tally

commit 49397b48b5b9c69fe020cc885882e7dc5c40eb71
parent 8e5f0edddfd1e53101fa9a863a578b373ec4a4b4
author Owen Rusk <owen@papermothgames.com>
date   2026-03-11 20:05:33 -0500

tests: one share on its own looks like noise

diff --git a/tests/test_shamir.py b/tests/test_shamir.py
index e8cfcec..572c044 100644
--- a/tests/test_shamir.py
+++ b/tests/test_shamir.py
@@ -2,6 +2,7 @@ import itertools
 import os
 import random
 import unittest
+from collections import Counter
 
 from tally import shamir
 
@@ -52,6 +53,15 @@ class ShamirTest(unittest.TestCase):
             with self.subTest(k=k, n=n):
                 self.assertNotEqual(shamir.combine(shares[: k - 1]), secret)
 
+    def test_one_share_of_two_looks_like_noise(self) -> None:
+        # every byte of the secret is 0. a single share should still be all over the place
+        secret = bytes(6000)
+        for x, data in shamir.split(secret, 2, 3):
+            counts = Counter(data)
+            with self.subTest(x=x):
+                self.assertEqual(len(counts), 256)
+                self.assertLess(max(counts.values()), 3 * len(secret) // 256)
+
     def test_bad_k_and_n(self) -> None:
         for k, n in [(1, 3), (4, 3), (2, 256), (0, 0)]:
             with self.assertRaises(ValueError):