@@ -182,9 +182,10 @@ First, a new block header is allocated and filled with the relevant data (previo
Bitcoin uses \emph{SHA-256 function squared}, due to the birthday attacks on the smaller but related SHA-1 hash. SHA-1's resistance to birthday attacks has been known to be vulnerable and a collaboration between Google Research and CWI Amsterdam has shown it is possible two create two distinct PDF files which result in the same SHA-1 hash \cite{SHAttered}.
\vspace{\baselineskip}% space line for dramatic purposes
\section{Incentives}
\label{sec:incentives}
There is a difference between \emph{mining} and \emph{minting} a coin. Minting is the creation of coins, real or virtual, with doing a negligible amount of work, i.e. what federal banks are doing. Mining on the other hand requires doing hard work, in the case of Bitcoin solving hash puzzles with a very low chance of success.
There is a difference between \emph{mining} and \emph{minting} a coin. Minting is the creation of coins, real or virtual, by doing a negligible amount of work, for instance what federal banks are doing. Mining on the other hand requires doing hard work, in the case of Bitcoin solving hash puzzles with a very low chance of success.
As Jemima Kelly put it for Reuters \cite{ReutersMining}:
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@@ -566,10 +567,11 @@ Those include the large data centers run by the ``Big Four'': Amazon, Google, Fa
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Another interesting illustration is NSA's Utah Data Center, formally known as ``Intelligence Community Comprehensive National Cybersecurity Initiative Data Center''.
Another interesting illustration is NSA's Utah Data Center, formally known as ``Intelligence Community Comprehensive National Cybersecurity Initiative Data Center'', shown in figure \ref{fig:utahdatacenter}
\begin{figure}[!htbp]
\centering
\caption{NSA Utah Data Center, Source: Parker Higgins \cite{WikipediaNSAUtah}}
@@ -783,9 +785,9 @@ A general concern with Proof Of Stake methods is often referred to as the \emph{
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\section{Delegated Proof Of Stake}
This consensus mechanism was first implemented by the BitShares blockchain and has been updated several times since. Broadly speaking, it is comparable to the U.S. electoral college system. Under DPOS, the stakeholders can elect any number of \emph{witnesses} to generate blocks. In previous iteration the \emph{witnesses} were called \emph{delegates}, hence the name ``Delegated Proof Of Stake''\cite{BitsharesDPoS}.
This consensus mechanism was first implemented by the BitShares blockchain and has been updated several times since. Broadly speaking, it is comparable to the U.S. electoral college system. Under DPOS, the stakeholders can elect any number of \emph{witnesses} to generate blocks \cite{BitsharesDPoS}.
Witnesses serve the role of validating signatures and timestamping transactions by including them in blocks, therefore they are BitShares equivalent of miners (without the intensive work, of course). Each account is allowed one vote per share per witness, this process is known as \emph{approval voting}. The top $N$ witnesses by total approval are selected, where $N$ is defined such that at least 50\% of voting stakeholders believe there is sufficient decentralization. When stakeholders express their desired number of witnesses, they must also vote for at least that many witnesses. A stakeholder cannot vote for more decentralization than witnesses for which they actually cast votes.
Each time the elected witnesses produce a block, they are paid for their services. Their pay rate is set by the stakeholders via their elected delegates. If a witness fails to produce a block, then they are not paid, and may be voted out in the future, as they did not fulfill the promise to their voters. A single witness can't sign invalid blocks as the block needs confirmation by the other witnesses as well.
The elected witnesses are paid for producing each block. The pay rate is set by the stakeholders via their elected delegates. If a witness fails to produce a block, then they are not paid, and may be voted out in the future, as they did not fulfill the promise to their voters. A single witness can't sign invalid blocks as the block needs confirmation by the other witnesses as well\cite{BitsharesDPoS}.
The slate of active witnesses is updated daily when the votes are tallied. The witnesses are shuffled and each witness is given a turn to create one block at a fixed schedule, in the case of BitShares this is every 2 seconds. If a witness does not produce a block in their time slot, then that time slot is skipped, and the next witness produces the next block.
