ecp_alt.h

Go to the documentation of this file.

/*
 * Copyright (c) 2001-2019, Arm Limited and Contributors. All rights reserved.
 *
 * SPDX-License-Identifier: BSD-3-Clause
 */
#ifndef MBEDTLS_ECP_ALT_H
#define MBEDTLS_ECP_ALT_H
 
#if defined(MBEDTLS_ECP_ALT)
 
#ifdef __cplusplus
extern "C" {
#endif
 
typedef struct mbedtls_ecp_group
{
    mbedtls_ecp_group_id id;    
    mbedtls_mpi P;              
    mbedtls_mpi A;              
    mbedtls_mpi B;              
    mbedtls_ecp_point G;        
    mbedtls_mpi N;              
    size_t pbits;               
    size_t nbits;               
    unsigned int h;             
    int (*modp)(mbedtls_mpi *); 
    int (*t_pre)(mbedtls_ecp_point *, void *);  
    int (*t_post)(mbedtls_ecp_point *, void *); 
    void *t_data;               
    mbedtls_ecp_point *T;       
    size_t T_size;              
}
mbedtls_ecp_group;
 
#if !defined(MBEDTLS_ECP_WINDOW_SIZE)
/*
 * Maximum "window" size used for point multiplication.
 * Default: 6.
 * Minimum value: 2. Maximum value: 7.
 *
 * Result is an array of at most ( 1 << ( MBEDTLS_ECP_WINDOW_SIZE - 1 ) )
 * points used for point multiplication. This value is directly tied to EC
 * peak memory usage, so decreasing it by one should roughly cut memory usage
 * by two (if large curves are in use).
 *
 * Reduction in size may reduce speed, but larger curves are impacted first.
 * Sample performances (in ECDHE handshakes/s, with FIXED_POINT_OPTIM = 1):
 *      w-size:     6       5       4       3       2
 *      521       145     141     135     120      97
 *      384       214     209     198     177     146
 *      256       320     320     303     262     226
 *      224       475     475     453     398     342
 *      192       640     640     633     587     476
 */
#define MBEDTLS_ECP_WINDOW_SIZE    6   
#endif /* MBEDTLS_ECP_WINDOW_SIZE */
 
#if !defined(MBEDTLS_ECP_FIXED_POINT_OPTIM)
/*
 * Trade memory 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.
 *
 * Change this value to 0 to reduce peak memory usage.
 */
#define MBEDTLS_ECP_FIXED_POINT_OPTIM  1   
#endif /* MBEDTLS_ECP_FIXED_POINT_OPTIM */
 
/* \} name SECTION: Module settings */
 
#define MBEDTLS_ECP_BUDGET( ops )   /* no-op; for compatibility */
 
#ifdef __cplusplus
}
#endif
 
#endif /* MBEDTLS_ECP_ALT */
 
#endif /* MBEDTLS_ECP_ALT_H */