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Prepare ecp_group for future extensions

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Manuel Pégourié-Gonnard 2013-09-16 18:56:28 +02:00 committed by Paul Bakker
parent 456d3b9b0b
commit c972770f78
2 changed files with 17 additions and 18 deletions
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21
include/polarssl/ecp.h
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@ -98,28 +98,35 @@ ecp_point;
/**
* \brief ECP group structure
*
* The curves we consider are defined by y^2 = x^3 - 3x + B mod P,
* The curves we consider are defined by y^2 = x^3 + A x + B mod P,
* and a generator for a large subgroup of order N is fixed.
*
* pbits and nbits must be the size of P and N in bits.
*
* If modp is NULL, reduction modulo P is done using a generic
* algorithm. Otherwise, it must point to a function that takes an mpi
* in the range 0..2^(2*pbits) and transforms it in-place in an integer
* of little more than pbits, so that the integer may be efficiently
* brought in the 0..P range by a few additions or substractions. It
* must return 0 on success and a POLARSSL_ERR_ECP_XXX error on failure.
* If modp is NULL, reduction modulo P is done using a generic algorithm.
* Otherwise, it must point to a function that takes an mpi in the range
* 0..2^(2*pbits)-1 and transforms it in-place in an integer of little more
* than pbits, so that the integer may be efficiently brought in the 0..P-1
* range by a few additions or substractions. It must return 0 on success and
* non-zero on failure.
*/
typedef struct
{
ecp_group_id id; /*!< RFC 4492 group ID */
mpi P; /*!< prime modulus of the base field */
mpi A; /*!< currently unused (-3 assumed) */
mpi B; /*!< constant term in the equation */
ecp_point G; /*!< generator of the subgroup used */
mpi N; /*!< the order of G */
size_t pbits; /*!< number of bits in P */
size_t nbits; /*!< number of bits in N */
unsigned int h; /*!< cofactor (unused now: assume 1) */
int (*modp)(mpi *); /*!< function for fast reduction mod P */
int (*t_pre)(ecp_point *, void *); /*!< currently unused */
int (*t_post)(ecp_point *, void *); /*!< currently unused */
void *t_data; /*!< currently unused */
ecp_point *T; /*!< pre-computed points (unused now) */
size_t T_size; /*!< number for pre-computed points */
}
ecp_group;

14
library/ecp.c
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@ -114,17 +114,7 @@ void ecp_group_init( ecp_group *grp )
if( grp == NULL )
return;
grp->id = 0;
mpi_init( &grp->P );
mpi_init( &grp->B );
ecp_point_init( &grp->G );
mpi_init( &grp->N );
grp->pbits = 0;
grp->nbits = 0;
grp->modp = NULL;
memset( grp, 0, sizeof( ecp_group ) );
}
/*
@ -165,6 +155,8 @@ void ecp_group_free( ecp_group *grp )
mpi_free( &grp->B );
ecp_point_free( &grp->G );
mpi_free( &grp->N );
memset( grp, 0, sizeof( ecp_group ) );
}
/*