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Add ge25519_clear_cofactor()

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This commit is contained in:
Frank Denis 2023-09-09 13:25:09 +02:00
parent 1bafad7899
commit 21223ba7a1
1 changed files with 16 additions and 8 deletions
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24
src/libsodium/crypto_core/ed25519/ref10/ed25519_ref10.c
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@ -2512,6 +2512,21 @@ sc25519_is_canonical(const unsigned char s[32])
return (c != 0);
}
/* multiply by the cofactor */
static void
ge25519_clear_cofactor(ge25519_p3 *p3)
{
ge25519_p1p1 p1;
ge25519_p2 p2;
ge25519_p3_dbl(&p1, p3);
ge25519_p1p1_to_p2(&p2, &p1);
ge25519_p2_dbl(&p1, &p2);
ge25519_p1p1_to_p2(&p2, &p1);
ge25519_p2_dbl(&p1, &p2);
ge25519_p1p1_to_p3(p3, &p1);
}
static void
ge25519_elligator2(unsigned char s[32], const fe25519 r, const unsigned char x_sign)
{
@ -2565,14 +2580,7 @@ ge25519_elligator2(unsigned char s[32], const fe25519 r, const unsigned char x_s
abort(); /* LCOV_EXCL_LINE */
}
/* multiply by the cofactor */
ge25519_p3_dbl(&p1, &p3);
ge25519_p1p1_to_p2(&p2, &p1);
ge25519_p2_dbl(&p1, &p2);
ge25519_p1p1_to_p2(&p2, &p1);
ge25519_p2_dbl(&p1, &p2);
ge25519_p1p1_to_p3(&p3, &p1);
ge25519_clear_cofactor(&p3);
ge25519_p3_tobytes(s, &p3);
}