Verify binary against Bitcoin Core release PGP key

Dockerfile

@@ -8,14 +8,16 @@ RUN VERSION=`cat /tmp/VERSION` && \
     TARBALL="bitcoin-${VERSION}-x86_64-linux-gnu.tar.gz" && \
     chmod a+x /usr/local/bin/* && \
     apt-get update && \
-    apt-get install -y curl && \
+    apt-get install -y curl gpg && \
     cd /tmp && \
     curl -O https://bitcoin.org/bin/bitcoin-core-${VERSION}/${TARBALL} && \
     curl -O https://bitcoin.org/bin/bitcoin-core-${VERSION}/SHA256SUMS.asc && \
+    gpg --recv-keys 01EA5486DE18A882D4C2684590C8019E36C2E964 && \
+    gpg --verify SHA256SUMS.asc && \
     grep $TARBALL SHA256SUMS.asc | sha256sum -c && \
     tar -zxvf $TARBALL && \
     mv bitcoin-${VERSION}/bin/* /usr/local/bin/ && \
-    apt-get purge -y curl && \
+    apt-get purge -y curl gpg && \
     apt-get clean && rm -rf /var/lib/apt/lists/* /tmp/* /var/tmp/*
 
 VOLUME ["/data"]