Switch blocksize and count when reading from urandom with dd, to prevent...

Switch blocksize and count when reading from urandom with dd, to prevent getting fewer bytes for the secret key.

setup/webmail.sh

@@ -36,7 +36,7 @@ if [ ! -d /usr/local/lib/roundcubemail ]; then
 fi
 
 # Generate a safe 24-character secret key of safe characters.
-SECRET_KEY=$(dd if=/dev/random bs=20 count=1 2>/dev/null | base64 | fold -w 24 | head -n 1)
+SECRET_KEY=$(dd if=/dev/random bs=1 count=18 2>/dev/null | base64 | fold -w 24 | head -n 1)
 
 # Create a configuration file.
 #