/*************************************************************************
* Copyright (C) 2021 Intel Corporation
*
* Licensed under the Apache License,  Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* 	http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law  or agreed  to  in  writing,  software
* distributed under  the License  is  distributed  on  an  "AS IS"  BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the  specific  language  governing  permissions  and
* limitations under the License.
*************************************************************************/

#include "owndefs.h"

#if (_IPP32E >= _IPP32E_K1)

#include "pcpgfpecstuff.h"
#include "pcpgfpstuff.h"

#include "ifma_defs.h"
#include "ifma_ecpoint_p256.h"
#include "ifma_arith_method.h"

IPP_OWN_DEFN(IppStatus, gfec_SignDSA_nistp256_avx512, (const IppsBigNumState *pMsgDigest,
                                                       const IppsBigNumState *pRegPrivate,
                                                       IppsBigNumState *pEphPrivate,
                                                       IppsBigNumState *pSignR,
                                                       IppsBigNumState *pSignS,
                                                       IppsGFpECState *pEC,
                                                       Ipp8u *pScratchBuffer))
{
   IPP_UNREFERENCED_PARAMETER(pScratchBuffer);

   IppStatus sts = ippStsNoErr;

   gsModEngine *pME = GFP_PMA(ECP_GFP(pEC));
   gsModEngine *nME = ECP_MONT_R(pEC);

   const int orderBits = ECP_ORDBITSIZE(pEC);
   const int orderLen  = BITS_BNU_CHUNK(orderBits);

   ifmaArithMethod *pmeth = (ifmaArithMethod *)GFP_METHOD_ALT(pME);
   ifmaArithMethod *nmeth = (ifmaArithMethod *)GFP_METHOD_ALT(nME);

   ifma_import to_radix52   = pmeth->import_to52;
   ifma_export from_radix52 = pmeth->export_to64;

   /* Mod engine (mod p) */
   ifma_decode p_from_mont    = pmeth->decode;

   /* Mod engine (mod n - subgroup order) */
   ifma_encode n_to_mont    = nmeth->encode;
   ifma_decode n_from_mont  = nmeth->decode;
   ifma_mul n_mul           = nmeth->mul;
   ifma_add n_add           = nmeth->add;
   ifma_inv n_inv           = nmeth->inv;
   ifma_red n_red           = nmeth->red;

   /* Copy scalar */
   BNU_CHUNK_T *pExtendedScalar = cpGFpGetPool(2, pME);
   cpGFpElementCopyPad(pExtendedScalar, orderLen + 1, BN_NUMBER(pEphPrivate), BN_SIZE(pEphPrivate));

   __ALIGN64 P256_POINT_IFMA P;

   if (ECP_PREMULBP(pEC)) {
      ifma_ec_nistp256_mul_pointbase(&P, (Ipp8u *)pExtendedScalar, orderBits);
   } else {
      BNU_CHUNK_T* pPool = cpGFpGetPool(3, pME);

      /* Convert base point to a new Montgomery domain */
      __ALIGN64 P256_POINT_IFMA G52;
      recode_point_to_mont52(&G52, ECP_G(pEC), pPool, pmeth, pME);

      ifma_ec_nistp256_mul_point(&P, &G52, (Ipp8u *)pExtendedScalar, orderBits);

      cpGFpReleasePool(3, pME);
   }

   /*
   // signR = int(ephPublic.x) (mod order)
   */
   /* Extract affine P.x */
   ifma_ec_nistp256_get_affine_coords(&(P.x), NULL, &P);

   P.x = p_from_mont(P.x);
   P.x = n_red(P.x);

   /*
   // signS = (1/ephPrivate)*(pMsgDigest + private*signR) (mod order)
   */
   m512 ephPrivateInv = setzero_i64();
   BNU_CHUNK_T *pTmp  = cpGFpGetPool(1, pME);
   ZEXPAND_COPY_BNU(pTmp, orderLen, BN_NUMBER(pEphPrivate), BN_SIZE(pEphPrivate));
   ephPrivateInv = to_radix52(pTmp);

   ephPrivateInv = n_to_mont(ephPrivateInv);
   ephPrivateInv = n_inv(ephPrivateInv);

   /* Message */
   m512 msgDigest = setzero_i64();
   ZEXPAND_COPY_BNU(pTmp, orderLen, BN_NUMBER(pMsgDigest), BN_SIZE(pMsgDigest));
   msgDigest = to_radix52(pTmp);
   msgDigest = n_red(msgDigest); /* reduce just in case */
   msgDigest = n_to_mont(msgDigest);

   /* Regular private key */
   m512 regPrivate = setzero_i64();
   ZEXPAND_COPY_BNU(pTmp, orderLen, BN_NUMBER(pRegPrivate), BN_SIZE(pRegPrivate));
   regPrivate = to_radix52(pTmp);
   regPrivate = n_to_mont(regPrivate);

   m512 signS;

   signS = n_to_mont(P.x);
   signS = n_mul(regPrivate, signS);
   signS = n_add(signS, msgDigest);
   signS = n_mul(signS, ephPrivateInv);
   signS = n_from_mont(signS);

   const mask8 isZero = (mask8)(is_zero_i64(signS) | is_zero_i64(P.x));
   if ((mask8)0xFF == isZero)
      sts = ippStsEphemeralKeyErr;

   from_radix52((Ipp64u *)pTmp, signS);
   ZEXPAND_COPY_BNU(BN_NUMBER(pSignS), BN_SIZE(pSignS), pTmp, orderLen);

   from_radix52((Ipp64u *)pTmp, P.x);
   ZEXPAND_COPY_BNU(BN_NUMBER(pSignR), BN_SIZE(pSignR), pTmp, orderLen);

   /* Clear secret data */
   clear_secrets(&regPrivate, &(P.x), &signS);

   cpGFpReleasePool(3, pME);

   return sts;
}

#endif // (_IPP32E >= _IPP32E_K1)
