Add mbedtls_mpi_core_ct_uint_table_lookup tests

Signed-off-by: Janos Follath <janos.follath@arm.com>

scripts/mbedtls_dev/bignum_core.py

@@ -69,6 +69,44 @@ class BignumCoreShiftR(BignumCoreTarget, metaclass=ABCMeta):
             for count in counts:
                 yield cls(input_hex, descr, count).create_test_case()
 
+class BignumCoreCTLookup(BignumCoreTarget, metaclass=ABCMeta):
+    """Test cases for mbedtls_mpi_core_ct_uint_table_lookup()."""
+    count = 0
+    test_function = "mpi_core_ct_uint_table_lookup"
+    test_name = "Constant time MPI table lookup"
+
+    bitsizes = [
+            (32, "One limb"),
+            (192, "Smallest curve sized"),
+            (512, "Largest curve sized"),
+            (2048, "Small FF/RSA sized"),
+            (4096, "Large FF/RSA sized"),
+            ]
+
+    window_sizes = [ 0, 1, 2, 3, 4, 5, 6 ]
+
+    def __init__(self,
+                 bitsize: int, descr: str, window_size: int) -> None:
+        self.bitsize = bitsize
+        self.bitsize_description = descr
+        self.window_size = window_size
+
+    def arguments(self) -> List[str]:
+        return [str(self.bitsize), str(self.window_size)]
+
+    def description(self) -> str:
+        return '{} - {} MPI with {} bit window'.format(
+                BignumCoreCTLookup.test_name,
+                self.bitsize_description,
+                self.window_size
+                )
+
+    @classmethod
+    def generate_function_tests(cls) -> Iterator[test_case.TestCase]:
+        for bitsize, bitsize_description in cls.bitsizes:
+            for window_size in cls.window_sizes:
+                yield (cls(bitsize, bitsize_description, window_size)
+                       .create_test_case())
 
 class BignumCoreOperation(bignum_common.OperationCommon, BignumCoreTarget, metaclass=ABCMeta):
     #pylint: disable=abstract-method

tests/suites/test_suite_bignum_core.function

@@ -941,3 +941,40 @@ exit:
     mbedtls_mpi_free( &RR_REF );
 }
 /* END_CASE */
+
+/* BEGIN_CASE */
+void mpi_core_ct_uint_table_lookup( int bitlen, int window_size )
+{
+    size_t limbs = BITS_TO_LIMBS( bitlen );
+    size_t count = ( (size_t) 1 ) << window_size;
+
+    mbedtls_mpi_uint *table = NULL;
+    ASSERT_ALLOC( table, limbs * count );
+
+    mbedtls_mpi_uint *dest = NULL;
+    ASSERT_ALLOC( dest, limbs );
+
+    /*
+     * Fill the table with a unique counter so that differences are easily
+     * detected. (And have their relationship to the index relatively non-trivial just
+     * to be sure.)
+     */
+    for( size_t i = 0; i < count * limbs; i++ )
+    {
+        table[i] = ~i - 1;
+    }
+
+    for( size_t i = 0; i < count; i++ )
+    {
+        memset( dest, 0x00, limbs * sizeof( *dest ) );
+        mbedtls_mpi_core_ct_uint_table_lookup( dest, table, limbs, count, i );
+
+        mbedtls_mpi_uint *current = table + i * limbs;
+        ASSERT_COMPARE( dest, limbs * sizeof( *dest ),
+                        current, limbs * sizeof( *current ) );
+    }
+
+exit:
+    ;
+}
+/* END_CASE */