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Commit d366db60 authored by Jussi Kivilinna's avatar Jussi Kivilinna Committed by Herbert Xu
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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: default avatarJussi Kivilinna <jussi.kivilinna@mbnet.fi>
Signed-off-by: default avatarHerbert Xu <herbert@gondor.apana.org.au>
parent ce6dd368

crypto/arc4.c

+6 −6
Original line number Original line Diff line number Diff line
@@ -22,8 +22,8 @@ 
#define ARC4_BLOCK_SIZE		1

#define ARC4_BLOCK_SIZE		1





struct arc4_ctx {

struct arc4_ctx {

	u8 S[256];

	u32 S[256];

	u8 x, y;

	u32 x, y;

};

};





static int arc4_set_key(struct crypto_tfm *tfm, const u8 *in_key,

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;

		ctx->S[i] = i;





	for (i = 0; i < 256; i++) {

	for (i = 0; i < 256; i++) {

		u8 a = ctx->S[i];

		u32 a = ctx->S[i];

		j = (j + in_key[k] + a) & 0xff;

		j = (j + in_key[k] + a) & 0xff;

		ctx->S[i] = ctx->S[j];

		ctx->S[i] = ctx->S[j];

		ctx->S[j] = a;

		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,

static void arc4_crypt(struct arc4_ctx *ctx, u8 *out, const u8 *in,

		       unsigned int len)

		       unsigned int len)

{

{

	u8 *const S = ctx->S;

	u32 *const S = ctx->S;

	u8 x, y, a, b;

	u32 x, y, a, b;

	u8 ty, ta, tb;

	u32 ty, ta, tb;





	if (len == 0)

	if (len == 0)

		return;

		return;