Video and slides synchronized, mp3 and slide download available at URL http://bit.ly/2aaR8pC. Chris Anderson discusses Document Coin and using blockchain in new and innovative ways. He presents the JavaScript Cryptography code line by line and runs test cases using Prova in the browser. Filmed at qconlondon.com. Chris Anderson co-founded Couchbase in 2009, kicking off big changes in the mobile database industry. He advises digital economy companies on IoT, big data, sync, and blockchain technology. He’s currently building Document Coin, an alternate approach to crypto-currency that locates scarcity and value in the social network of users.

1. D O C U M E N T C O I N
C RY P T O C U R R E N C Y F O R T H E G I F T E C O N O M Y
Chris Anderson
@jchris
jchris@gmail.com
QCon London 2016

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Watch the video with slide
synchronization on InfoQ.com!
https://www.infoq.com/presentations/
document-coin

3. Purpose of QCon
- to empower software development by facilitating the spread of
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Strategy
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change and innovation in your teams
- speakers and topics driving the evolution and innovation
- connecting and catalyzing the influencers and innovators
Highlights
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Presented at QCon London
www.qconlondon.com

4. TA K E H O M E L E S S O N S
• Blockchain without global consensus is interesting
• WebCrypto APIs will bring innovation to blockchain
applications
• Application developers not cryptographers?!?
• IETF JOSE means standardized implementations

5. T H E D O Y L E O W L
https://www.flickr.com/photos/ultimatekiwi/5154416336/

6. I D E O L O G Y
B A C K G R O U N D A S S U M P T I O N S

7. L E G I B I L I T Y
W H E R E W O U L D Y O U R A T H E R L I V E ?

8. VA L U E
H O W W E K N O W S O M E T H I N G I S I M P O R TA N T

9. I N E Q U A L I T Y
9 9 % O F P E O P L E H A V E 6 0 % O F T H E W E A LT H

10. P R O G R E S S I V I S M
A D J U S T I N G T H E C U R V E

11. G L O B A L PA R T I A L O R D E R I N G
D O W E N E E D I T ?

12. P I R A H Ã
W E C A N L I V E W I T H O U T N U M B E R S

13. G I F T E C O N O M Y
C A N W E S C A L E I T ?

14. S U B J E C T I V E VA L U E
E V E RY O N E S E E S A D I F F E R E N T PA R T I A L O R D E R I N G

15. W E B O F T R U S T
P R I O R A R T

16. C E R T I F I C AT E A U T H O R I T Y
W H O WA T C H E S T H E WA T C H E R S ?

17. N O W W E H AV E N P R O B L E M S
K E Y S I G N I N G PA R T Y

18. O B J E C T B L O C K C H A I N
• Blockchain allows us to create digital objects
• Heirlooms
• Gamify the web of trust

19. I N T E R N E T T H I N G S
F R O M C L A S S E S T O I N S TA N C E S

20. G I V E T R E E
• Per document blockchain
• Don’t wait for global consensus
• Data provenance structures allows the tracking of how
ownership of a piece of data got to you
• TODO: Encrypt the content of the coins.

21. G I V E T R E E
s(A1)
mint
B1
s(mint)
A1
Child nodes are signed
by the keys encoded as
owner of parent blocks.
A2

22. VA L I D AT E T H E G I V E T R E E
• Verify the root content hash and mint signature match
the unique coin id.
• For each child in the tree, verify that the signature is
correct and comes from the public key listed in the
parent block.
• Application level policy can flag branches of the tree
that exceed a give limit. Physical objects are
simulated with a give limit of one.

23. G I V E T R E E
to (Maude keys)
on (content hash)
signed (Maude)
mint
mintMaude

24. G I V E T R E E
to (The Dude)
on (parent hash)
signed (Maude)
mint
s(mint)
A1
A1
Maude
The Dude

25. G I V E T R E E
to (Donny keys)
on (parent hash)
signed (The Dude)
s(A1)
mint
s(mint)
B1
A1
B1
Maude
The Dude
Donny

26. G I V E T R E E
to (Walter keys)
on (parent hash)
signed (The Dude)
s(A1)
mint
s(mint)
B2
A1
B1 B2
"It went OK, the old
man told me to take
any rug in the house."
Maude
The Dude
Donny Walter

27. G I V E T R E E
to (Walter keys)
on (parent hash)
signed (The Dude)
s(A1)
mint
s(mint)
B1
A1 A2
B1 B2
Maude
The Dude
Donny Walter
Bunny

28. G I V E T R E E
to (Larry keys)
on (parent hash)
signed (Bunny)
s(A1)
mint
s(A2)
s(mint)
C1
A1 A2
B1 B2 C1
Maude
The Dude
Donny Walter
Bunny
Larry

29. L I M I TAT I O N S
• The model, even if perfectly implemented, isn’t
designed to prevent double spending, just to detect
it.
• Research project, currently only dealing with public
content and signatures.
• Haven’t implemented the Bill Murray rule yet.
• Want multi-sig mint blocks

30. I M P L E M E N TAT I O N
• Cisco’s JOSE https://github.com/cisco/node-jose
• Prova test runner http://github.com/azer/prova
• Recursion!

31. P R O VA
T E S T I N T H E B R O W S E R W I T H O U T A N Y B U I L D S C R I P T S

32. P R O VA
A U T O M A G I C A L R E L O A D A N D R U N

33. C I S C O N O D E - J O S E
E A S Y A N D C O N S I S T E N T W R A P P E R A R O U N D W E B C RY P T O

34. VA L I D AT E A C O I N
• Validate the root of the Give Tree
• Coin ID is correct
• Content signature matches
• Recursively validate all child nodes
• Give limit policy violations are business errors, not
validation errors

35. VA L I D AT E T H E R O O T

36. VA L I D AT E T H E R O O T

37. VA L I D AT E C H I L D R E N
Empty Callback!

38. VA L I D AT E C H I L D R E N
Recursion!

39. N E X T S T E P S
• Encrypted content
• PouchDB storage & sync
• Photo sharing application
• Public key graph browser

40. … P R O F I T
• Distributed PKI
• Illustrate to users the value
of partial disclosure
• Ecosystem interop
• Native HTML5 blockchain
• Platform for p2p social apps

41. C O N C L U S I O N
• We are the world
computer, build expressive
software
• Blockchain assumptions
can be inverted
• There is more room for
innovation than we think

42. D O C U M E N T C O I N
C RY P T O C U R R E N C Y F O R T H E G I F T E C O N O M Y
Chris Anderson
@jchris
jchris@gmail.com
QCon London 2016

43. Watch the video with slide
synchronization on InfoQ.com!
https://www.infoq.com/presentations
/document-coin