From 4d0c5f8603ecf055959f08ab9135177e1618585f Mon Sep 17 00:00:00 2001
From: Sachin Parekh <sachin.parekh@espressif.com>
Date: Wed, 5 Jan 2022 15:23:44 +0530
Subject: [PATCH] ecp: Add support for hardware implementation of ECP routines 
  - ESP32C2 has a hardware ECC accelerator that supports NIST P-192 and NIST
 P-256 curves,     which can increase the performance of the point
 multiplication and point     verification operation.   - Provision is also
 added to fallback to software implementation in     case the curve is not
 from the supported curves

- Override ecp_mul_restartable_internal with accelerator
  - Many ECC operations use the internal API ecp_mul_restartable_internal
    instead of the public API mbedtls_ecp_mul for point multiplication.
    This will improve the performance of all those parent operations as
    well

(cherry picked from commit 0ecb27b9d88059e8980c8ae6e111283f5f2859f8)
---
 library/ecp.c | 31 +++++++++++++++++++++++++++++++
 1 file changed, 31 insertions(+)

diff --git a/library/ecp.c b/library/ecp.c
index 08fbe86c7..97eeaeba8 100644
--- a/library/ecp.c
+++ b/library/ecp.c
@@ -1354,6 +1354,7 @@ cleanup:
 #endif /* !defined(MBEDTLS_ECP_NO_FALLBACK) || !defined(MBEDTLS_ECP_NORMALIZE_JAC_ALT) */
 }
 
+#if !defined(MBEDTLS_ECP_MUL_ALT)
 /*
  * Normalize jacobian coordinates of an array of (pointers to) points,
  * using Montgomery's trick to perform only one inversion mod P.
@@ -1476,6 +1477,7 @@ cleanup:
     mbedtls_mpi_free(&tmp);
     return ret;
 }
+#endif /* MBEDTLS_ECP_MUL_ALT */
 
 /*
  * Point doubling R = 2 P, Jacobian coordinates
@@ -1679,6 +1681,7 @@ cleanup:
 #endif /* !defined(MBEDTLS_ECP_NO_FALLBACK) || !defined(MBEDTLS_ECP_ADD_MIXED_ALT) */
 }
 
+#if !defined(MBEDTLS_ECP_MUL_ALT)
 /*
  * Randomize jacobian coordinates:
  * (X, Y, Z) -> (l^2 X, l^3 Y, l Z) for random l
@@ -2413,6 +2416,8 @@ cleanup:
     return ret;
 }
 
+#endif /* MBEDTLS_ECP_MUL_ALT */
+
 #endif /* MBEDTLS_ECP_SHORT_WEIERSTRASS_ENABLED */
 
 #if defined(MBEDTLS_ECP_MONTGOMERY_ENABLED)
@@ -2424,6 +2429,7 @@ cleanup:
  * For scalar multiplication, we'll use a Montgomery ladder.
  */
 
+#if !defined(MBEDTLS_ECP_MUL_ALT)
 /*
  * Normalize Montgomery x/z coordinates: X = X/Z, Z = 1
  * Cost: 1M + 1I
@@ -2623,18 +2629,27 @@ cleanup:
     return ret;
 }
 
+#endif /* MBEDTLS_ECP_MUL_ALT */
 #endif /* MBEDTLS_ECP_MONTGOMERY_ENABLED */
 
+#if !defined(MBEDTLS_ECP_MUL_ALT)
 /*
  * Restartable multiplication R = m * P
  *
  * This internal function can be called without an RNG in case where we know
  * the inputs are not sensitive.
  */
+#if defined(MBEDTLS_ECP_MUL_ALT_SOFT_FALLBACK)
+int ecp_mul_restartable_internal_soft(mbedtls_ecp_group *grp, mbedtls_ecp_point *R,
+                                    const mbedtls_mpi *m, const mbedtls_ecp_point *P,
+                                    int (*f_rng)(void *, unsigned char *, size_t), void *p_rng,
+                                    mbedtls_ecp_restart_ctx *rs_ctx)
+#else
 static int ecp_mul_restartable_internal(mbedtls_ecp_group *grp, mbedtls_ecp_point *R,
                                         const mbedtls_mpi *m, const mbedtls_ecp_point *P,
                                         int (*f_rng)(void *, unsigned char *, size_t), void *p_rng,
                                         mbedtls_ecp_restart_ctx *rs_ctx)
+#endif
 {
     int ret = MBEDTLS_ERR_ECP_BAD_INPUT_DATA;
 #if defined(MBEDTLS_ECP_INTERNAL_ALT)
@@ -2698,6 +2713,7 @@ cleanup:
 
     return ret;
 }
+#endif /* MBEDTLS_ECP_MUL_ALT */
 
 /*
  * Restartable multiplication R = m * P
@@ -2724,7 +2740,10 @@ int mbedtls_ecp_mul(mbedtls_ecp_group *grp, mbedtls_ecp_point *R,
     return mbedtls_ecp_mul_restartable(grp, R, m, P, f_rng, p_rng, NULL);
 }
 
+#if !defined(MBEDTLS_ECP_VERIFY_ALT)
+
 #if defined(MBEDTLS_ECP_SHORT_WEIERSTRASS_ENABLED)
+
 /*
  * Check that an affine point is valid as a public key,
  * short weierstrass curves (SEC1 3.2.3.1)
@@ -2762,6 +2781,7 @@ cleanup:
     return ret;
 }
 #endif /* MBEDTLS_ECP_SHORT_WEIERSTRASS_ENABLED */
+#endif /* MBEDTLS_ECP_VERIFY_ALT */
 
 #if defined(MBEDTLS_ECP_SHORT_WEIERSTRASS_ENABLED)
 /*
@@ -2915,6 +2935,8 @@ int mbedtls_ecp_muladd(mbedtls_ecp_group *grp, mbedtls_ecp_point *R,
 }
 #endif /* MBEDTLS_ECP_SHORT_WEIERSTRASS_ENABLED */
 
+#if !defined(MBEDTLS_ECP_VERIFY_ALT)
+
 #if defined(MBEDTLS_ECP_MONTGOMERY_ENABLED)
 #if defined(MBEDTLS_ECP_DP_CURVE25519_ENABLED)
 #define ECP_MPI_INIT(s, n, p) { s, (n), (mbedtls_mpi_uint *) (p) }
@@ -3026,11 +3048,19 @@ static int ecp_check_pubkey_mx(const mbedtls_ecp_group *grp, const mbedtls_ecp_p
 }
 #endif /* MBEDTLS_ECP_MONTGOMERY_ENABLED */
 
+#endif /* MBEDTLS_ECP_VERIFY_ALT */
+
+#if !defined(MBEDTLS_ECP_VERIFY_ALT)
 /*
  * Check that a point is valid as a public key
  */
+#if defined(MBEDTLS_ECP_VERIFY_ALT_SOFT_FALLBACK)
+int mbedtls_ecp_check_pubkey_soft(const mbedtls_ecp_group *grp,
+                                const mbedtls_ecp_point *pt)
+#else
 int mbedtls_ecp_check_pubkey(const mbedtls_ecp_group *grp,
                              const mbedtls_ecp_point *pt)
+#endif
 {
     /* Must use affine coordinates */
     if (mbedtls_mpi_cmp_int(&pt->Z, 1) != 0) {
@@ -3049,6 +3079,7 @@ int mbedtls_ecp_check_pubkey(const mbedtls_ecp_group *grp,
 #endif
     return MBEDTLS_ERR_ECP_BAD_INPUT_DATA;
 }
+#endif /* MBEDTLS_ECP_VERIFY_ALT */
 
 /*
  * Check that an mbedtls_mpi is valid as a private key