Colin G Platt On Peer-to-Peer

Last week I went out with for a beer and pizza with Colin G Platt of Blockchain Insider fame after we did a podcast interview about my book The Basics of Bitcoins and Blockchains at the 11FS office in Devonshire Square in London. Quite appropriately we settled down at the The Bell, a pub in east London and sometime home of the Ethereum London meetups, and talked about how peer-to-peer cryptocurrency payments are.

Here’s a summary of our conversation. Obviously it is heavily edited and we’re not as witty or eloquent as this in real life (well I’m not anyway).

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Bitcoin’s payments are not peer-to-peer!

This post is adapted from an article first published on R3’s Medium.

In this post I articulate what a peer-to-peer transaction is, why Bitcoin transactions are not peer-to-peer, and why it is important to understand the differences clearly. I describe the benefits of peer-to-peer transactions and discuss that Corda is the closest architecture to take advantage of those benefits.

Note: This post has prompted some welcome discussions around Bitcoin’s permissionlessness and censorship resistance.  I should make clear that in this piece I’m discussing how I think about peer-to-peer, and not whether Bitcoin’s transactions, or transactions on any other platform are centralised or censorship resistant.  I think it’s important to understand the distinction clearly.

We are always told that Bitcoin is peer-to-peer, but is it? It turns out Satoshi is almost always grossly misunderstood by both the mainstream media and Bitcoin proponents. Bitcoin payments are not peer-to-peer. While Bitcoin’s bookkeepers (non-mining full nodes) and database writers (miners) exist in a peer-to-peer architecture with no central actor containing a master copy of the Bitcoin ledger, Bitcoin payments themselves are not peer-to-peer.

Physical peer to peer transactions

Peer-to-peer means something moving from me to you. When I hand you a banknote, physical cash, and you accept it, I have settled my financial obligation with you without needing a middle man to approve, or who can censor, the transaction. This is a peer-to-peer transaction (it is also censorship resistant). The result is that instead of me having a claim against the central bank (which is what cash is), you now do.

Digital peer to peer transactions?

If you and I have bank accounts with the same bank, and I want to pay you digitally via the bank, data doesn’t move from my computer to your computer. What happens is that I instruct my bank to move money from my account to your account. If all is well, the bank debits my account and credits your account.  The result is that instead of me having a claim against the bank (that’s what bank deposits are), you now do. The bank is an intermediary, in the sense that it carries out the transaction. This is not peer-to-peer.  It is also not permissionless (we need the bank’s permission to have accounts there) or censorship resistant (the bank can decide not to carry out the instruction).

If you and I have accounts with an “e-wallet”, for example Venmo, Alipay, WeChat, Uber, Grab, or whatever, and I want to pay you, again it’s not a peer-to-peer payment despite what they may say in their marketing materials. Data doesn’t move from my mobile phone to your mobile phone. What happens is I instruct the wallet provider to debit my account and credit your account. The result is that instead of me having a claim against the wallet provider, you now do. The e-wallet is an intermediary, in the sense that it carries out the transaction. This is also not peer-to-peer.  It is also not permissionless, or censorship resistant.

Are Bitcoin transactions peer-to-peer?

And if you and I operate within the confines of the Bitcoin network, the payment is not peer-to-peer. No data moves from my computer or phone to your computer or phone. Instead, I instruct the group of approximately 10 miners to competitively accept my transaction which effectively debits my bitcoin account and credits your bitcoin account, and I hope that the bookkeepers (the nodes) accept and relay the block that my transaction ends up being recorded in. We can call the miners and bookkeepers the “Bitcoin bookkeeping cloud”. The result is that instead of me holding bitcoins in my account, you now do. This is the same, more or less, as the situation with banks and e-wallets, with the exception that I’m instructing a bunch of competing entities to process my transaction instead of instructing my specific bank or e-wallet.  Is it permissionless?  Yes to the extent that anyone can create a Bitcoin address.  Is it censorship resistant?  Yes,  well, ish, to the extent that the miners mining the longest chain don’t collectively want to censor the transaction, and that the community chooses to accept their chain.


What we have learnt from Bitcoin is that we can decouple the single-spending of digital assets (which is what Bitcoin’s bookkeeping cloud does) from the provision of services against those assets (a service being something like foreign exchange).

When something can be moved from one hard drive to another, with guarantees of its authenticity, uniqueness, and inability to double spend, then we have a true digital token that behaves like its physical equivalent.

We are not there yet with Bitcoin. Bitcoin does not behave like a digital token. But it has shown us the way.

The industry is still figuring out ways of creating digital assets that can move from peer to peer without necessarily being trapped in account balances controlled by third parties, with all the drag that comes with that.

Why does this matter?

The thing about peer-to-peer transactions is that in some respects they are exceedingly efficient — they don’t rely on layers of middlemen to credit and debit accounts, each charging fees and each doing it at their own convenience. We can agree a trade bilaterally and settle it, at our own convenience, without a third party needing to be awake and operational, and without relying on their settlement processes (and fees!). Just like a digital version of physical cash. Real peer-to-peer tokenised transactions can settle more quickly, with fewer costs and risks associated with relying on third parties. This can also de-risk the entire financial system by reducing the number of systemically important too-big-to-fail entities.


At this stage, it seems that Corda is a platform whose assets have the most token-like properties. In a Corda transaction, data representing the asset moves from the sender to the receiver, with only the minimal required amount of information going to a notary service to prevent the double spend.  This is unlike Bitcoin or Ethereum where all the parties on the whole network see and validate the full instruction.

In another post I will describe the natural evolution of this thinking: Single-spend-as-a-service. This is the direction that the industry is heading in — the hugely valuable decoupling of double-spend prevention from the control of digital assets.


What is Blockchain?

Yesterday I did an recording where the interviewer asked me a simple question – what is blockchain? This got me thinking – I had no go-to answer for this. People use this word to cover a wide range of networks and platforms, and some platforms such as R3’s Corda (Note: I work at R3) are categorised as “blockchain” platforms, when they don’t even bundle transactions into blocks!

The best description I could come up with was:

Blockchain is a word used to describe a bundle of technologies that allow digital assets to be created and passed from party to party with guarantees that the assets are authentic and haven’t been copied or counterfeited all without needing to trust a third party to open and maintain accounts for customers.

To break this down a bit:

Blockchain is a word…

I’ve stopped describing a blockchain as a data structure – the word just simply isn’t used exclusively in this context any more.

…used to describe a bundle of technologies…

Cryptographic hashing, public key cryptography, peer-to-peer networks, data sharing over the internet, databases, data structures, even zero knowledge proofs and other fancy new mathematical techniques.

…that allow digital assets to be created…

Sometimes mined, sometimes pre-mined, sometimes created within smart contracts, sometimes created from nothing. Now of course we aren’t talking about assets like photographs and documents which may be copied and shared, we are talking about assets where it is important that there aren’t copies, such as native cryptocurrency tokens, and legal agreements between issuers and bearers – which is what financial assets are.

…and passed from party to party…

This is the bit that is badly explained in the general blockchain narrative. People describe cryptocurrency payments as peer-to-peer. They are not. Most blockchain platforms and networks are architected as peer-to-peer networks (ie there is no “master” or golden copy of the ledger that is more senior than others), but the payments themselves are not sent from peer to peer. Think about it – if I send you a bitcoin I do not send data from my computer to your computer, as I would if I gave you some physical cash. Instead, I instruct the “cloud” of Bitcoin nodes to spend some BTC under my control and put them under your control. In fact, Corda is the only popular platform where data representing the token or asset is actually sent from the sender to receiver.

…with guarantees that the assets are authentic…

Using digital signatures and chains of transactions that enable you to trace the asset token back to when it was created – either mined or created in some sort of smart contract.

…and haven’t been copied or counterfeited…

If there’s one thing the blockchain industry has taught us, it’s that digital assets can be double spent. So the platforms have mechanasms to detect and resolve attempted double spends.

…all without needing to trust a third party to open and maintain accounts for customers.

All cryptocurrencies use the concept of accounts – this is your address or addresses managed by your wallet. But the difference is that you created your account at your end by plucking random numbers and using your random number as your private key, without having to go to a third party to open an account.

One of the key benefits of these digital assets, is that as tokens they can represent almost anything, and they can exist on the same ledger platform. We no longer need a “cash ledger” for money, an “equities ledger” for shares and random invoices floating around between companies as pdf attachments. We can tokenise all the things and transact on them together in so called “atomic transactions”, and they can also be subject to transparent and shared logic – smart contracts. But I’ll go into more detail about those benefits in another post.

Banking When the Bank is Shut – Token Maximalism

In this post I describe why freeing financial assets from the books of custodians and returning control of them to their owners as tokens could create significant benefits to an economy. This brings together concepts from traditional finance, cryptocurrencies, and enterprise blockchains.


Today, your digital financial assets (cash, equities, bonds etc) are trapped in the accounts of custodians who have a temporary monopoly over the services you are able to access. We have bundled together prevention of double spend with the provision of additional services. We can now split these services up: by recording financial assets as tokens with distributed bookkeeping, and where owners have direct control over those assets, we are able to free up the assets and put them to better use, increasing liquidity and utility value of all assets, increasing the competition for financial services, and potentially even increasing the quality and velocity of business done in an ecosystem.

The argument is as follows:

  1. Financial assets are trapped in account balances managed by specific custodians acting as bookkeepers, who have a temporary monopoly over providing services against those assets.
  2. Distributed ledgers allow the recording and transfer of assets with the prevention of double spend, without forcing the owner to use a specific service provider.
  3. Assets recorded as tokens can move more freely, increasing the liquidity and utility value of those assets.  Competition is increased, as asset owners have the ability to select (financial) service providers in real-time.
  4. Businesses who self-bookkeep assets as tokens may reduce their reliance on 3rd parties, allowing them to do business at their own speed rather than being subject to 3rd party drag.


Financial assets are trapped in account balances

Custodians. Traditional financial assets (money, shares, bonds etc) are held by custodians who manage the accounts of their customers. Custodians are special businesses, usually licensed and regulated, and they keep lists of who owns what. Among other things, they make debits and credits between their customers who hold accounts with them and they ensure that the same asset can not be sent to two different parties (the double spend). They are licensed to do business if they behave in certain ways as demanded by their regulators.

Cash custodians. Your bank (or building society or credit union) is your cash custodian. You don’t directly manage your own digital cash as files on your hard drive, your bank does it for you. You have an account with your bank and when you want to do something with your money, you instruct your bank to make a payment on your behalf, or when you want to convert your bank deposit into physical banknotes. They then may or may not act on your instruction, perhaps with a delay, and perhaps with a fee associated.

Asset custodians. Your non-cash financial assets (shares, bonds, etc) are managed by an asset custodian, often called a securities depository. They too have their business processes, opening hours, and of course fees. Usually households and businesses do not have accounts directly with the depository, usually there are other layers of businesses such as securities servicing companies, fund managers, and brokers who all add value and charge fees. For example, you may use a broker to find a fund manager who uses another broker to buy asset, held at a custodian who performs securities services on the asset which is held at the securities depository.

This chain of ownership can be complex and needs to be traversed each time there is an “event” with the underlying asset. If, for example, if you own a share of a company, and the company issues a dividend, somehow money needs to move from the company’s bank account to your bank account. This plays out as a series of debits and credits across potentially a number of banks, with the ownership of the cash changing several times before it ends up in your bank account.

Trapped. In all cases, your assets are trapped in the books of the custodian. In no cases do you yourself hold the asset (unlike with physical cash or bearer bonds). For digital assets, the “golden source” is always someone else. (Even with Bitcoin and public blockchain cryptocurrencies, the golden source of ownership is the respective blockchain, not your own hard drive, though you uniquely hold a private key which you use to create a payment instruction that the network will deem valid)

Operational costs. When you instruct your bank or asset custodian, it makes a decision whether it’s going to act on it or not. Usually it acts, sometimes immediately, other times more slowly, and usually for an implicit or explicit fee. Sometimes, for different reasons, your bookkeeper prevents you (or someone pretending to be you) from accessing our money, perhaps if you want to withdraw a substantial amount, or make a large payment, or make a payment to a beneficiary who the bank deems high risk, or perform unusual activity. This is not always necessarily a bad thing.


Custodians acting as bookkeepers have a temporary monopoly

When you have deposits in a bank and you want to consume financial services, at that moment you have no choice but to use that bank’s services. Your money is under the control of that bank.

Cash. For example if you have SGD 100,000 at Citibank and you want to convert it into GBP, you have to use Citibank’s FX rates. You can’t scan the market, decide that you want to use DBS’s more attractive FX rate, and have DBS do the FX for you. You would need to instruct Citibank to move the money to your account at DBS (assuming you have one), perhaps incurring a withdrawal fee, perhaps subject to delays or other financial or temporal penalties and drag, before seeing a deposit appear in your account at DBS.

Asset custodians. The same principle applies with other financial service custodians, but more acutely. Although in many countries, households are able to access banking facilities on an almost continuous basis, with the appearance of being able to make 24×7 real time payments, non-cash financial assets are less well served. Often, services are provided during traditional office hours. This is especially common for non-money financial assets such as securities. There are in general fewer asset custodians than cash custodians, creating what is in effect an oligopoly or in some countries a monopoly, leading to a stagnancy in innovation in the sector and a tax on the real economy.

Downtime. Sometimes for various reasons, your custodians are non-operational. Perhaps they are performing scheduled systems maintenance; perhaps it’s unscheduled maintenance; perhaps they have a bug; perhaps they are getting hacked.

At other times your bookkeeper is not open for business, either because it is their policy to be closed at weekends, or because of their IT or business failures or because they are being cyber attacked or they may not have enough liquidity (money) to support a large outgoing payment.

Irrespective of the reason, you’re stuffed and the matter is out of your hands – possibly you can’t do anything with your assets. This is one of the downsides of relying on 3rd parties. This happens more often than you might imagine. See: Bank of England, Reserve Bank of Zimbabwe, ANZ, ABSA, TSB (down for two weeks!), DBS bank, OCBC bank etc etc, or when other 3rd parties who provide intermediary messaging fail (Visa, Mastercard).

Source: Citibank iPhone app


Assets recorded as tokens can move more freely

Financial assets are just agreements. The vast majority of financial assets are digital-only, or “scripless” in the jargon. They exist as entries in databases of custodians rather than as bits of paper held in vaults. This digitisation is a good thing and has enabled innovation and competition. Financial assets can be represented digitally natively because they are nothing but legal agreements between issuer and owner. Even money is an agreement between the issuer (central bank, commercial bank, wallet, etc) and the owner. These financial assets are unlike physical assets (mangos, fish, lettuce etc) which cannot exist entirely digitally.

Tokenised. What do we mean by tokenised? In this case I mean that the assets are represented by lumps of data sitting in a ledger that is not managed by a single authority but instead governed by some agreed rules, which act to prevent the double spending of these assets. Often instructions are automatically executed by multiple parties in a network who need to agree with each other about whether the transactions fulfil the rules of the network (so called “smart contracts”).

Pedantry note: We use the word tokens to mean different things in different contexts. In the physical world, a token is the asset with value, eg a fairground ride token, a banknote, a casino chip. In the blockchain world, we use the word token but data isn’t passed from owner to owner, instead the tokens are recorded on a ledger replicated by a group of computers. When I pay you in BTC, I do not pass some data from my computer to your computer as I would pass a banknote from my hand to yours; instead I instruct the Bitcoin bookkeepers to essentially debit my account and credit yours (I know, I know, UTXOs but they are linked to account numbers). By this definition, the only “blockchain” platform that I am aware of that actually has digital tokens is R3’s Corda (Note: I work at R3 and I think Corda is great) where the data that represents the assets are passed from owner to owner in a peer-to-peer manner.

Moving more freely. If assets are recorded on a distributed ledger and controlled by private keys held by the owner, they are more free to have actions performed on them (eg transfer of ownership, accessing a service), without a specific temporary monopolistic custodian needing to be “awake”, and without being held hostage to the custodian’s speed, execution accuracy and financial and operational drag.


Tokenised assets can be more liquid

Liquidity. What does liquidity mean? It means that you can do what you want with the asset, whether that is sell it quickly at a predictable price without moving the market away from you too much, or whether it is easily and quickly giving it to another party (presumably in exchange for something). Cash in a bank account is fairly liquid (subject to daily limits, bank opening hours, cut-offs etc) whereas a physical house is less liquid. Physical cash is liquid as long as the party you are trying to pay is physically nearby; to make physical cash payments at a distance is troublesome.

Tokenised assets. If assets are tokenised on a blockchain platform that is open all hours and which is not controlled by a single entity but instead is governed by multiple competing entities (‘miners’ / ‘orderers’ / ‘notary services’ etc), and there is a defined way of interacting with that platform, you can do more with the tokens than with balances held in accounts controlled by single entities who may be non-operational. You can find more venues for trading your assets – they are more liquid.


Tokenised assets can have more utility value

Utility value. When is a dollar more valuable than another dollar? When you can do the thing you want to do with it. Ten dollars in your pocket does not have the same total value as ten dollars in your bank account, or $10 in your Uber wallet, or your $10 Starbucks voucher. Although they have the same nominal value ($10), they have different usefulness or utility value.

The relative value of those forms of money depends on what you want to do with it.

For example, if you want to buy lunch at a street food stall, and they only accept cash, then your bank deposit, Uber credit and Starbucks voucher are all useless in that scenario. They have a utility value multiplier of 0. Conversely, if you want to transfer money to your friend who is not standing right beside you, the physical banknote in your pocket is pretty much useless.

The Uber credit is great if you want to call a cab (yes, I know, hire a “private hire vehicle operated by an independent self-employed driver”, whatever), or buy some lukewarm food, but not good for much else. Likewise, the Starbucks voucher can get you your caffeine or sugar hit but you can’t pay your rent with it.

So we can separate the nominal value of the money (a dollar is a dollar) from the utility of that dollar (can I do the thing I want to do with it, right now?).

Tokenised money. Tokenised money has more utility value than money held hostage in an account in a couple of ways:

  1. Banking when the bank is shut. Depending on the platform on which it is tokenised, it can be moved/paid/reassigned irrespective of if the issuer is online or not. The blockchain platform guarantees the bookkeeping and promises to not allow double spends. This decouples the issuance of the asset from the bookkeeping and service provision, and also means that the holder of the asset is not beholden to a specific bookkeeper to be awake and working when the holder wants to transact.
  2. Atomic transactions and delivery vs payment. This is huge. As more assets become tokenised, transactions can be created that making changes to multiple assets simultaneously. For example, an invoice can be marked as “paid” in the same transaction as the movement of the payment – and both parties can see this simultaneously without further reconciliation. A share can be marked as “ex-dividend” at the same time as a payment made from the issuer to the beneficiary, with no confusion. A bond can be marked as “post-coupon” at the same time as the coupon is paid. A share can transferred in the same transaction as the payment. A bilateral financial derivative can have some event recorded triggered by something else, such that both parties are in do doubt as to the status of it. And so on.

To summarise, tokenised free-flowing money may be more useful and hence more desirable and valuable as an asset, than money held hostage by a specific bookkeeper. When other assets become tokenised on ledgers, this utility value becomes even more pronounced.

Other tokenised assets. Everything that can be represented entirely digitally, and that needs to move across organisational boundaries with guarantees of authenticity and liveness (what is the current state of this?) are most usefully represented as tokens on distributed ledgers. This includes cash and securities but also commercial agreements such as purchase orders and invoices.


Tokenised assets can increase financial services competition

Service provision. Not all banks or custodian provide all or equivalent services. If you want to consume a service that is not offered by your bookkeeper, you need to move your money or assets elsewhere.

Tokenised assets. Because your token is effectively self-custodied (only you have the private key that can generate valid transactions), you can choose your service provider at any time. If you want to do FX, you can select the cheapest FX provider that you have a relationship with, and user their services immediately. This increases competition and financial service providers will need to step up their game. Competition is healthy. With tokenised assets can may be able to select service providers in real time and instruct any of them to perform services on your assets with the click of a button.


Businesses who self-bookkeep can do business at their own speed

Transacting directly. Be removing the bookkeeping function from a specific entity and effectively self-bookkeeping, you can transact at your own pace, when you want, rather than being beholden to the manager of your account-based balance.

This can reduce 3rd party drag and return benefits (speed, cost, operational efficiency) to the real economy.

An economy that can do business at the speed of corporates, without the operational and financial hinderance and friction of cascading chains of 3rd parties, could gain a competitive advantage over those economies who choose not to implement this decentralised financial market infrastructure (dFMI – hat tip to Robert Sams for coining this phrase and Tim Swanson for popularising it).  Specifically what is decentralised?  At the very least, the double spend prevention.  Everything else, such as services, can be competed for in a market environment.



Owners of digital financial assets, especially money, rely on centralised and quasi-monopolistic bookkeepers, usually private entities. The bookkeeper’s incentives (making money from bookkeeping and providing services) are not aligned with those of the customers (being able to do what they want with their assets, including selecting different service providers). Blockchains and distributed ledgers can create decentralised financial market infrastructure and return the bookkeeping, control and management of assets back to the owners.

Traditional custodians of cash and other assets should think about how they might operate in the new world of dFMI. There are plenty of roles for them – decentralised ledgers need to be governed, assets need to be issued, and lifecycle events still need to be managed, though tokenised digital assets may have more automation built into them in the first place.

Jurisdictions who implement decentralised financial market infrastructure could quickly become more competitive than those who don’t, and a small increase in efficiency and commercial attractiveness can, over time, have a positive effect on GDP and lead to large systemic productivity advantages to that jurisdiction.


The Basics of Bitcoins and Blockchains

Last December I was approached by a publisher, Mango, who asked me if I would write a book about blockchain technology.  A little nervously, I agreed, and I’m excited to announce the result of six months of effort:

The basics of bitcoins and blockchains - book cover

The Basics of Bitcoins and Blockchains is an essential guide for anyone who needs to learn about cryptocurrencies, ICOs, and business blockchains.  Written in plain English, it provides a balanced and hype-free grounding in the essential concepts behind the revolutionary technology.

I wrote The Basics for an audience of business people, students, practitioners, and those who are simply interested in this technology.  I tried to make it entertaining even for those who are already working in the cryptocurrency or blockchain industry.  For example, did you know:

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Frictionless Tokens Create Friction

We’re gonna need another intermediary…

In 2013-15 it was trendy for online merchants to pretend to accept bitcoin as payment. It was a very cheap way to get positive media mentions and seem innovative. Overstock, Dell, Tiger direct… they were all at it after they realised it was all media upside. Even Virgin Galactic accepted bitcoin as payment for trips to space at some point (Note: I think paying for a trip to space with bitcoins is actually quite cool).

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A gentle introduction to digital tokens

Digital tokens have come to the fore recently, firstly with excitement about cryptocurrencies such as bitcoin, then with digital tokens being used to represent different assets on a blockchain.  What are they?  How can you digitise a token?  Why is it important?

When I hear the word ‘token’ I think of round plastic things like a casino chip, or something which I can use to exchange for a beer under a specific system or in a specific marketplace.

My idea of tokens.

We will explore the original usage of the phrase ‘digital token’, then take a look into the world of cryptocurrency tokens, differentiating between blockchain-native tokens like BTC on Bitcoin or ETH on Ethereum, and asset-backed tokens like IOUs on Ripple.

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