/*************************************************************************
* Copyright (C) 2002 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.
//     Decrypt byte data stream according to TDES (CFB mode)
//
//  Contents:
//     ippsTDESDecryptCFB()
//
//
*/

#include "owndefs.h"

#include "owncp.h"
#include "pcpdes.h"
#include "pcptool.h"


/*F*
//    Name: ippsTDESDecryptCFB
//
// Purpose: Decrypt byte data block stream according to TDES in CFB mode.
//
// Returns:                Reason:
//    ippStsNullPtrErr        pCtx1 == NULL
//                            pCtx2 == NULL
//                            pCtx3 == NULL
//                            pSrc == NULL
//                            pDst == NULL
//    ippStsContextMatchErr   pCtx1->idCtx != idCtxDES
//                            pCtx2->idCtx != idCtxDES
//                            pCtx3->idCtx != idCtxDES
//    ippStsLengthErr         len <1
//    ippStsCFBSizeErr        (1>cfbBlkSize || cfbBlkSize>MBS_DES)
//    ippStsUnderRunErr       (len%cfbBlkSize)
//    ippStsNoErr             no errors
//
// Parameters:
//    pSrc        pointer to the source byte data stream
//    pDst        pointer to the target byte data stream
//    len         plaintext stream length (bytes)
//    cfbBlkSize  CFB block size (bytes)
//    pCtx1-3     pointers to the DES context
//    pIV         pointer to the init vector
//    padding     the padding scheme indicator
//
*F*/
/* clang-format off */
IPPFUN(IppStatus, ippsTDESDecryptCFB,(const Ipp8u* pSrc,
                                      Ipp8u* pDst,
                                      int len,
                                      int cfbBlkSize,
                                      const IppsDESSpec* pCtx1,
                                      const IppsDESSpec* pCtx2,
                                      const IppsDESSpec* pCtx3,
                                      const Ipp8u* pIV,
                                      IppsPadding padding))
/* clang-format on */
{
    Ipp64u inpBuffer[2];
    Ipp64u outBuffer;

    /* test contexts */
    IPP_BAD_PTR3_RET(pCtx1, pCtx2, pCtx3);

    IPP_BADARG_RET(!VALID_DES_ID(pCtx1), ippStsContextMatchErr);
    IPP_BADARG_RET(!VALID_DES_ID(pCtx2), ippStsContextMatchErr);
    IPP_BADARG_RET(!VALID_DES_ID(pCtx3), ippStsContextMatchErr);
    /* test source and destination pointers */
    IPP_BAD_PTR3_RET(pSrc, pDst, pIV);
    /* test stream length */
    IPP_BADARG_RET((len < 1), ippStsLengthErr);
    /* test CFB value */
    IPP_BADARG_RET(((1 > cfbBlkSize) || (MBS_DES < cfbBlkSize)), ippStsCFBSizeErr);

    /* force ippPaddingNONE padding */
    if (ippPaddingNONE != padding)
        padding = ippPaddingNONE;
    /* test stream integrity */
    //IPP_BADARG_RET(((len%cfbBlkSize) && (ippPaddingNONE==padding)), ippStsUnderRunErr);
    IPP_BADARG_RET((len % cfbBlkSize), ippStsUnderRunErr);

    /* read IV */
    CopyBlock8(pIV, inpBuffer);

    /* decrypt data block-by-block of cfbLen each */
    while (len >= cfbBlkSize) {
        int n;

        /* decryption */
        outBuffer = Cipher_DES(inpBuffer[0], DES_EKEYS(pCtx1), DESspbox);
        outBuffer = Cipher_DES(outBuffer, DES_DKEYS(pCtx2), DESspbox);
        outBuffer = Cipher_DES(outBuffer, DES_EKEYS(pCtx3), DESspbox);

        /* store output and put feedback into the buffer */
        for (n = 0; n < cfbBlkSize; n++) {
            ((Ipp8u*)(inpBuffer + 1))[n] = pSrc[n];
            pDst[n]                      = (Ipp8u)(((Ipp8u*)&outBuffer)[n] ^ pSrc[n]);
        }

        /* shift buffer for the next CFB operation */
        if (MBS_DES == cfbBlkSize)
            inpBuffer[0] = inpBuffer[1];
        else
#if (IPP_ENDIAN == IPP_BIG_ENDIAN)
            inpBuffer[0] =
                LSL64(inpBuffer[0], cfbBlkSize * 8) | LSR64(inpBuffer[1], 64 - cfbBlkSize * 8);
#else
            inpBuffer[0] =
                LSR64(inpBuffer[0], cfbBlkSize * 8) | LSL64(inpBuffer[1], 64 - cfbBlkSize * 8);
#endif

        pSrc += cfbBlkSize;
        pDst += cfbBlkSize;
        len -= cfbBlkSize;
    }

    return ippStsNoErr;
}
