Blockchain Study(1) - What is Blockchain? Introduce blockchain

1. BLOCK CHAIN
introduce block chain

2. - Index -
1. Decentralized
2. BlockChain
3. BlockChain Example
4. Q/A

3. What is Decentralized?

4. http://howtodoit.nl/

5. https://bluzelle.com

6. Why Decentralized?
http://wisefree.tistory.com/483

7. Why Decentralized?

8. What is BlockChain?

9. A blockchain, originally block chain, is a continuously growing list of
records, called blocks, which are linked and secured using
cryptography. Each block typically contains a cryptographic hash of
the previous block, a timestamp and transaction data. By design, a
blockchain is inherently resistant to modification of the data. It is "an
open, distributed ledger that can record transactions between two
parties efficiently and in a verifiable and permanent way". For use as
a distributed ledger, a blockchain is typically managed by a peer-to-
peer network collectively adhering to a protocol for validating new
blocks. Once recorded, the data in any given block cannot be altered
retroactively without the alteration of all subsequent blocks, which
requires collusion of the network majority.
WIKI

10. A blockchain, originally block chain, is a continuously growing list of
records, called blocks, which are linked and secured using
cryptography. Each block typically contains a cryptographic hash of
the previous block, a timestamp and transaction data. By design, a
blockchain is inherently resistant to modification of the data. It is "an
open, distributed ledger that can record transactions between two
parties efficiently and in a verifiable and permanent way". For use as
a distributed ledger, a blockchain is typically managed by a peer-to-
peer network collectively adhering to a protocol for validating new
blocks. Once recorded, the data in any given block cannot be altered
retroactively without the alteration of all subsequent blocks, which
requires collusion of the network majority.
WIKI

11. 녹색 최초 블록(Genesis Block) : 최초 생성된 블록
검은색은 해시파워(CPU power)를 통한 경쟁에서 승리한 후, 블록
- 실제 블록체인의 일부가된 블록
보라색은 경쟁에서 실패한 블록.
- 네트워크 상에서 공유되지 못함. (인정 X)
- 이러한 블록은 폐기
따라서 Genesis Block으로 부터 경쟁에서 이긴 블록들로 이루어진 체인은
"주체인 (Main Chain)"이라고 부른다.
이러한 Main Chain 상의 블록에 있는 데이터 내역만이 유효하다.

12. 현재 상태(State)에서 특정 지갑(하늘색) 에서 송금하라는 명령을 받아서 새로운 상태로 변경된다.
Transaction 에서 일어난 하늘색 부분의 결과로 Create 된 빨간색 부분이 새로운 State’에 등록된
다.
즉 특정 Transaction이 일어나면 새로운 상태가 저장되고 이러한 블록들이 생성됨에 따라
전체 네트워크의 상태변환을 통해 유지된다.

13. 각 해시파워를 통해 생성된 블록은 위 그림과 같은 구조를 가진다.
1. Time : 타임스템프
2. Nonce : 최초 0에서 시작, 조건을 만족하는 해쉬값을 찾아낼 때 까지의 1씩 증가하는 계산수
3. Prevhash : 이전블록에 대한 참조(이전 블록의 해시)
4. Transaction : 이전 블록 이후에 발생된 모든 트랜잭션(Transaction)의 목록
이 과정을 통해서 지속적으로 성장하는 블록체인이 생성된다. 그리고 비트코인과 같은 코인/토큰
장부의 최신상태를 나타내기 위해서 지속적인 업데이트(블록 생성)가 이루어진다.

14. 왼쪽: Merkle tree(머클트리)의 몇몇 노드만 보아도 곁가지(branch)의 유효성을 입증가능
오른쪽: Merkle tree의 어떤 부분을 바꾸려는 시도는 결국 상위 해쉬값 어딘가에 불일치를 만든다.
블록에 포함된 모든 트랜잭션 정보에 의해 생성되는 Merkle tree는 루트 해시가 들어있는 200 바
이트 정도의 데이터이다. 하위 노드들의 해쉬값이 상위노드에 영향을 주기 때문이다. 만약 최하단
의 머클트리의 트랜잭션 정보를 바꿔치기할 경우, 부모 해쉬값들이 변하게 된다. 결국 전체 트리의
루트값이 바뀌게 되어 결과론적으로 이 블록의 해쉬가 달라진다.
즉, 이 블록은 완전히 다른 블록으로 처리된다.

15. 앞서 설명한 부분을 보충하자면,
1) 개별 거래 해쉬값을 변경(해킹)
2) 머클트리 해쉬값 변경됨
3) 블록해더 정보값이 변경됨
4) 새로운 블록해쉬로 변경됨
-> 완전히 다른 블록으로 처리
From: CODEMATH
To : HORDE
Amount : 200 BTC
From: XYRHO
To : HORDE
Amount : 10 BTC
a7fb341e … 32ca8da …
947cd5af2 …
소프트웨어 버전
블록생성 시각
이전 블록 해쉬
채굴 난이도
머클트리해쉬
Nonce
000007eac…
개별
거래
…
…
개별
거래
해쉬값
머클트리
해쉬값
블록해쉬
블록해더

16. BlockChain Example

17. Cybersecurity
Guardtime – This company is creating “keyless” signature systems using blockchain which is currently used to secure the health
records of one million Estonian citizens.
REMME is a decentralized authentication system which aims to replace logins and passwords with SSL certificates stored on a
blockchain.

18. Healthcare
Gem – This startup is working with the Centre for Disease Control to put disease outbreak data onto a blockchain which it says will
increase the effectiveness of disaster relief and response.
SimplyVital Health – Has two health-related blockchain products in development, ConnectingCare which tracks the progress of
patients after they leave the hospital, and Health Nexus, which aims to provide decentralized blockchain patient records.
MedRec – An MIT project involving blockchain electronic medical records designed to manage authentication, confidentiality and
data sharing.

19. Financial services
ABRA – A cryptocurrency wallet which uses the Bitcoin blockchain to hold and track balances stored in different currencies.
Bank Hapoalim – A collaboration between the Israeli bank and Microsoft to create a blockchain system for managing bank
guarantees.
Barclays – Barclays has launched a number of blockchain initiatives involving tracking financial transactions, compliance and
combating fraud. It states that “Our belief ...is that blockchain is a fundamental part of the new operating system for the planet.”
Maersk – The shipping and transport consortium has unveiled plans for a blockchain solution for streamlining marine insurance.
Aeternity – Allows the creation of smart contracts which become active when network consensus agrees that conditions have
been met – allowing for automated payments to be made when parties agree that conditions have been met, for example.
Augur – Allows the creation of blockchain-based predictions markets for the trading of derivatives and other financial instruments
in a decentralized ecosystem.

20. Manufacturing and industrial
Provenance – This project aims to provide a blockchain-based provenance record of transparency within supply chains.
Jiocoin – India's biggest conglomerate, Reliance Industries, has said that it is developing a blockchain-based supply chain logistics
platform along with its own cryptocurrency, Jiocoin.
Hijro – Previously known as Fluent, aims to create a blockchain framework for collaborating on prototyping and proof-of-concept.
SKUChain – Another blockchain system for allowing tracking and tracing of goods as they pass through a supply chain.
Blockverify - A blockchain platform which focuses on anti-counterfeit measures, with initial use cases in the diamond,
pharmaceuticals and luxury goods markets.
Transactivgrid – A business-led community project based in Brooklyn allowing members to locally produce and cell energy, with
the goal of reducing costs involved in energy distribution.
STORJ.io – Distributed and encrypted cloud storage, which allows users to share unused hard drive space.

21. Government
Dubai – Dubai has set sights on becoming the world's first blockchain-powered state. In 2016 representatives of 30 government
departments formed a committee dedicated to investigating opportunities across health records, shipping, business registration
and preventing the spread of conflict diamonds.
Estonia – The Estonian government has partnered with Ericsson on an initiative involving creating a new data center to move
public records onto the blockchain. 20
South Korea – Samsung is creating blockchain solutions for the South Korean government which will be put to use in public
safety and transport applications.
Govcoin – The UK Department of Work and Pensions is investigating using blockchain technology to record and administer
benefit payments.
Democracy.earth – This is an open-source project aiming to enable the creation of democratically structured organizations, and
potentially even states or nations, using blockchain tools.
Followmyvote.com – Allows the creation of secure, transparent voting systems, reducing opportunities for voter fraud and
increasing turnout through improved accessibility to democracy.

22. Retail
OpenBazaar – OpenBazaar is an attempt to build a decentralized market where goods and services can be traded with no
middle-man.
Loyyal – This is a blockchain-based universal loyalty framework, which aims to allow consumers to combine and trade loyalty
rewards in new ways, and retailers to offer more sophisticated loyalty packages.
Blockpoint.io – Allows retailers to build payment systems around blockchain currencies such as Bitcoin, as well as blockchain
derived gift cards and loyalty schemes.

23. Real Estate
Ubiquity – This startup is creating a blockchain-driven system for tracking the complicated legal process which creates friction
and expense in real estate transfer.
Transport and Tourism
IBM Blockchain Solutions – IBM has said it will go public with a number of non-finance related blockchain initiatives with global
partners in 2018. This video envisages how efficiencies could be driven in the vehicle leasing industry.
Arcade City – An application which aims to beat Uber at their own game by moving ride sharing and car hiring onto the
blockchain.
La'Zooz – A community-owned platform for synchronizing empty seats with passengers in need of a lift in real-time.
Webjet – The online travel portal is developing a blockchain solution to allow stock of empty hotel rooms to be efficiently
tracked and traded, with payment fairly routed to the network of middle-men sites involved in filling last-minute vacancies.

24. Media
Kodak – Kodak recently sent its stock soaring after announcing that it is developing a blockchain system for tracking
intellectual property rights and payments to photographers.
Ujomusic – Founded by singer-songwriter Imogen Heap to record and track royalties for musicians, as well as allowing them to
create a record of ownership of their work.
It is exciting to see all these developments. I am sure not all of these will make it into successful long-term ventures but if they
indicate one thing, then it is the vast potential the blockchain technology is offering.
Bernard Marr is a best-selling author & keynote speaker on business, technology and big data. His new book is Data Strategy.
To read his future posts simply join his network here.

25. –CodeMath
Let’s study blockchain!
Q/A