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dropzone-lib Drop Zone

NPM Package Build Status

An Anonymous Peer-To-Peer Local Contraband Marketplace built with Bitcoin.

Author's Manifesto

Drop Zone

To whom it may concern,

Markets are objects of censorship and always have been. There is a presumed division, that renders commerce distinct from the notion of free speech. But I will allege that the act of commerce is, itself, indistinct from speech. Where or how one spends their value is a decision as personal and poignant as any words ever spoken or letters ever written.

As a unfortunate consequence of freedom, bad actors will engage in repugnant trade that impinges upon the rights and freedoms of others. It is the job of humanity to cooperate and see to it that trade, such as this, becomes unprofitable. Whether it is accomplished through technological achievement or through the adjustment of social mores, or perhaps a simple appeal to the underlying natural law, it is not the job of bad acting third parties to force into hiding commerce that must be dealt with by means of an adjustment to the global, social conscience.

Cooperation, in the manner I was just speaking about, has never been plausible until the invention of The Blockchain. I will not foist upon Satoshi's humble creation such impracticable possibilities as the achievement of world peace.
But in approaching Drop Zone, I am attempting to do nothing more than what is possible and possibly more efficient than what exists. I wish for Drop Zone to be nothing more than an appendage to The Blockchain. As such, it is every bit as much Bitcoin as Bitcoin itself. Just as a fungible Bitcoin enables the exchange of spaceless value with near impunity, Drop Zone removes the ability of unwelcome parties from glancing over the shoulders of those in the act of an exchange, whatever it entails. This technology disrupts the ability of buyers to gain insight into the identities or movements of suppliers making supply chains far less vulnerable to disruption. It is this innovation that separates this project from all other decentralized market solutions.

Whereas Bitcoin forces us to consider the nature of money and value, Drop Zone will do the same for commerce. At its root, Bitcoin is a message passing system. Those messages that are passed, unlike any electronic message that's come before it, articulate value. Commerce is, and has always been, similarly inclined toward message passing. Whether in-person, over email, or through large, online shopping carts, fundamentally, commerce is composed of messages that are in service of the transaction wherein a final message of value is sent to a recipient in exchange for a negotiated good or service. As such, Drop Zone is a secure message passing protocol inasmuch as it is a platform for commerce. And while the problem is far beyond the scope or capabilities of the protocol in its most fundamental form, the observant might even see the tenuous skeleton of a full-fledged reputation system. Such a project is, in itself, as important and difficult as any facing this decentralized ecosystem.

I hope that Drop Zone lets us all dream of a day when no man will any longer be made to suffer indignity for simply engaging in unpopular or stigmatized commerce. May all commerce be created equal.

Today is a Beautiful day,

Miracle Max quia omnis qui se exaltat humiliabitur et qui se humiliat exaltabitur

Important Whitepaper Errata

  • The white paper expressed 8 digits of precision for the listing radius. This implementation instead uses 6 digits. If additional precision is later deemed necessary, a field can be added to the listing to accomodate enhanced precision
  • The white paper expressed pkeys (addresses) as being encoded ints. These are instead encoded as variable length strings.
  • The white paper expressed transaction ids as being encoded ints. These are instead encoded as variable length strings.

Getting Started in your Web Browser

Download our packaged dropzone-lib.min.js and include it in your html via a script tag:

<script src="dropzone-lib.min.js"></script>

Getting Started in node

Before you begin you'll need to have Node.js v0.12 installed. There are several options for installation. One method is to use nvm to easily switch between different versions, or download directly from Node.js.

npm install -g dropzone-lib

Using dropzone-lib

The library syntax is still being finalized, but almost all dropzone functions are currently supported in this library.

Define a Connection/Driver

Unless you plan to feed raw binary data into objects yourself (more on this later) you're going to want to start by connecting dropzone to a blockchain.

Blockchain connection objects should be created at the inception of your program. Currently (and let's be real here - all that matters), Bitcoin connections are the only supported blockchain connections.

An SPV driver is still being developed, but for the time being, support exists for the following block explorers, which are queried via http: BlockchainDotInfo, BlockrIo, Insight, Toshi, and SoChain. Only Insight, Toshi, and SoChain support all functions via cors requests.

Toshi is the reccommended driver for read queries at this time due to its speed.

BlockrIo is the reccommended driver for write/save operations at this time. Toshi seems to have problems with relaying to the mempool quickly.

Mainnet Connections are created like so:

var dropzone = require('dropzone-lib');
var Toshi = dropzone.drivers.Toshi;

// By default, connections are instantiated to mainnet
connMainnet = new Toshi({}, function(err, toshiConnection){ 
  // Connection initialized...

Testnet Connections are created with the isMutable parameter set to true:

var dropzone = require('dropzone-lib');
// If you're not save()'ing transactions, toshi is actually a better driver
// SoChain was used here to demonstrate that multiple explorers are supported:
var SoChain = dropzone.drivers.SoChain;

connTestnet = new SoChain({isMutable: true});

Load a listing from a transaction id

This example loads the Miracle Max bible listing from the blockchain. Note that "Listings" contain the up-to-date state of an Item, and will reflect the attributes present in the original listing, plus all modifications to that listing thereafter.

var Listing = dropzone.Listing;

var BIBLE_TXID = '6a9013b8684862e9ccfb527bf8f5ea5eb213e77e3970ff2cd8bbc22beb7cebfb';

bible = new Listing(connMainnet, BIBLE_TXID);

// Scans the seller's address for the original listing, plus all updates:
bible.getAttributes(function (err, attrs) {
  if (err) throw err;


Find all Listings created in the last 'n' blocks

To find all items created between blocks 371814 to 371810:

var Item = dropzone.messages.Item;

Item.findCreatesSinceBlock(connMainnet, 371814, 4, function (err, items) {
  if (err) throw err;

  for (i=0; i < items.length; i++) {

Load a Seller profile from an address

This example loads the Miracle Max seller profile from the blockchain. Note that "SellerProfile" contains the up-to-date state of an seller, and will reflect the attributes present in the original seller declaration, plus all modifications to that declaration thereafter.

var SellerProfile = dropzone.SellerProfile;

var maxProfile = new SellerProfile(connMainnet, '17Q4MX2hmktmpuUKHFuoRmS5MfB5XPbhod');

// Scans the seller's address for the original declaration, plus all updates:
maxProfile.getAttributes(function (err, attrs) {
  if (err) throw err;


Load an invoice from a transaction id

This example loads an invoice message directly. "Messages" do not track state outside the current transaction, and can be located in dropzone.messages. These messages are loosely based on an ORM pattern's 'model'.

var Invoice = dropzone.messages.Invoice;

var INVOICE_TXID = 'e5a564d54ab9de50fc6eba4176991b7eb8f84bbeca3482ca032c12c1c0050ae3';

Invoice.find(connMainnet, INVOICE_TXID, function (err, invoice) {

Load an item from raw transaction hex string

For those who have a transaction already available, and simply want to de-serialize that transaction into its Drop Zone representation, the code to do so is as follows:

var Invoice = dropzone.messages.Invoice;

var txId = '6a9013b8684862e9ccfb527bf8f5ea5eb213e77e3970ff2cd8bbc22beb7cebfb';
var txHex = '01000000017....'; // Be sure to include the entire hex here

var record = new TxDecoder(new Transaction(txHex), {prefix: 'DZ'});

var item = new Item(connMainnet, {data:, txid: txId,
  receiverAddr: record.receiverAddr, senderAddr: record.senderAddr});


Create a Seller Profile:

Before you can post items for sale, you'll need to provide some basic info on how people can message you. Optionally, you may want to set up a nickname.

var Seller = dropzone.messages.Seller;
var privKey = bitcore.PrivateKey.fromWIF('seller-private-mainnet-key-wif-here')

new Seller(connMainnet, {
  description: 'Optional Description',
  alias: 'Satoshi Nakatoto',
  receiverAddr: privKey.toAddress(,
  // NOTE: This is a testnet address, unconnected to your mainnet privKey:
  communicationsAddr: 'n3EMs5L3sHcZqRy35cmoPFgw5AzAtWSDUv'
  }).save(privKey.toWIF(), function (err, seller) {
  if (err) throw err;

  console.log("Created Seller at: "+seller.txid);

Create an Item (For retrieval with Listing):

For those who have a transaction already available, and simply want to de-serialize that transaction into its Drop Zone representation, the code to do so is as follows:

var Item = dropzone.messages.Item;

new Item(connMainnet, {
  description: 'Item Description',
  priceCurrency: 'BTC',
  priceInUnits: 100000000,
  expirationIn: 6*24*7, // One week.
  latitude: 51.500782, 
  longitude: -0.124669,
  radius: 1000}).save('seller-private-key-wif-here', function (err, item) {
  if (err) throw err;

  console.log("Created Item at: "+item.txid);

Update the Item (For retrieval with Listing):

If you want to update your listing, it's pretty easy to do. Check it out player:

var Item = dropzone.messages.Item;
var itemCreateTxid = '6a9013b8684862e9ccfb527bf8f5ea5eb213e77e3970ff2cd8bbc22beb7cebfb';
var sellerAddr = '17Q4MX2hmktmpuUKHFuoRmS5MfB5XPbhod'

new Item(connMainnet, {
  createTxid: itemCreateTxid,
  receiverAddr: senderAddr, 
  description: 'New & Updated Item Description',
  }).save('seller-private-key-wif-here', function (err, item) {
  if (err) throw err

  console.log("Item Update: "+item.txid);

Create an Invoice

To create an invoice, as a seller:

var Invoice = dropzone.messages.Invoice;
var buyerAddress = '14zBTbnhzHjdAKkaR4J9kCPiyVyNoaqoti'; // A mainnet addess, Negotiated over testnet.

new Invoice(connMainnet, { 
  expirationIn: 6,
  amountDue: 100000000,
  receiverAddr: buyerAddress 
  }).save('seller-private-key-wif-here', function (err, invoice) {
  if (err) throw err;

  console.log("Created Invoice at: "+invoice.txid);

Create an Payment (aka a 'Product Review'):

For a buyer who has received an item, and wishes to review it

var Payment = dropzone.messages.Payment;
var sellerAddress = '17Q4MX2hmktmpuUKHFuoRmS5MfB5XPbhod';

new Payment(connMainnet, { 
  description: 'High Quality, no issues',
  // Quality attributes must be integers gte 0 and lte 8:
  deliveryQuality: 8,
  productQuality: 8, 
  communicationsQuality: 8,
  receiverAddr: sellerAddress
  }).save('seller-private-key-wif-here', function (err, payment) {
  if (err) throw err;

  console.log("Created Payment/Review at: "+payment.txid);

Messaging over Testnet

In Drop Zone, negotiations between sellers and buyers is performed over the bitcoin testnet. Why testnet?

  • Well, it's cheap.
  • And, there's no need to preserve the contents of communications for very long. (In fact the mempool is often enough)
  • testnet offers a pretty excellent queueing system, that doesn't require running a server, and that persists even when your client isn't running.
  • It's really easy to work with if you're already using this library anyways.
  • It should be trivial for mobile bitcoin wallets to support in the future.

Initiate a message (Generally By a buyer):

For a buyer who wishes to communicate with a seller, they must first send a key-negotiation/initialization request:

// This code is running from the buyer's web browser:
var sellerTestnetAddr = 'mi37WkBomHJpUghCn7Vgh3ah33h6L9Nkqw';

// Save this for as long as you need to converse!
// (And kindly throw it away when you're done conversing.)
// NOTE: The conversation key has nothing to do with the bitcoin key.
var buyerConversationPrivkey = crypto.randomBytes(128); 

var buyerToSeller = new Session(connTestnet, 'buyer-testnet-private-key-wif',
  buyerConversationPrivkey, {receiverAddr: sellerTestnetAddr});

// This authenticate() message sends a transaction to the seller that allows
// the buyer to compute the shared symmKey through DH:
buyerToSeller.authenticate(function (err, chatInit) {
  if (err) throw err;
  console.log("Buyer initiated a connection via transaction: "+chatInit.txid);

Authenticating a message initiation request:

The seller can list sessions (authenticated or otherwise) using the Seller.all method. In this example, we'll assume the initiation request was the first session in this list, and authenticate it.

// This code is running from the seller's web browser:
Session.all(connTestnet, sellerTestnetAddr, function (err, sessions) {
  if (err) throw err;

  console.log("We found "+sessions.length+" sessions");

  var sellerConversationPrivkey = crypto.randomBytes(128); 

  var sellerToBuyer = new Session(connTestnet,
    'seller-testnet-private-key-wif', sellerConversationPrivkey,
    {withChat: sessions[0]});

  // This authenticate() message sends a transaction to the buyer that allows
  // the buyer to compute the shared symmKey through DH:
  sellerToBuyer.authenticate(function (err, chatAuth) {
    if (err) throw err;
    console.log("Session authenticated via the transaction:"+chatAuth.txid);


Once authenticated, on either the seller or buyer's browser, a message can be communicated via the send() method of their Session object:

sellerToBuyer.send('Hello Buyer, what you need bro?', function(err, bitcoinTx) {
  // Standard callback here..
} )


Code released under the MIT license.

Copyright 2015 Miracle Max


An Anonymous Peer-To-Peer Local Contraband Marketplace




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