private void deleteSigns(String filename) throws Exception {
		// check that the folder "filename" under the certificate folder is legal
		String pathname = (Server.SERVERDIRECTORIES[2] + "/" + filename);
		File file = new File(pathname);
		// Signature folder doesn't exist or path doesn't exist
		if(file == null || !file.exists()) {
			System.out.println("Server: No signatures deleted for '" + filename + "'");
		// Signature folder does exist
		} else {
			if(!file.isDirectory()) {
				throw new IllegalArgumentException("ERROR: Certificates for filename '" + pathname + "' can't be deleted: '" +
						pathname + "' is not a directory name.");
			}
			
			// Find all child files in the folder and delete them
			System.out.println("Server: Deleting signatures for '" + filename + "'");
			File[] fileSigns = file.listFiles();
			boolean success = false;
			for(File f: fileSigns) {
				success = f.delete();
				if(!success) {
					throw new Exception("ERROR: Could not delete file '" + f.getAbsolutePath() + "' on Server");
				}
			}
		}
	}