sub computeSHA1 () {
	# Passed a file path, opens the file and calculates the SHA1 value
	my $srcfile = shift;
	print "DEBUG: computeSHA1: arrived\n" if ($debug);
	my $sha1post = Digest::SHA1->new;
	open my $filehandle, $srcfile or &usage("computeSHA: Failed to open " . $srcfile . ": " . $!, 2);
	$sha1post->addfile($filehandle);
	print "DEBUG: downloadSHA1: Calculating SHA1 for $srcfile\n" if ($debug);
	close $filehandle;
	return $sha1post->hexdigest;
}

sub downloadSHA1 () {
	# Passed a URL for a file, looks for the SHA1 file and returns the value
	my $url = shift;
	print "DEBUG: downloadSHA1: arrived\n" if ($debug);
	my $SHAurl = $url . ".sha1";
	my $browser = LWP::UserAgent->new;
	# Get the SHA1 value from $SHAurl
	my $SHAcall = $browser->get($SHAurl);
	print "DEBUG: downloadSHA1: Getting SHA1 from $SHAurl\n" if ($debug);
	&usage("downloadSHA1: Could not fetch SHA1 at " . $SHAurl, 5) unless $SHAcall->is_success;
 	return $SHAcall->content;
}