Merge pull request #7230 from gabor-mezei-arm/6850_Secp256r1_fast_reduction
Extract Secp256r1 fast reduction from the prototype
diff --git a/library/ecp_curves.c b/library/ecp_curves.c
index f60f8b1..db21d7d 100644
--- a/library/ecp_curves.c
+++ b/library/ecp_curves.c
@@ -4580,6 +4580,8 @@
#endif
#if defined(MBEDTLS_ECP_DP_SECP256R1_ENABLED)
static int ecp_mod_p256(mbedtls_mpi *);
+MBEDTLS_STATIC_TESTABLE
+int mbedtls_ecp_mod_p256_raw(mbedtls_mpi_uint *X, size_t X_limbs);
#endif
#if defined(MBEDTLS_ECP_DP_SECP384R1_ENABLED)
static int ecp_mod_p384(mbedtls_mpi *);
@@ -5098,6 +5100,87 @@
#endif /* MBEDTLS_ECP_DP_SECP224R1_ENABLED */
+#if defined(MBEDTLS_ECP_DP_SECP256R1_ENABLED)
+
+/*
+ * Fast quasi-reduction modulo p256 (FIPS 186-3 D.2.3)
+ */
+static int ecp_mod_p256(mbedtls_mpi *N)
+{
+ int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
+ size_t expected_width = 2 * 256 / biL;
+ MBEDTLS_MPI_CHK(mbedtls_mpi_grow(N, expected_width));
+ ret = mbedtls_ecp_mod_p256_raw(N->p, expected_width);
+cleanup:
+ return ret;
+}
+
+MBEDTLS_STATIC_TESTABLE
+int mbedtls_ecp_mod_p256_raw(mbedtls_mpi_uint *X, size_t X_limbs)
+{
+ if (X_limbs != 2 * 256 / biL) {
+ return MBEDTLS_ERR_ECP_BAD_INPUT_DATA;
+ }
+
+ INIT(256);
+
+ ADD(8); ADD(9);
+ SUB(11); SUB(12); SUB(13); SUB(14); NEXT; // A0
+
+ ADD(9); ADD(10);
+ SUB(12); SUB(13); SUB(14); SUB(15); NEXT; // A1
+
+ ADD(10); ADD(11);
+ SUB(13); SUB(14); SUB(15); NEXT; // A2
+
+ ADD(11); ADD(11); ADD(12); ADD(12); ADD(13);
+ SUB(15); SUB(8); SUB(9); NEXT; // A3
+
+ ADD(12); ADD(12); ADD(13); ADD(13); ADD(14);
+ SUB(9); SUB(10); NEXT; // A4
+
+ ADD(13); ADD(13); ADD(14); ADD(14); ADD(15);
+ SUB(10); SUB(11); NEXT; // A5
+
+ ADD(14); ADD(14); ADD(15); ADD(15); ADD(14); ADD(13);
+ SUB(8); SUB(9); NEXT; // A6
+
+ ADD(15); ADD(15); ADD(15); ADD(8);
+ SUB(10); SUB(11); SUB(12); SUB(13); // A7
+
+ RESET;
+
+ /* Use 2^224 * (2^32 - 1) + 2^192 + 2^96 - 1
+ * to modulo reduce the final carry. */
+ ADD_LAST; NEXT; // A0
+ ; NEXT; // A1
+ ; NEXT; // A2
+ SUB_LAST; NEXT; // A3
+ ; NEXT; // A4
+ ; NEXT; // A5
+ SUB_LAST; NEXT; // A6
+ ADD_LAST; // A7
+
+ RESET;
+
+ /* Use 2^224 * (2^32 - 1) + 2^192 + 2^96 - 1
+ * to modulo reduce the carry generated by the previous reduction. */
+ ADD_LAST; NEXT; // A0
+ ; NEXT; // A1
+ ; NEXT; // A2
+ SUB_LAST; NEXT; // A3
+ ; NEXT; // A4
+ ; NEXT; // A5
+ SUB_LAST; NEXT; // A6
+ ADD_LAST; // A7
+
+ LAST;
+
+ return 0;
+}
+
+#endif /* MBEDTLS_ECP_DP_SECP256R1_ENABLED */
+
#undef LOAD32
#undef MAX32
#undef A
@@ -5118,8 +5201,7 @@
MBEDTLS_ECP_DP_SECP256R1_ENABLED ||
MBEDTLS_ECP_DP_SECP384R1_ENABLED */
-#if defined(MBEDTLS_ECP_DP_SECP256R1_ENABLED) || \
- defined(MBEDTLS_ECP_DP_SECP384R1_ENABLED)
+#if defined(MBEDTLS_ECP_DP_SECP384R1_ENABLED)
/*
* The reader is advised to first understand ecp_mod_p192() since the same
* general structure is used here, but with additional complications:
@@ -5240,43 +5322,6 @@
N->p[bits / 8 / sizeof(mbedtls_mpi_uint)] += msw;
}
-#if defined(MBEDTLS_ECP_DP_SECP256R1_ENABLED)
-/*
- * Fast quasi-reduction modulo p256 (FIPS 186-3 D.2.3)
- */
-static int ecp_mod_p256(mbedtls_mpi *N)
-{
- INIT(256);
-
- ADD(8); ADD(9);
- SUB(11); SUB(12); SUB(13); SUB(14); NEXT; // A0
-
- ADD(9); ADD(10);
- SUB(12); SUB(13); SUB(14); SUB(15); NEXT; // A1
-
- ADD(10); ADD(11);
- SUB(13); SUB(14); SUB(15); NEXT; // A2
-
- ADD(11); ADD(11); ADD(12); ADD(12); ADD(13);
- SUB(15); SUB(8); SUB(9); NEXT; // A3
-
- ADD(12); ADD(12); ADD(13); ADD(13); ADD(14);
- SUB(9); SUB(10); NEXT; // A4
-
- ADD(13); ADD(13); ADD(14); ADD(14); ADD(15);
- SUB(10); SUB(11); NEXT; // A5
-
- ADD(14); ADD(14); ADD(15); ADD(15); ADD(14); ADD(13);
- SUB(8); SUB(9); NEXT; // A6
-
- ADD(15); ADD(15); ADD(15); ADD(8);
- SUB(10); SUB(11); SUB(12); SUB(13); LAST; // A7
-
-cleanup:
- return ret;
-}
-#endif /* MBEDTLS_ECP_DP_SECP256R1_ENABLED */
-
#if defined(MBEDTLS_ECP_DP_SECP384R1_ENABLED)
/*
* Fast quasi-reduction modulo p384 (FIPS 186-3 D.2.4)
diff --git a/library/ecp_invasive.h b/library/ecp_invasive.h
index 1972f8c..cb16d23 100644
--- a/library/ecp_invasive.h
+++ b/library/ecp_invasive.h
@@ -33,8 +33,7 @@
#if defined(MBEDTLS_TEST_HOOKS) && defined(MBEDTLS_ECP_C)
-#if defined(MBEDTLS_ECP_DP_SECP256R1_ENABLED) || \
- defined(MBEDTLS_ECP_DP_SECP384R1_ENABLED)
+#if defined(MBEDTLS_ECP_DP_SECP384R1_ENABLED)
/* Preconditions:
* - bits is a multiple of 64 or is 224
* - c is -1 or -2
@@ -117,6 +116,28 @@
#endif /* MBEDTLS_ECP_DP_SECP224R1_ENABLED */
+#if defined(MBEDTLS_ECP_DP_SECP256R1_ENABLED)
+
+/** Fast quasi-reduction modulo p256 (FIPS 186-3 D.2.3)
+ *
+ * \param[in,out] X The address of the MPI to be converted.
+ * Must have exact limb size that stores a 512-bit MPI
+ * (double the bitlength of the modulus).
+ * Upon return holds the reduced value which is
+ * in range `0 <= X < 2 * N` (where N is the modulus).
+ * The bitlength of the reduced value is the same as
+ * that of the modulus (256 bits).
+ * \param[in] X_limbs The length of \p X in limbs.
+ *
+ * \return \c 0 on success.
+ * \return #MBEDTLS_ERR_ECP_BAD_INPUT_DATA if \p X_limbs is not the
+ * limb size that sores a 512-bit MPI.
+ */
+MBEDTLS_STATIC_TESTABLE
+int mbedtls_ecp_mod_p256_raw(mbedtls_mpi_uint *X, size_t X_limbs);
+
+#endif
+
#if defined(MBEDTLS_ECP_DP_SECP521R1_ENABLED)
/** Fast quasi-reduction modulo p521 = 2^521 - 1 (FIPS 186-3 D.2.5)
diff --git a/scripts/mbedtls_dev/ecp.py b/scripts/mbedtls_dev/ecp.py
index 354b234..ffe48fc 100644
--- a/scripts/mbedtls_dev/ecp.py
+++ b/scripts/mbedtls_dev/ecp.py
@@ -145,6 +145,79 @@
return True
+class EcpP256R1Raw(bignum_common.ModOperationCommon,
+ EcpTarget):
+ """Test cases for ECP P256 fast reduction."""
+ symbol = "-"
+ test_function = "ecp_mod_p256_raw"
+ test_name = "ecp_mod_p256_raw"
+ input_style = "fixed"
+ arity = 1
+
+ moduli = ["ffffffff00000001000000000000000000000000ffffffffffffffffffffffff"] # type: List[str]
+
+ input_values = [
+ "0", "1",
+
+ # Modulus - 1
+ "ffffffff00000001000000000000000000000000fffffffffffffffffffffffe",
+
+ # Maximum canonical P256 multiplication result
+ ("fffffffe00000002fffffffe0000000100000001fffffffe00000001fffffffc"
+ "00000003fffffffcfffffffffffffffffffffffc000000000000000000000004"),
+
+ # Generate an overflow during reduction
+ ("0000000000000000000000010000000000000000000000000000000000000000"
+ "00000000000000000000000000000000000000000000000000000000ffffffff"),
+
+ # Generate an underflow during reduction
+ ("0000000000000000000000000000000000000000000000000000000000000010"
+ "ffffffff00000000000000000000000000000000000000000000000000000000"),
+
+ # Generate an overflow during carry reduction
+ ("aaaaaaaa00000000000000000000000000000000000000000000000000000000"
+ "00000000000000000000000000000000aaaaaaacaaaaaaaaaaaaaaaa00000000"),
+
+ # Generate an underflow during carry reduction
+ ("000000000000000000000001ffffffff00000000000000000000000000000000"
+ "0000000000000000000000000000000000000002000000020000000100000002"),
+
+ # First 8 number generated by random.getrandbits(512) - seed(2,2)
+ ("4067c3584ee207f8da94e3e8ab73738fcf1822ffbc6887782b491044d5e34124"
+ "5c6e433715ba2bdd177219d30e7a269fd95bafc8f2a4d27bdcf4bb99f4bea973"),
+ ("82523e86feac7eb7dc38f519b91751dacdbd47d364be8049a372db8f6e405d93"
+ "ffed9235288bc781ae66267594c9c9500925e4749b575bd13653f8dd9b1f282e"),
+ ("e8624fab5186ee32ee8d7ee9770348a05d300cb90706a045defc044a09325626"
+ "e6b58de744ab6cce80877b6f71e1f6d2ef8acd128b4f2fc15f3f57ebf30b94fa"),
+ ("829a48d422fe99a22c70501e533c91352d3d854e061b90303b08c6e33c729578"
+ "2d6c797f8f7d9b782a1be9cd8697bbd0e2520e33e44c50556c71c4a66148a86f"),
+ ("e89204e2e8168561867e5e15bc01bfce6a27e0dfcbf8754472154e76e4c11ab2"
+ "fec3f6b32e8d4b8a8f54f8ceacaab39e83844b40ffa9b9f15c14bc4a829e07b0"),
+ ("bd143fa9b714210c665d7435c1066932f4767f26294365b2721dea3bf63f23d0"
+ "dbe53fcafb2147df5ca495fa5a91c89b97eeab64ca2ce6bc5d3fd983c34c769f"),
+ ("74667bffe202849da9643a295a9ac6decbd4d3e2d4dec9ef83f0be4e80371eb9"
+ "7f81375eecc1cb6347733e847d718d733ff98ff387c56473a7a83ee0761ebfd2"),
+ ("d08f1bb2531d6460f0caeef038c89b38a8acb5137c9260dc74e088a9b9492f25"
+ "8ebdbfe3eb9ac688b9d39cca91551e8259cc60b17604e4b4e73695c3e652c71a"),
+
+ # Next 2 number generated by random.getrandbits(256)
+ "c5e2486c44a4a8f69dc8db48e86ec9c6e06f291b2a838af8d5c44a4eb3172062",
+ "d4c0dca8b4c9e755cc9c3adcf515a8234da4daeb4f3f87777ad1f45ae9500ec9"
+ ]
+
+ @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
+
+
class EcpP521R1Raw(bignum_common.ModOperationCommon,
EcpTarget):
"""Test cases for ecp quasi_reduction()."""
diff --git a/tests/suites/test_suite_ecp.function b/tests/suites/test_suite_ecp.function
index ee9f157..ecb3546 100644
--- a/tests/suites/test_suite_ecp.function
+++ b/tests/suites/test_suite_ecp.function
@@ -9,8 +9,7 @@
#include "bignum_mod_raw_invasive.h"
#if defined(MBEDTLS_TEST_HOOKS) && \
- (defined(MBEDTLS_ECP_DP_SECP256R1_ENABLED) || \
- defined(MBEDTLS_ECP_DP_SECP384R1_ENABLED))
+ defined(MBEDTLS_ECP_DP_SECP384R1_ENABLED)
#define HAVE_FIX_NEGATIVE
#endif
@@ -1389,6 +1388,49 @@
/* END_CASE */
/* BEGIN_CASE depends_on:MBEDTLS_TEST_HOOKS */
+void ecp_mod_p256_raw(char *input_N,
+ char *input_X,
+ char *result)
+{
+ mbedtls_mpi_uint *X = NULL;
+ mbedtls_mpi_uint *N = NULL;
+ mbedtls_mpi_uint *res = NULL;
+ size_t limbs_X;
+ size_t limbs_N;
+ size_t limbs_res;
+
+ mbedtls_mpi_mod_modulus m;
+ mbedtls_mpi_mod_modulus_init(&m);
+
+ TEST_EQUAL(mbedtls_test_read_mpi_core(&X, &limbs_X, input_X), 0);
+ TEST_EQUAL(mbedtls_test_read_mpi_core(&N, &limbs_N, input_N), 0);
+ TEST_EQUAL(mbedtls_test_read_mpi_core(&res, &limbs_res, result), 0);
+
+ size_t limbs = limbs_N;
+ size_t bytes = limbs * sizeof(mbedtls_mpi_uint);
+
+ TEST_EQUAL(limbs_X, 2 * limbs);
+ TEST_EQUAL(limbs_res, limbs);
+
+ TEST_EQUAL(mbedtls_mpi_mod_modulus_setup(
+ &m, N, limbs,
+ MBEDTLS_MPI_MOD_REP_MONTGOMERY), 0);
+
+ TEST_EQUAL(mbedtls_ecp_mod_p256_raw(X, limbs_X), 0);
+ TEST_LE_U(mbedtls_mpi_core_bitlen(X, limbs_X), 256);
+ mbedtls_mpi_mod_raw_fix_quasi_reduction(X, &m);
+ ASSERT_COMPARE(X, bytes, res, bytes);
+
+exit:
+ mbedtls_free(X);
+ mbedtls_free(res);
+
+ mbedtls_mpi_mod_modulus_free(&m);
+ mbedtls_free(N);
+}
+/* END_CASE */
+
+/* BEGIN_CASE depends_on:MBEDTLS_TEST_HOOKS */
void ecp_mod_p521_raw(char *input_N,
char *input_X,
char *result)