ecp.py: Added tests for mbedtls_ecp_mod_p255_raw

This patch introduces the `EcpP255Raw` test class for testing
the curve using the preestablished `ecp_mod_p_generic_raw()`
test. The test's logic has been updated accordingly.

Signed-off-by: Minos Galanakis <minos.galanakis@arm.com>

scripts/mbedtls_dev/ecp.py

@@ -711,6 +711,88 @@ class EcpP256K1Raw(bignum_common.ModOperationCommon,
         return  ["MBEDTLS_ECP_DP_SECP256K1"] + args
 
 
+class EcpP255Raw(bignum_common.ModOperationCommon,
+                 EcpTarget):
+    """Test cases for ECP 25519 fast reduction."""
+    symbol = "-"
+    test_function = "ecp_mod_p_generic_raw"
+    test_name = "mbedtls_ecp_mod_p255_raw"
+    input_style = "fixed"
+    arity = 1
+    dependencies = ["MBEDTLS_ECP_DP_CURVE25519_ENABLED"]
+
+    moduli = [("7fffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffed")] # type: List[str]
+
+    input_values = [
+        "0", "1",
+
+        # Modulus - 1
+        ("7fffffffffffffffffffffffffffffffffffffffffffffffffffffff"
+        "ffffffec"),
+
+        # Modulus + 1
+        ("7fffffffffffffffffffffffffffffffffffffffffffffffffffffff"
+        "ffffffee"),
+
+        # 2^255 - 1
+        ("7fffffffffffffffffffffffffffffffffffffffffffffffffffffff"
+         "ffffffff"),
+
+        # Maximum canonical P255 multiplication result
+        ("3fffffffffffffffffffffffffffffffffffffffffffffffffffffff"
+         "ffffffec000000000000000000000000000000000000000000000000"
+         "0000000000000190"),
+
+        # First 8 number generated by random.getrandbits(510) - seed(2,2)
+        ("1019f0d64ee207f8da94e3e8ab73738fcf1822ffbc6887782b491044d5"
+         "e341245c6e433715ba2bdd177219d30e7a269fd95bafc8f2a4d27bdcf4"
+         "bb99f4bea973"),
+        ("20948fa1feac7eb7dc38f519b91751dacdbd47d364be8049a372db8f6e"
+         "405d93ffed9235288bc781ae66267594c9c9500925e4749b575bd13653"
+         "f8dd9b1f282e"),
+        ("3a1893ea5186ee32ee8d7ee9770348a05d300cb90706a045defc044a09"
+         "325626e6b58de744ab6cce80877b6f71e1f6d2ef8acd128b4f2fc15f3f"
+         "57ebf30b94fa"),
+        ("20a6923522fe99a22c70501e533c91352d3d854e061b90303b08c6e33c"
+         "7295782d6c797f8f7d9b782a1be9cd8697bbd0e2520e33e44c50556c71"
+         "c4a66148a86f"),
+        ("3a248138e8168561867e5e15bc01bfce6a27e0dfcbf8754472154e76e4"
+         "c11ab2fec3f6b32e8d4b8a8f54f8ceacaab39e83844b40ffa9b9f15c14"
+         "bc4a829e07b0"),
+        ("2f450feab714210c665d7435c1066932f4767f26294365b2721dea3bf6"
+         "3f23d0dbe53fcafb2147df5ca495fa5a91c89b97eeab64ca2ce6bc5d3f"
+         "d983c34c769f"),
+        ("1d199effe202849da9643a295a9ac6decbd4d3e2d4dec9ef83f0be4e80"
+         "371eb97f81375eecc1cb6347733e847d718d733ff98ff387c56473a7a8"
+         "3ee0761ebfd2"),
+        ("3423c6ec531d6460f0caeef038c89b38a8acb5137c9260dc74e088a9b9"
+         "492f258ebdbfe3eb9ac688b9d39cca91551e8259cc60b17604e4b4e736"
+         "95c3e652c71a"),
+
+        # Next 2 number generated by random.getrandbits(255)
+        ("62f1243644a4a8f69dc8db48e86ec9c6e06f291b2a838af8d5c44a4eb3"
+         "172062"),
+        ("6a606e54b4c9e755cc9c3adcf515a8234da4daeb4f3f87777ad1f45ae9"
+         "500ec9"),
+    ]
+
+    @property
+    def arg_a(self) -> str:
+        return super().format_arg('{:x}'.format(self.int_a)).zfill(2 * self.hex_digits)
+
+    def result(self) -> List[str]:
+        result = self.int_a % self.int_n
+        return [self.format_result(result)]
+
+    @property
+    def is_valid(self) -> bool:
+        return True
+
+    def arguments(self):
+        args = super().arguments()
+        return  ["MBEDTLS_ECP_DP_CURVE25519"] + args
+
+
 class EcpP448Raw(bignum_common.ModOperationCommon,
                  EcpTarget):
     """Test cases for ECP P448 fast reduction."""

tests/suites/test_suite_ecp.function

@@ -1348,6 +1348,13 @@ void ecp_mod_p_generic_raw(int curve_id,
             curve_bits = 256;
             curve_func = &mbedtls_ecp_mod_p256k1_raw;
             break;
+#endif
+#if defined(MBEDTLS_ECP_DP_CURVE25519_ENABLED)
+        case MBEDTLS_ECP_DP_CURVE25519:
+            limbs = 2 * limbs_N;
+            curve_bits = 255;
+            curve_func = &mbedtls_ecp_mod_p255_raw;
+            break;
 #endif
         default:
             mbedtls_test_fail("Unsupported curve_id", __LINE__, __FILE__);