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static initialize comb table

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MBEDTLS_ECP_FIXED_POINT_OPTIM aims to speed up ecc multiplication performance.

We compute the comb table in runtime now. It is a costly operation.

This patch add a pre-computed table to initialize well-known curves. It speed up ECDSA signature verify process in runtime by using more ROM size.

Signed-off-by: kXuan <kxuanobj@gmail.com>
This commit is contained in:
kXuan
2021-04-08 14:32:06 +08:00
parent 6d84e917bb
commit ba9cb76e9f
4 changed files with 4035 additions and 27 deletions
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8
include/mbedtls/ecp.h
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@ -229,7 +229,7 @@ typedef struct mbedtls_ecp_group
int (*t_post)(mbedtls_ecp_point *, void *); /*!< Unused. */
void *t_data; /*!< Unused. */
mbedtls_ecp_point *T; /*!< Pre-computed points for ecp_mul_comb(). */
size_t T_size; /*!< The number of pre-computed points. */
size_t T_size; /*!< The number of dynamic allocated pre-computed points. */
}
mbedtls_ecp_group;
@ -276,15 +276,15 @@ mbedtls_ecp_group;
#if !defined(MBEDTLS_ECP_FIXED_POINT_OPTIM)
/*
* Trade memory for speed on fixed-point multiplication.
* Trade ROM usage for speed on fixed-point multiplication.
*
* This speeds up repeated multiplication of the generator (that is, the
* multiplication in ECDSA signatures, and half of the multiplications in
* ECDSA verification and ECDHE) by a factor roughly 3 to 4.
*
* The cost is increasing EC peak memory usage by a factor roughly 2.
* The cost is increasing ROM usage by a factor roughly 2.
*
* Change this value to 0 to reduce peak memory usage.
* Change this value to 0 to reduce ROM usage.
*/
#define MBEDTLS_ECP_FIXED_POINT_OPTIM 1 /**< Enable fixed-point speed-up. */
#endif /* MBEDTLS_ECP_FIXED_POINT_OPTIM */