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Source code changes of the file "curve448-eh-to-x.c" between
nettle-3.7.1.tar.gz and nettle-3.7.2.tar.gz

About: Nettle is a low-level cryptographic library.

curve448-eh-to-x.c  (nettle-3.7.1):curve448-eh-to-x.c  (nettle-3.7.2)
skipping to change at line 55 skipping to change at line 55
Montgomery curve, and return the x coordinate. */ Montgomery curve, and return the x coordinate. */
void void
curve448_eh_to_x (mp_limb_t *xp, const mp_limb_t *p, mp_limb_t *scratch) curve448_eh_to_x (mp_limb_t *xp, const mp_limb_t *p, mp_limb_t *scratch)
{ {
#define up p #define up p
#define vp (p + ecc->p.size) #define vp (p + ecc->p.size)
#define t0 scratch #define t0 scratch
#define tp (scratch + ecc->p.size) #define tp (scratch + ecc->p.size)
const struct ecc_curve *ecc = &_nettle_curve448; const struct ecc_curve *ecc = &_nettle_curve448;
mp_limb_t cy;
/* If u = U/W and v = V/W are the coordinates of the point on /* If u = U/W and v = V/W are the coordinates of the point on
edwards448 we get the curve448 x coordinate as edwards448 we get the curve448 x coordinate as
x = v^2 / u^2 = (V/W)^2 / (U/W)^2 = (V/U)^2 x = v^2 / u^2 = (V/W)^2 / (U/W)^2 = (V/U)^2
*/ */
/* Needs a total of 5*size storage. */ /* Needs a total of 5*size storage. */
ecc->p.invert (&ecc->p, t0, up, tp); ecc->p.invert (&ecc->p, t0, up, tp);
ecc_mod_mul (&ecc->p, t0, t0, vp, tp); ecc_mod_mul (&ecc->p, t0, t0, vp, tp);
ecc_mod_sqr (&ecc->p, t0, t0, tp); ecc_mod_sqr_canonical (&ecc->p, xp, t0, tp);
cy = mpn_sub_n (xp, t0, ecc->p.m, ecc->p.size);
cnd_copy (cy, xp, t0, ecc->p.size);
#undef up #undef up
#undef vp #undef vp
#undef t0 #undef t0
#undef tp #undef tp
} }
 End of changes. 3 change blocks. 
4 lines changed or deleted 1 lines changed or added

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