Blockchain is a distributed ledger or database that records transactions in a way that makes it difficult or impossible to change, hack, or cheat the system. It was originally developed for the digital currency Bitcoin but is now being explored for other uses. However, the document argues that blockchain is not well-suited for most applications and should only be used in very specific cases where there is no trust between parties, data must be immutable, or regulation cannot be relied upon. In most situations, a traditional centralized database is more practical and suitable.

1. What is Blockchain?
And why should we care
Paul Johnston @PaulDJohnston Medium/Twitter

2. Paul Johnston
Twitter and Medium: @PaulDJohnston
Discuss Cloud / Serverless / Being a
Chief Technology Officer (CTO) / Climate
Change
Interim CTO/Consultant (currently
available)
Ex-AWS - the largest cloud company in
the world
Startup founder, Advisor and
Conference series founder

3. ETHICS WHITEPAPER - THE STATE OF DATA
CENTRE ENERGY USE IN 2018
bit.ly/2024wp

4. https://www.change.org/p/sustainable-servers-by-2024

5. Data Centres are responsible for
more than 2%
of Global Carbon Emissions
(This will become important later in the talk)

6. What actually is Blockchain?
(aka Distributed Ledger Technology)

7. A Ledger

8. A Ledger with Hashes per Record
Each record has it’s own one-way hash.
Utterly unfeasible to reverse.
Easily verifies the transaction hasn’t been changed.

9. A “Block” of Hashed Transactions
The block has a hash of all the block’s hashes

10. Block 1
Block 2
Block 3
}
}
}
(Genesis)

11. Block 1
Block 2
Block 3
Reference block 2 hash
Reference block 1 hash

12. Block 1
Block 2
Block 3
Blockchain
A
Chain
of
Blocks

13. A Distributed Ledger
!
"#
$
New blocks
are agreed
between all

14. A Distributed Ledger
!
"#
$
The more copies
distributed the
harder it is to fake
or change the
ledger
% %
%
%
%
%
%
%
%
%
%
%
%
%
%
% %
%
%
%
%
%
%
%
%

15. “All very interesting … but why
is this useful?”

16. Blockchain is…
• Tamper-Evident Append-Only
Ledger
• Quick to verify
• Impossibly slow to fake
(cryptographic hashes)
• A Merkle Tree - a hash of
hashes (1979)
• Used in Bitcoin

17. Bitcoin
• Uses a blockchain ledger
• “Proof of Work” - literally
guessing numbers to win a
Bitcoin lottery - Bitcoin
“Mining”
• Very inefficient
• Strongly libertarian ideology

18. Bitcoin will use 0.5% of
world’s electricity by end of 2018
(and it’s literally just using computers to guess numbers)

19. Bitcoin = ⚡Ireland
#ClimateChange

20. Bitcoin is bad
If you have any, get rid of it. Have nothing to do with it.

21. Cryptocurrencies

22. Cryptocurrencies
• Many other similar altcoins
based on Bitcoin
• Popular ones include
Ethereum and Ripple
• Unregulated
• Some use Proof of Stake not
Proof of Work which is a little
better, but still not great.

23. ICOs

24. Initial Coin Offerings (ICOs)
• Create an altcoin
• Offer investors “tokens”
• Investors hope the coins go up
in value
• Again, unregulated

25. Cryptocurrencies and ICOs are
unregulated finance

26. BE CAREFUL!

27. Back to Blockchain

28. Is Blockchain Technology Useful?
• The promises out there are the
same promises of Bitcoin
• Decentralised
• Append-Only
• Tamper-Evident
• Also with added “Smart
Contracts” (Ethereum)

29. A Blockchain Classic
Do I need Blockchain?
No

30. Australian Govt - “Nah Mate!”
• $700k research into
Blockchain for US Govt
• Anonymity is “not a good fit”
for government projects
“for every use of blockchain
that you would consider
today, there is a better
technology”
- Peter Alexander, Chief
Digital Officer, Australian
Govt Digital Transformation
Agency

31. Reddit Humour
https://www.reddit.com/r/ProgrammerHumor/comments/7etmm1/a_diagram_to_help_you_decide_whether_blockchain/

32. https://xkcd.com/2030/

33. Become Leonardo da Vinci
• Blockchains for Art - Verisart
• Claim you painted the Mona Lisa (as Terence Eden
did)
• If the ledger cannot change, then errors cannot be
changed
• https://shkspr.mobi/blog/2018/06/how-i-became-
leonardo-da-vinci-on-the-blockchain/
• Put bad data in, you just distribute encrypted bad
data

34. Blockchain Smart Contracts
• Unalterable Electronic
Contracts
• Contract is code
• Bug in code, led to $160m loss
for a company called Parity
• Unalterable contract means
$160m is irretrievable

35. Blockchain Success Stories?
• Economist Technology Quarterly
September 2018
• $1Bn+ investment in first 5 months
of 2018 - positive?
• Very few actual successes
• “Special hammer looking for the
right nail”

36. More info… David Gerard
• David Gerard @davidgerard on Twitter
• https://davidgerard.co.uk/blockchain/
• Book: Attack of the 50 Foot Blockchain
• Where I got a chunk of my slides (with
permission - thank you David): https://
davidgerard.co.uk/blockchain/
2018/04/19/welcome-to-the-
blockchain-slides-from-berenbergs-
blockchain-from-hype-to-reality/

37. So don’t use Blockchain?

38. Know your tools

39. Know other tools?
Cloud
Serverless
Kubernetes
Peer to Peer
AWS
Hybrid
Badger
Istio
VMWare
Red Hat
Azure
O’Reilly

40. Blockchain
• Decentralised
• Append Only
• Tamper Evident
• Ledger

41. When to use Blockchain?
• Zero trust in other parties
(trustless)
• Require unalterable data
• Where regulation or law is
unhelpful (be careful!)

42. When to use Blockchain?
• Zero trust in other parties
(trustless)
• Require unalterable data
• Where regulation or law is
unhelpful (be careful!)
• Compatible with Christian
Values?

43. Blockchain only fits
very specific use cases

44. Blockchain
Do I need Blockchain?
Almost certainly not

45. Blockchain
Do I need Blockchain?
Almost certainly not
Just use a normal Database

46. What is Blockchain?
And why should we care
Paul Johnston @PaulDJohnston Medium/Twitter