What is the
tangle?

To attach a transaction

you must "confirm"

2 old transactions

they did

the same

meet the "directed acyclic graph" (D A G)

anatomy of a transaction 

PoW

older tx

bundle info

how much?

tx's "name"

0 when value==0

where?

There are advantages.

• no need to download the whole ledger
• everyone can add new tx
• you can create an offline ledger  ("subtangle") and add all of its tx later
• the more people add tx the faster it gets
• a tx can (but doesn't have to) contain a value
• adding a tx is free

figure it out yourself:

https://simulation1.tangle.works/

Seeds, signatures & Addresses

• Seed = origin for "random" numbers
  • keep it safe as a password 
• ​"Winternitz" One-time signatures
  • index based deterministic signatures
• Address: derivate hash of your seed
  • since based on the seed they're reproducible
  • if you would use one address more than once
    attackers could bruteforce guessing your seed.

Infrastructure

(optional)

https://iota.dance/nodes

IRI

• IOTA Reference Implementation
• Java
• it's basically a "full" wallet ;)
• needs "neighbor" nodes to work
  • the more neighbors the faster
• must be visible from the outside world

https://github.com/iotaledger/iri

nelson.cli

• https://github.com/SemkoDev/nelson.cli
• discovers and evaluates neighbors
• node.js
• controls an IRI's neighbor settings
• visualizations available

Nelson.GUI

• https://github.com/SemkoDev/nelson.gui
• see who's connected to your node
• (node.js)

Tools

Desktop wallet

https://github.com/iotaledger/wallet

CLI wallet

https://github.com/iotaledger/cli-app

the tangle.org

Coding

https://github.com/coding-berlin/iota-demos

stable APIs

• Javascript
• Python
• Go

https://iota.readme.io/v1.2.0/reference

Hello IRI

const IOTA = require('iota.lib.js');
const iota = new IOTA({
    'provider': process.env.IRI_URL
});

iota.api.getNodeInfo( (error, success) => {
    if (error) {
        console.error(error);
    } else {
        console.dir(success);
    }
});

Attach a transaction

const IOTA = require('iota.lib.js');
const iota = new IOTA({
    'provider': process.env.IRI_URL
});

iota.api.getNewAddress('SOMESEEDTHATYOU9ENERATEDONYOUROWN', {}, (error, address) => {
    if (error) { return  console.error(error); }
    console.log('Got address: ' + address);
    const transfer = [{
        address: address,
        value: 0,
        message: iota.utils.toTrytes('hello world from coding berlin.'),
        tag: 'CODIN9BERLIN'
    }]
    const  depth = 8; // Depth for the tip selection
    const  minWeightMagnitude = 18; // If we're on the mainnet, minWeightMagnitude is 18
    // the sendTransfer API wrapper takes care of prepareTransfers, attachToTangle, broadcast and storeTransactions
    iota.api.sendTransfer( seed, depth, minWeightMagnitude, transfer, ( error, attached ) => {
        if (error) {
            return console.error(error);
        }
        console.log("Successfully attached your transaction to the Tangle with transaction", attached);
    });
});

IRI does the heavy lifting for us

https://thetangle.org/transaction/TPEKZPGXVSVZRVK9OEHHTRJBPBWNSAUABFBQ9LUATPIHMYPQXCQVYQPLLJGZMPYJHRX9KXZVTJA999999

List all transfers (aka bundles)

require('dotenv').config();
const IOTA = require('iota.lib.js');
const iota = new IOTA({
    'provider': process.env.IRI_URL
});
iota.api.getTransfers(process.env.CB_SEED, {}, (error, transfers) => {
    
    if (error) {
        console.error(error);
        return;
    }
    transfers.forEach(bundle => {
        bundle.forEach(t => {  
            let time = new Date(1000 * t.timestamp).toLocaleString();
            console.log(`${time} hash:${t.hash} value:${t.value} bundle:${t.bundle}} `);
        })
    })
});

Transfer list

And then

Masked Authenticated Messaging

• encrypted
• confirmed / authenticated
• streamed

MAM

https://github.com/coding-berlin/iota-demos/tree/master/mam

Attach a MAM message

require('dotenv').config();
var inquirer = require('inquirer');
var IOTA  = require('iota.lib.js');
var Mam = require('mam.client.js/lib/mam.node.js')

const iota = new IOTA({
    'provider': process.env.IRI_URL
});
const seed = process.env.CB_SEED;
// Initialise MAM State - PUBLIC
let mamState = Mam.init(iota, seed)

function promptMessage() {
    return inquirer.prompt([{type: 'input', name:'message', message: 'message' }]);
}

function publish(message) {
    let payload = iota.utils.toTrytes(message);
    let mamMessage = Mam.create(mamState, payload);   // Create MAM Payload - STRING OF TRYTES
        mamState = mamMessage.state // Save new mamState
        
        console.log('Root: ', mamMessage.root)
        //console.log('Address: ', mamMessage.address)
        return Mam.attach(mamMessage.payload, mamMessage.address)
}

(async () => {
  while(1) {
    let result = await promptMessage(); 
    let transactions = await publish(result.message);
    console.dir(transactions);
  }
})();
 

Decode MAM messages

require('dotenv').config();
var inquirer = require('inquirer');
var IOTA  = require('iota.lib.js');
var Mam = require('mam.client.js/lib/mam.node.js')

const iota = new IOTA({
    'provider': process.env.IRI_URL
});
Mam.init(iota)

const seed = process.env.CB_SEED;
const root = process.argv[2];

const logData = data => console.log(iota.utils.fromTrytes(data));

Mam.fetch(root, 'public', null, logData).then(resp => {
    console.dir(resp);
})

Sensor data marketplace

• attach your sensor data to the tangle
• charge for its usage
• "data is the new oil" vs. "big data = big business"

https://data.iota.org/