Contents

GFpECSetSubgroup

Sets up the parameters defining an elliptic curve points subgroup.

Syntax

IppStatus ippsGFpECSetSubGroup(const IppsGFpElement* pX, const IppsGFpElement* pY, const IppsBigNumState* pOrder, const IppsBigNumState* pCofactor, IppsGFpECState* pEC);

Include Files

ippcp.h

Parameters

pX, pY

Pointers to the X and Y coordinates of the base point of the elliptic curve.

pOrder

Pointer to the big number context storing the order of the base point.

pCofactor

Pointer to the big number context storing the cofactor.

pEC

Pointer to the context of the elliptic curve.

Description

This function sets up an elliptic curve as the subgroup generated by the base point over the finite field.

Note

Only the pEC parameter is required. You can omit the other parameters by setting their values to NULL or zero.

Return Values

ippStsNoErr

Indicates no error. Any other value indicates an error or warning.

ippStsNullPtrErr

Indicates an error condition if pEC is NULL.

ippStsContextMatchErr

Indicates an error condition in the following cases:

  • IppsGFpECState context parameter does not match the operation.

  • Any of the pointers to elliptic curve parameters is not zero and the context parameter does not match the operation.

ippStsBadArgErr

Indicates an error condition if any of the specified IppsBigNumState contexts defines zero or a negative number.

ippStsOutOfRangeErr

Indicates an error if the base point coordinates (pX, pY) do not belong to the finite field over which the elliptic curve is initialized.

ippStsRangeErr

Indicates an error condition in the following cases:

  • The size of the base point order exceeds the maximal size of the order for the given curve.

  • The bit size of the cofactor exceeds the bit size of the element of the finite field over which the elliptic curve is initialized.

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