From 811215cadcbda2ed1962ed6f51400c8fe8fa7bca Mon Sep 17 00:00:00 2001
From: Simon <simon@bitcartel.com>
Date: Wed, 21 Mar 2018 01:13:31 -0700
Subject: [PATCH] Verify the challenge file exists before asking user to input
 randomness.

---
 src/bin/compute.rs | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/src/bin/compute.rs b/src/bin/compute.rs
index 955dd83..a703305 100644
--- a/src/bin/compute.rs
+++ b/src/bin/compute.rs
@@ -7,8 +7,17 @@ use powersoftau::*;
 
 use std::fs::OpenOptions;
 use std::io::{self, Read, BufReader, Write, BufWriter};
+use std::path::Path;
+use std::process;
 
 fn main() {
+
+    // Check that the user placed the challenge file into the local directory
+    if !Path::new("./challenge").exists() {
+        println!("Error: ./challenge file not found.");
+        process::exit(1);
+    }
+
     // Create an RNG based on a mixture of system randomness and user provided randomness
     let mut rng = {
         use byteorder::{ReadBytesExt, BigEndian};