Fix a typo in the definition of nullifier integrity.

Signed-off-by: Daira Hopwood <daira@jacaranda.org>

protocol/protocol.tex

@@ -1877,7 +1877,7 @@ $\changed{\vpubOld\; +} \vsum{i=1}{\NOld} \vOld{i} = \vpubNew + \vsum{i=1}{\NNew
 
 \subparagraph{\Nullifier{} integrity}
 
-for each $i \in \setofNew$:
+for each $i \in \setofOld$:
 $\nfOld{i} = \PRFnf{\AuthPrivateOld{i}}(\NoteAddressRandOld{i})$.
 
 \subparagraph{Spend authority} \label{spendauthority}
@@ -4055,6 +4055,7 @@ The errors in the proof of Ledger Indistinguishability mentioned in
 
 \begin{itemize}
     \item Add abstract and keywords.
+    \item Fix a typo in the definition of \nullifier integrity.
 \end{itemize}
 
 \introlist