A talk at the University of Bonn Computer Science Colloquium. It covers how distributed ledgers (blockchains) combined with decentralised linked data technologies such as Solid can support the management of personal data avoiding the issues highlighted in the media around for example, Facebook and Cambridge Analytica. 1. https://www.informatik.uni-bonn.de/de/kolloquium/2018ws/towards-the-decentralisation-of-personal-data-through-blockchains-and-linked-data

1. Towards the
Decentralisation of
Personal Data through
Blockchains & Linked Data
Prof. John Domingue (@johndmk)
Director, Knowledge Media Institute,
the Open University, UK
http://kmi.open.ac.uk/
http://blockchain.open.ac.uk/

2. Outline
• Motivation
• Linked Data and Knowledge Graphs
• Blockchains
• LinkChains
• Educational experiments at the OU
• Summary

3. Motivation

4. “We demonstrated that the Web had failed
instead of served humanity, as it was supposed
to have done, and failed in many places,” he
told me. The increasing centralization of the
Web, he says, has “ended up producing—with
no deliberate action of the people who
designed the platform—a large-scale emergent
phenomenon which is anti-human.”

5. "deeply personal … weaponised
against us with military efficiency"

6. Data
https://www.theguardian.com/commentisfree/2018/mar/28/all-the-data-facebook-google-has-on-you-privacy
• 5.5 GB
• Everywhere you’ve
been
• Everything you’ve
ever searched (and
deleted)
• Advertisement profile
• All the apps you use
• All your YouTube
history

7. Thin Files and Data Poor
7

8. Self Sovereign Identity
8

9. Linked Data and
Knowledge Graphs

10. Linked Data

11. May 2007
12 datasets
20 links
Linked Data

12. June 2018
1,224 datasets
16,113 links
Maintained by John P. McCrae for the Insight Centre for Data Analytics

13. 13

14. 14

15. Amsterdam
15
Adapted from https://www.ambiverse.com/knowledge-graphs-encyclopaedias-for-machines/ using data from
http://lookup.dbpedia.org/api/search.asmx/KeywordSearch?QueryClass=place&QueryString=amsterdam

16. Blockchains

17. Blockchain
17
World Economic Forum Survey Projects
Blockchain ‘Tipping Point’ by 2023
Santander: Blockchain Tech Can Save Banks
$20 Billion a Year

19. Everledger
www.everledger.io

20. https://www.docusign.com/blog/the-future-of-car-leasing-is-as-easy-as-click-sign-drive/

21. http://motherboard.vice.com/read/transactive-grid-ethereum-brooklyn-microgrid

22. Ledgers

23. Cryptographic Hash Function
https://en.wikipedia.org/wiki/Cryptographic_hash_function

24. Blockchain = an Immutable Linked List

25. Blockchain = an Immutable Linked List

26. Proof of Work
• Find x such that f(nonce + x) < t
(cryptographic hash)
"Hello, world!0" =>
1312af178c253f84028d480a6adc1e25e81caa44c749ec81976192e2ec934c64
"Hello, world!1" =>
e9afc424b79e4f6ab42d99c81156d3a17228d6e1eef4139be78e948a9332a7d8
"Hello, world!2" =>
ae37343a357a8297591625e7134cbea22f5928be8ca2a32aa475cf05fd4266b7 ...
"Hello, world!4248" =>
6e110d98b388e77e9c6f042ac6b497cec46660deef75a55ebc7cfdf65cc0b965
"Hello, world!4249" =>
c004190b822f1669cac8dc37e761cb73652e7832fb814565702245cf26ebb9e6
"Hello, world!4250" =>
0000c3af42fc31103f1fdc0151fa747ff87349a4714df7cc52ea464e12dcd4e9

27. Proof of Work
• Hard to outpace the entire rest of the network… a 51% attack could
do it, but otherwise it is like buying thousands of lottery tickets –
doesn’t help you that much!
Source: Marc Eisenstadt ‘What is the genius behind Bitcoin’

28. BitCoin Mining
http://knkx.org/post/central-wash-home-nations-biggest-bitcoin-mine-more-coming

29. Consensus Mechanisms (1/6)

30. Consensus Mechanisms (2/6)

31. Consensus Mechanisms (3/6)

32. Consensus Mechanisms (4/6)

33. Consensus Mechanisms (5/6)

34. Consensus Mechanisms (6/6)

35. http://ethdocs.org/en/latest/account-management.html
Every account is defined by a pair of keys,
a private key and public key
A keyfile holds encoded key pair
data as JSON with the private key
encrypted with a user given
password
Accounts are indexed by their address
which is derived from the public key by
taking the last 20 bytes
Accounts use public key
cryptography to sign transaction.
Ethereum External Accounts

36. Ethereum Virtual Machine
Sources: Ethereum Development Tutorial
The Ethereum Virtual Machine can be thought of as a large decentralized computer
containing millions of objects, called "accounts", which have the ability to maintain
an internal database, execute code and talk to each other.
There are 2 types of Accounts:
Externally owned account (EOA):
an account controlled by a private
key that has the ability to send
ether and messages from it.
‘Smart’ Contract: an account
that has its own code, and is
controlled by code.
Any user can trigger an action by sending a transaction from an EOA, setting
Ethereum's wheels in motion.
If the destination of the transaction
is another EOA, then the transaction
may transfer some ether but
otherwise does nothing
However, if the destination is a
‘Smart’ Contract, then the
contract in turn activates, and
automatically runs its code.

37. LinkChains

38. Decentralized web apps
share access to data stores

39. Different app and storage providers
compete independently

40. Linked Data Platform (LDP) defines a set of
rules for HTTP operations on web resources,
some based on RDF, to provide an architecture
for read-write Linked Data on the web.

41. contract ERC721 {
// ERC20 compatible functions
function name() constant returns (string name);
function symbol() constant returns (string symbol);
function totalSupply() constant returns (uint256 totalSupply);
function balanceOf(address _owner) constant returns (uint balance);
// Functions that define ownership
function ownerOf(uint256 _tokenId) constant returns (address owner);
function approve(address _to, uint256 _tokenId);
function takeOwnership(uint256 _tokenId);
function transfer(address _to, uint256 _tokenId);
function tokenOfOwnerByIndex(address _owner, uint256 _index) constant returns
(uint tokenId);
// Token metadata
function tokenMetadata(uint256 _tokenId) constant returns (string infoUrl);
// Events
event Transfer(address indexed _from, address indexed _to, uint256 _tokenId);
event Approval(address indexed _owner, address indexed _approved, uint256
_tokenId); }

42. LinkChain Components
SOLID Personal
Data Pod
Web/Mobile
Application or Client
Private data
soley under
user control
User controlled
read/write access

43. LinkChain Components
SOLID Personal
Data Pod
Decentralised data
storage
Web/Mobile
Application or Client
Private data
soley under
user control
Public and private data
User controlled
read/write access
Public and
private data
storage and
access

44. LinkChain Components
SOLID Personal
Data Pod
Decentralised data
storage
Web/Mobile
Application or Client
Private data
soley under
user control
Public and private data
Decentralised ledger and
‘global computer’
User controlled
read/write access
Public and
private data
storage and
access
Recording, Verification
and Asset Transfer

45. Educational
experiments at the
OU

46. The Open University
2

47. OpenLearn

49. Student Controlled
Education

50. Microcredentials

51. Open Badge 2.0
https://medium.com/openbadges/open-badges-2-0-b7f67d2c3191

52. OpenLearn Badges on the blockchain

53. Demos of movies available at: http://blockchain.open.ac.uk/
Peer Reputation and Badging

54. Reputation Contract
Functions:
Storage:
sendReputation
getPersonBalance()
getReputationAttribute
attribs[address = > Attrib]
Attrib { uint balanceOf;
mapping(string => uint);
string[] attribStrings
}
Reputation
Attribute
token
Balances
Reputation Smart Contract
Tokens left
to assign
My Reputation
Peer Reputation Page
Kevin’s Reputation View
Communication: 14
Collaboration: 06
Organisation: 12
Ethics: 05
Problem Solving: 10
Engagement: 04
your Ethereum address
password to private key
Signing this transaction will transfer stated
Reputation Tokens + ETH gas payment from
your account. Estimated gas cost is 0.02 ETH.
Maximum gas cost is set to 0.05 ETH
Transfer
Reputation Tokens Left: 57
number of tokens to transfer
Assign Reputation
My Reputation
Peer Reputation Page
Michelle’s Reputation View
Communication: 06
Collaboration: 02
Organisation: 10
Ethics: 12
Problem Solving: 08
Engagement: 16
your Ethereum address
password to private key
Signing this transaction will transfer stated
Reputation Tokens + ETH gas payment from
your account. Estimated gas cost is 0.02 ETH.
Maximum gas cost is set to 0.05 ETH
Transfer
Reputation Tokens Left: 68
number of tokens to transfer
Assign Reputation
Signed
TX
Reputation
Attribute
token
Balances
Tokens left
to assign
Michelle transfers 4 Reputation tokens for ‘Organisation’ to Kevin

55. Michelle transfers 4 Reputation tokens for ‘Organisation’ to Kevin

56. Michelle transfers 4 Reputation tokens for ‘Organisation’ to Kevin

57. Block no: 45566778
Michelle transfers 4 Reputation tokens for ‘Organisation’ to Kevin

58. Michelle transfers 4 Reputation tokens for ‘Organisation’ to Kevin

59. Michelle transfers 4 Reputation tokens for ‘Organisation’ to Kevin

60. Michelle transfers 4 Reputation tokens for ‘Organisation’ to Kevin

61. Michelle transfers 4 Reputation tokens for ‘Organisation’ to Kevin

62. Michelle transfers 4 Reputation tokens for ‘Organisation’ to Kevin

63. Michelle transfers 4 Reputation tokens for ‘Organisation’ to Kevin

64. Active Badges

65. Rise of the Uber University

66. Uber-style Teaching

67. LinkChain Components
SOLID Personal
Data Pod
Decentralised data
storage
Web/Mobile
Application or Client
Private data
soley under
user control
Public and private data
Decentralised ledger and
‘global computer’
User controlled
read/write access
Public and
private data
storage and
access
Recording, Verification
and Asset Transfer

68. Learning Record IPFS IPFS
IPFSIPFS
LinkChain Components
Solid Personal
Data Pod
IPFS decentralised data
storage
Token Metadata incl.
Student Solid URLs
Signed token metadata URL
and badge issuing contracts
Students access
and update
learning
achievements
Storing and
retrieving
token
metadata
Badge issuing and badge
issuing rights

69. Closing Comments
and Summary

70. Global Higher and Further Education
Blockchain

71. Startups in the CV/Accreditation Space

72. instituteofcoding.org

74. Europass2 Digitally Signed Credentials

75. Summary: Managing Private Data
• Societal and technical motivations for
moving to decentralized platforms
• Blockchains provide a mechanism for adding
decentralized trust to decentralized data
stores
• Semantic approaches can aid with indexing
and interoperability

76. Summary: Benefits for Education
• Inbuilt identity management
• Data controlled/owned by learners rather
than any single institution
• Increases transparency
• Reduces risk of fraud
• Supports automation
• Permits disintermediation
• Lowering of process costs
– Lowers entry barriers to education market
– ‘university of one’

77. Acknowledgements
• KMi@OU Implementation Team
– Michelle Bachler
– Kevin Quick
– Allan Third
– Chris Valentine
– Umar Mir
– Zeeshan Jan
– Manoharan Ramachandran

78. blockchain.open.ac.uk