Commit ed3377db authored by Niels Möller's avatar Niels Möller
Browse files

Reduce ecc_add_eh scratch need.

parent 43d4d194
2014-07-17 Niels Möller <>
* ecc-add-eh.c (ecc_add_eh): Reduce scratch need.
* ecc-internal.h (ECC_ADD_EH_ITCH): Reduced to 6*size.
* testsuite/curve25519-dup-test.c (test_main): Free allocated
......@@ -65,47 +65,49 @@ ecc_add_eh (const struct ecc_curve *ecc,
Computation Operation Live variables
B = z1^2 sqr B
C = x1*x2 mul B, C
D = y1*y2 mul B, C, D
E = b*C*D 2 mul B, C, D, E
F = B - E B, C, D, E, F
G = B + E C, D, F, G
x3 = z1*F*[(x1+y1)(x2+y2) - C - D] 3 mul C, D, G
C = x1*x2 mul C
D = y1*y2 mul C, D
T = (x1+y1)(x2+y2) - C - D C, D, T
E = b*C*D 2 mul C, E, T (Replace C <-- D - C)
B = z1^2 sqr B, C, E, T
F = B - E B, C, E, F, T
G = B + E C, F, G, T
x3 = z1*F*T 3 mul C, F, G, T
y3 = z1*G*(D-C) 2 mul F, G
z3 = F*G mul
#define B (scratch)
#define C (scratch + 1*ecc->size)
#define D (scratch + 2*ecc->size)
#define C (scratch)
#define D (scratch + 1*ecc->size)
#define T (scratch + 2*ecc->size)
#define E (scratch + 3*ecc->size)
#define F (scratch + 4*ecc->size)
#define G (scratch + 5*ecc->size)
#define T (scratch + 6*ecc->size)
ecc_modp_sqr (ecc, B, z1);
#define B (scratch + 4*ecc->size)
#define F D
#define G E
ecc_modp_mul (ecc, C, x1, x2);
ecc_modp_mul (ecc, D, y1, y2);
ecc_modp_mul (ecc, T, C, D);
ecc_modp_mul (ecc, E, T, ecc->b);
ecc_modp_add (ecc, x3, x1, y1);
ecc_modp_add (ecc, y3, x2, y2);
ecc_modp_mul (ecc, T, x3, y3);
ecc_modp_sub (ecc, T, T, C);
ecc_modp_sub (ecc, T, T, D);
ecc_modp_mul (ecc, x3, C, D);
ecc_modp_mul (ecc, E, x3, ecc->b);
ecc_modp_sub (ecc, C, D, C);
ecc_modp_sqr (ecc, B, z1);
ecc_modp_sub (ecc, F, B, E);
ecc_modp_add (ecc, G, B, E);
ecc_modp_add (ecc, G, B, E);
/* x3 */
ecc_modp_add (ecc, B, x1, y1);
ecc_modp_add (ecc, E, x2, y2);
ecc_modp_mul (ecc, T, B, E);
ecc_modp_sub (ecc, T, T, C);
ecc_modp_sub (ecc, x3, T, D);
ecc_modp_mul (ecc, T, x3, z1);
ecc_modp_mul (ecc, x3, T, F);
ecc_modp_mul (ecc, B, F, T);
ecc_modp_mul (ecc, x3, B, z1);
/* y3 */
ecc_modp_sub (ecc, C, D, C);
ecc_modp_mul (ecc, T, z1, C);
ecc_modp_mul (ecc, y3, T, G);
ecc_modp_mul (ecc, B, G, C);
ecc_modp_mul (ecc, y3, B, z1);
/* z3 */
ecc_modp_mul (ecc, T, F, G);
mpn_copyi (z3, T, ecc->size);
ecc_modp_mul (ecc, B, F, G);
mpn_copyi (z3, B, ecc->size);
......@@ -242,7 +242,7 @@ sec_modinv (mp_limb_t *vp, mp_limb_t *ap, mp_size_t n,
#define ECC_DUP_EH_ITCH(size) (5*(size))
#define ECC_ADD_JJA_ITCH(size) (6*(size))
#define ECC_ADD_JJJ_ITCH(size) (8*(size))
#define ECC_ADD_EH_ITCH(size) (8*(size))
#define ECC_ADD_EH_ITCH(size) (6*(size))
#define ECC_ADD_EHH_ITCH(size) (9*(size))
#define ECC_MUL_G_ITCH(size) (9*(size))
#if ECC_MUL_A_WBITS == 0
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