[PATCH -mm crypto] AES: remove crypto_fl_tab and replace crypto_il_tab with isb_tab

Huang, Ying
2008-03-11T04:42:38Z

Remove crypto_fl_tab from aes implementation. Because mix_col(1,n) = n,
all information in cryto_fl_tab is in crypto_ft_tab too.
crypto_il_tab is replaced by isb_tab, the byte shift is done
during decryption.

These changes reduce the encryption cache footprint to 50% and
decryption cache footprint to 53.1%. The code size is increased
slightly. On my Intel CORE micro-architecture CPU, there is almost no
performance penalty.

This patch has been built and tested against 2.6.25-rc3-mm1.

This patch is only for generic C implementation. If this kind of idea
is desired, I will implement the ASM version for x86.

Signed-off-by: Huang Ying <ying.huang@intel.com>

---
crypto/aes_generic.c | 47 ++++++++++++++++-------------------------------
include/crypto/aes.h | 2 --
2 files changed, 16 insertions(+), 33 deletions(-)

--- a/crypto/aes_generic.c
+++ b/crypto/aes_generic.c
@@ -63,18 +63,14 @@ static inline u8 byte(const u32 x, const
static u8 pow_tab[256] __initdata;
static u8 log_tab[256] __initdata;
static u8 sbx_tab[256] __initdata;
-static u8 isb_tab[256] __initdata;
+static u8 isb_tab[256];
static u32 rco_tab[10];

u32 crypto_ft_tab[4][256];
-u32 crypto_fl_tab[4][256];
u32 crypto_it_tab[4][256];
-u32 crypto_il_tab[4][256];

EXPORT_SYMBOL_GPL(crypto_ft_tab);
-EXPORT_SYMBOL_GPL(crypto_fl_tab);
EXPORT_SYMBOL_GPL(crypto_it_tab);
-EXPORT_SYMBOL_GPL(crypto_il_tab);

static inline u8 __init f_mult(u8 a, u8 b)
{
@@ -122,12 +118,6 @@ static void __init gen_tabs(void)
for (i = 0; i < 256; ++i) {
p = sbx_tab[i];

- t = p;
- crypto_fl_tab[0][i] = t;
- crypto_fl_tab[1][i] = rol32(t, 8);
- crypto_fl_tab[2][i] = rol32(t, 16);
- crypto_fl_tab[3][i] = rol32(t, 24);
-
t = ((u32) ff_mult(2, p)) |
((u32) p << 8) |
((u32) p << 16) | ((u32) ff_mult(3, p) << 24);
@@ -139,12 +129,6 @@ static void __init gen_tabs(void)

p = isb_tab[i];

- t = p;
- crypto_il_tab[0][i] = t;
- crypto_il_tab[1][i] = rol32(t, 8);
- crypto_il_tab[2][i] = rol32(t, 16);
- crypto_il_tab[3][i] = rol32(t, 24);
-
t = ((u32) ff_mult(14, p)) |
((u32) ff_mult(9, p) << 8) |
((u32) ff_mult(13, p) << 16) |
@@ -173,10 +157,10 @@ static void __init gen_tabs(void)
} while (0)

#define ls_box(x) \
- crypto_fl_tab[0][byte(x, 0)] ^ \
- crypto_fl_tab[1][byte(x, 1)] ^ \
- crypto_fl_tab[2][byte(x, 2)] ^ \
- crypto_fl_tab[3][byte(x, 3)]
+ (crypto_ft_tab[2][byte(x, 0)] & 0x000000ff) ^ \
+ (crypto_ft_tab[3][byte(x, 1)] & 0x0000ff00) ^ \
+ (crypto_ft_tab[0][byte(x, 2)] & 0x00ff0000) ^ \
+ (crypto_ft_tab[1][byte(x, 3)] & 0xff000000)

#define loop4(i) do { \
t = ror32(t, 8); \
@@ -303,11 +287,12 @@ EXPORT_SYMBOL_GPL(crypto_aes_set_key);
k += 4; \
} while (0)

-#define f_rl(bo, bi, n, k) do { \
- bo[n] = crypto_fl_tab[0][byte(bi[n], 0)] ^ \
- crypto_fl_tab[1][byte(bi[(n + 1) & 3], 1)] ^ \
- crypto_fl_tab[2][byte(bi[(n + 2) & 3], 2)] ^ \
- crypto_fl_tab[3][byte(bi[(n + 3) & 3], 3)] ^ *(k + n); \
+#define f_rl(bo, bi, n, k) do { \
+ bo[n] = (crypto_ft_tab[2][byte(bi[n], 0)] & 0x000000ff) ^ \
+ (crypto_ft_tab[3][byte(bi[(n + 1) & 3], 1)] & 0x0000ff00) ^ \
+ (crypto_ft_tab[0][byte(bi[(n + 2) & 3], 2)] & 0x00ff0000) ^ \
+ (crypto_ft_tab[1][byte(bi[(n + 3) & 3], 3)] & 0xff000000) ^ \
+ *(k + n); \
} while (0)

#define f_lround(bo, bi, k) do {\
@@ -375,11 +360,11 @@ static void aes_encrypt(struct crypto_tf
k += 4; \
} while (0)

-#define i_rl(bo, bi, n, k) do { \
- bo[n] = crypto_il_tab[0][byte(bi[n], 0)] ^ \
- crypto_il_tab[1][byte(bi[(n + 3) & 3], 1)] ^ \
- crypto_il_tab[2][byte(bi[(n + 2) & 3], 2)] ^ \
- crypto_il_tab[3][byte(bi[(n + 1) & 3], 3)] ^ *(k + n); \
+#define i_rl(bo, bi, n, k) do { \
+ bo[n] = (u32)isb_tab[byte(bi[n], 0)] ^ \
+ ((u32)isb_tab[byte(bi[(n + 3) & 3], 1)] << 8) ^ \
+ ((u32)isb_tab[byte(bi[(n + 2) & 3], 2)] << 16) ^ \
+ ((u32)isb_tab[byte(bi[(n + 1) & 3], 3)] << 24) ^ *(k + n); \
} while (0)

#define i_lround(bo, bi, k) do {\
--- a/include/crypto/aes.h
+++ b/include/crypto/aes.h
@@ -22,9 +22,7 @@ struct crypto_aes_ctx {
};

extern u32 crypto_ft_tab[4][256];
-extern u32 crypto_fl_tab[4][256];
extern u32 crypto_it_tab[4][256];
-extern u32 crypto_il_tab[4][256];

int crypto_aes_set_key(struct crypto_tfm *tfm, const u8 *in_key,
unsigned int key_len);