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/* 
// 
//  Purpose:
//     Cryptography Primitive.
//     PRNG Functions
// 
//  Contents:
//        cpPRNGenRange()
//
*/

#include "owndefs.h"
#include "owncp.h"
#include "pcpbn.h"
#include "pcphash.h"
#include "pcpprng.h"
#include "pcptool.h"

/* generates random string of specified bitSize length
   within specified ragnge lo < r < Hi
   returns:
      0 random bit string not generated
      1 random bit string generated
     -1 detected internal error (ippStsNoErr != rndFunc())
*/
int cpPRNGenRange(BNU_CHUNK_T* pRand,
            const BNU_CHUNK_T* pLo, cpSize loLen,
            const BNU_CHUNK_T* pHi, cpSize hiLen,
                  IppBitSupplier rndFunc, void* pRndParam)
{
   int bitSize = BITSIZE_BNU(pHi,hiLen);
   BNU_CHUNK_T topMask = MASK_BNU_CHUNK(bitSize);

   #define MAX_COUNT (1000)
   int n;
   for(n=0; n<MAX_COUNT; n++) {
      cpSize randLen;
      IppStatus sts = rndFunc((Ipp32u*)pRand, bitSize, pRndParam);
      if(ippStsNoErr!=sts) return -1;

      pRand[hiLen-1] &= topMask;
      randLen = cpFix_BNU(pRand, hiLen);
      if((0 < cpCmp_BNU(pRand, randLen, pLo, loLen)) && (0 < cpCmp_BNU(pHi, hiLen, pRand, randLen)))
         return 1;
   }
   #undef MAX_COUNT

   return 0; /* no random matched to (Lo,Hi) */
}