Delete ecc_mod_inv_redc

diff --git a/ChangeLog b/ChangeLog
index aae9374e5669f8335b79c2f79e705a9458480b42..c4678b22d0423c9689223cfba5a52532ce076f42 100644 (file)
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,8 @@
 2020-10-20  Niels Möller  <nisse@lysator.liu.se>
 
+       * ecc-mod-inv.c (ecc_mod_inv_redc): Deleted, no longer needed.
+       (ecc_mod_inv_destructive): Deleted, merged with ecc_mod_inv.
+
        * ecc-secp256r1.c (ecc_secp256r1_inv): New function, modular
        inverse using powering.
        (_nettle_secp_256r1): Analogous updates. Increases signing

diff --git a/ecc-internal.h b/ecc-internal.h
index b4dfad2e46fe121b3b74e97143eebbc34e73c874..d26458e1e76bc566d2c4865feaf59496c7f41e63 100644 (file)
--- a/ecc-internal.h
+++ b/ecc-internal.h
@@ -54,7 +54,6 @@
 #define ecc_mod_random _nettle_ecc_mod_random
 #define ecc_mod _nettle_ecc_mod
 #define ecc_mod_inv _nettle_ecc_mod_inv
-#define ecc_mod_inv_redc _nettle_ecc_mod_inv_redc
 #define ecc_hash _nettle_ecc_hash
 #define gost_hash _nettle_gost_hash
 #define ecc_a_to_j _nettle_ecc_a_to_j
@@ -235,7 +234,6 @@ ecc_mod_func ecc_pp1_redc;
 ecc_mod_func ecc_pm1_redc;
 
 ecc_mod_inv_func ecc_mod_inv;
-ecc_mod_inv_func ecc_mod_inv_redc;
 
 void
 ecc_mod_add (const struct ecc_modulo *m, mp_limb_t *rp,
@@ -441,7 +439,7 @@ curve448_eh_to_x (mp_limb_t *xp, const mp_limb_t *p,
 
 /* Current scratch needs: */
 #define ECC_MOD_INV_ITCH(size) (2*(size))
-/* Only valid when using the general ecc_mod_inv/ecc_mod_inv_redc ! */
+/* Only valid when using the general ecc_mod_inv ! */
 #define ECC_J_TO_A_ITCH(size) (4*(size))
 #define ECC_EH_TO_A_ITCH(size, inv) (2*(size)+(inv))
 #define ECC_DUP_JJ_ITCH(size) (4*(size))

diff --git a/ecc-mod-inv.c b/ecc-mod-inv.c
index 570f05683ae7195098939845eb9dd1db1614669b..a0c1097ee01ae27a3e604bc405d4c2238580757b 100644 (file)
--- a/ecc-mod-inv.c
+++ b/ecc-mod-inv.c
@@ -54,19 +54,22 @@ cnd_neg (int cnd, mp_limb_t *rp, const mp_limb_t *ap, mp_size_t n)
     }
 }
 
-/* Compute v = a^{-1} mod m, with running time depending only on the
-   size. Returns zero if a == 0 (mod m), to be consistent with
-   a^{phi(m)-1}. Also needs (m+1)/2, and m must be odd. The value at
-   ap is destroyed in the process.
+/* Compute a^{-1} mod m, with running time depending only on the size.
+   Returns zero if a == 0 (mod m), to be consistent with a^{phi(m)-1}.
+   Also needs (m+1)/2, and m must be odd.
+
+   Needs 2n limbs available at rp, and 2n additional scratch limbs.
 */
 
 /* FIXME: Could use mpn_sec_invert (in GMP-6), but with a bit more
    scratch need since it doesn't precompute (m+1)/2. */
-static void
-ecc_mod_inv_destructive (const struct ecc_modulo *m,
-                        mp_limb_t *vp, mp_limb_t *ap)
+void
+ecc_mod_inv (const struct ecc_modulo *m,
+            mp_limb_t *vp, const mp_limb_t *in_ap,
+            mp_limb_t *scratch)
 {
-#define bp (ap + n)
+#define ap scratch
+#define bp (scratch + n)
 #define up (vp + n)
 
   mp_size_t n = m->size;
@@ -91,6 +94,7 @@ ecc_mod_inv_destructive (const struct ecc_modulo *m,
   mpn_zero (up+1, n - 1);
   mpn_copyi (bp, m->m, n);
   mpn_zero (vp, n);
+  mpn_copyi (ap, in_ap, n);
 
   for (i = m->bit_size + GMP_NUMB_BITS * n; i-- > 0; )
     {
@@ -154,36 +158,3 @@ ecc_mod_inv_destructive (const struct ecc_modulo *m,
 #undef bp
 #undef up
 }
-
-/* Needs 2n limbs available at rp, and 2n additional scratch
-   limbs. */
-void
-ecc_mod_inv (const struct ecc_modulo *m,
-            mp_limb_t *vp, const mp_limb_t *ap,
-            mp_limb_t *scratch)
-{
-  mpn_copyi (scratch, ap, m->size);
-  ecc_mod_inv_destructive (m, vp, scratch);
-}
-
-/* Inversion, with input and output in redc form. I.e., we want v =
-   a^-1 (mod m), but inputs and outputs are v' = vB, a' = aB. Then
-   v' a' = B^2 (mod b), and we do the inversion as
-
-     v' = (a / B^2)^-1 (mod m)
-*/
-
-void
-ecc_mod_inv_redc (const struct ecc_modulo *m,
-                 mp_limb_t *vp, const mp_limb_t *ap,
-                 mp_limb_t *scratch)
-{
-  mpn_copyi (scratch, ap, m->size);
-
-  mpn_zero (scratch + m->size, m->size);
-  m->reduce (m, scratch, scratch);
-  mpn_zero (scratch + m->size, m->size);
-  m->reduce (m, scratch, scratch);
-
-  ecc_mod_inv_destructive (m, vp, scratch);
-}