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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_base_point_mul()
49 //
50 */
51 
52 #include "owndefs.h"
53 #include "owncp.h"
54 #include "pcpgfpecstuff.h"
55 #include "pcpmask_ct.h"
56 
gfec_base_point_mul(BNU_CHUNK_T * pRdata,const Ipp8u * pScalar8,int scalarBitSize,IppsGFpECState * pEC)57 void gfec_base_point_mul(BNU_CHUNK_T* pRdata, const Ipp8u* pScalar8, int scalarBitSize, IppsGFpECState* pEC)
58 {
59    /* size of window, get function and pre-computed table */
60    int window_size = ECP_PREMULBP(pEC)->w;
61    selectAP select_affine_point = ECP_PREMULBP(pEC)->select_affine_point;
62    const BNU_CHUNK_T* pTbl = ECP_PREMULBP(pEC)->pTbl;
63 
64    IppsGFpState* pGF = ECP_GFP(pEC);
65    gsModEngine* pGFE = GFP_PMA(pGF);
66    int elmLen = GFP_FELEN(pGFE);
67 
68    mod_neg negF = GFP_METHOD(pGFE)->neg;
69 
70    BNU_CHUNK_T* mont1 = GFP_MNT_R(pGFE);
71 
72    /* number of points per table slot */
73    int tslot_point = 1<<(window_size-1);
74    int tslot_size = tslot_point * (elmLen*2);
75 
76    BNU_CHUNK_T* negtmp = cpGFpGetPool(1, pGFE);  /* temporary element */
77    BNU_CHUNK_T* pointT = cpEcGFpGetPool(1, pEC); /* temporary point */
78 
79    Ipp8u digit, sign;
80    int mask = (1<<(window_size+1)) -1;
81    int bit = 0;
82 
83    /* processing of window[0] */
84    int wvalue = *((Ipp16u*)&pScalar8[0]);
85    wvalue = (wvalue << 1) & mask;
86 
87    booth_recode(&sign, &digit, (Ipp8u)wvalue, window_size);
88    select_affine_point(pRdata, pTbl, digit);
89 
90    negF(negtmp, pRdata+elmLen, pGFE);
91    cpMaskedReplace_ct(pRdata+elmLen, negtmp, elmLen, ~cpIsZero_ct(sign));
92    cpGFpElementCopy(pRdata+elmLen*2, mont1, elmLen);
93    cpGFpElementCopy(pointT+elmLen*2, mont1, elmLen);
94 
95    /* processing of other windows.. [1],[2],... */
96    for(bit+=window_size, pTbl+=tslot_size; bit<=scalarBitSize; bit+=window_size, pTbl+=tslot_size) {
97       wvalue = *((Ipp16u*)&pScalar8[(bit-1)/8]);
98       wvalue = (wvalue>> ((bit-1)%8)) & mask;
99 
100       booth_recode(&sign, &digit, (Ipp8u)wvalue, window_size);
101       select_affine_point(pointT, pTbl, digit);
102 
103       negF(negtmp, pointT+elmLen, pGFE);
104       cpMaskedReplace_ct(pointT+elmLen, negtmp, elmLen, ~cpIsZero_ct(sign));
105 
106       gfec_affine_point_add(pRdata, pRdata, pointT, pEC);
107    }
108 
109    cpEcGFpReleasePool(1, pEC);
110    cpGFpReleasePool(1, pGFE);
111 }
112