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crypto: arc4 - improve performance by using u32 for ctx and variables

This patch changes u8 in struct arc4_ctx and variables to u32 (as AMD seems
to have problem with u8 array). Below are tcrypt results of old 1-byte block
cipher versus ecb(arc4) with u8 and ecb(arc4) with u32.

tcrypt results, x86-64 (speed ratios: new-u32/old, new-u8/old):

                  u32    u8
AMD Phenom II   : x3.6   x2.7
Intel Core 2    : x2.0   x1.9

tcrypt results, i386 (speed ratios: new-u32/old, new-u8/old):

                  u32    u8
Intel Atom N260 : x1.5   x1.4

Cc: Jon Oberheide <jon@oberheide.org>
Signed-off-by: Jussi Kivilinna <jussi.kivilinna@mbnet.fi>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
master
Jussi Kivilinna 10 years ago
committed by Herbert Xu
parent
commit
d366db605c
  1. 12
      crypto/arc4.c

12
crypto/arc4.c

@ -22,8 +22,8 @@
#define ARC4_BLOCK_SIZE 1
struct arc4_ctx {
u8 S[256];
u8 x, y;
u32 S[256];
u32 x, y;
};
static int arc4_set_key(struct crypto_tfm *tfm, const u8 *in_key,
@ -39,7 +39,7 @@ static int arc4_set_key(struct crypto_tfm *tfm, const u8 *in_key,
ctx->S[i] = i;
for (i = 0; i < 256; i++) {
u8 a = ctx->S[i];
u32 a = ctx->S[i];
j = (j + in_key[k] + a) & 0xff;
ctx->S[i] = ctx->S[j];
ctx->S[j] = a;
@ -53,9 +53,9 @@ static int arc4_set_key(struct crypto_tfm *tfm, const u8 *in_key,
static void arc4_crypt(struct arc4_ctx *ctx, u8 *out, const u8 *in,
unsigned int len)
{
u8 *const S = ctx->S;
u8 x, y, a, b;
u8 ty, ta, tb;
u32 *const S = ctx->S;
u32 x, y, a, b;
u32 ty, ta, tb;
if (len == 0)
return;

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