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40
41 /*
42 //
43 // Purpose:
44 // Cryptography Primitive.
45 // DL over Prime Field
46 //
47 */
48
49 #include "owndefs.h"
50 #include "owncp.h"
51 #include "pcpdlp.h"
52 #include "pcptool.h"
53
54 /*
55 // Size of scratch buffer, involved in MontExp operation
56 //
57 // nExponents - number of exponents
58 // expBitSize - (max) sizeof exponent (in bits)
59 // modulusBitSize - size of modulus (bits)
60 */
cpMontExpScratchBufferSize(cpSize modulusBitSize,cpSize expBitSize,cpSize nExponents)61 static cpSize cpMontExpScratchBufferSize(cpSize modulusBitSize, cpSize expBitSize, cpSize nExponents)
62 {
63 /* sizeof table element */
64 cpSize elmDataSize = BITS_BNU_CHUNK(modulusBitSize) * sizeof(BNU_CHUNK_T);
65 /* get window_size */
66 cpSize w = (nExponents == 1) ? cpMontExp_WinSize(expBitSize) : /* use optimal window size, if single-scalar operation */
67 nExponents; /* or pseudo-oprimal if multi-scalar operation */
68
69 /* number of table entries */
70 cpSize nPrecomputed = 1 << w;
71
72 cpSize bufferSize = elmDataSize*nPrecomputed + (CACHE_LINE_SIZE - 1);
73 return bufferSize;
74 }