Rename ecp_internal.h to ecp_alt.h
This gives it a more descriptive name and indicates to alt developers
that the definitions inside are not fully internal and are available
to alt developers for use.
Signed-off-by: Chris Jones <christopher.jones@arm.com>
diff --git a/library/ecp_alt.h b/library/ecp_alt.h
new file mode 100644
index 0000000..6b1b29f
--- /dev/null
+++ b/library/ecp_alt.h
@@ -0,0 +1,297 @@
+/**
+ * \file ecp_alt.h
+ *
+ * \brief Function declarations for alternative implementation of elliptic curve
+ * point arithmetic.
+ */
+/*
+ * Copyright The Mbed TLS Contributors
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/*
+ * References:
+ *
+ * [1] BERNSTEIN, Daniel J. Curve25519: new Diffie-Hellman speed records.
+ * <http://cr.yp.to/ecdh/curve25519-20060209.pdf>
+ *
+ * [2] CORON, Jean-S'ebastien. Resistance against differential power analysis
+ * for elliptic curve cryptosystems. In : Cryptographic Hardware and
+ * Embedded Systems. Springer Berlin Heidelberg, 1999. p. 292-302.
+ * <http://link.springer.com/chapter/10.1007/3-540-48059-5_25>
+ *
+ * [3] HEDABOU, Mustapha, PINEL, Pierre, et B'EN'ETEAU, Lucien. A comb method to
+ * render ECC resistant against Side Channel Attacks. IACR Cryptology
+ * ePrint Archive, 2004, vol. 2004, p. 342.
+ * <http://eprint.iacr.org/2004/342.pdf>
+ *
+ * [4] Certicom Research. SEC 2: Recommended Elliptic Curve Domain Parameters.
+ * <http://www.secg.org/sec2-v2.pdf>
+ *
+ * [5] HANKERSON, Darrel, MENEZES, Alfred J., VANSTONE, Scott. Guide to Elliptic
+ * Curve Cryptography.
+ *
+ * [6] Digital Signature Standard (DSS), FIPS 186-4.
+ * <http://nvlpubs.nist.gov/nistpubs/FIPS/NIST.FIPS.186-4.pdf>
+ *
+ * [7] Elliptic Curve Cryptography (ECC) Cipher Suites for Transport Layer
+ * Security (TLS), RFC 4492.
+ * <https://tools.ietf.org/search/rfc4492>
+ *
+ * [8] <http://www.hyperelliptic.org/EFD/g1p/auto-shortw-jacobian.html>
+ *
+ * [9] COHEN, Henri. A Course in Computational Algebraic Number Theory.
+ * Springer Science & Business Media, 1 Aug 2000
+ */
+
+#ifndef MBEDTLS_ECP_INTERNAL_H
+#define MBEDTLS_ECP_INTERNAL_H
+
+#if !defined(MBEDTLS_CONFIG_FILE)
+#include "mbedtls/config.h"
+#else
+#include MBEDTLS_CONFIG_FILE
+#endif
+
+#if defined(MBEDTLS_ECP_INTERNAL_ALT)
+
+/**
+ * \brief Indicate if the Elliptic Curve Point module extension can
+ * handle the group.
+ *
+ * \param grp The pointer to the elliptic curve group that will be the
+ * basis of the cryptographic computations.
+ *
+ * \return Non-zero if successful.
+ */
+unsigned char mbedtls_internal_ecp_grp_capable( const mbedtls_ecp_group *grp );
+
+/**
+ * \brief Initialise the Elliptic Curve Point module extension.
+ *
+ * If mbedtls_internal_ecp_grp_capable returns true for a
+ * group, this function has to be able to initialise the
+ * module for it.
+ *
+ * This module can be a driver to a crypto hardware
+ * accelerator, for which this could be an initialise function.
+ *
+ * \param grp The pointer to the group the module needs to be
+ * initialised for.
+ *
+ * \return 0 if successful.
+ */
+int mbedtls_internal_ecp_init( const mbedtls_ecp_group *grp );
+
+/**
+ * \brief Frees and deallocates the Elliptic Curve Point module
+ * extension.
+ *
+ * \param grp The pointer to the group the module was initialised for.
+ */
+void mbedtls_internal_ecp_free( const mbedtls_ecp_group *grp );
+
+#if defined(MBEDTLS_ECP_SHORT_WEIERSTRASS_ENABLED)
+
+#if defined(MBEDTLS_ECP_RANDOMIZE_JAC_ALT)
+/**
+ * \brief Randomize jacobian coordinates:
+ * (X, Y, Z) -> (l^2 X, l^3 Y, l Z) for random l.
+ *
+ * \param grp Pointer to the group representing the curve.
+ *
+ * \param pt The point on the curve to be randomised, given with Jacobian
+ * coordinates.
+ *
+ * \param f_rng A function pointer to the random number generator.
+ *
+ * \param p_rng A pointer to the random number generator state.
+ *
+ * \return 0 if successful.
+ */
+int mbedtls_internal_ecp_randomize_jac( const mbedtls_ecp_group *grp,
+ mbedtls_ecp_point *pt, int (*f_rng)(void *, unsigned char *, size_t),
+ void *p_rng );
+#endif
+
+#if defined(MBEDTLS_ECP_ADD_MIXED_ALT)
+/**
+ * \brief Addition: R = P + Q, mixed affine-Jacobian coordinates.
+ *
+ * The coordinates of Q must be normalized (= affine),
+ * but those of P don't need to. R is not normalized.
+ *
+ * This function is used only as a subrutine of
+ * ecp_mul_comb().
+ *
+ * Special cases: (1) P or Q is zero, (2) R is zero,
+ * (3) P == Q.
+ * None of these cases can happen as intermediate step in
+ * ecp_mul_comb():
+ * - at each step, P, Q and R are multiples of the base
+ * point, the factor being less than its order, so none of
+ * them is zero;
+ * - Q is an odd multiple of the base point, P an even
+ * multiple, due to the choice of precomputed points in the
+ * modified comb method.
+ * So branches for these cases do not leak secret information.
+ *
+ * We accept Q->Z being unset (saving memory in tables) as
+ * meaning 1.
+ *
+ * Cost in field operations if done by [5] 3.22:
+ * 1A := 8M + 3S
+ *
+ * \param grp Pointer to the group representing the curve.
+ *
+ * \param R Pointer to a point structure to hold the result.
+ *
+ * \param P Pointer to the first summand, given with Jacobian
+ * coordinates
+ *
+ * \param Q Pointer to the second summand, given with affine
+ * coordinates.
+ *
+ * \return 0 if successful.
+ */
+int mbedtls_internal_ecp_add_mixed( const mbedtls_ecp_group *grp,
+ mbedtls_ecp_point *R, const mbedtls_ecp_point *P,
+ const mbedtls_ecp_point *Q );
+#endif
+
+/**
+ * \brief Point doubling R = 2 P, Jacobian coordinates.
+ *
+ * Cost: 1D := 3M + 4S (A == 0)
+ * 4M + 4S (A == -3)
+ * 3M + 6S + 1a otherwise
+ * when the implementation is based on the "dbl-1998-cmo-2"
+ * doubling formulas in [8] and standard optimizations are
+ * applied when curve parameter A is one of { 0, -3 }.
+ *
+ * \param grp Pointer to the group representing the curve.
+ *
+ * \param R Pointer to a point structure to hold the result.
+ *
+ * \param P Pointer to the point that has to be doubled, given with
+ * Jacobian coordinates.
+ *
+ * \return 0 if successful.
+ */
+#if defined(MBEDTLS_ECP_DOUBLE_JAC_ALT)
+int mbedtls_internal_ecp_double_jac( const mbedtls_ecp_group *grp,
+ mbedtls_ecp_point *R, const mbedtls_ecp_point *P );
+#endif
+
+/**
+ * \brief Normalize jacobian coordinates of an array of (pointers to)
+ * points.
+ *
+ * Using Montgomery's trick to perform only one inversion mod P
+ * the cost is:
+ * 1N(t) := 1I + (6t - 3)M + 1S
+ * (See for example Algorithm 10.3.4. in [9])
+ *
+ * This function is used only as a subrutine of
+ * ecp_mul_comb().
+ *
+ * Warning: fails (returning an error) if one of the points is
+ * zero!
+ * This should never happen, see choice of w in ecp_mul_comb().
+ *
+ * \param grp Pointer to the group representing the curve.
+ *
+ * \param T Array of pointers to the points to normalise.
+ *
+ * \param t_len Number of elements in the array.
+ *
+ * \return 0 if successful,
+ * an error if one of the points is zero.
+ */
+#if defined(MBEDTLS_ECP_NORMALIZE_JAC_MANY_ALT)
+int mbedtls_internal_ecp_normalize_jac_many( const mbedtls_ecp_group *grp,
+ mbedtls_ecp_point *T[], size_t t_len );
+#endif
+
+/**
+ * \brief Normalize jacobian coordinates so that Z == 0 || Z == 1.
+ *
+ * Cost in field operations if done by [5] 3.2.1:
+ * 1N := 1I + 3M + 1S
+ *
+ * \param grp Pointer to the group representing the curve.
+ *
+ * \param pt pointer to the point to be normalised. This is an
+ * input/output parameter.
+ *
+ * \return 0 if successful.
+ */
+#if defined(MBEDTLS_ECP_NORMALIZE_JAC_ALT)
+int mbedtls_internal_ecp_normalize_jac( const mbedtls_ecp_group *grp,
+ mbedtls_ecp_point *pt );
+#endif
+
+#endif /* MBEDTLS_ECP_SHORT_WEIERSTRASS_ENABLED */
+
+#if defined(MBEDTLS_ECP_MONTGOMERY_ENABLED)
+
+#if defined(MBEDTLS_ECP_DOUBLE_ADD_MXZ_ALT)
+int mbedtls_internal_ecp_double_add_mxz( const mbedtls_ecp_group *grp,
+ mbedtls_ecp_point *R, mbedtls_ecp_point *S, const mbedtls_ecp_point *P,
+ const mbedtls_ecp_point *Q, const mbedtls_mpi *d );
+#endif
+
+/**
+ * \brief Randomize projective x/z coordinates:
+ * (X, Z) -> (l X, l Z) for random l
+ *
+ * \param grp pointer to the group representing the curve
+ *
+ * \param P the point on the curve to be randomised given with
+ * projective coordinates. This is an input/output parameter.
+ *
+ * \param f_rng a function pointer to the random number generator
+ *
+ * \param p_rng a pointer to the random number generator state
+ *
+ * \return 0 if successful
+ */
+#if defined(MBEDTLS_ECP_RANDOMIZE_MXZ_ALT)
+int mbedtls_internal_ecp_randomize_mxz( const mbedtls_ecp_group *grp,
+ mbedtls_ecp_point *P, int (*f_rng)(void *, unsigned char *, size_t),
+ void *p_rng );
+#endif
+
+/**
+ * \brief Normalize Montgomery x/z coordinates: X = X/Z, Z = 1.
+ *
+ * \param grp pointer to the group representing the curve
+ *
+ * \param P pointer to the point to be normalised. This is an
+ * input/output parameter.
+ *
+ * \return 0 if successful
+ */
+#if defined(MBEDTLS_ECP_NORMALIZE_MXZ_ALT)
+int mbedtls_internal_ecp_normalize_mxz( const mbedtls_ecp_group *grp,
+ mbedtls_ecp_point *P );
+#endif
+
+#endif /* MBEDTLS_ECP_MONTGOMERY_ENABLED */
+
+#endif /* MBEDTLS_ECP_INTERNAL_ALT */
+
+#endif /* ecp_alt.h */
+