improved random pw generation, no external package

Dockerfile

@@ -21,14 +21,12 @@ RUN \
         libboost-system-dev \
         libboost-test-dev \
         libboost-thread-dev \
-        libdigest-sha-perl \
         libevent-dev \
         libminiupnpc-dev \
         libssl-dev \
         libtool \
         libzmq3-dev \
         libzmq5 \
-        perl \
         pkg-config \
     && \
     apt-get clean && \

bitcoind.run

@@ -3,7 +3,7 @@
 export HOME="/var/lib/bitcoind"
 
 # gen random pw for rpc server
-RANDOMPW=$(dd if=/dev/urandom bs=10 count=1 status=none | shasum | cut -b 1-20)
+RANDOMPW=$(tr -dc 'a-f0-9' < /dev/urandom | head -c20)
 
 cat <<EOF > $HOME/bitcoin.conf
 rpcuser=${BITCOIND_RPCUSER:-rpcuser}