow and doesn't scale
• Crypto mining makes irrelevant strangers rich
• High volatility makes cryptos suitable mostly for the black market

ZOLD is:

• Fast
• Scalable
• Anonymous

ZOLD principles include:

• The entire code base is open source
• There is no mining; the only way to get ZOLD is to receive it from someone else
• Only 2⁶³ numerals (no fractions) can technically be issued
• The first wallet belongs to the issuer and may have a negative balance
• A wallet is an XML file
• There is no central ledger, each wallet has its own personal ledger
• Each transaction in the ledger is confirmed by RSA encryption
• The network of communicating nodes maintains wallets of users
• Anyone can add a node to the network

How to Use

Install Ruby 2.2+, Rubygems, and then run:

$ gem install zold

Then, either run it as a node:

$ zold start

Or do one of the following:

• zold init creates a new wallet (you have to provide PGP keys)
• zold pull pulls a wallet from the network
• zold balance checks the balance of a wallet
• zold send creates a new transaction
• zold push pushes a wallet to the network

For more options and commands just run:

$ zold --help

Glossary

A node is an HTTP server with a RESTful API, a maintainer of wallets.

A client is a command line Ruby gem zold.

A wallet is an XML file with a ledger of all transactions inside.

A transaction is a money transferring operation between two wallets.

Data

A wallet may look like this:

<wallet>
  <id>123456</id>
  <pkey><!-- public RSA key, 256 bytes --></pkey>
  <ledger>
    [...]
    <txn id="35">
      <date>2017-07-19T21:24:51.136Z</date>
      <beneficiary>927284</beneficiary>
      <amount>-560</amount>
      <sign><!-- RSA signature of the payer --></sign>
    </txn>
  </ledger>
</wallet>

Wallet <id> is an unsigned 32-bit integer.

Transaction id is an unsigned 16-bit integer.

Transaction date is an unsigned 32-bit integer, meaning milliseconds since epoch.

All amounts are signed 64-bit integers, where 1ZLD by convention equals to 2²⁴ (16,777,216). Thus, the technical capacity of the currency is 549,755,813,888 (half a trillion).

The <sign> exists only in transactions with negative amount. It contains an RSA signature of a data block, created by the wallet owner: date, amount, beneficiary and 64 bytes of salt.

The list of a few backbone nodes is hard-coded in this Git repository.

Architecture

Pull. The client connects to a random closest node and pulls a wallet. If the node doesn't have the wallet, it tries to find it in the network. Then, it calculates and prints the balance to the user.

Commit. The user provides the amount and the destination wallet name. The client pulls the destination wallet and adds a new XML element <txn/> to both wallets.

Push. The client sends two wallets to a random closest node, which checks the validity of the deduction and propagates both wallets to all other nodes in a 2PC manner: acknowledgment first, commit next. If a node receives a wallet that contains transactions that are younger than transactions in its local copy, a merge operation is performed. If the balance after the merge is negative, the push is rejected.

Init. The client creates an empty wallet XML and assigns a random id for it.

Start. The node manifests itself to one of the backbone nodes, which propagates the manifestation to other nodes, they propagate further. When any node goes down, the node that detected such a situation, notifies other nodes and they exlude the failed node from the list.

Corner Cases

Too long wallet. If a wallet has too many transactions, its validation will take too long, since will require many cross-wallet checks. How to solve this?

DDoS. We may have too many simultaneous push operations to the network, which may/will cause troubles. What to do?

License (MIT)

Copyright (c) 2018 Zerocracy, Inc.

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the 'Software'), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.