Commit 7dac0dd6 authored by Daniel P. Berrangé's avatar Daniel P. Berrangé
Browse files

crypto: convert xts_mult_x to use xts_uint128 type 



Using 64-bit arithmetic increases the performance for xts-aes-128
when built with gcrypt:

  Encrypt: 355 MB/s -> 545 MB/s
  Decrypt: 362 MB/s -> 568 MB/s

Reviewed-by: default avatarAlberto Garcia <berto@igalia.com>
Signed-off-by: default avatarDaniel P. Berrangé <berrange@redhat.com>
parent db217c69

crypto/xts.c

+28 −12
Original line number Diff line number Diff line
@@ -24,6 +24,7 @@ 
 */



#include "qemu/osdep.h"

#include "qemu/bswap.h"

#include "crypto/xts.h"



typedef union {
@@ -39,19 +40,34 @@ static inline void xts_uint128_xor(xts_uint128 *D, 
    D->u[1] = S1->u[1] ^ S2->u[1];

}



static void xts_mult_x(uint8_t *I)

static inline void xts_uint128_cpu_to_les(xts_uint128 *v)

{

    int x;

    uint8_t t, tt;

    cpu_to_le64s(&v->u[0]);

    cpu_to_le64s(&v->u[1]);

}



    for (x = t = 0; x < 16; x++) {

        tt = I[x] >> 7;

        I[x] = ((I[x] << 1) | t) & 0xFF;

        t = tt;

static inline void xts_uint128_le_to_cpus(xts_uint128 *v)

{

    le64_to_cpus(&v->u[0]);

    le64_to_cpus(&v->u[1]);

}

    if (tt) {

        I[0] ^= 0x87;



static void xts_mult_x(xts_uint128 *I)

{

    uint64_t tt;



    xts_uint128_le_to_cpus(I);



    tt = I->u[0] >> 63;

    I->u[0] <<= 1;



    if (I->u[1] >> 63) {

        I->u[0] ^= 0x87;

    }

    I->u[1] <<= 1;

    I->u[1] |= tt;



    xts_uint128_cpu_to_les(I);

}
@@ -79,7 +95,7 @@ static void xts_tweak_encdec(const void *ctx, 
    xts_uint128_xor(dst, dst, iv);



    /* LFSR the tweak */

    xts_mult_x(iv->b);

    xts_mult_x(iv);

}
@@ -134,7 +150,7 @@ void xts_decrypt(const void *datactx, 
    if (mo > 0) {

        xts_uint128 S, D;

        memcpy(&CC, &T, XTS_BLOCK_SIZE);

        xts_mult_x(CC.b);

        xts_mult_x(&CC);



        /* PP = tweak decrypt block m-1 */

        memcpy(&S, src, XTS_BLOCK_SIZE);