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40 
41 /*
42 //
43 //  Purpose:
44 //     Intel(R) Integrated Performance Primitives. Cryptography Primitives.
45 //     Internal EC over GF(p^m) basic Definitions & Function Prototypes
46 //
47 //     Context:
48 //        gfec_MulPoint()
49 //
50 */
51 
52 #include "owndefs.h"
53 #include "owncp.h"
54 #include "pcpgfpecstuff.h"
55 #include "gsscramble.h"
56 #include "pcpmask_ct.h"
57 
58 
gfec_point_mul(BNU_CHUNK_T * pRdata,const BNU_CHUNK_T * pPdata,const Ipp8u * pScalar8,int scalarBitSize,IppsGFpECState * pEC,Ipp8u * pScratchBuffer)59 void gfec_point_mul(BNU_CHUNK_T* pRdata,
60               const BNU_CHUNK_T* pPdata,
61               const Ipp8u* pScalar8, int scalarBitSize,
62                     IppsGFpECState* pEC, Ipp8u* pScratchBuffer)
63 {
64    int pointLen = ECP_POINTLEN(pEC);
65 
66    /* optimal size of window */
67    const int window_size = 5;
68 
69    /* aligned pre-computed table */
70    BNU_CHUNK_T* pTable = (BNU_CHUNK_T*)IPP_ALIGNED_PTR(pScratchBuffer, CACHE_LINE_SIZE);
71    setupTable(pTable, pPdata, pEC);
72 
73    {
74       IppsGFpState* pGF = ECP_GFP(pEC);
75       gsModEngine* pGFE = GFP_PMA(pGF);
76       int elemLen = GFP_FELEN(pGFE);
77 
78       mod_neg negF = GFP_METHOD(pGFE)->neg;
79 
80       BNU_CHUNK_T* pHy = cpGFpGetPool(1, pGFE);
81 
82       BNU_CHUNK_T* pTdata = cpEcGFpGetPool(1, pEC); /* points from the pool */
83       BNU_CHUNK_T* pHdata = cpEcGFpGetPool(1, pEC);
84 
85       int wvalue;
86       Ipp8u digit, sign;
87       int mask = (1<<(window_size+1)) -1;
88       int bit = scalarBitSize-(scalarBitSize%window_size);
89 
90       /* first window */
91       if(bit) {
92          wvalue = *((Ipp16u*)&pScalar8[(bit-1)/8]);
93          wvalue = (wvalue>> ((bit-1)%8)) & mask;
94       }
95       else
96          wvalue = 0;
97       booth_recode(&sign, &digit, (Ipp8u)wvalue, window_size);
98       gsScrambleGet_sscm(pTdata, pointLen, pTable, digit-1, 5-1);
99 
100       for(bit-=window_size; bit>=window_size; bit-=window_size) {
101          gfec_point_double(pTdata, pTdata, pEC); /* probablyit's better to have separate calls */
102          gfec_point_double(pTdata, pTdata, pEC); /* instead of gfec_point_double_k() */
103          gfec_point_double(pTdata, pTdata, pEC);
104          gfec_point_double(pTdata, pTdata, pEC);
105          gfec_point_double(pTdata, pTdata, pEC);
106 
107          wvalue = *((Ipp16u*)&pScalar8[(bit-1)/8]);
108          wvalue = (wvalue>> ((bit-1)%8)) & mask;
109          booth_recode(&sign, &digit, (Ipp8u)wvalue, window_size);
110          gsScrambleGet_sscm(pHdata, pointLen, pTable, digit-1, 5-1);
111 
112          negF(pHy, pHdata+elemLen, pGFE);
113          cpMaskedReplace_ct(pHdata+elemLen, pHy, elemLen, ~cpIsZero_ct(sign));
114          gfec_point_add(pTdata, pTdata, pHdata, pEC);
115       }
116 
117       /* last window */
118       gfec_point_double(pTdata, pTdata, pEC);
119       gfec_point_double(pTdata, pTdata, pEC);
120       gfec_point_double(pTdata, pTdata, pEC);
121       gfec_point_double(pTdata, pTdata, pEC);
122       gfec_point_double(pTdata, pTdata, pEC);
123 
124       wvalue = *((Ipp16u*)&pScalar8[0]);
125       wvalue = (wvalue << 1) & mask;
126       booth_recode(&sign, &digit, (Ipp8u)wvalue, window_size);
127       gsScrambleGet_sscm(pHdata, pointLen, pTable, digit-1, 5-1);
128 
129       negF(pHy, pHdata+elemLen, pGFE);
130       cpMaskedReplace_ct(pHdata+elemLen, pHy, elemLen, ~cpIsZero_ct(sign));
131       gfec_point_add(pTdata, pTdata, pHdata, pEC);
132 
133       cpGFpElementCopy(pRdata, pTdata, pointLen);
134 
135       cpEcGFpReleasePool(2, pEC);
136       cpGFpReleasePool(1, pGFE);
137    }
138 }
139