.. _mbx_nistp256-384-521_ecpublic_key:


mbx_nistp256/384/521_ecpublic_key
=================================


Computes a public key.


Syntax
------


mbx_status mbx_nistp256_ecpublic_key_mb8(int64u\* pa_pubx[8], int64u\*
pa_puby[8], const int64u\* pa_pubz[8], const int64u\* const pa_skey[8],
int8u\* pBuffer);


mbx_status mbx_nistp256_ecpublic_key_ssl_mb8(BIGNUM\* pa_pubx[8],
BIGNUM\* pa_puby[8], const BIGNUM\* pa_pubz[8], const BIGNUM\* const
pa_skey[8], int8u\* pBuffer);


mbx_status mbx_nistp384_ecpublic_key_mb8(int64u\* pa_pubx[8], int64u\*
pa_puby[8], const int64u\* pa_pubz[8], const int64u\* const pa_skey[8],
int8u\* pBuffer);


mbx_status mbx_nistp384_ecpublic_key_ssl_mb8(BIGNUM\* pa_pubx[8],
BIGNUM\* pa_puby[8], const BIGNUM\* pa_pubz[8], const BIGNUM\* const
pa_skey[8], int8u\* pBuffer);


mbx_status mbx_nistp521_ecpublic_key_mb8(int64u\* pa_pubx[8], int64u\*
pa_puby[8], const int64u\* pa_pubz[8], const int64u\* const pa_skey[8],
int8u\* pBuffer);


mbx_status mbx_nistp521_ecpublic_key_ssl_mb8(BIGNUM\* pa_pubx[8],
BIGNUM\* pa_puby[8], const BIGNUM\* pa_pubz[8], const BIGNUM\* const
pa_skey[8], int8u\* pBuffer);


Include Files
-------------


``crypto_mb/ec_nistp256.h``


``crypto_mb/ec_nistp384.h``


``crypto_mb/ec_nistp521.h``


Parameters
----------


.. list-table:: 
   :header-rows: 0

   * -      pa_pubx   
     -  Array of pointers to the vectors of computed public key x-coordinates.
   * -      pa_puby   
     -  Array of pointers to the vectors of computed public key y-coordinates.
   * -      pa_pubz   
     -  Array of pointers to the vectors of computed public key z-coordinates.
   * -      pa_skey   
     -  Array of pointers to the vectors of private keys.
   * -      pBuffer   
     -  Pointer to the work buffer.




Description
-----------


Each function targets at the elliptic curve (EC) specified in thename
(nistp256, nistp384 or nistp521). The function computes public keys
using private keys specified by the pa_skey parameter. If z-coordinate
of computed public is required (pa_pubz is not ``NULL``), then computed
public keys are stored using projective coordinates. If pa_pubz is
``NULL``, then computed public keys are stored using affine coordinates.


The work buffer specified by the pBuffer parameteris not currently used
and can be ``NULL``.


.. note::


   All the functions above have own "twins" with "_ssl" in the name. The
   "twin" associated with the EC acts the same. The single difference in
   comparison with mbx_nistp256/384/521_ecpublic_key() is representation
   of the parameters. mbx_nistp256/384/521_ecpublic_key_ssl() functions
   use BIGNUM datatype instead of vector.


Return Values
-------------


The mbx_nistp256/384/521_ecpublic_key functions return the status that
indicates whether the operation completed successfully or not. The
status value of 0 indicates that all operations completed successfully.
The error condition can be analyzed by the MBX_GET_STS() call.