--- /dev/null
+/* LibTomCrypt, modular cryptographic library -- Tom St Denis
+ *
+ * LibTomCrypt is a library that provides various cryptographic
+ * algorithms in a highly modular and flexible manner.
+ *
+ * The library is free for all purposes without any express
+ * guarantee it works.
+ */
+
+/**
+ @file gcm_add_iv.c
+ GCM implementation, add IV data to the state, by Tom St Denis
+*/
+#include "tomcrypt.h"
+
+#ifdef LTC_GCM_MODE
+
+/**
+ Add IV data to the GCM state
+ @param gcm The GCM state
+ @param IV The initial value data to add
+ @param IVlen The length of the IV
+ @return CRYPT_OK on success
+ */
+int gcm_add_iv(gcm_state *gcm,
+ const unsigned char *IV, unsigned long IVlen)
+{
+ unsigned long x, y;
+ int err;
+
+ LTC_ARGCHK(gcm != NULL);
+ if (IVlen > 0) {
+ LTC_ARGCHK(IV != NULL);
+ }
+
+ /* must be in IV mode */
+ if (gcm->mode != LTC_GCM_MODE_IV) {
+ return CRYPT_INVALID_ARG;
+ }
+
+ if (gcm->buflen >= 16 || gcm->buflen < 0) {
+ return CRYPT_INVALID_ARG;
+ }
+
+ if ((err = cipher_is_valid(gcm->cipher)) != CRYPT_OK) {
+ return err;
+ }
+
+
+ /* trip the ivmode flag */
+ if (IVlen + gcm->buflen > 12) {
+ gcm->ivmode |= 1;
+ }
+
+ x = 0;
+#ifdef LTC_FAST
+ if (gcm->buflen == 0) {
+ for (x = 0; x < (IVlen & ~15); x += 16) {
+ for (y = 0; y < 16; y += sizeof(LTC_FAST_TYPE)) {
+ *(LTC_FAST_TYPE_PTR_CAST(&gcm->X[y])) ^= *(LTC_FAST_TYPE_PTR_CAST(&IV[x + y]));
+ }
+ gcm_mult_h(gcm, gcm->X);
+ gcm->totlen += 128;
+ }
+ IV += x;
+ }
+#endif
+
+ /* start adding IV data to the state */
+ for (; x < IVlen; x++) {
+ gcm->buf[gcm->buflen++] = *IV++;
+
+ if (gcm->buflen == 16) {
+ /* GF mult it */
+ for (y = 0; y < 16; y++) {
+ gcm->X[y] ^= gcm->buf[y];
+ }
+ gcm_mult_h(gcm, gcm->X);
+ gcm->buflen = 0;
+ gcm->totlen += 128;
+ }
+ }
+
+ return CRYPT_OK;
+}
+
+#endif
+
+
+/* ref: $Format:%D$ */
+/* git commit: $Format:%H$ */
+/* commit time: $Format:%ai$ */