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40 
41 /*
42 //
43 //  Purpose:
44 //     Intel(R) Integrated Performance Primitives. Cryptography Primitives.
45 //     EC over GF(p) Operations
46 //
47 //     Context:
48 //        ippsGFpECGetPointOctString()
49 //
50 */
51 #include "pcpgfpecessm2.h"
52 #include "pcpgfpecstuff.h"
53 
54 /*F*
55 //    Name: ippsGFpECGetPointOctString
56 //
57 // Purpose: Converts a point on EC into x||y octstring
58 //
59 // Returns:                   Reason:
60 //    ippStsNullPtrErr           pPoint == NULL / pEC == NULL / pStr == NULL
61 //    ippStsContextMatchErr      pEC, pPoint invalid context
62 //    ippStsNotSupportedModeErr  pGFE->extdegree > 1
63 //    ippStsSizeErr              strLen is not equal to double GFp element
64 //    ippStsOutOfRangeErr        the point does not belong to the EC
65 //    ippStsPointAtInfinity      a point on infinity cannot be converted to a string
66 //    ippStsNoErr                no errors
67 //
68 // Parameters:
69 //    pStr     pointer to the string to read from
70 //    strLen   length of the string
71 //    pPoint   pointer to output point
72 //    pEC      EC ctx
73 //
74 *F*/
75 IPPFUN(IppStatus, ippsGFpECGetPointOctString, (const IppsGFpECPoint* pPoint,
76    Ipp8u* pStr, int strLen, IppsGFpECState* pEC)) {
77    IPP_BAD_PTR3_RET(pPoint, pEC, pStr);
78    IPP_BADARG_RET(pPoint->idCtx != idCtxGFPPoint, ippStsContextMatchErr);
79    IPP_BADARG_RET(pEC->idCtx != idCtxGFPEC, ippStsContextMatchErr);
80    IPP_BADARG_RET(!pEC->subgroup, ippStsContextMatchErr);
81    IPP_BADARG_RET(1 < pEC->pGF->pGFE->extdegree, ippStsNotSupportedModeErr);
82 
83    {
84       gsModEngine* pGFE = pEC->pGF->pGFE;
85       int elemLen = BITS2WORD8_SIZE(pGFE->modBitLen);
86       IPP_BADARG_RET(strLen != elemLen * 2, ippStsSizeErr);
87       IPP_BADARG_RET(pPoint->elementSize != pGFE->modLen, ippStsOutOfRangeErr);
88 
89       {
90          int finitePoint;
91          IppsGFpElement ptX, ptY;
92 
93          cpGFpElementConstruct(&ptX, cpGFpGetPool(1, pGFE), pGFE->modLen);
94          cpGFpElementConstruct(&ptY, cpGFpGetPool(1, pGFE), pGFE->modLen);
95          finitePoint = gfec_GetPoint(ptX.pData, ptY.pData, pPoint, pEC);
96          if (finitePoint) {
97             ippsGFpGetElementOctString(&ptX, pStr, elemLen, pEC->pGF);
98             pStr += elemLen;
99             ippsGFpGetElementOctString(&ptY, pStr, elemLen, pEC->pGF);
100          }
101 
102          cpGFpReleasePool(2, pGFE); /* release ptX and ptY from the pool */
103 
104          return finitePoint ? ippStsNoErr : ippStsPointAtInfinity;
105       }
106    }
107 }
108