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Correct an error pointed out in NCC's Blossom audit affecting the first 10 blocks of the chain. 

Signed-off-by: Daira Hopwood <daira@jacaranda.org>
This commit is contained in:
Daira Hopwood 2019-05-01 10:59:07 +01:00
parent 1258385ab5
commit 65d43bfac4
1 changed files with 15 additions and 7 deletions
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22
protocol/protocol.tex
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@ -9002,7 +9002,7 @@ Define:
\begin{formulae}
\hfuzz=10pt
\item $\mean(S) := \hfrac{\ssum{i=1}{\length(S)} S_i}{\length(S)}$
\item $\median(S) := \sorted(S)_{\sceiling{\length(S) / 2}}$
\item $\median(S) := \sorted(S)_{\sceiling{(\length(S)+1) / 2}}$
\item $\bound{\Lower}{\Upper}(x) := \maximum(\Lower, \minimum(\Upper, x)))$
\item $\trunc{x} := \begin{cases}
\floor{x},&\caseif x \geq 0 \\
@ -9049,12 +9049,16 @@ The \targetThreshold for a given \blockHeight $\BlockHeight$ is then calculated
\end{formulae}
\vspace{-2ex}
\pnote{
The convention used for the height parameters to $\MedianTime$, $\ActualTimespan$,
$\ActualTimespanDamped$, $\ActualTimespanBounded$, $\MeanTarget$, $\Threshold$, and
$\ThresholdBits$ is that these functions use only information from \blocks \emph{preceding}
the given \blockHeight.
}
\begin{pnotes}
\item The convention used for the height parameters to the functions $\MedianTime$, $\MeanTarget$,
$\ActualTimespan$, $\ActualTimespanDamped$, $\ActualTimespanBounded$, $\Threshold$, and $\ThresholdBits$
is that these functions use only information from \blocks \emph{preceding} the given \blockHeight.
\item When the $\median$ function is applied to a sequence of even length (which only happens
in the definition of $\MedianTime$ during the first $\PoWAveragingWindow - 1$ \blocks of
the \blockchain), the element that begins the second half of the sequence is taken.
This corresponds to the \zcashd implementation, but was not specified correctly in versions
of this specification prior to 2019.0-beta-40.
\end{pnotes}
On the test network from \blockHeight $299188$ onward, the difficulty adjustment algorithm
is changed to allow minimum-difficulty \blocks, as described in \cite{ZIP-205}.
@ -9945,6 +9949,10 @@ Peter Newell's illustration of the Jubjub bird, from \cite{Carroll1902}.
\begin{itemize}
\item Fix a specification error in the Founders' Reward calculation during
the slow start period.
\item Correct an inconsistency in difficulty adjustment between the spec and
\zcashd implementation for the first $\PoWAveragingWindow - 1$ \blocks
of the \blockchain. This inconsistency was pointed out by NCC Group
in their \Blossom specification audit.
\blossom{
\item Revert changes for funding streams from Withdrawn \cite{ZIP-207}.
}