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| author | Niels Möller <nisse@lysator.liu.se> | 2020-11-06 21:13:13 +0100 |
|---|---|---|
| committer | Niels Möller <nisse@lysator.liu.se> | 2020-11-06 21:13:13 +0100 |
| commit | 0e08b1c78b2f3c9fd166ee4ca03e66a52dda3ebf (patch) | |
| tree | 8f2a17d1402278122f18b15423f5847650052785 | |
| parent | d6f3118575ad48fbae0e29d8e88280e4d6b7210e (diff) | |
| download | nettle-0e08b1c78b2f3c9fd166ee4ca03e66a52dda3ebf.tar.gz | |
Reduce scratch need for ecc_curve25519_sqrt
| -rw-r--r-- | ChangeLog | 3 | ||||
| -rw-r--r-- | ecc-curve25519.c | 12 |
2 files changed, 8 insertions, 7 deletions
@@ -1,5 +1,8 @@ 2020-11-06 Niels Möller <nisse@lysator.liu.se> + * ecc-curve25519.c (ecc_curve25519_sqrt): Reduce scratch need to + 6*size. + * ecc-add-jja.c (ecc_add_jja): Delete an unneeded copy. 2020-11-05 Niels Möller <nisse@lysator.liu.se> diff --git a/ecc-curve25519.c b/ecc-curve25519.c index b53915c1..5d221ae3 100644 --- a/ecc-curve25519.c +++ b/ecc-curve25519.c @@ -205,8 +205,8 @@ ecc_curve25519_zero_p (const struct ecc_modulo *p, mp_limb_t *xp) #error Broken curve25519 parameters #endif -/* Needs 3*n space + scratch for ecc_mod_pow_252m3. */ -#define ECC_25519_SQRT_ITCH (7*ECC_LIMB_SIZE) +/* Needs 2*n space + scratch for ecc_mod_pow_252m3. */ +#define ECC_25519_SQRT_ITCH (6*ECC_LIMB_SIZE) static int ecc_curve25519_sqrt(const struct ecc_modulo *p, mp_limb_t *rp, @@ -217,13 +217,12 @@ ecc_curve25519_sqrt(const struct ecc_modulo *p, mp_limb_t *rp, #define uv3 scratch #define uv7 (scratch + ECC_LIMB_SIZE) -#define uv7p (scratch + 2*ECC_LIMB_SIZE) #define v2 uv7 #define uv uv3 #define v4 uv7 -#define scratch_out (scratch + 3 * ECC_LIMB_SIZE) +#define scratch_out (scratch + 2 * ECC_LIMB_SIZE) #define x2 scratch #define vx2 (scratch + ECC_LIMB_SIZE) @@ -235,8 +234,8 @@ ecc_curve25519_sqrt(const struct ecc_modulo *p, mp_limb_t *rp, ecc_mod_mul (p, uv3, uv, v2, scratch_out); /* uv3, v2 */ ecc_mod_sqr (p, v4, v2, scratch_out); /* uv3, v4 */ ecc_mod_mul (p, uv7, uv3, v4, scratch_out); /* uv7 */ - ecc_mod_pow_252m3 (p, uv7p, uv7, scratch_out);/* uv3, uv7p */ - ecc_mod_mul (p, rp, uv7p, uv3, scratch_out); /* none */ + ecc_mod_pow_252m3 (p, rp, uv7, scratch_out); /* uv3, uv7p */ + ecc_mod_mul (p, rp, rp, uv3, scratch_out); /* none */ /* Check sign. If square root exists, have v x^2 = ±u */ ecc_mod_sqr (p, x2, rp, t0); @@ -252,7 +251,6 @@ ecc_curve25519_sqrt(const struct ecc_modulo *p, mp_limb_t *rp, #undef uv3 #undef uv7 -#undef uv7p #undef v2 #undef uv #undef v4 |