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Chapter 2 Algorithm Info Types 73
AI_ECParameters
AI_ECParameters
Purpose:
This AI allows you to specify EC parameters to be used for elliptic curve operations.
Type of information this allows you to use:
information that was either generated by AI_ECParamGen or which has been imported
from an external source. An algorithm object of type
AI_ECParameters is initialized
either as the
resultAlgorithmObject
from a call to B_GenerateParameters
(
AI_ECParamGen) or by simply calling B_SetAlgorithmInfo (AI_ECParameters or
AI_ECParameters_BER).
The resulting
AI_ECParameters algorithm object may then be used with AI_ECKeyGen
to generate keys or with
AI_EC_DHKeyAgree to execute key agreements.
Format of info supplied to B_SetAlgorithmInfo:
pointer to an A_EC_PARAMS structure:
typedef struct {
unsigned int version; /* implementation version */
unsigned int fieldType; /* indicates type of base field */
ITEM fieldInfo; /* The prime number if fieldType = FT_FP; */
/* the basis polynomial if fieldType = FT_F2_POLYNOMIAL; */
/* and the degree of the field if fieldType = FT_F2_ONB */
ITEM coeffA; /* elliptic curve coefficient */
ITEM coeffB; /* elliptic curve coefficient */
ITEM base; /* base point of elliptic curve */
ITEM order; /* order of subgroup’s generating element */
ITEM cofactor; /* the cofactor of the subgroup */
unsigned int pointRepresentation; /* not used. */
/* set to CI_NO_COMPRESS as a default */
unsigned int fieldElementBits; /* field element size in bits */
} A_EC_PARAMS;