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Made ecp_mul() faster and truly SPA resistant

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Manuel Pégourié-Gonnard
2012-11-21 13:00:58 +01:00
committed by Paul Bakker
parent 7652a593d6
commit b63f9e98f5
3 changed files with 119 additions and 79 deletions
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18
include/polarssl/ecp.h
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@@ -97,17 +97,23 @@ ecp_group;
#define POLARSSL_ECP_DP_SECP384R1 3
#define POLARSSL_ECP_DP_SECP521R1 4
/**
* Maximum bit size of the groups (that is, of N)
*/
#define POLARSSL_ECP_MAX_N_BITS 521
/*
* Maximum NAF width used for point multipliation. Default: 7.
* Maximum window size (actually, NAF width) used for point multipliation.
* Default: 7.
* Minimum value: 2. Maximum value: 8.
*
* Result is an array of at most ( 1 << ( POLARSSL_ECP_NAF_WIDTH - 1 ) )
* 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.
*
* Reduction in size may reduce speed for big curves.
*/
#define POLARSSL_ECP_NAF_WIDTH 7 /**< Maximum NAF width used. */
#define POLARSSL_ECP_WINDOW_SIZE 7 /**< Maximum NAF width used. */
#ifdef __cplusplus
extern "C" {
@@ -236,7 +242,11 @@ int ecp_sub( const ecp_group *grp, ecp_point *R,
*
* \return 0 if successful,
* POLARSSL_ERR_MPI_MALLOC_FAILED if memory allocation failed
* POLARSSL_ERR_ECP_GENERIC if m < 0
* POLARSSL_ERR_ECP_GENERIC if m < 0 of m has greater bit
* length than N, the number of points in the group.
*
* \note This function executes a constant number of operations
* for random m in the allowed range.
*/
int ecp_mul( const ecp_group *grp, ecp_point *R,
const mpi *m, const ecp_point *P );