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Avoid unaligned access in smult_curve25519_donna_c64.c if required

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This commit is contained in:
Frank Denis 2014-05-09 18:39:14 -07:00
parent 23aac61bd0
commit 8631fe9d1a
1 changed files with 39 additions and 9 deletions
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48
src/libsodium/crypto_scalarmult/curve25519/donna_c64/smult_curve25519_donna_c64.c
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@ -189,14 +189,44 @@ fsquare_times(felem output, const felem in, limb count) {
output[4] = r4;
}
#ifndef CPU_ALIGNED_ACCESS_REQUIRED
# define U8TO64(p) (*((const uint64_t *) (p)))
# define U64TO8(p, v) (*((uint64_t *) (p)) = (v))
#else
static force_inline uint64_t
U8TO64(const unsigned char *p) {
return
(((uint64_t)(p[0] & 0xff) ) |
((uint64_t)(p[1] & 0xff) << 8) |
((uint64_t)(p[2] & 0xff) << 16) |
((uint64_t)(p[3] & 0xff) << 24) |
((uint64_t)(p[4] & 0xff) << 32) |
((uint64_t)(p[5] & 0xff) << 40) |
((uint64_t)(p[6] & 0xff) << 48) |
((uint64_t)(p[7] & 0xff) << 56));
}
static force_inline void
U64TO8(unsigned char *p, uint64_t v) {
p[0] = (v ) & 0xff;
p[1] = (v >> 8) & 0xff;
p[2] = (v >> 16) & 0xff;
p[3] = (v >> 24) & 0xff;
p[4] = (v >> 32) & 0xff;
p[5] = (v >> 40) & 0xff;
p[6] = (v >> 48) & 0xff;
p[7] = (v >> 56) & 0xff;
}
#endif
/* Take a little-endian, 32-byte number and expand it into polynomial form */
static void
fexpand(limb *output, const u8 *in) {
output[0] = *((const uint64_t *)(in)) & 0x7ffffffffffff;
output[1] = (*((const uint64_t *)(in+6)) >> 3) & 0x7ffffffffffff;
output[2] = (*((const uint64_t *)(in+12)) >> 6) & 0x7ffffffffffff;
output[3] = (*((const uint64_t *)(in+19)) >> 1) & 0x7ffffffffffff;
output[4] = (*((const uint64_t *)(in+25)) >> 4) & 0xfffffffffffff;
output[0] = U8TO64(in) & 0x7ffffffffffff;
output[1] = (U8TO64(in+6) >> 3) & 0x7ffffffffffff;
output[2] = (U8TO64(in+12) >> 6) & 0x7ffffffffffff;
output[3] = (U8TO64(in+19) >> 1) & 0x7ffffffffffff;
output[4] = (U8TO64(in+25) >> 4) & 0xfffffffffffff;
}
/* Take a fully reduced polynomial form number and contract it into a
@ -251,10 +281,10 @@ fcontract(u8 *output, const felem input) {
t[4] += t[3] >> 51; t[3] &= 0x7ffffffffffff;
t[4] &= 0x7ffffffffffff;
*((uint64_t *)(output)) = t[0] | (t[1] << 51);
*((uint64_t *)(output+8)) = (t[1] >> 13) | (t[2] << 38);
*((uint64_t *)(output+16)) = (t[2] >> 26) | (t[3] << 25);
*((uint64_t *)(output+24)) = (t[3] >> 39) | (t[4] << 12);
U64TO8(output, t[0] | (t[1] << 51));
U64TO8(output + 8, (t[1] >> 13) | (t[2] << 38));
U64TO8(output + 16, (t[2] >> 26) | (t[3] << 25));
U64TO8(output + 24, (t[3] >> 39) | (t[4] << 12));
}
/* Input: Q, Q', Q-Q'