What is a blockchain?

2018 is poised to be year when cryptocurrencies become mainstream. The original cryptocurrency, Bitcoin, has entered the common jargon of the modern world last year as its valuation hit record a record high of nearly 20k USD/BTC, and stayed in the news as its valuation dropped to more reasonable levels. Ethereum is also gaining recognition as it became the #2 cryptocurrency in terms of market capitalization. In short, a little over 8 years since the creation of Bitcoin cryptocurrencies are gaining recognition and acceptance in the “real” world.

Cryptocurrencies are created as part of something called a blockchain. And more than cryptocurrencies, it is the blockchain idea which is expected to have a huge impact on the computing world, at least for the next couple of years. As such it is a good idea to learn what a blockchain is, at both a basic and more advanced level.

The Basics

At its core, a blockchain is a distributed ledger. Those with an accounting background will immediately recognize what a ledger is — it is a record of transactions. A blockchain is distributed, which means that entries in the ledger are written by many parties, as opposed to by one centralized authority.

Like an ordinary paper ledger, blockchains are write-once. Once a block has been verified and added to the blockchain it cannot be erased or modified. This insures that transactions cannot be taken back.

The Nodes

All these “parties” are actually computers running a node for the blockchain’s network on the internet. This involves executing software which contributes to the blockchain network. Depending on the network involved there may be several types of nodes in a blockchain; this will be explored in depth later.

The Blocks

Nodes compile a number of transactions into a block. How large the blocks are, and how often they are verified, varies widely between blockchains. For example, the Bitcoin blockchain generates a block every 10 minutes. The Ethereum blockchain, in comparison, generates a block in less than 20 seconds, and Bitshares blocks are generated every 3 seconds at most. A number of factors affect block time; if you’re not intimidated by math check out this article for more information.

The Chain

Blockchains are so named because each new block is appended to the previous block, effectively forming a chain. In fact one can always look at certain information in the latest block of any given blockchain and trace the blockchain’s history all the way back to its very first block.


Since blocks are appended to the blockchain by several different nodes, there needs to be a way to ensure that only the block with the right data can be added at any given time. Otherwise there would be no way of ensuring the continuity of the blockchain from the genesis block to the most current one.

This is where hashing comes in. Hashing is a cryptographical technique that is used to generate a unique code that can be used to identify a set of data, rather like a fingerprint. The hash is generated from the transactions contained in the block and recorded as data in the block, which also includes the hash from the previous block. This is one of the mechanisms used to verify any new blocks. If the previous-block hash does not match the previous block’s recorded hash, then the current block is invalid and cannot be added to the chain.

The actual library used to generate the hashes depends on the blockchain. SHA256 is a popular one and is used by Bitcoin. Other libraries include scrypt, X11, Cryptonight and ETHash.

Hashing produces a completely different string if there is any change whatsoever to the original hashed content. The SHA256 library can produce a very large number of distinct values (3.4028237e+38) so arriving at the same value from two different pieces of content is extremely unlikely. By comparison, the chances of winning the Powerball lottery in the USA is 1 in 2.92e8. One could win this lottery 4 times and that would still be less likely than generating the same hash from 2 different sources. Thus the use of hash values makes blockchains virtually tamper-proof.

This was a very basic overview of blockchains. We’ve barely scratched the surface. In my next few articles I will be providing more in-depth coverage on subjects such as concensus algorithms, blockchain node types, the relationship between blockchains and cryptocurrencies, and how the blockchain can be used by businesses to streamline processes and reduce processing costs.

For audiophiles only

Ever wondered what it’s like to put a pair of $55,000 headphones on and listening to your favorite tracks? This guy has experienced the Sennheiser Orpheus.

Gender bias?

An interesting article in the New Yorker raises the question: do gender stereotypes let some murderers get away with their crime(s)?

Good riddance to 2017

Welcome 2018. And as for the annus horribilis that was 2017, well, I’m perfectly happy to see the back of it.

Honestly, it was just awful, despite a pleasant start with family. This year we’ve had one of the girls involved in a shockingly severe accident on her scooter, I have reportedly fought the mumps (that’s Halifax for ya) and possibly mono in the fall. I also spent half the year in depression which was not quite properly treated,which culminated in my firing one month before Christmas. Yay.

Of course I may well be better off not working for Ping anymore. I never quite fit in there the way I did at Actional, where I spent 8 years before being laid off. Then again that layoff did leave me rather more bitter than before. It certainly left me feeling that I can’t trust employers at all. The phrase “human resources” says it all – as an employee you’re a resource to te company, alongside capital, real estate, computers and office furniture. You are no more than that. Companies realize the negative connotation of the name and sometimes call it something else like “people operations”, but there’s no real difference. I can call myself Sebastian Vettel all I want, that’s not going to make me a four-time F1 world champion.

Perhaps my error has been in seeking salaried work when I should rather try to develop my own ideas. And so I find still a little optimism going into the new year. Maybe I can find my real calling this year. We will see.

The best of Marty Feldman

Marty Feldman was not as well-known in North America as he was in the UK, and many here may think that his bulging eyes made him a bit of a one-trick comic but he was a comedy genius.

Seen in the Rideau Centre

Yes, that’s an Apple Store across the way from a MAC store.

At the Disney Store

Disney Store Ottawa
Disney Store Ottawa

The Disney Store at Rideau Centre, which as a parent I am contractually obligated to visit. They own pretty much 100% of the entertainment industry at this point, but I can’t help but notice how little stuff they have related to films and shows they did before 1990, which is a shame.


I know that Ottawa can be cold but ice *inside* a hotel window?

Haircuts for kids

If you’re going to get your child’s hair cut this is the place to do it! Chiquicuts on Clyde in Ottawa.

Dream final?

Oh boy, FIFA’s gone and done it again. Its own site proudly trumpets “Dramatic semis produce dream final“, and the article goes on to proclaim that a Japan-USA rematch is “the gold medal match fans the world over were hoping to see”.

Well, it’s the final that FIFA was hoping to see, clearly. When you put things in those precise terms, FIFAbots, people might at some point assume that the result of the Canada-USA match was rigged. And given FIFA’s own notorious problems with corruption and people at very high levels passing brown envelopes full of money up and down the chain to ensure expected results (let’s not kid ourselves, that’s how Qatar got the next world cup) it really should make more people wonder whether FIFA has perhaps taken a position on the match that was not exactly impartial.

And when I now hear that FIFA is looking into punishing Canadian players for their post-game comments, while the real outrages that took place on the field remain unquestioned, I can’t help but see Sepp Blatter as your traditional mafia don, preordering the result of important games and exacting a capricious, autocratic revenge on anyone who dares question his dictatorship. Remember how this is the same idiot who didn’t think there was anything wrong with Thierry Henry’s infamous handball which sent big-market France to the World Cup finals and sent small-market Ireland homeward.

It’s time to call a spade a spade here. FIFA and its leadership are corrupt to the core and everybody knows it. It’s time for serious football to organize in an organization which is not so completely and utterly rotten.

edit: I’ve decided to save a copy of FIFA’s “dream final” text to this post, as I have a feeling that it will probably be heavily edited later.