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/* 
//     Intel(R) Integrated Performance Primitives. Cryptography Primitives.
//     Operations over GF(p).
// 
//     Context:
//        ippsGFpInit
// 
// 
*/
#include "owndefs.h"
#include "owncp.h"

#include "pcpgfpstuff.h"
#include "pcpgfpxstuff.h"
#include "pcptool.h"


/*F*
// Name: ippsGFpInit
//
// Purpose: initializes prime finite field GF(p)
//
// Returns:                   Reason:
//    ippStsNullPtrErr           NULL == pGFpMethod
//                               NULL == pGFp
//
//    ippStsSizeErr              !(IPP_MIN_GF_BITSIZE <= primeBitSize <=IPP_MAX_GF_BITSIZE
//
//    ippStsContextMatchErr      invalid pPrime->idCtx
//
//    ippStsBadArgErr            pGFpMethod != ippsGFpMethod_pXXX() or != ippsGFpMethod_pArb()
//                               prime != pGFpMethod->modulus
//                               prime <0
//                               bitsize(prime) != primeBitSize
//                               prime <IPP_MIN_GF_CHAR
//                               prime is even
//
//    ippStsNoErr                no error
//
// Parameters:
//    pPrimeBN       pointer to the data representation Finite Field element
//    primeBitSize   length of Finite Field data representation array
//    pGFpMethod     pointer to Finite Field Element context
//    pGFp           pointer to Finite Field context is being initialized
*F*/
IPPFUN(IppStatus, ippsGFpInit,(const IppsBigNumState* pPrimeBN, int primeBitSize, const IppsGFpMethod* pGFpMethod, IppsGFpState* pGFp))
{
   IPP_BADARG_RET(!pPrimeBN && !pGFpMethod, ippStsNullPtrErr);

   IPP_BADARG_RET((primeBitSize< IPP_MIN_GF_BITSIZE) || (primeBitSize> IPP_MAX_GF_BITSIZE), ippStsSizeErr);

   /* use ippsGFpInitFixed() if NULL==pPrimeBN */
   if(!pPrimeBN)
      return ippsGFpInitFixed(primeBitSize, pGFpMethod, pGFp);

   /* use ippsGFpInitArbitrary() if NULL==pGFpMethod */
   if(!pGFpMethod)
      return ippsGFpInitArbitrary(pPrimeBN, primeBitSize, pGFp);

   /* test parameters if both pPrimeBN and method are defined */
   else {
      IppStatus sts;

      /* test input prime */
      pPrimeBN = (IppsBigNumState*)( IPP_ALIGNED_PTR(pPrimeBN, BN_ALIGNMENT) );
      IPP_BADARG_RET(!BN_VALID_ID(pPrimeBN), ippStsContextMatchErr);
      IPP_BADARG_RET(BN_SIGN(pPrimeBN)!= IppsBigNumPOS, ippStsBadArgErr);                                   /* prime is negative */
      IPP_BADARG_RET(BITSIZE_BNU(BN_NUMBER(pPrimeBN),BN_SIZE(pPrimeBN)) != primeBitSize, ippStsBadArgErr);  /* primeBitSize == bitsize(prime) */
      IPP_BADARG_RET((BN_SIZE(pPrimeBN)==1) && (BN_NUMBER(pPrimeBN)[0]<IPP_MIN_GF_CHAR), ippStsBadArgErr);  /* prime < 3 */
      IPP_BADARG_RET(0==(BN_NUMBER(pPrimeBN)[0] & 1), ippStsBadArgErr);                                     /* prime is even */

      /* test if method is prime based */
      IPP_BADARG_RET(cpID_Prime!=(pGFpMethod->modulusID & cpID_Prime), ippStsBadArgErr);

      /* test if size of the prime is matched to method's prime  */
      IPP_BADARG_RET(pGFpMethod->modulusBitDeg && (primeBitSize!=pGFpMethod->modulusBitDeg), ippStsBadArgErr);

      /* if method assumes fixed prime value */
      if(pGFpMethod->modulus) {
         int primeLen = BITS_BNU_CHUNK(primeBitSize);
         IPP_BADARG_RET(cpCmp_BNU(BN_NUMBER(pPrimeBN), primeLen, pGFpMethod->modulus, primeLen), ippStsBadArgErr);
      }

      /* init GF */
      sts = cpGFpInitGFp(primeBitSize, pGFp);

      /* set up GF  and find quadratic nonresidue */
      if(ippStsNoErr==sts) {
         cpGFpSetGFp(BN_NUMBER(pPrimeBN), primeBitSize, pGFpMethod, pGFp);
      }

      return sts;
   }
}