Commit cc36930e authored by Daniel P. Berrangé's avatar Daniel P. Berrangé
Browse files

crypto: introduce a xts_uint128 data type 



The new type is designed to allow use of 64-bit arithmetic instead
of operating 1-byte at a time. The following patches will use this to
improve performance.

Reviewed-by: default avatarAlberto Garcia <berto@igalia.com>
Signed-off-by: default avatarDaniel P. Berrangé <berrange@redhat.com>
parent 299ec878

crypto/xts.c

+26 −20
Original line number Diff line number Diff line
@@ -26,6 +26,12 @@ 
#include "qemu/osdep.h"

#include "crypto/xts.h"



typedef union {

    uint8_t b[XTS_BLOCK_SIZE];

    uint64_t u[2];

} xts_uint128;





static void xts_mult_x(uint8_t *I)

{

    int x;
@@ -85,7 +91,7 @@ void xts_decrypt(const void *datactx, 
                 uint8_t *dst,

                 const uint8_t *src)

{

    uint8_t PP[XTS_BLOCK_SIZE], CC[XTS_BLOCK_SIZE], T[XTS_BLOCK_SIZE];

    xts_uint128 PP, CC, T;

    unsigned long i, m, mo, lim;



    /* get number of blocks */
@@ -102,10 +108,10 @@ void xts_decrypt(const void *datactx, 
    }



    /* encrypt the iv */

    encfunc(tweakctx, XTS_BLOCK_SIZE, T, iv);

    encfunc(tweakctx, XTS_BLOCK_SIZE, T.b, iv);



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

        xts_tweak_encdec(datactx, decfunc, src, dst, T);

        xts_tweak_encdec(datactx, decfunc, src, dst, T.b);



        src += XTS_BLOCK_SIZE;

        dst += XTS_BLOCK_SIZE;
@@ -113,27 +119,27 @@ void xts_decrypt(const void *datactx, 


    /* if length is not a multiple of XTS_BLOCK_SIZE then */

    if (mo > 0) {

        memcpy(CC, T, XTS_BLOCK_SIZE);

        xts_mult_x(CC);

        memcpy(&CC, &T, XTS_BLOCK_SIZE);

        xts_mult_x(CC.b);



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

        xts_tweak_encdec(datactx, decfunc, src, PP, CC);

        xts_tweak_encdec(datactx, decfunc, src, PP.b, CC.b);



        /* Pm = first length % XTS_BLOCK_SIZE bytes of PP */

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

            CC[i] = src[XTS_BLOCK_SIZE + i];

            dst[XTS_BLOCK_SIZE + i] = PP[i];

            CC.b[i] = src[XTS_BLOCK_SIZE + i];

            dst[XTS_BLOCK_SIZE + i] = PP.b[i];

        }

        for (; i < XTS_BLOCK_SIZE; i++) {

            CC[i] = PP[i];

            CC.b[i] = PP.b[i];

        }



        /* Pm-1 = Tweak uncrypt CC */

        xts_tweak_encdec(datactx, decfunc, CC, dst, T);

        xts_tweak_encdec(datactx, decfunc, CC.b, dst, T.b);

    }



    /* Decrypt the iv back */

    decfunc(tweakctx, XTS_BLOCK_SIZE, iv, T);

    decfunc(tweakctx, XTS_BLOCK_SIZE, iv, T.b);

}
@@ -146,7 +152,7 @@ void xts_encrypt(const void *datactx, 
                 uint8_t *dst,

                 const uint8_t *src)

{

    uint8_t PP[XTS_BLOCK_SIZE], CC[XTS_BLOCK_SIZE], T[XTS_BLOCK_SIZE];

    xts_uint128 PP, CC, T;

    unsigned long i, m, mo, lim;



    /* get number of blocks */
@@ -163,10 +169,10 @@ void xts_encrypt(const void *datactx, 
    }



    /* encrypt the iv */

    encfunc(tweakctx, XTS_BLOCK_SIZE, T, iv);

    encfunc(tweakctx, XTS_BLOCK_SIZE, T.b, iv);



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

        xts_tweak_encdec(datactx, encfunc, src, dst, T);

        xts_tweak_encdec(datactx, encfunc, src, dst, T.b);



        dst += XTS_BLOCK_SIZE;

        src += XTS_BLOCK_SIZE;
@@ -175,22 +181,22 @@ void xts_encrypt(const void *datactx, 
    /* if length is not a multiple of XTS_BLOCK_SIZE then */

    if (mo > 0) {

        /* CC = tweak encrypt block m-1 */

        xts_tweak_encdec(datactx, encfunc, src, CC, T);

        xts_tweak_encdec(datactx, encfunc, src, CC.b, T.b);



        /* Cm = first length % XTS_BLOCK_SIZE bytes of CC */

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

            PP[i] = src[XTS_BLOCK_SIZE + i];

            dst[XTS_BLOCK_SIZE + i] = CC[i];

            PP.b[i] = src[XTS_BLOCK_SIZE + i];

            dst[XTS_BLOCK_SIZE + i] = CC.b[i];

        }



        for (; i < XTS_BLOCK_SIZE; i++) {

            PP[i] = CC[i];

            PP.b[i] = CC.b[i];

        }



        /* Cm-1 = Tweak encrypt PP */

        xts_tweak_encdec(datactx, encfunc, PP, dst, T);

        xts_tweak_encdec(datactx, encfunc, PP.b, dst, T.b);

    }



    /* Decrypt the iv back */

    decfunc(tweakctx, XTS_BLOCK_SIZE, iv, T);

    decfunc(tweakctx, XTS_BLOCK_SIZE, iv, T.b);

}