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/* 
//     Intel(R) Integrated Performance Primitives. Cryptography Primitives.
//     EC over GF(p^m) definitinons
// 
//     Context:
//        ippsGFpECInitStd256r1()
//
*/

#include "owndefs.h"
#include "owncp.h"
#include "pcpgfpecstuff.h"
#include "pcpeccp.h"


static void cpGFpECSetStd(int aLen, const BNU_CHUNK_T* pA,
                          int bLen, const BNU_CHUNK_T* pB,
                          int xLen, const BNU_CHUNK_T* pX,
                          int yLen, const BNU_CHUNK_T* pY,
                          int rLen, const BNU_CHUNK_T* pR,
                          BNU_CHUNK_T h,
                          IppsGFpECState* pEC)
{
   IppsGFpState* pGF = ECP_GFP(pEC);
   gsModEngine* pGFE = GFP_PMA(pGF);
   int elemLen = GFP_FELEN(pGFE);

   IppsGFpElement elmA, elmB;
   IppsBigNumState R, H;

   /* convert A ans B coeffs into GF elements */
   cpGFpElementConstruct(&elmA, cpGFpGetPool(1, pGFE), elemLen);
   cpGFpElementConstruct(&elmB, cpGFpGetPool(1, pGFE), elemLen);
   ippsGFpSetElement((Ipp32u*)pA, BITS2WORD32_SIZE(BITSIZE_BNU(pA,aLen)), &elmA, pGF);
   ippsGFpSetElement((Ipp32u*)pB, BITS2WORD32_SIZE(BITSIZE_BNU(pB,bLen)), &elmB, pGF);
   /* and set EC */
   ippsGFpECSet(&elmA, &elmB, pEC);

   /* construct R and H */
   cpConstructBN(&R, rLen, (BNU_CHUNK_T*)pR, NULL);
   cpConstructBN(&H, 1, &h, NULL);
   /* convert GX ans GY coeffs into GF elements */
   ippsGFpSetElement((Ipp32u*)pX, BITS2WORD32_SIZE(BITSIZE_BNU(pX,xLen)), &elmA, pGF);
   ippsGFpSetElement((Ipp32u*)pY, BITS2WORD32_SIZE(BITSIZE_BNU(pY,yLen)), &elmB, pGF);
   /* and init EC subgroup */
   ippsGFpECSetSubgroup(&elmA, &elmB, &R, &H, pEC);
}

/*F*
// Name: ippsGFpECInitStd256r1
//
// Purpose: Initializes the context of EC256r1
//
// Returns:                   Reason:
//    ippStsNullPtrErr              NULL == pEC
//                                  NULL == pGFp
//
//    ippStsContextMatchErr         invalid pGFp->idCtx
//
//    ippStsBadArgErr               pGFp does not specify the finite field over which the given
//                                  standard elliptic curve is defined
//
//    ippStsNoErr                   no error
//
// Parameters:
//    pGFp       Pointer to the IppsGFpState context of the underlying finite field
//    pEC        Pointer to the context of the elliptic curve being initialized.
//
*F*/

IPPFUN(IppStatus, ippsGFpECInitStd256r1,(const IppsGFpState* pGFp, IppsGFpECState* pEC))
{
   IPP_BAD_PTR2_RET(pGFp, pEC);

   pGFp = (IppsGFpState*)( IPP_ALIGNED_PTR(pGFp, GFP_ALIGNMENT) );
   IPP_BADARG_RET( !GFP_TEST_ID(pGFp), ippStsContextMatchErr );

   {
      gsModEngine* pGFE = GFP_PMA(pGFp);

   /* test if GF is prime GF */
      IPP_BADARG_RET(!GFP_IS_BASIC(pGFE), ippStsBadArgErr);
      /* test underlying prime value*/
      IPP_BADARG_RET(cpCmp_BNU(secp256r1_p, BITS_BNU_CHUNK(256), GFP_MODULUS(pGFE), BITS_BNU_CHUNK(256)), ippStsBadArgErr);

      pEC = (IppsGFpECState*)( IPP_ALIGNED_PTR(pEC, ECGFP_ALIGNMENT) );

      ippsGFpECInit(pGFp, NULL, NULL, pEC);
      cpGFpECSetStd(BITS_BNU_CHUNK(256), secp256r1_a,
                    BITS_BNU_CHUNK(256), secp256r1_b,
                    BITS_BNU_CHUNK(256), secp256r1_gx,
                    BITS_BNU_CHUNK(256), secp256r1_gy,
                    BITS_BNU_CHUNK(256), secp256r1_r,
                    secp256r1_h,
                    pEC);

      return ippStsNoErr;
   }
}