Add a reference to [BCCGLRT2014].

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

protocol/protocol.tex

@@ -3964,7 +3964,7 @@ A \defining{\representedPairing} $\GroupP{}$ consists of:
 proving a particular \statement, dependent on \primary and \auxiliaryInputs,
 in zero knowledge --- that is, without revealing information about the
 \auxiliaryInputs other than that implied by the \statement.} The type of
-\zeroKnowledgeProvingSystem needed by \Zcash is a \defining{\ppzkSNARK}.
+\zeroKnowledgeProvingSystem needed by \Zcash is a \defining{\ppzkSNARK} \cite{BCCGLRT2014}.
 
 \introlist
 A \ppzkSNARK instance $\ZK$ defines:
@@ -10768,6 +10768,12 @@ Peter Newell's illustration of the Jubjub bird, from \cite{Carroll1902}.
 \lsection{Change History}{changehistory}
 
 
+\historyentry{2020.1.12}{2020-08-03}
+\begin{itemize}
+    \item Add a reference to \cite{BCCGLRT2014} in \crossref{abstractzk}.
+\end{itemize}
+
+
 \historyentry{2020.1.11}{2020-07-13}
 \begin{itemize}
     \item Change instances of ``the production network'' to ``\Mainnet'', and

protocol/zcash.bib

@@ -95,6 +95,16 @@ Lecture Notes in Computer Science; Springer, 2013.},
    urldate={2016-09-01}
 }
 
+@misc{BCCGLRT2014,
+   presort={BCCGLRT2014},
+   author={Nir Bitansky and Ran Canetti and Alessandro Chiesa and Shafi Goldwasser and Huijia Lin and Aviad Rubinstein and Eran Tromer},
+   title={The Hunting of the {SNARK}},
+   url={https://eprint.iacr.org/2014/580},
+   urldate={2020-08-01},
+   howpublished={Cryptology ePrint Ar\-chive: Report 2014/580.
+Received July~24, 2014.}
+}
+
 @misc{AKLGL2010,
    presort={AKLGL2010},
    author={Diego Aranha and Koray Karabina and Patrick Longa and Catherine Gebotys and Julio López},