<!DOCTYPEhtml><htmllang="ko"><head><metacharset="UTF-8"><title>쉽게설명하는블록체인:지분증명이란?</title><metahttp-equiv="X-UA-Compatible"content="IE=edge"/><metaname="viewport"content="width=device-width,initial-scale=1,maximum-scale=3.0,minimum-scale=1,user-scalable=yes"><linkrel="stylesheet"type='text/css'href="https://cdn.banksalad.com/fonts/noto/NotoSansKR.css"><linkrel="stylesheet"type='text/css'href="https://cdn.banksalad.com/fonts/jua/style.css"><linkrel="stylesheet"href="https://banksalad.com/dist/contents.min.css"></head><body><divclass="contents__detail"><pstyle="text-align:justify;">이칼럼은<ahref="https://banksalad.com/contents/%EC%89%BD%EA%B2%8C-%EC%84%A4%EB%AA%85%ED%95%98%EB%8A%94-%EB%B8%94%EB%A1%9D%EC%B2%B4%EC%9D%B8-%EC%84%B8%EA%B7%B8%EC%9C%97-Segwit-%EC%9D%B4%EB%9E%80-9gjVA"target="_blank"onclick="ga('send','event','쉽게설명하는블록체인세그윗Segwit이란이동','이동_매거진상세','쉽게설명하는블록체인세그윗Segwit이란_쉽게-설명하는-블록체인-세그윗-Segwit-이란-9gjVA');fbq('trackCustom','이동_매거진상세',{timeStamp:newDate(),category:'쉽게설명하는블록체인세그윗Segwit이란이동',label:'쉽게설명하는블록체인세그윗Segwit이란_쉽게-설명하는-블록체인-세그윗-Segwit-이란-9gjVA'});">쉽게설명하는블록체인:세그윗(Segwit)이란?</a>에이어연재됩니다.</p><br/><br/><h1><b>지분증명이란?</b></h1><br/><h2><b>작업증명vs지분증명</b></h2><pstyle="text-align:justify;">작업증명(ProofofWork)이라는개념은처음접하는사람들에겐생소한용어이기도하지만블록체인을공부하는사람들에게는기본중의기본이면서도어려운내용이기도하다.<br/>작업증명(ProofofWork)을간략히요약하자면컴퓨터의연산력을바탕으로합의에도달하고그연산력이빠를수록블록에기록할수있는권한이더많이부여된다는것이핵심이었다.</p><divclass="contents__detail__image__containergreater-than-mobile"style="text-align:center;"><imgalt="작업증명과지분증명"style="width:524px;"src="https://cdn.banksalad.com/entities/etc/1528944197646-pc_group_0.png"><spanclass="blind">PoW:Miner가해시연산을하는하드웨어를가지고작업증명메커니즘을통해블록생성.연산능력에비례해서데이터업데이트권한획득.PoS:Validator가현재보유하고있는자산(Stake)양에비례해서데이터업데이트권한획득.블록에는검증자들각자가자산을보유하는‘자산증명리스트’를포함.</span><br/><br/><imgalt="지분증명"style="width:524px;"src="https://cdn.banksalad.com/entities/etc/1528944224514-pc_group_1.png"><spanclass="blind">비트코인6개가진사람>비트코인1개가진사람(x6)업데이트권한이더많음</span></div><divclass="contents__detail__image__containerless-than-mobile"style="text-align:center;"><imgalt="작업증명과지분증명"src="https://cdn.banksalad.com/entities/etc/1528944208408-mobile_group_0.png"><spanclass="blind">PoW:Miner가해시연산을하는하드웨어를가지고작업증명메커니즘을통해블록생성.연산능력에비례해서데이터업데이트권한획득.PoS:Validator가현재보유하고있는자산(Stake)양에비례해서데이터업데이트권한획득.블록에는검증자들각자가자산을보유하는‘자산증명리스트’를포함.</span><br/><br/><imgalt="지분증명"src="https://cdn.banksalad.com/entities/etc/1528944235725-mobile_group_1.png"><spanclass="blind">PoW:Miner가해시연산을하는하드웨어를가지고작업증명메커니즘을통해블록생성.연산능력에비례해서데이터업데이트권한획득.PoS:Validator가현재보유하고있는자산(Stake)양에비례해서데이터업데이트권한획득.블록에는검증자들각자가자산을보유하는‘자산증명리스트’를포함.</span></div><pstyle="text-align:justify;text-decoration:underline;">>ProofofStake(지분증명)는간단히말해작업이아닌더많은지분(해당코인)을가지고있을수록그에비례하여블록에기록할권한이더많이부여되는것이다.</p><pstyle="text-align:justify;">코인을가지고있는노드들모두가합의를통해블록에데이터를추가할수있게되는것이고코인을많이가진노드는데이터를업데이트할권한이더많이주어지는것이ProofofStake이고,</p><pstyle="text-align:justify;font-weight:bold;"><u>PoW와마찬가지로블록이생성될때보상이지급되는데지분에대한이자의개념으로보상이</u><br/>지급된다는것이둘의다른점이라면다른점이다.</p><pstyle="text-align:center;"><imgalt="지분증명의자산내역증명"style="width:193px;"src="https://cdn.banksalad.com/entities/etc/1528944246512-pc_group_2.png"></p><pstyle="text-align:justify;">그림과같이각자산을보유하는노드들은자신이합의하는블록에자산을증명함으로서데이터를업데이트하게된다.</p><pstyle="text-align:justify;">다시말해본인이옳다고생각하는블록에동의를하면서자신이가진Stake(지분)을해당블록에보여주고증명하는것이고그결과밑의그림처럼과반수의자산이동의한블록이더빠르고더길게블록들을형성하게된다.</p><divclass="contents__detail__image__containergreater-than-mobile"><imgalt="지분증명합의메커니즘"src="https://cdn.banksalad.com/entities/etc/1528944256300-pc_group_3.png"></div><divclass="contents__detail__image__containerless-than-mobile"><imgalt="지분증명합의메커니즘"src="https://cdn.banksalad.com/entities/etc/1528944264006-mobile_group_3.png"></div><br/><pstyle="text-align:justify;">위그림처럼체인이갈라지는포킹(Forking)이일어나게되더라도더많은자산을검증(보유)하는체인이결국엔살아남게되는것이PoS합의메커니즘의운영방식이다.</p><pstyle="text-align:justify;">이렇게코인을소유하고있는사람누구나가데이터베이스를업데이트할수있게되는데이를단순하게생각하면정말위험하다고볼수있다.돈을많이가진사람일수록장부에작성할권한이많이주어진다니지분이많은사람이악의적인공격을가하게된다면해당블록체인은위험에처하게될수밖에없다.</p><pstyle="text-align:justify;">가령A라는친구가이더리움전체지분의51%를소유하고있는경우이더리움데이터업데이트의권한은A가쥐고흔들수있다고볼수있다.</p><pstyle="text-align:justify;">따라서A가싫어하는B라는사람이100억원이라는자산가치의이더리움을보유하고있을경우A가B의이더리움기록을없는기록을만들어버릴수있는것이다.</p><br/><h3style="font-size:18px;text-decoration:underline;">그럼에도왜많은개발자들이PoS를선호하는것일까?</h3><pstyle="text-align:justify;">-기존PoW방식은블록체인의정당성을확인할수있지만채굴노드의경우하드웨어를직접적으로갖춰야하고에너지소모가굉장히클뿐더러대량의채굴기를돌리는경우지리적으로도넓은평지를가지고있어야가능하다왜냐하면채굴기자체에서발생하는열과소음이상당하기때문이다.</p><pstyle="text-align:justify;">-PoW에서51%의해시파워를가지는비용=약1조<br/><spanstyle="margin-left:10px;">PoS에서전세계자산의51%=약100조</span></p><pstyle="text-align:justify;">이렇게100배가량의차이가나타나기때문에PoS가중앙집권화가더어렵고코인을가진노드누구나네트워크에허가없이참여하기때문에오히려더분산화가더잘된다고볼수있고더많은사람들이의사결정과정에쉽게참여할수있다.</p><br/><h1><b>즉,PoS(ProofofStake)는</b></h1><pstyle="text-align:justify;">1.더쉬운방식으로더많은노드들이참여할수있으며</p><pstyle="text-align:justify;">2.더분산화된합의방식이될수있는방향을제시하고</p><pstyle="text-align:justify;">3.이는특정블록체인에해당하는코인을가질수록데이터업데이트의권한이주어지기때문이고이로인해정말많은사람들이의사결정에참여할수있게만드는블록업데이트방식이다.</p><br/><h1><b>그렇다면PoS가가지고있는문제점은과연무엇일까?</b></h1><pstyle="text-align:justify;">>PoS의가장큰문제점은자산증명을하는데있어한계비용(marginalcost)이전혀없다는것이다.이문제를'NothingatStake'라한다.</p><pstyle="text-align:justify;">이게과연무슨말일까?</p><pstyle="text-align:justify;">아래그림을보면</p><divclass="contents__detail__image__containergreater-than-mobile"style="text-align:center;"><imgalt="지분증명의NothingatStake"style="width:524px;"src="https://cdn.banksalad.com/entities/etc/1528944277023-pc_group_4.png"><spanclass="blind">1.하나의거래에서서로다른거래내용발생2.모든노드들은제한없이여러블록에자신의지분을증명할수있음.</span></div><divclass="contents__detail__image__containerless-than-mobile"><imgalt="지분증명의NothingatStake"src="https://cdn.banksalad.com/entities/etc/1528944287026-mobile_group_4.png"><spanclass="blind">1.하나의거래에서서로다른거래내용발생2.모든노드들은제한없이여러블록에자신의지분을증명할수있음.</span></div><pstyle="text-align:justify;">여기서'여러블록에증명한다'는것은두개로갈린체인의거래가모두맞는거래라고검증(validating)하는것.그래야둘중어떤거래가참이든거짓이든계속체인이유지되든이득을보기때문.</p><pstyle="text-align:justify;">이경우두가지유형의공격이가능하다.</p><divclass="contents__detail__image__containergreater-than-mobile"style="text-align:center;"><imgalt="LongRangeAttack"style="width:550px;"src="https://cdn.banksalad.com/entities/etc/1528944297256-pc_group_5.png"><spanclass="blind">[LongRangeAttack]3-1.많은지분을가진노드가공격을목적으로두개의블록에모두증명을해놓고‘거짓’인체인도‘참’인것처럼길게체인형성시킴.</span></div><divclass="contents__detail__image__containerless-than-mobile"><imgalt="LongRangeAttack"src="https://cdn.banksalad.com/entities/etc/1528944307301-mobile_group_5.png"><spanclass="blind">[LongRangeAttack]3-1.많은지분을가진노드가공격을목적으로두개의블록에모두증명을해놓고‘거짓’인체인도‘참’인것처럼길게체인형성시킴.</span></div><pstyle="text-align:justify;">그림의LongRangeAttack의경우</p><pstyle="text-align:justify;">블록에새로참여한검증자(Validator)는어느것이정당한블록체인인지알수있는방법이없다.그래서새로많은지분을사들여검증에참여하는노드가거짓인블록체인에증명(합의)을해버릴경우제대로된거래를한사람은모두공격에당하는꼴이되는것.</p><pstyle="text-align:justify;">또다른하나는</p><divclass="contents__detail__image__containergreater-than-mobile"style="text-align:center;"><imgalt="ShortRangeAttack"style="width:550px;"src="https://cdn.banksalad.com/entities/etc/1528944316528-pc_group_6.png"><spanclass="blind">[ShortRangeAttack]3-2.공격자가이중지불로블록을추가.이때검증자(Validator)들은블록의정당성여부와관계없이양쪽모두에자신들의지분을증명하는것이유리하다.그래야어느것이참이되든보상을받을수있기때문.</span></div><divclass="contents__detail__image__containerless-than-mobile"><imgalt="ShortRangeAttack"src="https://cdn.banksalad.com/entities/etc/1528944325356-mobile_group_6.png"><spanclass="blind">[ShortRangeAttack]3-2.공격자가이중지불로블록을추가.이때검증자(Validator)들은블록의정당성여부와관계없이양쪽모두에자신들의지분을증명하는것이유리하다.그래야어느것이참이되든보상을받을수있기때문.</span></div><pstyle="text-align:justify;">ShortRangeAttack에서는<br/>그림과마찬가지로포킹이일어날시검증자(validator)들이어느쪽체인에든무조건증명(합의)하는것이유리하다.</p><pstyle="text-align:justify;">오히려양쪽체인에증명(합의)하지않으면손해를볼수밖에없게되는상황인것이다.왜냐하면어떤쪽이정당한블록체인이되어살아남든합의하는것에는제한이없으므로양쪽에모두지분을증명해놓아야어떤식으로든보상을받을수있기때문이다.</p><pstyle="text-align:justify;">다시말해NothingatStake는말그대로어느쪽이든잃을것이없다는것이다.</p><pstyle="text-align:justify;">그렇다면이심각한문제를어떻게해결할것인가?</p><pstyle="text-align:justify;">그래서이더리움개발자들은'보증금'과'벌금'제도를부가해서이를해결하려고하고있다.</p><pstyle="text-align:justify;">말그대로검증자(validator)들이지분을블록상에서증명할때보증금을어느정도걸어놓고그블록이거짓임이드러나게되면보증금에서벌금을차감하는방식으로해결방안을모색하고있는중이다.그래서'nothingatstake'에서'somethingatstake'로만들어정당한블록이생성되도록하는것이다.</p><pstyle="text-align:justify;">이렇게좀더효율적이라고평가받는PoS는현재블록체인시스템에서적용이되기시작하여현재높은주가를달리고있고이시스템은이더리움을기반으로안정화되어가는중이다.</p></div></body></html>