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Cache pre-computed points for ecp_mul()

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Up to 1.25 speedup on ECDSA sign for small curves, but mainly useful as a
preparation for fixed-point mult (a few prototypes changed in constness).
This commit is contained in:
Manuel Pégourié-Gonnard 2013-09-17 19:13:10 +02:00 • committed by Paul Bakker
parent 56cd319f0e
commit 161ef968db
6 changed files with 147 additions and 47 deletions
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11
include/polarssl/ecp.h
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@ -155,16 +155,15 @@ ecp_keypair;
/*
* Maximum window size (actually, NAF width) used for point multipliation.
* Default: 7.
* Default: 8.
* Minimum value: 2. Maximum value: 8.
*
* Result is an array of at most ( 1 << ( POLARSSL_ECP_WINDOW_SIZE - 1 ) )
* points used for point multiplication, so at most 64 by default.
* In practice, most curves will use less precomputed points.
* points used for point multiplication.
*
* Reduction in size may reduce speed for big curves.
*/
#define POLARSSL_ECP_WINDOW_SIZE 7 /**< Maximum NAF width used. */
#define POLARSSL_ECP_WINDOW_SIZE 8 /**< Maximum NAF width used. */
/*
* Point formats, from RFC 4492's enum ECPointFormat
@ -472,7 +471,7 @@ int ecp_sub( const ecp_group *grp, ecp_point *R,
* has very low overhead, it is recommended to always provide
* a non-NULL f_rng parameter when using secret inputs.
*/
int ecp_mul( const ecp_group *grp, ecp_point *R,
int ecp_mul( ecp_group *grp, ecp_point *R,
const mpi *m, const ecp_point *P,
int (*f_rng)(void *, unsigned char *, size_t), void *p_rng );
@ -531,7 +530,7 @@ int ecp_check_privkey( const ecp_group *grp, const mpi *d );
* in order to ease use with other structures such as
* ecdh_context of ecdsa_context.
*/
int ecp_gen_keypair( const ecp_group *grp, mpi *d, ecp_point *Q,
int ecp_gen_keypair( ecp_group *grp, mpi *d, ecp_point *Q,
int (*f_rng)(void *, unsigned char *, size_t),
void *p_rng );