From ad40f2caa74716b930000bd4518f16674e626b75 Mon Sep 17 00:00:00 2001
From: Arun Isaac
Date: Tue, 15 Jul 2025 17:44:59 +0100
Subject: Standardize before encryption.

* pyhegp/pyhegp.py (hegp_encrypt): Standardize before encryption.
(hegp_decrypt): Unstandardize after decryption.
(encrypt): Pass in mean and standard deviation from summary file to
hegp_encrypt.
* tests/test_pyhegp.py (test_hegp_encryption_decryption_are_inverses):
Pass in mean and standard deviation to hegp_encrypt.
---
 tests/test_pyhegp.py | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

(limited to 'tests/test_pyhegp.py')

diff --git a/tests/test_pyhegp.py b/tests/test_pyhegp.py
index 304e74b..6cb35de 100644
--- a/tests/test_pyhegp.py
+++ b/tests/test_pyhegp.py
@@ -54,13 +54,16 @@ def no_column_zero_standard_deviation(matrix):
     arrays("float64",
            array_shapes(min_dims=2, max_dims=2),
            elements=st.floats(min_value=0, max_value=100)))
-)
+       # Reject matrices with zero standard deviation columns since
+       # they trigger a division by zero.
+       .filter(no_column_zero_standard_deviation))
 def test_hegp_encryption_decryption_are_inverses(plaintext):
+    mean = np.mean(plaintext, axis=0)
+    standard_deviation = np.std(plaintext, axis=0)
     rng = np.random.default_rng()
     key = random_key(rng, len(plaintext))
-    # FIXME: We don't use maf at the moment.
-    maf = None
-    assert hegp_decrypt(hegp_encrypt(plaintext, maf, key), key) == approx(plaintext)
+    assert hegp_decrypt(hegp_encrypt(plaintext, mean, standard_deviation, key),
+                        mean, standard_deviation, key) == approx(plaintext)
 
 @given(arrays("float64",
               array_shapes(min_dims=2, max_dims=2),
-- 
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