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<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>Blockchain! Blockchain! Blockchain! - Build Your Own Blockchains in Ruby from Zero (Scratch)</title>
<style>
html, body { margin: 0; padding: 0; }
body { font-family: Verdana, Geneva, Arial, Helvetica, sans-serif; }
a:link, a:visited { color: black; }
h1 { font-size: 30pt; }
h2 { font-size: 28pt; }
h3 { font-size: 25pt; }
p, li, dt, dd, td, th { font-size: 18pt; }
pre { font-size: 14pt; }
pre.small { font-size: 11pt; }
pre.code {
background-color: azure;
padding: 5px;
}
ul { list-style-type: square; }
.center { text-align: center; }
.slide { page-break-after: always;
min-height: 100mm;
padding: 40px;
border: 1px dotted black;
/*
background: -moz-linear-gradient( top, maroon, red);
*/
}
/*
for princexml (CSS3 paged media support)
@page { size: A4 landscape }
*/
</style>
</head>
<body>
<article id="presentation">
<section class="slide " id="1">
<!-- _S9SLIDE_ -->
<h1 id="alchemy---how-to-mine-digital-schilling-how-to-turn-digital-bits-into--or-">Alchemy - How-To Mine Digital Schilling? How-To Turn Digital Bits Into $$$ or €€€?</h1>
<p><strong>Transactions (Hyper) Ledger Book</strong></p>
<table>
<thead>
<tr>
<th>From</th>
<th>To</th>
<th style="text-align: right">Amount</th>
</tr>
</thead>
<tbody>
<tr>
<td>Grossklockner (†)</td>
<td>Sepp</td>
<td style="text-align: right">3798</td>
</tr>
<tr>
<td>Grossvenediger (†)</td>
<td>Franz</td>
<td style="text-align: right">3666</td>
</tr>
<tr>
<td>Dachstein (†)</td>
<td>Sissi</td>
<td style="text-align: right">2995</td>
</tr>
<tr>
<td>Wildspitze (†)</td>
<td>Maria</td>
<td style="text-align: right">3768</td>
</tr>
<tr>
<td> </td>
<td> </td>
<td style="text-align: right"> </td>
</tr>
<tr>
<td>Sissi</td>
<td>Eva</td>
<td style="text-align: right">20</td>
</tr>
<tr>
<td>Sepp</td>
<td>Maria</td>
<td style="text-align: right">17</td>
</tr>
<tr>
<td>Franz</td>
<td>Sissi</td>
<td style="text-align: right">3</td>
</tr>
<tr>
<td>Sepp</td>
<td>Ferdl</td>
<td style="text-align: right">100</td>
</tr>
<tr>
<td> </td>
<td> </td>
<td style="text-align: right"> </td>
</tr>
<tr>
<td>Franz</td>
<td>Max</td>
<td style="text-align: right">17</td>
</tr>
<tr>
<td>Maria</td>
<td>Adam</td>
<td style="text-align: right">4</td>
</tr>
</tbody>
</table>
<p>(†): Miner Transaction - New Schilling on the Market!</p>
<p>(Source: <a href="https://github.com/blockchainaustria/schilling">blockchainaustria/schilling</a>)</p>
</section>
<section class="slide " id="2">
<!-- _S9SLIDE_ -->
<h1 id="blockchain-blockchain-blockchain-decentralize-payments-decentralize-transactions-decentralize-blockchains">Blockchain! Blockchain! Blockchain! Decentralize Payments. Decentralize Transactions. Decentralize Blockchains.</h1>
<p>What’s Blockchain?</p>
<ul>
<li>Distributed Database?</li>
<li>Hyper Ledger Book?</li>
<li>Consensus with Proof-of-Work or Proof-of-Stake?</li>
<li>Digital Fingerprints? Cryptographic Hashes?</li>
<li>Lottery? Central Bank?</li>
<li>Byzantine-Generals Solution?</li>
</ul>
<p>Yes. Yes. Yes. Blockchain! Blockchain! Blockchain!</p>
<p>(Source: <a href="https://github.com/openblockchains/whatsblockchain">openblockchains/whatsblockchain</a>)</p>
</section>
<section class="slide " id="3">
<!-- _S9SLIDE_ -->
<h1 id="the-proof-of-the-pudding-is---the-bitcoin-btc-blockchains">The Proof of the Pudding is … The Bitcoin (BTC) Blockchain(s)</h1>
<p>A Success Story on the Blockchain.</p>
<p>May 22, 2010 - World’s 1st Bitcoin Payment</p>
<p>A developer bought two pizzas using 10 000 Bitcoin (BTC) - a then-little-known digital (crypto)currency.
Estimated worth about $40.</p>
<p>Triva Q: How much is one Bitcoin worth today? Q: How much are 10 000 Bitcoin worth today?</p>
</section>
<section class="slide " id="4">
<!-- _S9SLIDE_ -->
<h1 id="20-million-dollar-pizza-day---celebrating-the-birth-of-bitcoin-alchemy---">$20 Million Dollar Pizza Day - Celebrating the Birth of Bitcoin Alchemy - $$$</h1>
<p><img src="i/bitcoinmarket.png" alt="" /></p>
<p>(Source: <a href="https://coinmarketcap.com/currencies/bitcoin">coinmarketcap.com/currencies/bitcoin</a>)</p>
</section>
<section class="slide " id="5">
<!-- _S9SLIDE_ -->
<h1 id="lets-build-your-own-blockchain-in-ruby-from-zero--scratch">Let’s Build Your Own Blockchain in Ruby (From Zero / Scratch)</h1>
<p>Crypto God? Ruby Ninja / Rockstar?</p>
<p>Yes, you can.</p>
<p><img src="i/fake-dilbert-blockchain.png" alt="" /></p>
</section>
<section class="slide " id="6">
<!-- _S9SLIDE_ -->
<h1 id="code-code-code---a-blockchain-in-ruby-in-20-lines-a-blockchain-is-a-data-structure">Code, Code, Code - A Blockchain in Ruby in 20 Lines! A Blockchain is a Data Structure</h1>
<p>What’s Blockchain?</p>
<p>It’s a list (chain) of blocks linked and secured by digital fingerprints (also known as
crypto hashes).</p>
<pre><code class="language-ruby">require "digest" # for hash checksum digest function SHA256
class Block
attr_reader :index
attr_reader :timestamp
attr_reader :data
attr_reader :previous_hash
attr_reader :hash
def initialize(index, data, previous_hash)
@index = index
@timestamp = Time.now
@data = data
@previous_hash = previous_hash
@hash = calc_hash
end
def calc_hash
sha = Digest::SHA256.new
sha.update( @index.to_s + @timestamp.to_s + @data + @previous_hash )
sha.hexdigest
end
</code></pre>
<p>(Source: <a href="https://github.com/openblockchains/awesome-blockchains/blob/master/blockchain.rb/blockchain.rb">openblockchains/awesome-blockchains/blockchain.rb</a>)</p>
<p>Yes, that’s it.</p>
</section>
<section class="slide " id="7">
<!-- _S9SLIDE_ -->
<h1 id="code-code-code---a-blockchain-in-ruby-in-20-lines-a-blockchain-is-a-data-structure-cont">Code, Code, Code - A Blockchain in Ruby in 20 Lines! A Blockchain is a Data Structure (Cont.)</h1>
<p>Let’s add two helpers (<code>first</code>, <code>next</code>) for building (“mining”) blocks.</p>
<pre><code class="language-ruby">class Block
def self.first( data="Genesis" ) # create genesis (big bang! first) block
## uses index zero (0) and arbitrary previous_hash ("0")
Block.new( 0, data, "0" )
end
def self.next( previous, data="Transaction Data..." )
Block.new( previous.index+1, data, previous.hash )
end
end # class Block
</code></pre>
<p>(Source: <a href="https://github.com/openblockchains/awesome-blockchains/blob/master/blockchain.rb/blockchain.rb">openblockchains/awesome-blockchains/blockchain.rb</a>)</p>
</section>
<section class="slide " id="8">
<!-- _S9SLIDE_ -->
<h1 id="code-code-code---a-blockchain-in-ruby-in-20-lines-a-blockchain-is-a-data-structure-cont-1">Code, Code, Code - A Blockchain in Ruby in 20 Lines! A Blockchain is a Data Structure (Cont.)</h1>
<p>Let’s get started - build a blockchain a block at a time!</p>
<pre><code class="language-ruby">b0 = Block.first( "Genesis" )
b1 = Block.next( b0, "Transaction Data..." )
b2 = Block.next( b1, "Transaction Data......" )
b3 = Block.next( b2, "More Transaction Data..." )
blockchain = [b0, b1, b2, b3]
pp blockchain ## pp (pretty print to console)
</code></pre>
</section>
<section class="slide " id="9">
<!-- _S9SLIDE_ -->
<h1 id="code-code-code---a-blockchain-in-ruby-in-20-lines-a-blockchain-is-a-data-structure-cont-2">Code, Code, Code - A Blockchain in Ruby in 20 Lines! A Blockchain is a Data Structure (Cont.)</h1>
<blockquote>
<p>Wait, so a blockchain is just a linked list?</p>
<p>No. A linked list is only required to have a reference to the previous element,
a block must have an identifier depending on the previous block’s identifier,
meaning that you cannot replace a block without recomputing every single block that comes after.
In this implementation that happens as the previous digest is input in the calc_hash method.</p>
</blockquote>
<p>will log something like:</p>
<pre><code>[#<Block:0x1eed2a0
@index = 0,
@timestamp = 1637-09-15 20:52:38,
@data = "Genesis",
@previous_hash = "0",
@hash = "edbd4e11e69bc399a9ccd8faaea44fb27410fe8e3023bb9462450a0a9c4caa1b">,
#<Block:0x1eec9a0
@index = 1,
@timestamp = 1637-09-15 21:02:38,
@data = "Transaction Data...",
@previous_hash = "edbd4e11e69bc399a9ccd8faaea44fb27410fe8e3023bb9462450a0a9c4caa1b",
@hash = "eb8ecbf6d5870763ae246e37539d82e37052cb32f88bb8c59971f9978e437743">,
#<Block:0x1eec838
@index = 2,
@timestamp = 1637-09-15 21:12:38,
@data = "Transaction Data......",
@previous_hash = "eb8ecbf6d5870763ae246e37539d82e37052cb32f88bb8c59971f9978e437743",
@hash = "be50017ee4bbcb33844b3dc2b7c4e476d46569b5df5762d14ceba9355f0a85f4">,
...
</code></pre>
</section>
<section class="slide " id="10">
<!-- _S9SLIDE_ -->
<h1 id="what-about-proof-of-work-what-about-consensus">What about Proof-of-Work? What about Consensus?</h1>
<p>Making (Hash) Mining a Lottery - Find the Lucky Number</p>
<pre><code class="language-ruby">def calc_hash
sha = Digest::SHA256.new
sha.update( @index.to_s + @timestamp.to_s + @data + @previous_hash )
sha.hexdigest
end
</code></pre>
<p>The computer (node) in the blockchain network that computes the
next block with a valid hash wins the lottery.</p>
<p>For adding a block to the chain you get a reward! You get ~25~ 12.5 Bitcoin! (†)</p>
<p>Bitcoin adds a block every ten minutes.</p>
<p>(†) The reward gets halfed about every two years. In Sep’17 you’ll get 12.5 Bitcoin.</p>
</section>
<section class="slide " id="11">
<!-- _S9SLIDE_ -->
<h1 id="what-about-proof-of-work-what-about-consensus-cont">What about Proof-of-Work? What about Consensus? (Cont.)</h1>
<p>Random SHA256 hash #1: <code>c396de4c03ddb5275661982adc75ce5fc5905d2a2457d1266c74436c1f3c50f1</code></p>
<p>Random SHA256 hash #2: <code>493131e09c069645c82795c96e4715cea0f5558be514b5096d853a5b9899154a</code></p>
<p>Triva Q: What’s SHA256?</p>
<ul>
<li>(A) Still Hacking Anyway</li>
<li>(B) Secure Hash Algorithm</li>
<li>(C) Sweet Home Austria</li>
<li>(D) Super High Aperture</li>
</ul>
</section>
<section class="slide " id="12">
<!-- _S9SLIDE_ -->
<h1 id="what-about-proof-of-work-what-about-consensus-cont-1">What about Proof-of-Work? What about Consensus? (Cont.)</h1>
<p>A: SHA256 == Secure Hash Algorithms 256 Bits</p>
<p>Trivia: Designed by the National Security Agency (NSA) of the United States of America (USA).</p>
<p>Secure == Random e.g. Change one Letter and the Hash will Change Completely</p>
<p>Making (Hash) Mining a Lottery - Find the Lucky Number</p>
<p>Find a hash that starts with ten leading zeros e.g.</p>
<p><code>0000000000069645c82795c96e4715cea0f5558be514b5096d853a5b9899154a</code></p>
<p>Hard to compute! Easy to check / validate.</p>
</section>
<section class="slide " id="13">
<!-- _S9SLIDE_ -->
<h1 id="what-about-proof-of-work-what-about-consensus-cont-2">What about Proof-of-Work? What about Consensus? (Cont.)</h1>
<p>Making (Hash) Mining a Lottery - Find the Lucky Number (Nonce)</p>
<pre><code class="language-ruby">def compute_hash_with_proof_of_work( difficulty="00" )
nonce = 0
loop do
hash = calc_hash_with_nonce( nonce )
if hash.start_with?( difficulty )
return [nonce,hash] ## bingo! proof of work if hash starts with leading zeros (00)
else
nonce += 1 ## keep trying (and trying and trying)
end
end
end
def calc_hash_with_nonce( nonce=0 )
sha = Digest::SHA256.new
sha.update( nonce.to_s + @index.to_s + @timestamp.to_s + @data + @previous_hash )
sha.hexdigest
end
</code></pre>
<p>(Source: <a href="https://github.com/openblockchains/awesome-blockchains/blob/master/blockchain.rb/blockchain_with_proof_of_work.rb">awesome-blockchains/blockchain_with_proof_of_work.rb</a>)</p>
</section>
<section class="slide " id="14">
<!-- _S9SLIDE_ -->
<h1 id="what-about-proof-of-work-what-about-consensus-cont-3">What about Proof-of-Work? What about Consensus? (Cont.)</h1>
<p>Let’s rerun the sample with the proof of work machinery added.
Now the sample will pretty print (pp) something like:</p>
<pre><code>[#<Block:0x1e204f0
@index = 0,
@timestamp = 1637-09-20 20:13:38,
@data = "Genesis",
@previous_hash = "0",
@nonce = 242,
@hash = "00b8e77e27378f9aa0afbcea3a2882bb62f6663771dee053364beb1887e18bcf">,
#<Block:0x1e56e20
@index = 1,
@timestamp = 1637-09-20 20:23:38,
@data = "Transaction Data...",
@previous_hash = "00b8e77e27378f9aa0afbcea3a2882bb62f6663771dee053364beb1887e18bcf",
@nonce = 46,
@hash = "00aae8d2e9387e13c71b33f8cd205d336ac250d2828011f5970062912985a9af">,
#<Block:0x1e2bd58
@index = 2,
@timestamp = 1637-09-20 20:33:38,
@data = "Transaction Data......",
@previous_hash = "00aae8d2e9387e13c71b33f8cd205d336ac250d2828011f5970062912985a9af",
@nonce = 350,
@hash = "00ea45e0f4683c3bec4364f349ee2b6816be0c9fd95cfd5ffcc6ed572c62f190">,
...
</code></pre>
<p>See the difference?
All hashes now start with leading zeros (<code>00</code>)
and the nonce is the random “lucky number” that makes it happen.
That’s the magic behind the proof of work.</p>
</section>
<section class="slide " id="15">
<!-- _S9SLIDE_ -->
<h1 id="the-worlds-worst-database---bitcoin-blockchain-mining">The World’s Worst Database - Bitcoin Blockchain Mining</h1>
<ul>
<li>Uses approximately the same amount of electricity as could power an average American household
for a day per transaction</li>
<li>Supports 3 transactions / second across a global network with millions of CPUs/purpose-built ASICs</li>
<li>Takes over 10 minutes to “commit” a transaction</li>
<li>Doesn’t acknowledge accepted writes: requires you read your writes,
but at any given time you may be on a blockchain fork, meaning your write might not actually
make it into the “winning” fork of the blockchain (and no, just making it into the mempool doesn’t count).
In other words: “blockchain technology” cannot by definition tell you if a given write is ever
accepted/committed except by reading it out of the blockchain itself (and even then)</li>
<li>Can only be used as a transaction ledger denominated in a single currency,
or to store/timestamp a maximum of 80 bytes per transaction</li>
</ul>
<p>(Source: <a href="https://tonyarcieri.com/on-the-dangers-of-a-blockchain-monoculture">Tony Arcieri - On the dangers of a blockchain monoculture</a>)</p>
</section>
<section class="slide " id="16">
<!-- _S9SLIDE_ -->
<h1 id="tulip-mania-quiz---win-100-schilling-on-the-blockchain">Tulip Mania Quiz - Win 100 Schilling on the Blockchain!</h1>
<p>Q: Tulip Mania Bubble in Holland - What Year?</p>
<ul>
<li>(A) 1561</li>
<li>(B) 1637</li>
<li>(C) 1753</li>
<li>(D) 1817</li>
</ul>
<p>Q: What’s the Name of the Most Expensive Tulip?</p>
<ul>
<li>(A) Admiral van Eijck</li>
<li>(B) Admiral of Admirals</li>
<li>(C) Semper Augustus</li>
<li>(C) Semper Cesarus</li>
</ul>
</section>
<section class="slide " id="17">
<!-- _S9SLIDE_ -->
<h1 id="tulips-on-the-blockchain-adding-transactions">Tulips on the Blockchain! Adding Transactions</h1>
<p>Learn by Example from the Real World (Anno 1637) - Buy! Sell! Hold! Enjoy the Beauty of Admiral of Admirals, Semper Augustus and More.</p>
<p><strong>Transactions (Hyper) Ledger Book</strong></p>
<table>
<thead>
<tr>
<th>From</th>
<th>To</th>
<th>What</th>
<th style="text-align: right">Qty</th>
</tr>
</thead>
<tbody>
<tr>
<td>Dutchgrown (†)</td>
<td>Vincent</td>
<td>Tulip Bloemendaal Sunset</td>
<td style="text-align: right">10</td>
</tr>
<tr>
<td>Keukenhof (†)</td>
<td>Anne</td>
<td>Tulip Semper Augustus</td>
<td style="text-align: right">7</td>
</tr>
<tr>
<td> </td>
<td> </td>
<td> </td>
<td style="text-align: right"> </td>
</tr>
<tr>
<td>Flowers (†)</td>
<td>Ruben</td>
<td>Tulip Admiral van Eijck</td>
<td style="text-align: right">5</td>
</tr>
<tr>
<td>Vicent</td>
<td>Anne</td>
<td>Tulip Bloemendaal Sunset</td>
<td style="text-align: right">3</td>
</tr>
<tr>
<td>Anne</td>
<td>Julia</td>
<td>Tulip Semper Augustus</td>
<td style="text-align: right">1</td>
</tr>
<tr>
<td>Julia</td>
<td>Luuk</td>
<td>Tulip Semper Augustus</td>
<td style="text-align: right">1</td>
</tr>
<tr>
<td> </td>
<td> </td>
<td> </td>
<td style="text-align: right"> </td>
</tr>
<tr>
<td>Bloom & Blossom (†)</td>
<td>Daisy</td>
<td>Tulip Admiral of Admirals</td>
<td style="text-align: right">8</td>
</tr>
<tr>
<td>Vincent</td>
<td>Max</td>
<td>Tulip Bloemendaal Sunset</td>
<td style="text-align: right">2</td>
</tr>
<tr>
<td>Anne</td>
<td>Martijn</td>
<td>Tulip Semper Augustus</td>
<td style="text-align: right">2</td>
</tr>
<tr>
<td>Ruben</td>
<td>Julia</td>
<td>Tulip Admiral van Eijck</td>
<td style="text-align: right">2</td>
</tr>
<tr>
<td> </td>
<td> </td>
<td> </td>
<td style="text-align: right"> </td>
</tr>
<tr>
<td>Teleflora (†)</td>
<td>Max</td>
<td>Tulip Red Impression</td>
<td style="text-align: right">11</td>
</tr>
<tr>
<td>Anne</td>
<td>Naomi</td>
<td>Tulip Bloemendaal Sunset</td>
<td style="text-align: right">1</td>
</tr>
<tr>
<td>Daisy</td>
<td>Vincent</td>
<td>Tulip Admiral of Admirals</td>
<td style="text-align: right">3</td>
</tr>
<tr>
<td>Julia</td>
<td>Mina</td>
<td>Tulip Admiral van Eijck</td>
<td style="text-align: right">1</td>
</tr>
<tr>
<td> </td>
<td> </td>
<td> </td>
<td style="text-align: right"> </td>
</tr>
<tr>
<td>Max</td>
<td>Isabel</td>
<td>Tulip Red Impression</td>
<td style="text-align: right">2</td>
</tr>
</tbody>
</table>
<p>(†): Grower Transaction - New Tulips on the Market!</p>
<p>(Source: <a href="https://github.com/openblockchains/tulips">openblockchains/tulips</a>)</p>
</section>
<section class="slide " id="18">
<!-- _S9SLIDE_ -->
<h1 id="tulips-on-the-blockchain-adding-transactions-cont">Tulips on the Blockchain! Adding Transactions (Cont.)</h1>
<p><strong>Quotes - Blockchains are the next Internets / Tulips</strong></p>
<blockquote>
<p>People who compare digital tokens to tulips are essentially saying digital tokens are a bubble backed
by nothing but pure hype and speculation.</p>
<p>What they fail to understand is that tulips come from dirt, not a blockchain.</p>
<p>And as we all know, blockchain is possibly the best technological innovation since the internet.
It will have a tremendous impact on global business and society in general.
– <a href="http://tuliptoken.com">TulipToken</a></p>
</blockquote>
</section>
<section class="slide " id="19">
<!-- _S9SLIDE_ -->
<h1 id="tulips-on-the-blockchain-adding-transactions-cont-1">Tulips on the Blockchain! Adding Transactions (Cont.)</h1>
<pre><code class="language-ruby">b0 = Block.first(
{ from: "Dutchgrown", to: "Vincent", what: "Tulip Bloemendaal Sunset", qty: 10 },
{ from: "Keukenhof", to: "Anne", what: "Tulip Semper Augustus", qty: 7 } )
b1 = Block.next( b0,
{ from: "Flowers", to: "Ruben", what: "Tulip Admiral van Eijck", qty: 5 },
{ from: "Vicent", to: "Anne", what: "Tulip Bloemendaal Sunset", qty: 3 },
{ from: "Anne", to: "Julia", what: "Tulip Semper Augustus", qty: 1 },
{ from: "Julia", to: "Luuk", what: "Tulip Semper Augustus", qty: 1 } )
b2 = Block.next( b1,
{ from: "Bloom & Blossom", to: "Daisy", what: "Tulip Admiral of Admirals", qty: 8 },
{ from: "Vincent", to: "Max", what: "Tulip Bloemendaal Sunset", qty: 2 },
{ from: "Anne", to: "Martijn", what: "Tulip Semper Augustus", qty: 2 },
{ from: "Ruben", to: "Julia", what: "Tulip Admiral van Eijck", qty: 2 } )
...
</code></pre>
</section>
<section class="slide " id="20">
<!-- _S9SLIDE_ -->
<h1 id="tulips-on-the-blockchain-adding-transactions-cont-2">Tulips on the Blockchain! Adding Transactions (Cont.)</h1>
<p>resulting in:</p>
<pre><code>[#<Block:0x2da3da0
@hash="32bd169baebba0b70491b748329ab631c85175be15e1672f924ca174f628cb66",
@index=0,
@previous_hash="0",
@timestamp=1637-09-25 17:39:21,
@transactions=
[{:from=>"Dutchgrown", :to=>"Vincent", :what=>"Tulip Bloemendaal Sunset", :qty=>10},
{:from=>"Keukenhof", :to=>"Anne", :what=>"Tulip Semper Augustus", :qty=>7}],
@transactions_count=2>,
#<Block:0x2da2ff0
@hash="57b519a8903e45348ac8a739c788815e2bd90423663957f87e276307f77f1028",
@index=1,
@previous_hash=
"32bd169baebba0b70491b748329ab631c85175be15e1672f924ca174f628cb66",
@timestamp=1637-09-25 17:49:21,
@transactions=
[{:from=>"Flowers", :to=>"Ruben", :what=>"Tulip Admiral van Eijck", :qty=>5},
{:from=>"Vicent", :to=>"Anne", :what=>"Tulip Bloemendaal Sunset", :qty=>3},
{:from=>"Anne", :to=>"Julia", :what=>"Tulip Semper Augustus", :qty=>1},
{:from=>"Julia", :to=>"Luuk", :what=>"Tulip Semper Augustus", :qty=>1}],
@transactions_count=4>,
...
</code></pre>
</section>
<section class="slide " id="21">
<!-- _S9SLIDE_ -->
<h1 id="whats-blockchain-lite---ruby-edition">What’s Blockchain Lite - Ruby Edition?</h1>
<p>blockchain-lite library (gem: <a href="https://rubygems.org/gems/blockchain-lite"><code>blockchain-lite</code></a>) -
build your own blockchain with crypto hashes -
revolutionize the world with blockchains, blockchains, blockchains one block at a time</p>
<p><strong>Usage</strong></p>
<p>Let’s get started. Build your own blockchain one block at a time.</p>
<pre><code class="language-ruby">require 'blockchain-lite'
b0 = Block.first( 'Genesis' )
b1 = Block.next( b0, 'Transaction Data...' )
b2 = Block.next( b1, 'Transaction Data......' )
b3 = Block.next( b2, 'More Transaction Data...' )
blockchain = [b0, b1, b2, b3]
pp blockchainconsole.log( blockchain )
</code></pre>
</section>
<section class="slide " id="22">
<!-- _S9SLIDE_ -->
<h1 id="case-study----dutch-gulden-on-the-blockchain">Case Study - Dutch Gulden on the Blockchain!</h1>
<p><img src="i/guldenmarket.png" alt="" /></p>
<p>(Source: <a href="https://coinmarketcap.com/currencies/gulden">coinmarketcap.com/currencies/gulden</a>)</p>
</section>
<section class="slide " id="23">
<!-- _S9SLIDE_ -->
<h1 id="schilling-schilling-on-the-blockchain-rock-solid-alpine-dollar-from-austria">Schilling! Schilling! on the Blockchain! Rock-Solid Alpine Dollar from Austria</h1>
<p>Who’s in? Invest now!</p>
<p>Crypto #Schilling on the #Blockchain in 324 Days 7 Hours 30 Minutes!</p>
<p>Join the Rock-Solid Alpine Dollar Movement!</p>
<p>Learn more @ <a href="https://github.com/blockchainaustria/schilling">blockchainaustria/schilling</a></p>
</section>
<section class="slide " id="24">
<!-- _S9SLIDE_ -->
<h1 id="breaking-news-cryptokitties-yes-cute-little-cartoon-cats-on-the-blockchain">Breaking News: CryptoKitties (Yes, Cute Little Cartoon Cats) on the Blockchain!</h1>
<p>Collectible. Breedable. Adorable.</p>
<p>Collect and breed digital cats. Start meow. Buy! Sell! Hold!</p>
<p>Learn more @ <a href="https://cryptokitties.co">cryptokitties.co</a></p>
<p><img src="i/cryptokitties.png" alt="" /></p>
</section>
<section class="slide " id="25">
<!-- _S9SLIDE_ -->
<h1 id="breaking-news-cryptokitties-yes-cute-little-cartoon-cats-on-the-blockchain-cont">Breaking News: CryptoKitties (Yes, Cute Little Cartoon Cats) on the Blockchain! (Cont.)</h1>
<p>Latest (and Greatest) Investment Opportunity!</p>
<blockquote>
<p>Blockchain has unlocked the magic of digital scarcity, and combining that with the power of
making the digital goods persistent gives them a potential value that is only limited by how much
prestige a wealthy person might place on ownership of the item.</p>
<p>– <a href="https://twitter.com/tokenizedcap/status/938460753589424128">Justin Poirier</a></p>
</blockquote>
<blockquote>
<p>All I want for Christmas is a CryptoKitty.</p>
<p>– <a href="https://twitter.com/kaylaw/status/938590748655550464">Kayla Williams</a></p>
</blockquote>
<blockquote>
<p>I got a fever. And the only prescription is more CryptoKitties.</p>
<p>– <a href="https://twitter.com/ceduardosalazar/status/938558630663634944">Eduardo Salazar</a></p>
</blockquote>
<blockquote>
<p><a href="https://www.cryptokitties.co/kitty/104375">My Gen 7 CryptoKitty #104375</a>. The Future is Meow.</p>
<p>– <a href="https://twitter.com/TheAnshulDhawan/status/938551642202324993">Anshul Dhawan</a></p>
</blockquote>
<p><img src="i/cryptokitty46.png" alt="" /></p>
</section>
<section class="slide " id="26">
<!-- _S9SLIDE_ -->
<h1 id="bonus-blockchain-articles">Bonus: Blockchain Articles</h1>
<p><a href="http://rufuspollock.com/2016/07/02/reflections-on-the-blockchain"><strong>Reflections on the Blockchain</strong></a> by Rufus Pollock (Open Knowledge Foundation), July 2016 –
<em>The DAO: Code is not Law - and It’s Dangerous to Think So ++
The Internet changed the world - surely the Blockchain will too? ++
Gold-rush or Internet-rush? ++
Governance Matters in Bitcoin ++
The Myth of a Costless, Ownerless Network ++
Lessons from History</em></p>
<p><a href="https://tonyarcieri.com/on-the-dangers-of-a-blockchain-monoculture"><strong>On the Dangers of a Blockchain Monoculture</strong></a> by Tony Arcieri, January 2016 –
<em>The Bitcoin blockchain: the world’s worst database ++
Next-generation protocols ++
Decentralized ledger protocols ++
Bitcoin-NG ++
Blockchain! Blockchain! Blockchain! ++
The great decentralized database in the sky</em></p>
<p><a href="https://www.tbray.org/ongoing/When/201x/2017/05/13/Not-Believing-in-Blockchain"><strong>I Don’t Believe in Blockchain</strong></a> by Tim Bray, May 2017</p>
<p><a href="https://www.igvita.com/2014/05/05/minimum-viable-block-chain/"><strong>Minimum Viable Blockchain</strong></a> by Ilya Grigorik, May 2014 –
<em>Securing transactions with triple-entry bookkeeping ++
Securing transactions with PKI ++
Balance = Σ(receipts) ++
Multi-party transfers & verification ++
Double-spending and distributed consensus -
Requirements for a distributed consensus network;
Protecting the network from Sybil attacks;
Proof-of-work as a participation requirement ++
Building the minimum viable blockchain -
Adding “blocks” & transaction fee incentives;
Racing to claim the transaction fees;
Resolving chain conflicts;
Blocks are never final ++
Properties of the (minimum viable) blockchain</em></p>
<p><a href="https://www.oreilly.com/ideas/blockchains-by-analogies-and-applications"><strong>Blockchains by analogies and applications: How blockchain compares to Git, Raft, and other technologies.</strong></a>
by Kieren James-Lubin, January 2016 –
<em>Blockchains are databases ++
Understanding transactions ++
Persistent, replicated databases (related technology: Git) ++
Peer-to-peer networks (related technology: BitTorrent) ++
Distributed consensus (related technology: distributed databases, Raft) ++
Minting new coins (mining) ++
Embedded identities (related technology: TLS) ++
Smart contracts: Like SQL expressions & triggers ++
What can we really do with blockchains?</em></p>
</section>
<section class="slide " id="27">
<!-- _S9SLIDE_ -->
<h1 id="bonus-blockchain-books">Bonus: Blockchain Books</h1>
<p><a href="https://davidgerard.co.uk/blockchain/table-of-contents/"><strong>Attack of the 50 Foot Blockchain: Bitcoin, Blockchain, Ethereum & Smart Contracts</strong></a> by David Gerard, London, 2017 –
<em>What is a bitcoin? ++
The Bitcoin ideology ++
The incredible promises of Bitcoin! ++
Early Bitcoin: the rise to the first bubble ++
How Bitcoin mining centralised ++
Who is Satoshi Nakamoto? ++
Spending bitcoins in 2017 ++
Trading bitcoins in 2017: the second crypto bubble ++
Altcoins ++
Smart contracts, stupid humans ++
Business bafflegab, but on the Blockchain ++
Case study: Why you can’t put the music industry on a blockchain</em></p>
<p><a href="https://github.com/bitcoinbook/bitcoinbook/blob/second_edition/ch09.asciidoc"><strong>Mastering Bitcoin - Programming the Open Blockchain</strong></a> 2nd Edition,
by Andreas M. Antonopoulos, 2017 - FREE (Online Source Version) –
<em>What Is Bitcoin? ++
How Bitcoin Works ++
Bitcoin Core: The Reference Implementation ++
Keys, Addresses ++
Wallets ++
Transactions ++
Advanced Transactions and Scripting ++
The Bitcoin Network ++
The Blockchain ++
Mining and Consensus ++
Bitcoin Security ++
Blockchain Applications</em></p>
<p><a href="https://www.ibm.com/blockchain/what-is-blockchain.html"><strong>Blockchain for Dummies, IBM Limited Edition</strong></a> by Manav Gupta, 2017 - FREE (Digital Download w/ Email) –
<em>Grasping Blockchain Fundamentals ++
Taking a Look at How Blockchain Works ++
Propelling Business with Blockchains ++
Blockchain in Action: Use Cases ++
Hyperledger, a Linux Foundation Project ++
Ten Steps to Your First Blockchain application</em></p>
</section>
<section class="slide " id="28">
<!-- _S9SLIDE_ -->
<h1 id="bonus-awesome-blockchains">Bonus: Awesome Blockchains</h1>
<p>A collection about awesome blockchains - open distributed public databases w/ crypto hashes incl. git ;-). Blockchains are the new tulips. Distributed is the new centralized.</p>
<p>More @ <a href="https://github.com/openblockchains/awesome-blockchains">openblockchains/awesome-blockchains</a></p>
</section>
<section class="slide " id="29">
<!-- _S9SLIDE_ -->
<h1 id="bonus-git-git-git---the-stupid-content-tracker-with-crypto-hashes">Bonus: Git, Git, Git - The Stupid Content Tracker with Crypto Hashes</h1>
<p><em>Everything is local. Distributed is the new centralized.</em></p>
<blockquote>
<p>Yep, that’s the joke. Nobody has been able to explain to me how the “blockchain” buzzword is significantly different to “git repo”.
– <a href="https://twitter.com/yaakov_h/status/902659507255312384">Yaakov</a></p>
<p>But if you said “let’s build a currency where all transactions are stored in a git repo”
you wouldn’t be taken seriously for even 24 hrs.
– <a href="https://twitter.com/yaakov_h/status/902659847224664064">Yaakov</a></p>
</blockquote>
<blockquote>
<p>Soon explaining git like “a git repo is like a blockchain with commits instead of blocks”.
– <a href="https://twitter.com/nicoberger/status/901776907418697729">Nicolás Berger</a></p>
<p>“A local branch is like a state channel. It can be pushed and merged into the master blockchain at any moment.”
– <a href="https://twitter.com/nicoberger/status/901777571456614400">Nicolás Berger</a></p>
</blockquote>
<blockquote>