/*************************************************************************
* Copyright (C) 2014 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.
*************************************************************************/

/* 
// 
//  Purpose:
//     Cryptography Primitive.
//     HMAC General Functionality
// 
//  Contents:
//        ippsHMAC_Init()
//
*/

#include "owndefs.h"
#include "owncp.h"
#include "pcphmac.h"
#include "pcptool.h"

/*F*
//    Name: ippsHMAC_Init
//
// Purpose: Init HMAC state.
//
// Returns:                Reason:
//    ippStsNullPtrErr           pKey == NULL
//                               pState == NULL
//    ippStsLengthErr            keyLen <0
//    ippStsNotSupportedModeErr  if algID is not match to supported hash alg
//    ippStsNoErr                no errors
//
// Parameters:
//    pKey        pointer to the secret key
//    keyLen      length (bytes) of the secret key
//    pState      pointer to the HMAC state
//    hashAlg     hash alg ID
//
*F*/
IPPFUN(IppStatus, ippsHMAC_Init,(const Ipp8u* pKey, int keyLen, IppsHMACState* pCtx, IppHashAlgId hashAlg))
{
   //int mbs;

   /* get algorithm id */
   hashAlg = cpValidHashAlg(hashAlg);
   /* test hash alg */
   IPP_BADARG_RET(ippHashAlg_Unknown==hashAlg, ippStsNotSupportedModeErr);
   //mbs = cpHashMBS(hashAlg);

   /* test pState pointer */
   IPP_BAD_PTR1_RET(pCtx);

   /* test key pointer and key length */
   IPP_BAD_PTR1_RET(pKey);
   IPP_BADARG_RET(0>keyLen, ippStsLengthErr);

   /* set state ID */
   HMAC_SET_CTX_ID(pCtx);

   /* init hash context */
   ippsHashInit(&HASH_CTX(pCtx), hashAlg);

   {
      int n;

      /* hash specific */
      IppsHashState* pHashCtx = &HASH_CTX(pCtx);
      int mbs = cpHashMBS(hashAlg);
      int hashSize = cpHashSize(hashAlg);

      /* copyMask = keyLen>mbs? 0xFF : 0x00 */
      int copyMask = (mbs-keyLen) >>(BITSIZE(int)-1);

      /* actualKeyLen = keyLen>mbs? hashSize:keyLen */
      int actualKeyLen = (hashSize & copyMask) | (keyLen & ~copyMask);

      /* compute hash(key, keyLen) just in case */
      ippsHashUpdate(pKey, keyLen, pHashCtx);
      ippsHashFinal(HASH_BUFF(pHashCtx), pHashCtx);

      /* copy either key or hash(key) into ipad- and opad- buffers */
      MASKED_COPY_BNU(pCtx->ipadKey, (Ipp8u)copyMask, HASH_BUFF(pHashCtx), pKey, actualKeyLen);
      MASKED_COPY_BNU(pCtx->opadKey, (Ipp8u)copyMask, HASH_BUFF(pHashCtx), pKey, actualKeyLen);

      /* XOR-ing key */
      for(n=0; n<actualKeyLen; n++) {
         pCtx->ipadKey[n] ^= (Ipp8u)IPAD;
         pCtx->opadKey[n] ^= (Ipp8u)OPAD;
      }
      for(; n<mbs; n++) {
         pCtx->ipadKey[n] = (Ipp8u)IPAD;
         pCtx->opadKey[n] = (Ipp8u)OPAD;
      }

      /* ipad key processing */
      ippsHashUpdate(pCtx->ipadKey, mbs, pHashCtx);

      return ippStsNoErr;
   }
}
