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- /*
- * Copyright (C) 2016 Intel Corporation. All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- *
- * * Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- * * Redistributions in binary form must reproduce the above copyright
- * notice, this list of conditions and the following disclaimer in
- * the documentation and/or other materials provided with the
- * distribution.
- * * Neither the name of Intel Corporation nor the names of its
- * contributors may be used to endorse or promote products derived
- * from this software without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
- * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
- * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
- * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
- * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
- * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
- * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
- * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- *
- */
- #include "owndefs.h"
- #include "owncp.h"
- #include "pcpbn.h"
- #include "pcpmontgomery.h"
- /*
- // Binary method of Exponentiation
- */
- cpSize cpMontExpBin_BNU(BNU_CHUNK_T* dataY,
- const BNU_CHUNK_T* dataX, cpSize nsX,
- const BNU_CHUNK_T* dataE, cpSize nsE,
- IppsMontState* pMont)
- {
- cpSize nsM = MNT_SIZE(pMont);
- /*
- // test for special cases:
- // x^0 = 1
- // 0^e = 0
- */
- if( cpEqu_BNU_CHUNK(dataE, nsE, 0) ) {
- COPY_BNU(dataY, MNT_1(pMont), nsM);
- }
- else if( cpEqu_BNU_CHUNK(dataX, nsX, 0) ) {
- ZEXPAND_BNU(dataY, 0, nsM);
- }
- /* general case */
- else {
- BNU_CHUNK_T* dataM = MNT_MODULUS(pMont);
- BNU_CHUNK_T m0 = MNT_HELPER(pMont);
- /* Montgomery engine buffers */
- BNU_CHUNK_T* pKBuffer = MNT_KBUFFER(pMont);
- BNU_CHUNK_T* pProduct = MNT_PRODUCT(pMont);
- BNU_CHUNK_T* dataT = MNT_TBUFFER(pMont);
- /* execute most significant part pE */
- BNU_CHUNK_T eValue = dataE[nsE-1];
- int n = cpNLZ_BNU(eValue)+1;
- /* expand base and init result */
- ZEXPAND_COPY_BNU(dataT, nsM, dataX, nsX);
- COPY_BNU(dataY, dataT, nsM);
- eValue <<= n;
- for(; n<BNU_CHUNK_BITS; n++, eValue<<=1) {
- /* squaring R = R*R mod Modulus */
- cpMontSqr_BNU(dataY,
- dataY, nsM,
- dataM, nsM, m0,
- pProduct, pKBuffer);
- /* and multiply R = R*X mod Modulus */
- if(eValue & ((BNU_CHUNK_T)1<<(BNU_CHUNK_BITS-1)))
- cpMontMul_BNU(dataY,
- dataY, nsM,
- dataT, nsM,
- dataM, nsM, m0,
- pProduct, pKBuffer);
- }
- /* execute rest bits of E */
- for(--nsE; nsE>0; nsE--) {
- eValue = dataE[nsE-1];
- for(n=0; n<BNU_CHUNK_BITS; n++, eValue<<=1) {
- /* squaring: R = R*R mod Modulus */
- cpMontSqr_BNU(dataY,
- dataY, nsM,
- dataM, nsM, m0,
- pProduct, pKBuffer);
- if(eValue & ((BNU_CHUNK_T)1<<(BNU_CHUNK_BITS-1)))
- cpMontMul_BNU(dataY,
- dataY, nsM,
- dataT, nsM,
- dataM, nsM, m0,
- pProduct, pKBuffer);
- }
- }
- }
- return nsM;
- }
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