#include "tomcrypt.h"
#ifdef GCM_MODE
int
gcm_add_aad(gcm_state *gcm,
const
unsigned
char
*adata, unsigned
long
adatalen)
{
unsigned
long
x;
int
err;
#ifdef LTC_FAST
unsigned
long
y;
#endif
LTC_ARGCHK(gcm != NULL);
if
(adatalen > 0) {
LTC_ARGCHK(adata != NULL);
}
if
(gcm->buflen > 16 || gcm->buflen < 0) {
return
CRYPT_INVALID_ARG;
}
if
((err = cipher_is_valid(gcm->cipher)) != CRYPT_OK) {
return
err;
}
if
(gcm->mode == GCM_MODE_IV) {
if
(gcm->ivmode || gcm->buflen != 12) {
for
(x = 0; x < (unsigned
long
)gcm->buflen; x++) {
gcm->X[x] ^= gcm->buf[x];
}
if
(gcm->buflen) {
gcm->totlen += gcm->buflen * CONST64(8);
gcm_mult_h(gcm, gcm->X);
}
zeromem(gcm->buf, 8);
STORE64H(gcm->totlen, gcm->buf+8);
for
(x = 0; x < 16; x++) {
gcm->X[x] ^= gcm->buf[x];
}
gcm_mult_h(gcm, gcm->X);
XMEMCPY(gcm->Y, gcm->X, 16);
zeromem(gcm->X, 16);
}
else
{
XMEMCPY(gcm->Y, gcm->buf, 12);
gcm->Y[12] = 0;
gcm->Y[13] = 0;
gcm->Y[14] = 0;
gcm->Y[15] = 1;
}
XMEMCPY(gcm->Y_0, gcm->Y, 16);
zeromem(gcm->buf, 16);
gcm->buflen = 0;
gcm->totlen = 0;
gcm->mode = GCM_MODE_AAD;
}
if
(gcm->mode != GCM_MODE_AAD || gcm->buflen >= 16) {
return
CRYPT_INVALID_ARG;
}
x = 0;
#ifdef LTC_FAST
if
(gcm->buflen == 0) {
for
(x = 0; x < (adatalen & ~15); x += 16) {
for
(y = 0; y < 16; y +=
sizeof
(LTC_FAST_TYPE)) {
*((LTC_FAST_TYPE*)(&gcm->X[y])) ^= *((LTC_FAST_TYPE*)(&adata[x + y]));
}
gcm_mult_h(gcm, gcm->X);
gcm->totlen += 128;
}
adata += x;
}
#endif
for
(; x < adatalen; x++) {
gcm->X[gcm->buflen++] ^= *adata++;
if
(gcm->buflen == 16) {
gcm_mult_h(gcm, gcm->X);
gcm->buflen = 0;
gcm->totlen += 128;
}
}
return
CRYPT_OK;
}
#endif