.. _eccpgenkeypair:


ECCPGenKeyPair
==============


Generates a private key and computes public keys of the elliptic
cryptosystem over GF(p).


Syntax
------


IppStatus ippsECCPGenKeyPair(IppsBigNumState\* pPrivate,
IppsECCPPointState\* pPublic, IppsECCPState\* pECC, IppBitSupplier
rndFunc, void\* pRndParam);


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


``ippcp.h``


Parameters
----------


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

   * -  pPrivate   
     - Pointer to the private key ``privKey``.
   * - pPublic   
     - Pointer to the public key ``pubKey``.
   * - pECC   
     - Pointer to the context of the elliptic cryptosystem.
   * - rndFunc   
     - Specified Random Generator.
   * - pRndParam   
     - Pointer to the Random Generator context.




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


The function generates a private key ``privKey`` and computes a public
key ``pubKey`` of the elliptic cryptosystem over a finite field GF(*p*).
The generation process employs the user specified rndFunc Random
Generator.


The private key ``privKey`` is a number that lies in the range of [1,
*n*-1] where *n* is the order of the elliptic curve base point.


The public key ``pubKey`` is an elliptic curve point such that
``pubKey = privKey``\ · ``G``, where ``G`` is the base point of the
elliptic curve.


The memory size of the parameter ``privKey`` pointed by pPrivate must be
less than that of the base point which can also be defined by the
function
`ECCPGetOrderBitSize <eccpgetorderbitsize.html>`__.


The context of the point ``pubKey`` as an elliptic curve point must be
created by using the functions
`ECCPPointGetSize <eccppointgetsize.html>`__
and
`ECCPPointInit <eccppointinit.html>`__.


The elliptic curve domain parameters must be hitherto defined by one of
the functions:
`ECCPSet <eccpset.html>`__
or
`ECCPSetStd <eccpsetstd.html>`__.


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


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

   * - ippStsNoErr    
     - Indicates no error. Any other value indicates an error or warning.
   * - ippStsNullPtrErr   
     - Indicates an error condition if any of the specified pointers is NULL.
   * - ippStsContextMatchErr   
     - Indicates an error condition if one of the contexts pointed by pPrivate, pPublic, or pECC is not valid.
   * - ippStsSizeErr    
     - Indicates an error condition if the memory size of the parameter ``privKey`` pointed by pPrivate is less than that of the order of the elliptic curve base point.