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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: Alberto Garcia <berto@igalia.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
This commit is contained in:
Daniel P. Berrangé 2018-10-09 10:45:41 +01:00
parent 299ec87838
commit cc36930e40
1 changed files with 26 additions and 20 deletions
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46
crypto/xts.c
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@ -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);
}