Split mbedtls_gcm_update_ad out of mbedtls_gcm_starts
The GCM interface now has separate functions to start the operation
and to pass the associated data.
This is in preparation for allowing the associated data to be passed
in chunks with repeatated calls to mbedtls_gcm_update_ad().
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
diff --git a/include/mbedtls/gcm.h b/include/mbedtls/gcm.h
index 0bd6e1e..7218081 100644
--- a/include/mbedtls/gcm.h
+++ b/include/mbedtls/gcm.h
@@ -231,6 +231,26 @@
* \param iv The initialization vector. This must be a readable buffer of
* at least \p iv_len Bytes.
* \param iv_len The length of the IV.
+ *
+ * \return \c 0 on success.
+ */
+int mbedtls_gcm_starts( mbedtls_gcm_context *ctx,
+ int mode,
+ const unsigned char *iv,
+ size_t iv_len );
+
+/**
+ * \brief This function starts a GCM encryption or decryption
+ * operation.
+ *
+ * \note This function may only be called once per operation:
+ * you must pass the whole associated data in a single
+ * call. This limitation will be lifted in a future version
+ * of Mbed TLS.
+ *
+ * \param ctx The GCM context. This must have been started with
+ * mbedtls_gcm_starts() and must not have yet received
+ * any input with mbedtls_gcm_update().
* \param add The buffer holding the additional data, or \c NULL
* if \p add_len is \c 0.
* \param add_len The length of the additional data. If \c 0,
@@ -238,12 +258,9 @@
*
* \return \c 0 on success.
*/
-int mbedtls_gcm_starts( mbedtls_gcm_context *ctx,
- int mode,
- const unsigned char *iv,
- size_t iv_len,
- const unsigned char *add,
- size_t add_len );
+int mbedtls_gcm_update_ad( mbedtls_gcm_context *ctx,
+ const unsigned char *add,
+ size_t add_len );
/**
* \brief This function feeds an input buffer into an ongoing GCM