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/* 
// 
//  Purpose:
//     Cryptography Primitive.
//     SMS4 encryption/decryption
// 
//  Contents:
//        cpProcessSMS4_ofb8()
//
*/

#include "owncp.h"
#include "pcpsms4.h"
#include "pcptool.h"

#if !defined _PCP_SMS4_PROCESS_OFB8_H
#define _PCP_SMS4_PROCESS_OFB8_H

/*
// SMS4-OFB ecnryption/decryption
//
// Parameters:
//    pSrc        pointer to the source data buffer
//    pDst        pointer to the target data buffer
//    dataLen     input/output buffer length (in bytes)
//    ofbBlkSize  ofb block size (in bytes)
//    pCtx        pointer to the AES context
//    pIV         pointer to the initialization vector
*/
static void cpProcessSMS4_ofb8(const Ipp8u *pSrc, Ipp8u *pDst, int dataLen, int ofbBlkSize,
                        const IppsSMS4Spec* pCtx,
                        Ipp8u* pIV)
{
   Ipp32u tmpInpOut[2*MBS_SMS4/sizeof(Ipp32u)];

   CopyBlock16(pIV, tmpInpOut);

   while(dataLen>=ofbBlkSize) {
      /* block-by-block processing */
      cpSMS4_Cipher((Ipp8u*)tmpInpOut+MBS_SMS4, (Ipp8u*)tmpInpOut, SMS4_RK(pCtx));

      /* store output and shift inpBuffer for the next OFB operation */
      if(ofbBlkSize==MBS_SMS4) {
         ((Ipp32u*)pDst)[0] = tmpInpOut[0+MBS_SMS4/sizeof(Ipp32u)]^((Ipp32u*)pSrc)[0];
         ((Ipp32u*)pDst)[1] = tmpInpOut[1+MBS_SMS4/sizeof(Ipp32u)]^((Ipp32u*)pSrc)[1];
         ((Ipp32u*)pDst)[2] = tmpInpOut[2+MBS_SMS4/sizeof(Ipp32u)]^((Ipp32u*)pSrc)[2];
         ((Ipp32u*)pDst)[3] = tmpInpOut[3+MBS_SMS4/sizeof(Ipp32u)]^((Ipp32u*)pSrc)[3];
         tmpInpOut[0] = tmpInpOut[0+MBS_SMS4/sizeof(Ipp32u)];
         tmpInpOut[1] = tmpInpOut[1+MBS_SMS4/sizeof(Ipp32u)];
         tmpInpOut[2] = tmpInpOut[2+MBS_SMS4/sizeof(Ipp32u)];
         tmpInpOut[3] = tmpInpOut[3+MBS_SMS4/sizeof(Ipp32u)];
      }
      else {
         XorBlock(pSrc, tmpInpOut+MBS_SMS4/sizeof(Ipp32u), pDst, ofbBlkSize);
         CopyBlock16((Ipp8u*)tmpInpOut+ofbBlkSize, tmpInpOut);
      }

      pSrc += ofbBlkSize;
      pDst += ofbBlkSize;
      dataLen -= ofbBlkSize;
   }

   /* update pIV */
   CopyBlock16((Ipp8u*)tmpInpOut, pIV);
}

#endif /* #if !defined _PCP_SMS4_PROCESS_OFB8_H */