Those of you who have been following my recent posts about digital currencies may remember my recent discussion with Alex Tapscott, founder and CEO of Northwest Passage Ventures. He’s the co-author along with his dad, the business theorist Don Tapscott of the best selling book ‘The Trust Protocol: How Blockchain Technology Will Change Money, Business and the World. ” In my last post, we delved a little into the topic of blockchains, those public ledgers that allow digital currencies like bitcoin and others to be sent to others as a form of payment. Here, Alex discusses the different forms that a blockchain can take.

“There are lots of different ways to make a blockchain, with some being public and some private, and a lot of times people don’t really know what that means,” Alex said. “Basically a public blockchain is simply one that is open and permissionless, where anybody can access it regardless of where they are or who they are.

“And typically public blockchains have a native token, a cryptocurrency like bitcoin or in the case of Ethereum—a blockchain-based computing platform that can execute peer-to-peer contracts—a cryptocurrency called ether. Public blockchains have a lot of positive attributes. Because they’re open, they have many different participants, and the more participants there are, the more transaction validity you get.”

Alex acknowledged fears that cryptocurrencies might be hacked, with bitcoins or other currencies actually stolen, but said public blockchains help mitigate the risk.

“The more different people you have, the more distributed it is, which generally speaking reduces the chance of attack, because you have to attack many computers rather than one computer. Also, because you’ve got lots of different computers, there’s more energy and more computing power going into this blockchain, which makes it more secure for the most part.

“Now, there is a flipside to public blockchains which makes it somewhat limited, at least today. Transactions in a public blockchain have to be broadcast across the whole network. This means that the number of transactions that the blockchain can handle is limited because, remember, it does requires a lot of computing power and a lot of energy. So the question of scalability is one that’s still unresolved in public blockchains.”

By contrast, Alex noted that private blockchains are made up of participants who have permissioned access. And with fewer participants a private blockchain can manage a higher transaction volume, he said.

“And it can manage more types of transactions, too, because the rules are set by the participants, and they can change the rules to meet different types of assets. Everyone trusts each other somewhat, and can trust that they each have the necessary computing resources to manage the blockchain. That means it’s unlikely that someone won’t have the ability to participate fully.

“Also, because private blockchains are permissioned, they are, generally speaking, more palatable to regulators, because you could grant permission to different parties in a transaction. One of those parties could be an auditor like PricewaterhouseCoopers, for example. One of them could also be a regulator who could look in to see the metadata and validate what’s happening.”

In future posts, we’ll delve into a lot more about the future of cryptocurrencies, including setting up private blockchains, regulatory aspects, security and more. Watch for it!

I’ve had a great time chatting with cryptocurrency expert Alex Tapscott about the future of digital money, and how it may (probably) change our lives. In my last post with Alex—founder and CEO of Northwest Passage Ventures and coauthor with his dad Don of the book, “The Trust Protocol: How Blockchain Technology Will Change Money, Business and the World”—we discussed the all-important topic of security: Who actually is minding the store on these new types of monetary transactions involving such things as ether, bitcoin and other new digital currencies?

A major issue—perhaps the single most important issue, actually—is trust. There’s plenty of trust in the U.S. dollar, but what about bitcoin and other digital monies? I asked Alex how one establishes trust in this brave new world of digital currency?

“Traditionally we have an intermediary to establish trust, those agencies that verify the identity of parties, perform the processing, and the clearing and maintaining of reliable records. Now, intermediaries—call them banks, credit card issuers, PayPal, you name it—do a pretty good job at that, but they have certain limitations. They’re centralized, they cost money, they capture data, and doing so can slow things down if they’re using old technology.”

Well then, I thought. what’s the new paradigm for digital currency? Who is governing whether bitcoin and other digital monies are “real” or not? Alex discussed a bit about blockchain—bitcoin’s main technical innovation, a public ledger for bitcoin transactions allowing users to connect to the network, and send and verify transactions.

“With blockchain, you’ve got a new platform where trust is not established by a third party, but rather established through maximum collaboration and clever code,” Alex replied. “In a public blockchain (more on this later), you have an incentive mechanism in that users commit computing resources to validate transactions, and then are rewarded for reaching consensus on what is ‘true’ by receiving bitcoin or an Ethereum ether.”

But, I asked Alex, how do you validate a crypto transaction? After all, it’s not script, like the U.S. greenback or the euro.

“Right now, there are a whole bunch of different solutions that have been proposed. A mining method is called a ‘proof of work.’ So in exchange for doing lots of work, you have the chance of getting rewarded. But there are other different ways of validating a blockchain, like ‘proof of stake,’ which basically just confers validating power on whomever owns a share of the network.

“So, if you have 10 banks in the network, and each of them owns 10%, then no transaction is valid unless all 10, or some plurality or majority, can reach consensus,” he said.

Since we were dealing with the all-important topic of trust here, I had to ask: How much effort does it take to break a blockchain and steal money? Trust is the key to the new world of digital currency, right?

“One of the great advantages of the bitcoin blockchain is that validating transactions takes a lot of work, so guess what? Hacking transactions to try to break the blockchain—to steal money—takes an equal or greater amount of work! That’s what makes it really safe. So in order to hack a transaction on the bitcoin blockchain—to, say, send the same $20 twice or sell the same share 10 times because you’re trying to make 10 times the profit—you wouldn’t just have to rewrite one transaction. You’d have to rewrite every transaction, basically back to the beginning of the blockchain, and do so in a really short window.”

Alex told me he feels that proof-of-work blockchains that use a native token like bitcoin, or Ethereum’s ether, are the ones that are likely to succeed. “I think that private blockchains that don’t have that could work, but I don’t think they’ll ever be as secure.”

Next time, we’ll look a little closer at public versus private blockchains, to get a better feel for why Alex thinks one may prevail over the other, at least in the short term. Stay tuned!