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Use endomorphism in precomputations #20

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Jun 2, 2014
Merged

Use endomorphism in precomputations #20

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13 changes: 6 additions & 7 deletions src/ecmult_impl.h
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Original file line number Diff line number Diff line change
Expand Up @@ -206,13 +206,6 @@ void static secp256k1_ecmult(secp256k1_gej_t *r, const secp256k1_gej_t *a, const
int wnaf_na_lam[129]; int bits_na_lam = secp256k1_ecmult_wnaf(wnaf_na_lam, &na_lam, WINDOW_A);
int bits = bits_na_1;
if (bits_na_lam > bits) bits = bits_na_lam;

// calculate a_lam = a*lambda
secp256k1_gej_t a_lam; secp256k1_gej_mul_lambda(&a_lam, a);

// calculate odd multiples of a_lam
secp256k1_gej_t pre_a_lam[ECMULT_TABLE_SIZE(WINDOW_A)];
secp256k1_ecmult_table_precomp_gej(pre_a_lam, &a_lam, WINDOW_A);
#else
// build wnaf representation for na.
int wnaf_na[257]; int bits_na = secp256k1_ecmult_wnaf(wnaf_na, na, WINDOW_A);
Expand All @@ -223,6 +216,12 @@ void static secp256k1_ecmult(secp256k1_gej_t *r, const secp256k1_gej_t *a, const
secp256k1_gej_t pre_a[ECMULT_TABLE_SIZE(WINDOW_A)];
secp256k1_ecmult_table_precomp_gej(pre_a, a, WINDOW_A);

#ifdef USE_ENDOMORPHISM
secp256k1_gej_t pre_a_lam[ECMULT_TABLE_SIZE(WINDOW_A)];
for (int i=0; i<ECMULT_TABLE_SIZE(WINDOW_A); i++)
secp256k1_gej_mul_lambda(&pre_a_lam[i], &pre_a[i]);
#endif

// Splitted G factors.
secp256k1_num_t ng_1, ng_128;
secp256k1_num_init(&ng_1);
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