From e27738308cfb45d34e9a91335e65b12d7d6dde2e Mon Sep 17 00:00:00 2001
From: Waleed Elmelegy <waleed.elmelegy@arm.com>
Date: Tue, 21 May 2024 16:05:52 +0000
Subject: [PATCH] Merge mbedtls_mpi_core_sub() constant time testing and
 functional testing

Signed-off-by: Waleed Elmelegy <waleed.elmelegy@arm.com>
---
 tests/suites/test_suite_bignum_core.function  | 53 ++++++++-----------
 tests/suites/test_suite_bignum_core.misc.data |  6 ---
 2 files changed, 23 insertions(+), 36 deletions(-)

diff --git a/tests/suites/test_suite_bignum_core.function b/tests/suites/test_suite_bignum_core.function
index 61eeaf5451..1bb1ab06a4 100644
--- a/tests/suites/test_suite_bignum_core.function
+++ b/tests/suites/test_suite_bignum_core.function
@@ -660,31 +660,54 @@ void mpi_core_sub(char *input_A, char *input_B,
     memcpy(b, B.p, B.n * sizeof(mbedtls_mpi_uint));
     memcpy(x, X.p, X.n * sizeof(mbedtls_mpi_uint));
 
+    TEST_CF_SECRET(a, bytes);
+    TEST_CF_SECRET(b, bytes);
+
     /* 1a) r = a - b => we should get the correct carry */
     TEST_EQUAL(carry, mbedtls_mpi_core_sub(r, a, b, limbs));
 
+    TEST_CF_PUBLIC(a, bytes);
+    TEST_CF_PUBLIC(b, bytes);
+    TEST_CF_PUBLIC(r, bytes);
+
     /* 1b) r = a - b => we should get the correct result */
     TEST_MEMORY_COMPARE(r, bytes, x, bytes);
 
     /* 2 and 3 test "r may be aliased to a or b" */
     /* 2a) r = a; r -= b => we should get the correct carry (use r to avoid clobbering a) */
     memcpy(r, a, bytes);
+
+    TEST_CF_SECRET(r, bytes);
+    TEST_CF_SECRET(b, bytes);
+
     TEST_EQUAL(carry, mbedtls_mpi_core_sub(r, r, b, limbs));
 
+    TEST_CF_PUBLIC(r, bytes);
+    TEST_CF_PUBLIC(b, bytes);
+
     /* 2b) r -= b => we should get the correct result */
     TEST_MEMORY_COMPARE(r, bytes, x, bytes);
 
     /* 3a) r = b; r = a - r => we should get the correct carry (use r to avoid clobbering b) */
     memcpy(r, b, bytes);
+
+    TEST_CF_SECRET(r, bytes);
+    TEST_CF_SECRET(a, bytes);
+
     TEST_EQUAL(carry, mbedtls_mpi_core_sub(r, a, r, limbs));
 
+    TEST_CF_PUBLIC(r, bytes);
+    TEST_CF_PUBLIC(a, bytes);
+
     /* 3b) r = a - b => we should get the correct result */
     TEST_MEMORY_COMPARE(r, bytes, x, bytes);
 
     /* 4 tests "r may be aliased to [...] both" */
     if (A.n == B.n && memcmp(A.p, B.p, bytes) == 0) {
         memcpy(r, b, bytes);
+        TEST_CF_SECRET(r, bytes);
         TEST_EQUAL(carry, mbedtls_mpi_core_sub(r, r, r, limbs));
+        TEST_CF_PUBLIC(r, bytes);
         TEST_MEMORY_COMPARE(r, bytes, x, bytes);
     }
 
@@ -1317,33 +1340,3 @@ exit:
     mbedtls_free(X);
 }
 /* END_CASE */
-
-/* BEGIN_CASE */
-void mpi_core_check_sub_ct(char *input_A, char *input_B, int exp_ret)
-{
-    mbedtls_mpi_uint *A = NULL;
-    mbedtls_mpi_uint *B = NULL;
-    mbedtls_mpi_uint *X = NULL;
-    size_t A_limbs, B_limbs;
-    int ret;
-
-    TEST_EQUAL(0, mbedtls_test_read_mpi_core(&A, &A_limbs, input_A));
-    TEST_EQUAL(0, mbedtls_test_read_mpi_core(&B, &B_limbs, input_B));
-
-    TEST_EQUAL(A_limbs, B_limbs);
-
-    size_t limbs = A_limbs;
-    TEST_CALLOC(X, limbs);
-
-    TEST_CF_SECRET(A, A_limbs * sizeof(mbedtls_mpi_uint));
-    TEST_CF_SECRET(B, B_limbs * sizeof(mbedtls_mpi_uint));
-
-    ret = mbedtls_mpi_core_sub(X, A, B, limbs);
-    TEST_EQUAL(ret, exp_ret);
-
-exit:
-    mbedtls_free(A);
-    mbedtls_free(B);
-    mbedtls_free(X);
-}
-/* END_CASE */
diff --git a/tests/suites/test_suite_bignum_core.misc.data b/tests/suites/test_suite_bignum_core.misc.data
index ccf375052e..ba86029977 100644
--- a/tests/suites/test_suite_bignum_core.misc.data
+++ b/tests/suites/test_suite_bignum_core.misc.data
@@ -523,9 +523,3 @@ mpi_core_clz:64:0
 
 CLZ: 100000 0: skip overly long input
 mpi_core_clz:100000:0
-
-Constant time Subtraction
-mpi_core_check_sub_ct:"1234567890abcdef0":"10000000000000000":0
-
-Constant time Subtraction #2
-mpi_core_check_sub_ct:"10000000000000000":"1234567890abcdef0":1