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| author | Niels Möller <nisse@lysator.liu.se> | 2016-04-25 21:48:52 +0200 |
|---|---|---|
| committer | Niels Möller <nisse@lysator.liu.se> | 2016-04-25 21:48:52 +0200 |
| commit | b18472f886a673c2f823fc69cb4994942badeef1 (patch) | |
| tree | 3bb9240691cd3f930e04c01aca9e838cb6f31433 /curve25519-mul.c | |
| parent | dbd02e3047fae9634bec6ee95549f372134574a3 (diff) | |
| download | nettle-b18472f886a673c2f823fc69cb4994942badeef1.tar.gz | |
Update curve25519_mul, to align with RFC 7748.
Diffstat (limited to 'curve25519-mul.c')
| -rw-r--r-- | curve25519-mul.c | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/curve25519-mul.c b/curve25519-mul.c index adb20cbc..f5127d77 100644 --- a/curve25519-mul.c +++ b/curve25519-mul.c @@ -72,7 +72,11 @@ curve25519_mul (uint8_t *q, const uint8_t *n, const uint8_t *p) itch = ecc->p.size * 12; scratch = gmp_alloc_limbs (itch); + /* Note that 255 % GMP_NUMB_BITS == 0 isn't supported, so x1 always + holds at least 256 bits. */ mpn_set_base256_le (x1, ecc->p.size, p, CURVE25519_SIZE); + /* Clear bit 255, as required by RFC 7748. */ + x1[255/GMP_NUMB_BITS] &= ~((mp_limb_t) 1 << (255 % GMP_NUMB_BITS)); /* Initialize, x2 = x1, z2 = 1 */ mpn_copyi (x2, x1, ecc->p.size); |