Yes, You Can Put IoT on the Blockchain using Python and the ESP8266

Last year, we saw quite a bit of media attention paid to blockchain startups. They raised money from the public, then most of them vanished without a trace (or product). Ethics and legality of their fundraising model aside, a few of the ideas they presented might be worth revisiting one day.

One idea in particular that I’ve struggled with is the synthesis of IoT and blockchain technology. Usually when presented with a product or technology, I can comprehend how and/or why someone would use it – in this case I understand neither, and it’s been nagging at me from some quiet but irrepressible corner of my mind.

The typical IoT networks I’ve seen collect data using cheap and low-power devices, and transmit it to a central service without more effort spent on security than needed (and sometimes much less). On the other hand, blockchains tend to be an expensive way to store data, require a fair amount of local storage and processing power to fully interact with them, and generally involve the careful use of public-private key encryption.

I can see some edge cases where it would be useful, for example securely setting the state of some large network of state machines – sort of like a more complex version of this system that controls a single LED via Ethereum smart contract.

What I believe isn’t important though, perhaps I just lack imagination – so lets build it anyway.

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New Mooltipass Begins Development with Call for Collaborators

One of the most interesting aspects of our modern world is the ability to work collaboratively despite the challenges of geography and time zones. Distributed engineering is a trend which we’ve watched pick up steam over the years. One such example is the Mooltipass offline password keeper which was built by a distributed engineering team from all over the world. The project is back, and this time the goal is to add BLE to the mini version of the hardware. The call for collaborators was just posted on the project page so head over and check out how the collaboration works.

The key to the hardware is the use of a smartcard with proven encryption to store your passwords. Mooltipass is a secure interface between this card and a computer via USB. The new version will be a challenge as it introduces BLE for connectivity with smart phones. To help mitigate security risks, a second microcontroller is added to the existing design to act as a gatekeeper between the secure hardware and the BLE connection.

Mathieu Stephan is the driving force behind the Mooltipass project, which was one of the first projects on Hackaday.io and has been wildly successful in crowd funding and on Tindie. Mathieu and five other team members already have a proof of concept for the hardware. However, more collaborators are needed to help see all aspects of the project — hardware, firmware, and software — through to the end. This is a product, and in addition to building something awesome, the goal is to turn a profit.

How do you reconcile work on an Open Source project with a share of the spoils? Their plan is to log hours spent bringing the new Mooltipass to life and share the revenue using a site like colony.io. This is a tool built on the Ethereum blockchain to track contributions to open projects, assigning tokens that equate to value in the project. It’s an interesting approach and we’re excited to see how it takes shape.

You can catch up on the last few years of the Mooltipass adventure my checking out Mathieu’s talk during the 2017 Hackaday Superconference. If this article has you as excited about distributed engineer as we are, you need to check out the crew that’s building this year’s Open Hardware Summit badge!

Simple Ethereum Vending Machines with NodeMCU

Recently, we covered how to use the Etherscan API to query data (a wallet balance) from the Ethereum blockchain with NodeMCU. It’s a very useful method for retrieving information from a blockchain on embedded systems where storage and memory are an issue.

It has some limitations though. Most notably, it’s polling the API at some interval to retrieve information whether it has changed or not. I would like to be able to receive data more efficiently than this, and quickly enough to make simple vending machines possible. While we’ve seen videos of Bitcoin-based Red Bull vending machines before, they required an NFC card to use.

If we could receive information about Ethereum transactions quickly and reliably enough, we could build a similar vending machine without requiring an NFC card as an intermediary. Simply send to an address via some method, and receive goods!

It turns out we can do exactly that with NodeMCU using WebSocket. Like HTTP, WebSocket is a communications protocol that uses TCP connections (typically over port 80), but it allows full-duplex communication. In other words, you can establish a connection to a server, and send/receive messages without needing to poll the server.

As in the previous example, we’ll use a NodeMCU running Lua. You may wish to refer to it for compile options and information about the screen, which will be the same in this case. Unlike the previous article, you will not need an API key from Etherscan to use this service (not yet, anyway). As usual, we’ll start off by connecting to WiFi:

wifi.setmode(wifi.STATION)
wifi.setphymode(wifi.PHYMODE_B)
station_cfg={}
station_cfg.ssid="Your SSID"
station_cfg.pwd="Your Password"
station_cfg.save=true
wifi.sta.config(station_cfg)

Connecting to a server with WebSockets is easy, but since we’re not using HTTP, we’ll have to remove the https:// and replace that with ws://. (Note: not wss:// because we’ve not enabled encryption yet.)

ws:connect(‘ws://socket.etherscan.io/wshandler’)

Next, we need to report back when the connection is established as the trigger to run additional code. It will return an error code if the connection fails to be established. Handling these error codes in a sensible way is an excellent feature, but we’ll handle that later:

ws:on("connection", function(ws)
    print('got ws connection')
    end)

Now, we need to extend the above to subscribe to an Eth address, and add some new code to do something when a transaction occurs. Note that the API requires that you subscribe to an address within 60 seconds of connecting. It also states that you have to send a ping event to the server every 20 seconds to keep the connection alive, so we’ll need to set a recurring timer for that.

If you’re using ESPlorer, you can send the ping request manually by entering =ws:send('{"event": "ping"}') and pressing Send. This is a useful way to test the connection status.

The address I used seems to have frequent transactions so is reasonable for testing. Be advised though that sitting and waiting for a transaction to happen to test the code creates a slow development cycle so some patience is necessary here.

ws = websocket.createClient()
ws:on("connection", function(ws)
    print('got ws connection')
    ws:send('{"event": "txlist", "address": "0x2a65aca4d5fc5b5c859090a6c34d164135398226"}')
    end)

ws:on("receive", function(_, msg, opcode)
    print('got message:', msg, opcode)
    end)

You should see something like what follows below. The first message is a simple confirmation of connection, the second confirms your subscription to an address, and the third is what you get sent when a transaction occurs. You can subscribe to up to 30 addresses with a single connected device! Note that the data is all in JSON format, which is something we’ll take advantage of later.

got message: {"event":"welcome"} 1
got message: {"event":"subscribe-txlist", "status":"1", "message":"OK, 0x2a65aca4d5fc5b5c859090a6c34d164135398226"} 1
got message: {"event":"txlist","address":"0x2a65aca4d5fc5b5c859090a6c34d164135398226","result":[{"blockNumber":"5532531","timeStamp":"1525098009","hash":"0xe5ec497cb5b38811e8bf5db67a056a2bdd4aa9b68df5c8e8225cb300cbcfa413","nonce":"3363391","blockHash":"0xf446f77d92ed29c221e8451b8048113969ed305a7dd49177e10b422e8e2c4bda","transactionIndex":"172","from":"0x2a65aca4d5fc5b5c859090a6c34d164135398226","to":"0xec5fdfba35c01c6ad7a00085e70e8f30cd121597","value":"24418350000000000","gas":"50000","gasPrice":"4000000000","input":"0x","contractAddress":"","cumulativeGasUsed":"7896403","gasUsed":"21000","confirmations":"1"}]} 1

That’s quite a mess of transaction data, and unfortunately the datum of interest is in the ‘result’ field – which is nested JSON. In the last article, we converted simple JSON to a Lua table using the excellent sjson module. We’ll do the same here after verifying the message type is a transaction (txlist).

ws:on("receive", function(_, msg, opcode)
    print('got message:', msg, opcode)
    ok, ethdata = pcall(sjson.decode, msg)
    if ok then
        msgtype = (ethdata["event"])
        if msgtype == "txlist" then
...

The NodeMCU documentation specifically notes that nested JSON can cause out-of-memory errors. For that reason we use pcall (protected call) to contain any such errors when decoding our JSON message. Next, we extract the contents of the ‘value’ field, nested within the ‘result’ field:

if msgtype == "txlist" then
    wei = ethdata.result[1].value
    print (wei)
    eth = wei/1000000000000000000
    print (eth)
    end

It took me a few hours to figure out how to deal with nested tables, but in the end it was actually quite clean and easy — I was just being dense. Now, we need to add a basic provision to handle errors when the websocket is closed:

ws:on("close", function(_, status)
    print('connection closed', status)
    print('Reconnecting...')
    ws = nil -- required to Lua gc the websocket client
    tmr.alarm(0,4000,tmr.ALARM_SINGLE,transact) -- This reconnects after 4 seconds
end)

To wrap it all up, we encase the code in a couple of functions — first, one to establish a connection, subscribe to the right address, and notify when there is a transaction. Next we need one to display the amount of Eth transferred. Finally, we need a ‘ping’ function to call every 20 seconds or less to keep the connection alive. Overall this turned out to be more robust than expected and has yet to encounter an error. Check out the full code listing here. Note that I’ve also added a little code above to interface with a 128×32 OLED screen, the same one we used previously.

Now that it works, let’s consider im/practical applications. It’s a neat way to display Ethereum transactions in real-time, say if you do livestreaming and accept Eth donations and want them to trigger something fancy. Or, you could make a somewhat insecure vending machine. Clearly, getting a secure WebSocket up and running is the next order of business.

You could also set a timer where the length depends on the amount of Eth received. This would allow for things like public advertisements that go away for a while if someone pays a fee. (Please don’t do this!) Maybe a conference room for rent with the power controlled this way? Hackerspace membership payment? An electric bicycle that charges you for power used?

In any case, it’s not legal to use cryptocurrency as a form of payment in my country so I can’t implement any of the above examples at this time. If you’ve got a better application, please share it in the comments!

Accessing Blockchain on ESP8266 Using the NodeMCU Board

Blockchains claim to be public, distributed, effectively immutable ledgers. Unfortunately, they also tend to get a little bit huge – presently the Bitcoin blockchain is 194GB and Ethereum weighs in at 444GB. That poses quite an inconvenience for me, as I was looking at making some fun ‘Ethereum blockchain aware’ gadgets and that’s several orders of magnitude too much data to deal with on a microcontroller, not to mention the bandwidth cost if using 3G.

Having imagined a thin device that I could integrate into my mobile phone cover (or perhaps… a wallet?) dealing with the whole blockchain was clearly not a possibility. I could use a VPS or router to efficiently download the necessary data and respond to queries, but even that seemed like a lot of overhead, so I investigated available APIs.

As it turns out, several blockchain explorers offer APIs that do what I want. My efforts get an ESP8266 involved with the blockchain began with two of the available APIs: Ethplorer and Etherscan.

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Stretched PC Case Turned GPU Cryptominer

We don’t do financial planning here at Hackaday, so we won’t weigh in on the viability of making money mining cryptocurrency in such a volatile market. But we will say that if you’re going to build a machine to hammer away at generating Magical Internet Monies, you might as well make it cool. Even if you don’t turn a profit, at least you’ll have something interesting to look at while you weep over your electricity bill.

Sick of seeing the desktop machine he built a decade ago gathering dust, [plaggle24w5] decided to use it as the base for a cryptocurrency mining rig. Of course, none of the original internals would do him any good, but the case itself ended up being a useful base to expand on. With the addition of some 3D printed components, he stretched out the case and installed an array of video cards.

To start with, all the original plastic was ripped off, leaving just the bare steel case. He then jammed a second power supply into the original optical drive bays to provide the extra power those thirsty GPUs would soon be sucking down. He then designed some 3D printed arms which would push out the side panel of the case far enough that he could mount the video cards vertically alongside the case. Three case fans were then added to the bottom to blow air through the cards.

While [plaggle24w5] mentions this arrangement does work with the case standing up, there’s obviously not a lot of air getting to the fans on the bottom when they’re only an inch or so off the ground. Turning the case on its side, with the motherboard parallel to the floor, allows for much better airflow and results in a measurable dip in operating temperature. Just hope you never drop anything down onto the exposed motherboard…

Mining Bitcoin on desktop computers might be a distant memory, but the latest crop of cryptocurrencies are (for now) giving new players a chance to relive those heady early days.

IoT with the Ethereum Blockchain

Anyone keeping up with financial news today is surely inundated with stories about Bitcoin and other cryptocurrencies. While most of the news is about the potentially inflated value of some of these coins, and how drastically they have changed in price in just a decade, there are other interesting things going on behind the scenes. For example, the currency Ethereum allows for a distributed programming platform of sorts to be implemented in the blockchain, which [GusGorman402] has taken advantage of in his latest project (YouTube link, embedded below).

The device that he built is based on an ESP8266 which connects to a router running an instance of a Go Ethereum node. Essentially, he uses the Ethereum blockchain to control an LED connected to the ESP8266 using a feature of Ethereum called a smart contract. While this might be a misleading name, a smart contract is basically an autonomous program that can do virtually anything a programmer writes into it. While this is a roundabout way to write a “Hello World” program, it does demonstrate the power of the Ethereum platform when compared to other cryptocurrencies.

If you’re interested in currency trading, blockchains, cryptography, or the future of computing, be sure to check out the detailed video after the break. It’s a curious new tool, and it will be interesting to see how developers and hackers alike use it to accomplish things we’ve never thought of yet.

Continue reading “IoT with the Ethereum Blockchain”

Ethereum: GPU Mining Is Back But For How Long?

By now, everyone and their dog has at least heard of Bitcoin. While no government will accept tax payments in Bitcoin just yet, it’s ridiculously close to being real money. We’ve even paid for pizza delivery in Bitcoin. But it’s not the only cryptocurrency in town.

Ethereum initially launched in 2015 is an open source, it has been making headway among the 900 or so Bitcoin clones and is the number two cryptocurrency in the world, with only Bitcoin beating it in value. This year alone, the Ether has risen in value by around 4000%, and at time of writing is worth $375 per coin. And while the Bitcoin world is dominated by professional, purpose-built mining rigs, there is still room in the Ethereum ecosystem for the little guy or gal.

Ethereum is for Hackers

There may be many factors behind Ethereum’s popularity, however one reason is that the algorithm is designed to be resistant to ASIC mining. Unlike Bitcoin, anyone with a half decent graphics card or decent gaming rig can mine Ether, giving them the chance to make some digital currency. This is largely because mining Ethereum coins requires lots of high-speed memory, which ASICs lack. The algorithm also has built-in ASIC detection and will refuse to mine properly on them.

Small-scale Bitcoin miners were stung when the mining technology jumped from GPU to ASICs. ASIC-based miners simply outperformed the home gamer, and individuals suddenly discovered that their rigs were not worth much since there was a stampede of people trying to sell off their high-end GPU’s all at once. Some would go on to buy or build an ASIC but the vast majority just stopped mining. They were out of the game they couldn’t compete with ASICs and be profitable since mining in its self uses huge amounts of electricity.

Economies of scale like those in Bitcoin mining tend to favor a small number of very large players, which is in tension with the distributed nature of cryptocurrencies which relies on consensus to validate transactions. It’s much easier to imagine that a small number of large players would collude to manipulate the currency, for instance. Ethereum on the other hand hopes to keep their miners GPU-based to avoid huge mining farms and give the average Joe a chance at scoring big and discovering a coin on their own computer.

Ethereum Matters

Ethereum’s rise to popularity has basically undone Bitcoin’s move to ASICs, at least in the gamer and graphics card markets. Suddenly, used high-end graphics cards are worth something again. And there are effects in new equipment market. For instance, AMD cards seem to outperform other cards at the moment and they are taking advantage of this with their release of Mining specific GPU drivers for their new Vega architecture. Indeed, even though AMD bundled its hottest RX Vega 64 GPU with two games, a motherboard, and a CPU in an attempt to make the package more appealing to gamers than miners, AMD’s Radeon RX Vega 56 sold out in five minutes with Ethereum miners being blamed.

Besides creating ripples in the market for high-end gaming computers, cryptocurrencies are probably going to be relevant in the broader economy, and Ethereum is number two for now. In a world where even banks are starting to take out patents on blockchain technology in an attempt to get in on the action, cryptocurrencies aren’t as much of a fringe pursuit as they were a few years ago. Ethereum’s ASIC resistance is perhaps its killer feature, preventing centralization of control and keeping the little hacker in the mining game. Only time will tell if it’s going to be a Bitcoin contender, but it’s certainly worth keeping your eye on.