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crypto: good fast sc_invert moved to crypto-ops

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sowle 2020-12-24 17:38:40 +03:00
parent 25b1eed3da
commit 0a7b856d09
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GPG key ID: C07A24B2D89D49FC
2 changed files with 205 additions and 0 deletions
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204
src/crypto/crypto-ops.c
View file

@ -3519,3 +3519,207 @@ void sc_mul(unsigned char* s, const unsigned char* a, const unsigned char* b)
s[30] = s11 >> 9;
s[31] = s11 >> 17;
}
// out = z ^ -1 (= z ^ (L - 2) according to Fermat little theorem)
void sc_invert(unsigned char* out, const unsigned char* z)
{
memcpy(out, z, 32);
for (size_t i = 0; i < 128; ++i)
sc_mul(out, out, out);
sc_mul(out, out, z);
sc_mul(out, out, out);
sc_mul(out, out, out);
sc_mul(out, out, z);
sc_mul(out, out, out);
sc_mul(out, out, out);
sc_mul(out, out, out);
sc_mul(out, out, z);
sc_mul(out, out, out);
sc_mul(out, out, z);
sc_mul(out, out, out);
sc_mul(out, out, out);
sc_mul(out, out, z);
sc_mul(out, out, out);
sc_mul(out, out, z);
sc_mul(out, out, out);
sc_mul(out, out, z);
sc_mul(out, out, out);
sc_mul(out, out, z);
sc_mul(out, out, out);
sc_mul(out, out, out);
sc_mul(out, out, z);
sc_mul(out, out, out);
sc_mul(out, out, z);
sc_mul(out, out, out);
sc_mul(out, out, z);
sc_mul(out, out, out);
sc_mul(out, out, z);
sc_mul(out, out, out);
sc_mul(out, out, z);
sc_mul(out, out, out);
sc_mul(out, out, out);
sc_mul(out, out, out);
sc_mul(out, out, z);
sc_mul(out, out, out);
sc_mul(out, out, z);
sc_mul(out, out, out);
sc_mul(out, out, z);
sc_mul(out, out, out);
sc_mul(out, out, out);
sc_mul(out, out, z);
sc_mul(out, out, out);
sc_mul(out, out, z);
sc_mul(out, out, out);
sc_mul(out, out, z);
sc_mul(out, out, out);
sc_mul(out, out, z);
sc_mul(out, out, out);
sc_mul(out, out, out);
sc_mul(out, out, z);
sc_mul(out, out, out);
sc_mul(out, out, out);
sc_mul(out, out, z);
sc_mul(out, out, out);
sc_mul(out, out, out);
sc_mul(out, out, out);
sc_mul(out, out, out);
sc_mul(out, out, z);
sc_mul(out, out, out);
sc_mul(out, out, out);
sc_mul(out, out, z);
sc_mul(out, out, out);
sc_mul(out, out, z);
sc_mul(out, out, out);
sc_mul(out, out, z);
sc_mul(out, out, out);
sc_mul(out, out, z);
sc_mul(out, out, out);
sc_mul(out, out, out);
sc_mul(out, out, z);
sc_mul(out, out, out);
sc_mul(out, out, z);
sc_mul(out, out, out);
sc_mul(out, out, z);
sc_mul(out, out, out);
sc_mul(out, out, z);
sc_mul(out, out, out);
sc_mul(out, out, out);
sc_mul(out, out, out);
sc_mul(out, out, z);
sc_mul(out, out, out);
sc_mul(out, out, z);
sc_mul(out, out, out);
sc_mul(out, out, z);
sc_mul(out, out, out);
sc_mul(out, out, out);
sc_mul(out, out, out);
sc_mul(out, out, z);
sc_mul(out, out, out);
sc_mul(out, out, z);
sc_mul(out, out, out);
sc_mul(out, out, out);
sc_mul(out, out, z);
sc_mul(out, out, out);
sc_mul(out, out, out);
sc_mul(out, out, z);
sc_mul(out, out, out);
sc_mul(out, out, z);
sc_mul(out, out, out);
sc_mul(out, out, out);
sc_mul(out, out, out);
sc_mul(out, out, z);
sc_mul(out, out, out);
sc_mul(out, out, out);
sc_mul(out, out, z);
sc_mul(out, out, out);
sc_mul(out, out, z);
sc_mul(out, out, out);
sc_mul(out, out, out);
sc_mul(out, out, out);
sc_mul(out, out, out);
sc_mul(out, out, out);
sc_mul(out, out, out);
sc_mul(out, out, out);
sc_mul(out, out, z);
sc_mul(out, out, out);
sc_mul(out, out, out);
sc_mul(out, out, out);
sc_mul(out, out, z);
sc_mul(out, out, out);
sc_mul(out, out, out);
sc_mul(out, out, out);
sc_mul(out, out, z);
sc_mul(out, out, out);
sc_mul(out, out, z);
sc_mul(out, out, out);
sc_mul(out, out, out);
sc_mul(out, out, out);
sc_mul(out, out, out);
sc_mul(out, out, z);
sc_mul(out, out, out);
sc_mul(out, out, z);
sc_mul(out, out, out);
sc_mul(out, out, out);
sc_mul(out, out, out);
sc_mul(out, out, out);
sc_mul(out, out, z);
sc_mul(out, out, out);
sc_mul(out, out, z);
sc_mul(out, out, out);
sc_mul(out, out, out);
sc_mul(out, out, z);
sc_mul(out, out, out);
sc_mul(out, out, out);
sc_mul(out, out, out);
sc_mul(out, out, z);
sc_mul(out, out, out);
sc_mul(out, out, out);
sc_mul(out, out, z);
sc_mul(out, out, out);
sc_mul(out, out, z);
sc_mul(out, out, out);
sc_mul(out, out, z);
sc_mul(out, out, out);
sc_mul(out, out, out);
sc_mul(out, out, out);
sc_mul(out, out, z);
sc_mul(out, out, out);
sc_mul(out, out, z);
sc_mul(out, out, out);
sc_mul(out, out, z);
sc_mul(out, out, out);
sc_mul(out, out, z);
sc_mul(out, out, out);
sc_mul(out, out, out);
sc_mul(out, out, z);
sc_mul(out, out, out);
sc_mul(out, out, out);
sc_mul(out, out, z);
sc_mul(out, out, out);
sc_mul(out, out, z);
sc_mul(out, out, out);
sc_mul(out, out, z);
sc_mul(out, out, out);
sc_mul(out, out, out);
sc_mul(out, out, z);
sc_mul(out, out, out);
sc_mul(out, out, out);
sc_mul(out, out, out);
sc_mul(out, out, z);
sc_mul(out, out, out);
sc_mul(out, out, z);
sc_mul(out, out, out);
sc_mul(out, out, z);
sc_mul(out, out, out);
sc_mul(out, out, z);
sc_mul(out, out, out);
sc_mul(out, out, z);
sc_mul(out, out, out);
sc_mul(out, out, out);
sc_mul(out, out, z);
sc_mul(out, out, out);
sc_mul(out, out, out);
sc_mul(out, out, z);
sc_mul(out, out, out);
sc_mul(out, out, z);
}

1
src/crypto/crypto-ops.h
View file

@ -123,6 +123,7 @@ void sc_mulsub(unsigned char *, const unsigned char *, const unsigned char *, co
void sc_mul(unsigned char *, const unsigned char *, const unsigned char *);
int sc_check(const unsigned char *);
int sc_isnonzero(const unsigned char *); /* Doesn't normalize */
void sc_invert(unsigned char*, const unsigned char*);
void fe_sq(fe h, const fe f);
void fe_mul(fe, const fe, const fe);