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/*******************************************************************************
* Copyright 2010-2018 Intel Corporation
* All Rights Reserved.
*
* If this software was obtained under the Intel Simplified Software License,
* the following terms apply:
*
* The source code, information and material ("Material") contained herein is
* owned by Intel Corporation or its suppliers or licensors, and title to such
* Material remains with Intel Corporation or its suppliers or licensors. The
* Material contains proprietary information of Intel or its suppliers and
* licensors. The Material is protected by worldwide copyright laws and treaty
* provisions. No part of the Material may be used, copied, reproduced,
* modified, published, uploaded, posted, transmitted, distributed or disclosed
* in any way without Intel's prior express written permission. No license under
* any patent, copyright or other intellectual property rights in the Material
* is granted to or conferred upon you, either expressly, by implication,
* inducement, estoppel or otherwise. Any license under such intellectual
* property rights must be express and approved by Intel in writing.
*
* Unless otherwise agreed by Intel in writing, you may not remove or alter this
* notice or any other notice embedded in Materials by Intel or Intel's
* suppliers or licensors in any way.
*
*
* If this software was obtained under the Apache License, Version 2.0 (the
* "License"), the following terms apply:
*
* 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.
*******************************************************************************/
/*
// Intel(R) Integrated Performance Primitives. Cryptography Primitives.
//
// Context:
// cpFastMontMultiExp()
//
*/
#include "owndefs.h"
#include "owncp.h"
#include "pcpbn.h"
#include "pcpmontgomery.h"
static cpSize GetIndex(const Ipp8u** ppE, cpSize numItems, cpSize nBit)
{
cpSize shift = nBit%BYTESIZE;
cpSize offset= nBit/BYTESIZE;
cpSize index = 0;
cpSize n;
for(n=numItems; n>0; n--) {
const Ipp8u* pE = ppE[n-1] + offset;
Ipp8u e = pE[0];
index <<= 1;
index += (e>>shift) &1;
}
return index;
}
/*
// Computes multi-exponentiation
// y = x[0]^e[0] * x[1]^e[1] *...* x[numItems-1]^e[numItems-1] mod M
//
// Input:
// - table pTbl of precomuted values pTbl[i] = x[0]^i[0] * x[1]^i[1] *...* x[numItems-1]^i[numItems-1] mod M,
// where i[0], i[1], ..., i[numItems-1] are bits of i value;
// each entry has sizeM length (i.e. equial to modulo M size)
// - array of pointers to the BNU exponents e[0], e[1],...,e[numItems-1]
// - pointer to the Montgomery engine
*/
void cpFastMontMultiExp(BNU_CHUNK_T* pY,
const BNU_CHUNK_T* pPrecomTbl,
const Ipp8u** ppE, cpSize eItemBitSize,
cpSize numItems,
gsModEngine* pModEngine)
{
cpSize sizeM = MOD_LEN(pModEngine);
/* find 1-st non zero index */
cpSize eBitNumber;
cpSize tblIdx;
for(eBitNumber=eItemBitSize-1, tblIdx=0; !tblIdx && eBitNumber>=0; eBitNumber--)
tblIdx =GetIndex(ppE, numItems, eBitNumber);
COPY_BNU(pY, pPrecomTbl+tblIdx*sizeM, sizeM);
for(; eBitNumber>=0; eBitNumber--) {
cpMontMul_BNU(pY,
pY,
pY,
pModEngine);
tblIdx = GetIndex(ppE, numItems, eBitNumber);
if(tblIdx)
cpMontMul_BNU(pY,
pY,
pPrecomTbl+tblIdx*sizeM,
pModEngine);
}
}
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