GFpECGetSubgroup
GFpECGetSubgroup
Extracts the parameters (base point and its order) that define an elliptic curve point subgroup.
Syntax
IppStatus ippsGFpECGetSubGroup(IppsGFpState** const
ppGF
, IppsGFpElement*
pX
, IppsGFpElement*
pY
, IppsBigNumState*
pOrder
,IppsBigNumState*
pCofactor
, const IppsGFpECState*
pEC
);
Include Files
ippcp.h
Parameters
- ppGF
- Pointer to the context of the underlying finite field.
- pX,pY
- Pointers to theXandYcoordinates 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 extracts parameters of an elliptic curve subgroup. You can get any combination of the following parameters: the
X
and Y
coordinates, the order of the base point, and the value of the cofactor. To turn off extraction of a particular parameter of the elliptic curve, set the appropriate function parameter to NULL
.Return Values
- ippStsNoErr
- Indicates no error. Any other value indicates an error or warning.
- ippStsNullPtrErr
- Indicates an error condition if the specified pointerpECisNULL.
- ippStsContextMatchErr
- Indicates an error condition in the following cases:
- IppsGFpECStatecontext parameter does not match the operation.
- Any of the pointers to elliptic curve parameters is not zero and the corresponding context parameter does not match the operation.
- 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.
- ippStsLengthErr
- 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.