What is Hash function?

블록체인이나 암호화폐의 기술적 측면을 얘기하려면 가장 먼저 해시값과 해시함수라는 것을 알아야 한다.

해시함수란 암호학에서 유래한 개념으로 어떠한 길이의 데이터를 입력하여도 정해진 길이의 결과값(해시값)을 주는 함수로 정의할 수 있다. 즉, 어떤 데이터를 넣어도 256bits의 코드로 바꿔주는 알고리즘(SHA256)을 말하는 것이다.

예를들어, ‘가’라는 1글자의 데이터를 넣던, 책 한권의 데이터를 넣던 해시함수를 통과하면 0~9까지의 숫자와 a~f까지의 문자의 조합으로 이루어진 64글자(256bits)의 hash값으로 출력되게 하는 함수이다. 여기서 해시값은 8진수로 표시되기 때문에 각 글자당 4bits이고 64글자이므로 4×64=256bits 인 것이다.

다음은 해시 생성기와 해시함수를 쉽게 설명한 그림이다.
http://www.convertstring.com/ko/Hash/SHA256 (해시생성기)

그러나, 해시알고리즘의 핵심은 256bits의 해시값을 알고 있다고 하더라도 입력된 데이터 내용을 전혀 알 수 없다는 것이다. 동일한 데이터를 넣어야 동일한 hash값을 알 수 있을 뿐이다.

이 해시알고리즘은 서로가 갖고 있는 데이터의 무결성을 증명하는데 요긴하게 쓰인다. 예를들어, A가 중요한 데이터가 담긴 파일을 USB메모리에 담아 아프리카 오지에 있는 B에게 DHL을 통해 전달한다고 하자. 며칠후 B는 메모리를 받았지만, 중간에 누군가가 그 내용을 변경했을 가능성이 있지 않을까? 그런데 이를 확인하려면 A와 B는 전화통을 붙들고 일일이 그 내용을 확인해야 할 것이다. 그러나 그 데이터의 양이 만약 100기가라면? 생각만 해도 끔찍하다.
이때 해시알고리즘을 활용하면 간편해진다. 즉, A는 데이터파일을 메모리에 담아 보내면서 그 파일의 해시값을 B에게 문자로 전송한다. B는 받은 데이터파일을 해시 생성기에 넣어 A가 보내준 해시값과 일치하는 지만 확인하면 누군가 변조를 했는지 아닌지 확인할 수가 있을 것이다.
또 다른 예로, A가 중요한 데이터가 담긴 파일을 상사인 B를 거쳐 사장 C에게 보내는데 중간에 B가 데이터를 살짝 고쳐서 C에게 보고할 가능성이 있지 않을까? 이때도 A가 파일을 결재올리면서 그 파일의 해시값을 B와 C에게 보낸다면 C는 자신이 받은 파일을 해시생성기로 돌려 나온 해시값과 A가 보내온 해시값이 일치하는 지만 확인하면 된다.

블록체인에서 얘기하는 ‘마이닝(mining)’이라는 것이 바로 문제를 풀어서 해시값을 찾아내는 과정을 말한다. 엄밀히 말하면 랜덤하게 값을 입력해서 해당 해시값이 나오는지 확인하는 작업을 반복하는 것이다.
예를들어,
‘SHA256 해시의 결과가 다음과 같은 입력값을 찾으시오.

125fed6953ab43dbff05983daab34cc65a659a0ad53d59dd90c754ab44ed54ff0a’

라는 문제가 주지면, 컴퓨터는 해시함수에 랜덤하게 값을 입력하여 위 해시값이 나오게 되는 입력값을 찾아내는 작업을 마이닝이라고 하는 것이다.
문제의 난이도는 채굴에 참여하는 노드수에 따라 변경이 되는데,, 64개의 글자중 일정수의 ‘X’를 포함시켜 조정을 한다.
즉,

‘XXXXXXXXXXXb43dbff05983daab34cc65a659a0ad53d59dd90c754ab44ed54ff0a’

같은 방식으로..

Cryptobirge Coinbase opened a bidding service for Uzbekistan based on USD Coin

The company believes that stablebcoins can provide an opportunity for Uzbek clients to protect themselves from inflation.

This Tuesday, the American crypto-exchange Coinbase announced the launch of trading on the basis of the USD Coin (USDC) issued with its participation of steylcoin in 50 new countries. This is stated in the company’s blog, drew attention to ttrcoin.com. 

The company now provides its services in 103 countries whose residents have access to its Coinbase retail service and Coinbase Pro professional trading platform. 85 of them have access to USDC markets.

The new supported jurisdictions included four CIS countries – Armenia, Kazakhstan, Kyrgyzstan and Uzbekistan. 

The company expects that the USDC, being less volatile than conventional cryptocurrencies, will serve as a tool to attract new investors to this market.

“Our new customers in countries such as Argentina and Uzbekistan, where consumer prices are expected to increase by 10–20% in 2020, such as USDC steaklokoiny can provide an opportunity to protect themselves from inflation,” the statement said.

Today’s announcement is an important achievement for Coinbase and the distribution of cryptocurrency in general. A year ago, Coinbase was available to residents of only 32 countries.

According to Coinbase, now there are over 300 million USDC in circulation, which allows this token to be available to traders from all supported countries.

Whether the USDC trade will be available in other CIS countries is not reported yet. However, the company noted that work on expanding opportunities for fiat currency investment continues.

후오비코리아, ‘후오비 블록체인 커피하우스’ 런칭

[출처: 데이터넷]

Huobi Korea는 지난 21일 후오비 블록체인 커피하우스(Huobi Blockchain Coffeehouse)의 출범식과 함께 첫 ‘페이코인 밋업’을 진행했다. 이날 출범식에는 후오비코리아 조국봉 의장, 박시덕 대표, 다날 박성찬 회장, 달콤커피 지성원 대표와 양사 경영진 및 외부 인사 100여명이 참석했다.

후오비 블록체인 커피하우스는 국내 블록체인 생태계 조성, 국내외 기술 및 정보 교류, 국내 블록체인 경쟁력 강화를 목적으로 달콤커피와 협업해 달콤커피 논현점을 리모델링한 블록체인 워킹 스페이스(Working Space)다. 스타트업 기업들은 여기서 글로벌 네트워크 및 노하우 활용, 글로벌 시장 진출을 위한 자문, 단계별 육성 프로그램을 제공받을 수 있으며, 비즈니스 미팅, 밋업, 강연, 콘서트 등도 가능하다.

또한 별도로 구성된 블록체인 커피클럽은 블록체인 정보 교류와 함께 신디케이트 구성 및 블록체인 스타트업에 대한 자문, 투자 등 다양한 프로그램을 진행할 계획이라고 한다.

[출처: 데이터넷 기사 발췌]

블록체인이란?

사토시 나카모토라는 익명의 학자가 2007~2008년 금융위기사태를 겪으면서 중앙정부가 통제하는 금융시스템의 위험성을 인지하고 개인간의 지불거래가 가능한 전자화폐시스템을 고안하면서 이중지불문제를 해결하기 위한 방안으로 고안한 기술로서, 거래내역을 블럭에 담고 이를 이전의 블럭과 체인형태로 연결하고 수많은 컴퓨터(노드)에 동시에 복제하여 저장하는 분산형 데이터 저장기술이다. 거래가 발생할 때마다 모든 노드들이 정보를 공유하고 이를 자신이 갖고 있는 블록체인정보와 대조하여 데이터 위.변조를 방지하는 기술이다. 

대개 블록은 Version, 이전블록의 hash값, Merkle Hash, Time stamp, Bits(난이도 설정값), Nonce값으로 된 Head와 거래내역(transaction)을 저장하는 body로 구성되어져 있다. 
모든 node들은 거래내역들을 묶어서 블록은 만들고 난이도에 따른 해쉬함수의 Nonce값을 찾는 작업(채굴:mining)을 하게되고 가장 먼저 성공한 노드가 자신의 블록과 작업증명을 네트워크에 전송하고, 다른 노드들은 이 블록의 적합성을 검증. 참여 노드의 51%이상이 적합한 블록이라고 찬성하여 검증된 신규블록은 기존 블록체인에 추가된다. 

이 과정에 수많은 컴퓨터들이 자신들의 리소스를 동원하여 참여하게 되므로 그에 대한 보상으로 비트코인과 거래 수수료를 지급받게 된다. 

블록체인은 참여하고 자하는 누구나 채굴과정에 참여할 수 있는 Public blockchain과 특정 노드만 참여할 수 있는 Private blockchain으로 구분된다.

Huawei crisis?

5월 19일 로이터 통신에 따르면, 
According to Reuters on May 19,

도널드 트럼프 미국 대통령이 중국 기업 화웨이와 자국 기업의 거래를 제한함에 따라 구글이 화웨이 스마트폰에 안드로이드 관련 솔루션 공급을 중단할 방침을 밝혔으며, 때문에 화웨이가 차기 안드로이드 운영체제(OS)와 구글 플레이스토어, 지메일 등 서비스에 접근할 수 없게 된다고 합니다. 

US President Donald Trump has said that Google will stop supplying Android solutions to Huawei smartphones as it restricts transactions between Huawei and its own companies. This means that Huawei will not be able to access services such as the next Android OS, Google Play Store, and Gmail.

구글은 올해 개발자회의를 통해 차기 안드로이드 OS ‘안드로이드 Q’를 소개했다. 통상 제조사는 출시 전인 차기 OS 개발 과정에 접근할 수 있지만, 이번 거래 중단 조치에 따라 화웨이는 이런 혜택을 볼 수 없으며, 다만 안드로이드 체제 관련 제공되는 오픈소스를 통한 개발은 가능하다고 합니다. 그럼에도 불구하고 구글 플레이 스토어, 지메일 등 앱 서비스의 탑재는 금지될 것이기 때문에 중국 내수용은 몰라도 수출용 스마트폰은 큰 타격을 받을 것으로 판단됩니다. 앱을 설치할 수 없는 스마트폰은 빈껍데기에 불과하기 때문입니다. 

Google introduced its next Android OS, ‘Android Q’, through this year’s developer conference. Usually manufacturers can access the next OS development process before launch, but Huawei will not be able to benefit from this transaction suspension, but it will be possible to develop with open source provided for the Android system. Nonetheless, since it will be prohibited to install app services such as Google Play Store and Gmail, smartphones for export will be hit hard, even if they are not in China. Smartphones that can not install apps are just empty shells.

How does Blockchain work?

Picture a spreadsheet that is duplicated thousands of times across a network of computers. Then imagine that this network is designed to regularly update this spreadsheet and you have a basic understanding of the blockchain.

Information held on a blockchain exists as a shared — and continually reconciled — database. This is a way of using the network that has obvious benefits. The blockchain database isn’t stored in any single location, meaning the records it keeps are truly public and easily verifiable. No centralized version of this information exists for a hacker to corrupt. Hosted by millions of computers simultaneously, its data is accessible to anyone on the internet.

To go in deeper with the Google spreadsheet analogy, I would like you to read this piece from a blockchain specialist.

What is Blockchain Technology? A step-by-step guide than anyone can understand

“The traditional way of sharing documents with collaboration is to send a Microsoft Word document to another recipient, and ask them to make revisions to it. The problem with that scenario is that you need to wait until receiving a return copy before you can see or make other changes because you are locked out of editing it until the other person is done with it. That’s how databases work today. Two owners can’t be messing with the same record at once.That’s how banks maintain money balances and transfers; they briefly lock access (or decrease the balance) while they make a transfer, then update the other side, then re-open access (or update again).With Google Docs (or Google Sheets), both parties have access to the same document at the same time, and the single version of that document is always visible to both of them. It is like a shared ledger, but it is a shared document. The distributed part comes into play when sharing involves a number of people.

Imagine the number of legal documents that should be used that way. Instead of passing them to each other, losing track of versions, and not being in sync with the other version, why can’t *all* business documents become shared instead of transferred back and forth? So many types of legal contracts would be ideal for that kind of workflow. You don’t need a blockchain to share documents, but the shared documents analogy is a powerful one.” – William Mougayar, Venture advisor, 4x entrepreneur, marketer, strategist and blockchain specialist

The reason why the blockchain has gained so much admiration is that:

  • It is not owned by a single entity, hence it is decentralized
  • The data is cryptographically stored inside
  • The blockchain is immutable, so no one can tamper with the data that is inside the blockchain
  • The blockchain is transparent so one can track the data if they want to

[Source : https://blockgeeks.com/guides/what-is-blockchain-technology/ ]

What is Blockchain?

What is Blockchain Technology? A step-by-step guide than anyone can understand

“The blockchain is an incorruptible digital ledger of economic transactions that can be programmed to record not just financial transactions but virtually everything of value.” – Don & Alex Tapscott, authors Blockchain Revolution (2016).

A blockchain is, in the simplest of terms, a time-stamped series of immutable record of data that is managed by cluster of computers not owned by any single entity. Each of these blocks of data (i.e. block) are secured and bound to each other using cryptographic principles (i.e. chain).

So, what is so special about it and why are we saying that it has industry disrupting capabilities?

The blockchain network has no central authority — it is the very definition of a democratized system. Since it is a shared and immutable ledger, the information in it is open for anyone and everyone to see. Hence, anything that is built on the blockchain is by its very nature transparent and everyone involved is accountable for their actions.

Blockchain Explained

A blockchain carries no transaction cost. (An infrastructure cost yes, but no transaction cost.) The blockchain is a simple yet ingenious way of passing information from A to B in a fully automated and safe manner. One party to a transaction initiates the process by creating a block. This block is verified by thousands, perhaps millions of computers distributed around the net. The verified block is added to a chain, which is stored across the net, creating not just a unique record, but a unique record with a unique history. Falsifying a single record would mean falsifying the entire chain in millions of instances. That is virtually impossible. Bitcoin uses this model for monetary transactions, but it can be deployed in many others ways.

Blockchain is the most disruptive invention since the Internet itself

Think of a railway company. We buy tickets on an app or the web. The credit card company takes a cut for processing the transaction. With blockchain, not only can the railway operator save on credit card processing fees, it can move the entire ticketing process to the blockchain. The two parties in the transaction are the railway company and the passenger. The ticket is a block, which will be added to a ticket blockchain. Just as a monetary transaction on blockchain is a unique, independently verifiable and unfalsifiable record (like Bitcoin), so can your ticket be. Incidentally, the final ticket blockchain is also a record of all transactions for, say, a certain train route, or even the entire train network, comprising every ticket ever sold, every journey ever taken.

But the key here is this: it’s free. Not only can the blockchain transfer and store money, but it can also replace all processes and business models which rely on charging a small fee for a transaction. Or any other transaction between two parties.

Here is another example. The gig economy hub Fivver charges 0.5 dollars on a 5 transaction between individuals buying and selling services. Using blockchain technology the transaction is free. Ergo, Fivver will cease to exist. So will auction houses and any other business entity based on the market-maker principle.

Even recent entrants like Uber and AirBnB are threatened by blockchain technology. All you need to do is encode the transactional information for a car ride or an overnight stay, and again you have a perfectly safe way that disrupts the business model of the companies which have just begun to challenge the traditional economy. We are not just cutting out the fee-processing middle man, we are also eliminating the need for the match-making platform.

Because blockchain transactions are free, you can charge minuscule amounts, say 1/100 of a cent for a video view or article read. Why should I pay The Economist or National Geographic an annual subscription fee if I can pay per article on Facebook or my favorite chat app. Again, remember that blockchain transactions carry no transaction cost. You can charge for anything in any amount without worrying about third parties cutting into your profits.

Blockchain may make selling recorded music profitable again for artists by cutting out music companies and distributors like Apple or Spotify. The music you buy could even be encoded in the blockchain itself, making it a cloud archive for any song purchased. Because the amounts charged can be so small, subscription and streaming services will become irrelevant.

It goes further. Ebooks could be fitted with blockchain code. Instead of Amazon taking a cut, and the credit card company earning money on the sale, the books would circulate in encoded form and a successful blockchain transaction would transfer money to the author and unlock the book. Transfer ALL the money to the author, not just meager royalties. You could do this on a book review website like Goodreads, or on your own website. The marketplace Amazon is then unnecessary. Successful iterations could even include reviews and other third-party information about the book.

In the financial world the applications are more obvious and the revolutionary changes more imminent. Blockchains will change the way stock exchanges work, loans are bundled, and insurances contracted. They will eliminate bank accounts and practically all services offered by banks. Almost every financial institution will go bankrupt or be forced to change fundamentally, once the advantages of a safe ledger without transaction fees is widely understood and implemented. After all, the financial system is built on taking a small cut of your money for the privilege of facilitating a transaction. Bankers will become mere advisers, not gatekeepers of money. Stockbrokers will no longer be able to earn commissions and the buy/sell spread will disappear.

[ Source : https://blockgeeks.com/guides/what-is-blockchain-technology/ ]