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Diffstat (limited to 'ext/ipp/sources/ippcp/pcpgfp_sqrt.c')
| -rw-r--r-- | ext/ipp/sources/ippcp/pcpgfp_sqrt.c | 173 |
1 files changed, 173 insertions, 0 deletions
diff --git a/ext/ipp/sources/ippcp/pcpgfp_sqrt.c b/ext/ipp/sources/ippcp/pcpgfp_sqrt.c new file mode 100644 index 0000000..82f5a84 --- /dev/null +++ b/ext/ipp/sources/ippcp/pcpgfp_sqrt.c @@ -0,0 +1,173 @@ +/******************************************************************************* +* Copyright 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. +// Internal operations over prime GF(p). +// +// Context: +// cpGFpSqrt +// +*/ +#include "owncp.h" + +#include "pcpbn.h" +#include "pcpgfpstuff.h" + +//tbcd: temporary excluded: #include <assert.h> + +static int factor2(BNU_CHUNK_T* pA, int nsA) +{ + int factor = 0; + int bits; + + int i; + for(i=0; i<nsA; i++) { + int ntz = cpNTZ_BNU(pA[i]); + factor += ntz; + if(ntz<BITSIZE(BNU_CHUNK_T)) + break; + } + + bits = factor; + if(bits >= BITSIZE(BNU_CHUNK_T)) { + int nchunk = bits/BITSIZE(BNU_CHUNK_T); + cpGFpElementCopyPadd(pA, nsA, pA+nchunk, nsA-nchunk); + bits %= BITSIZE(BNU_CHUNK_T); + } + if(bits) + cpLSR_BNU(pA, pA, nsA, bits); + + return factor; +} + +static BNU_CHUNK_T* cpGFpExp2(BNU_CHUNK_T* pR, const BNU_CHUNK_T* pA, int e, gsModEngine* pGFE) +{ + cpGFpElementCopy(pR, pA, GFP_FELEN(pGFE)); + while(e--) { + GFP_METHOD(pGFE)->sqr(pR, pR, pGFE); + } + return pR; +} + + +/* returns: + 0, if a - qnr + 1, if sqrt is found +*/ +int cpGFpSqrt(BNU_CHUNK_T* pR, const BNU_CHUNK_T* pA, gsModEngine* pGFE) +{ + int elemLen = GFP_FELEN(pGFE); + int poolelementLen = GFP_PELEN(pGFE); + int resultFlag = 1; + + /* case A==0 */ + if( GFP_IS_ZERO(pA, elemLen) ) + cpGFpElementPadd(pR, elemLen, 0); + + /* general case */ + else { + BNU_CHUNK_T* q = cpGFpGetPool(4, pGFE); + BNU_CHUNK_T* x = q + poolelementLen; + BNU_CHUNK_T* y = x + poolelementLen; + BNU_CHUNK_T* z = y + poolelementLen; + + int s; + + //tbcd: temporary excluded: assert(q!=NULL); + + /* z=1 */ + GFP_ONE(z, elemLen); + + /* (modulus-1) = 2^s*q */ + cpSub_BNU(q, GFP_MODULUS(pGFE), z, elemLen); + s = factor2(q, elemLen); + + /* + // initialization + */ + + /* y = qnr^q */ + cpGFpExp(y, GFP_QNR(pGFE), q,elemLen, pGFE); + /* x = a^((q-1)/2) */ + cpSub_BNU(q, q, z, elemLen); + cpLSR_BNU(q, q, elemLen, 1); + cpGFpExp(x, pA, q, elemLen, pGFE); + /* z = a*x^2 */ + GFP_METHOD(pGFE)->mul(z, x, x, pGFE); + GFP_METHOD(pGFE)->mul(z, pA, z, pGFE); + /* R = a*x */ + GFP_METHOD(pGFE)->mul(pR, pA, x, pGFE); + + while( !GFP_EQ(z, MOD_MNT_R(pGFE), elemLen) ) { + int m = 0; + cpGFpElementCopy(q, z, elemLen); + + for(m=1; m<s; m++) { + GFP_METHOD(pGFE)->mul(q, q, q, pGFE); + if( GFP_EQ(q, MOD_MNT_R(pGFE), elemLen) ) + break; + } + + if(m==s) { + /* A is quadratic non-residue */ + resultFlag = 0; + break; + } + else { + /* exponent reduction */ + cpGFpExp2(q, y, (s-m-1), pGFE); /* q = y^(2^(s-m-1)) */ + GFP_METHOD(pGFE)->mul(y, q, q, pGFE); /* y = q^2 */ + GFP_METHOD(pGFE)->mul(pR, q, pR, pGFE); /* R = q*R */ + GFP_METHOD(pGFE)->mul(z, y, z, pGFE); /* z = z*y */ + s = m; + } + } + + /* choose smallest between R and (modulus-R) */ + GFP_METHOD(pGFE)->decode(q, pR, pGFE); + if(GFP_GT(q, GFP_HMODULUS(pGFE), elemLen)) + GFP_METHOD(pGFE)->neg(pR, pR, pGFE); + + cpGFpReleasePool(4, pGFE); + } + + return resultFlag; +} |