Introduction to Blockchain Technologies Sarah Azouvi (University College London) Privacy International Forum - 19/10/2017 1
Outline
Outline How it works
Outline How it works Privacy?
Outline How it works Privacy? New applications
Bitcoin • Bitcoin: decentralised cryptocurrency • No central authority, no banks, no government, no censorship, no international fees • Removes the need for a trusted third party
How does it work?
How does it work?
How does it work? pkA pkB
How does it work? pkA pkB tx(pk A pk B )
How does it work? pkA pkB tx(pk A pk B )
How does it work? pkA pkB tx(pk A pk B ) • Append-only • Transparent • Pseudonyms
How does it work? pkA pkB tx(pk A pk B ) • Append-only • Transparent • Pseudonyms
How does it work? tx(pk A pk B ) tx(pk A pk A ) ?
How does it work? Proof of work
How does it work? Proof of work
How does it work? Proof of work Previous hash tx(pk A pk B ) tx(pk C pk D ) tx(pk E pk F )
How does it work?
How does it work?
How does it work?
How does it work?
How does it work? Proof of work
How does it work? Proof of work Longest chain wins
Why does it work?
Why does it work? =
Why does it work? =
What does it guarantee? • A network of peers that do not trust each other agree on a set of transactions • Auditability • Immutability *
What it does not guarantee
What it does not guarantee • Privacy
What it does not guarantee • Privacy • Solve every problem
Privacy
Privacy • Transparent • Transactions are linked • Traceable!
Privacy • Transparent • Transactions are linked • Traceable!
Privacy pk A pk B pk C pk B pk D pk D pk F pk E
Privacy • Solution: mixing service pk A pk D pk B pk E pk C pk F
Privacy • Solution: mixing service pk A pk D pk B pk E pk C pk F
Privacy • Solution: mixing service pk A pk D pk B pk E pk C pk F • New currency: Zcash (ZKP), Monero (ring signatures)
Extensions
Extensions • Ethereum
Extensions • Ethereum • Identity management system
Extensions • Ethereum • Identity management system • Permissioned blockchains, no currencies
Extensions • Ethereum • Identity management system • Permissioned blockchains, no currencies • Privacy preserving blockchains
Extensions • Ethereum • Identity management system • Permissioned blockchains, no currencies • Privacy preserving blockchains • Many others decentralised applications!
Ethereum
Ethereum
Ethereum Smart Contract
Ethereum tx(pk B smart contract ) Smart Contract
Ethereum • ICO: Decentralised Kick-starter
Ethereum • ICO: Decentralised Kick-starter
Identity Management
Identity Management • Control over your data • Standardise identity management • Less complex
Identity Management
Identity Management
Identity Management
Identity Management
Industry application
Industry application
Industry application
Industry application
Research • Privacy • Sustainability • Scalability • New applications: decentralized versions of identity management, DNS and public-key infrastructures, notary publics, and file storage • Usability
Questions ?
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