Commit b87ec212 authored by Niels Möller's avatar Niels Möller

Rearrange cmac's block_mulx, make it closer to xts_shift.

* xts.c (xts_shift): Arrange with a single write to u64[1].
* cmac.c (block_mulx): Rewrite to work in the same way as
xts_shift, with 64-bit operations. XTS and CMAC use opposite
endianness, but otherwise, these two functions are identical.
parent 0beec6b2
2019-03-27 Niels Möller <nisse@lysator.liu.se>
* xts.c (xts_shift): Arrange with a single write to u64[1].
* cmac.c (block_mulx): Rewrite to work in the same way as
xts_shift, with 64-bit operations. XTS and CMAC use opposite
endianness, but otherwise, these two functions are identical.
2019-03-24 Niels Möller <nisse@lysator.liu.se>
From Simo Sorce:
......
......@@ -47,22 +47,27 @@
#include "macros.h"
/* shift one and XOR with 0x87. */
#if WORDS_BIGENDIAN
static void
block_mulx(union nettle_block16 *dst,
const union nettle_block16 *src)
{
uint64_t b1 = READ_UINT64(src->b);
uint64_t b2 = READ_UINT64(src->b+8);
b1 = (b1 << 1) | (b2 >> 63);
b2 <<= 1;
if (src->b[0] & 0x80)
b2 ^= 0x87;
WRITE_UINT64(dst->b, b1);
WRITE_UINT64(dst->b+8, b2);
uint64_t carry = src->u64[0] >> 63;
dst->u64[0] = (src->u64[0] << 1) | (src->u64[1] >> 63);
dst->u64[1] = (src->u64[1] << 1) ^ (0x87 & -carry);
}
#else /* !WORDS_BIGENDIAN */
#define LE_SHIFT(x) ((((x) & 0x7f7f7f7f7f7f7f7f) << 1) | \
(((x) & 0x8080808080808080) >> 15))
static void
block_mulx(union nettle_block16 *dst,
const union nettle_block16 *src)
{
uint64_t carry = (src->u64[0] & 0x80) >> 7;
dst->u64[0] = LE_SHIFT(src->u64[0]) | ((src->u64[1] & 0x80) << 49);
dst->u64[1] = LE_SHIFT(src->u64[1]) ^ (0x8700000000000000 & -carry);
}
#endif /* !WORDS_BIGENDIAN */
void
cmac128_set_key(struct cmac128_ctx *ctx, const void *cipher,
......
......@@ -57,8 +57,7 @@ xts_shift(union nettle_block16 *dst,
{
uint64_t carry = (src->u64[1] & 0x80) >> 7;
dst->u64[1] = BE_SHIFT(src->u64[1]) | ((src->u64[0] & 0x80) << 49);
dst->u64[0] = BE_SHIFT(src->u64[0]);
dst->u64[0] ^= 0x8700000000000000 & -carry;
dst->u64[0] = BE_SHIFT(src->u64[0]) ^ (0x8700000000000000 & -carry);
}
#else /* !WORDS_BIGENDIAN */
static void
......@@ -67,8 +66,7 @@ xts_shift(union nettle_block16 *dst,
{
uint64_t carry = src->u64[1] >> 63;
dst->u64[1] = (src->u64[1] << 1) | (src->u64[0] >> 63);
dst->u64[0] = src->u64[0] << 1;
dst->u64[0] ^= 0x87 & -carry;
dst->u64[0] = (src->u64[0] << 1) ^ (0x87 & -carry);
}
#endif /* !WORDS_BIGNDIAN */
......
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