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sha3: make size/speed optimization decision configurable

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Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Denys Vlasenko 2013-01-15 01:12:26 +01:00
parent 60cb48ca50
commit 30a8652fbf
2 changed files with 68 additions and 19 deletions
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10
libbb/Config.src
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@ -28,6 +28,16 @@ config MD5_SMALL
2 3.0 5088
3 (smallest) 5.1 4912
config SHA3_SMALL
int "SHA3: Trade bytes for speed (0:fast, 1:slow)"
default 1
range 0 1
help
Trade binary size versus speed for the sha3sum algorithm.
SHA3_SMALL=0 compared to SHA3_SMALL=1 (approximate):
64-bit x86: +270 bytes of code, 45% faster
32-bit x86: +450 bytes of code, 75% faster
config FEATURE_FAST_TOP
bool "Faster /proc scanning code (+100 bytes)"
default y

61
libbb/hash_md5_sha.c
View File

@ -918,6 +918,16 @@ void FAST_FUNC sha512_end(sha512_ctx_t *ctx, void *resbuf)
* Busybox modifications (C) Lauri Kasanen, under the GPLv2.
*/
#if CONFIG_SHA3_SMALL < 0
# define SHA3_SMALL 0
#elif CONFIG_SHA3_SMALL > 1
# define SHA3_SMALL 1
#else
# define SHA3_SMALL CONFIG_SHA3_SMALL
#endif
#define ARCH_IS_64BIT (sizeof(long) >= sizeof(uint64_t))
enum {
cKeccakR_SizeInBytes = 576 / 8,
cKeccakNumberOfRounds = 24,
@ -967,8 +977,6 @@ static const uint8_t KeccakF_Mod5[10] = {
static void KeccakF(uint64_t *state)
{
uint8_t x, y;
uint64_t temp;
uint64_t BC[5];
int round;
if (BB_BIG_ENDIAN) {
@ -979,30 +987,61 @@ static void KeccakF(uint64_t *state)
for (round = 0; round < cKeccakNumberOfRounds; ++round) {
/* Theta */
{
uint64_t BC[5];
for (x = 0; x < 5; ++x) {
BC[x] = state[x] ^ state[5 + x] ^ state[10 + x] ^
state[15 + x] ^ state[20 + x];
}
for (x = 0; x < 5; ++x) {
temp = BC[KeccakF_Mod5[x + 4]] ^
uint64_t temp = BC[KeccakF_Mod5[x + 4]] ^
rotl64(BC[KeccakF_Mod5[x + 1]], 1);
for (y = 0; y <= 20; y += 5) {
if (SHA3_SMALL && !ARCH_IS_64BIT) {
for (y = 0; y <= 20; y += 5)
state[y + x] ^= temp;
} else {
/* on 64-bit arch, this is actually smaller too */
state[0 + x] ^= temp;
state[5 + x] ^= temp;
state[10 + x] ^= temp;
state[15 + x] ^= temp;
state[20 + x] ^= temp;
}
}
}
/* Rho Pi */
temp = state[1];
if (SHA3_SMALL) {
uint64_t t1 = state[1];
for (x = 0; x < 24; ++x) {
BC[0] = state[KeccakF_PiLane[x]];
state[KeccakF_PiLane[x]] =
rotl64(temp, KeccakF_RotationConstants[x]);
temp = BC[0];
uint64_t t0 = state[KeccakF_PiLane[x]];
state[KeccakF_PiLane[x]] = rotl64(t1, KeccakF_RotationConstants[x]);
t1 = t0;
}
} else {
/* Especially large benefit for 32-bit arch:
* 64-bit rotations by non-constant usually are SLOW on those.
* We resort to unrolling here.
* This optimizes out KeccakF_PiLane[] and KeccakF_RotationConstants[],
* but generates 300-500 more bytes of code.
*/
uint64_t t0;
uint64_t t1 = state[1];
#define RhoPi_twice(x) \
t0 = state[KeccakF_PiLane[x ]]; state[KeccakF_PiLane[x ]] = rotl64(t1, KeccakF_RotationConstants[x ]); \
t1 = state[KeccakF_PiLane[x+1]]; state[KeccakF_PiLane[x+1]] = rotl64(t0, KeccakF_RotationConstants[x+1]);
RhoPi_twice(0); RhoPi_twice(2);
RhoPi_twice(4); RhoPi_twice(6);
RhoPi_twice(8); RhoPi_twice(10);
RhoPi_twice(12); RhoPi_twice(14);
RhoPi_twice(16); RhoPi_twice(18);
RhoPi_twice(20); RhoPi_twice(22);
#undef RhoPi_twice
}
/* Chi */
for (y = 0; y < 25; y += 5) {
for (y = 0; y <= 20; y += 5) {
uint64_t BC[5];
BC[0] = state[y + 0];
BC[1] = state[y + 1];
BC[2] = state[y + 2];