Restrict cipher_update() for GCM
diff --git a/include/polarssl/cipher.h b/include/polarssl/cipher.h
index cc69208..aad488f 100644
--- a/include/polarssl/cipher.h
+++ b/include/polarssl/cipher.h
@@ -512,6 +512,10 @@
* POLARSSL_ERR_CIPHER_FEATURE_UNAVAILABLE on an
* unsupported mode for a cipher or a cipher specific
* error code.
+ *
+ * \note If the underlying cipher is GCM, all calls to this
+ * function, except the last one before cipher_finish(),
+ * must have ilen a multiple of the block size.
*/
int cipher_update( cipher_context_t *ctx, const unsigned char *input, size_t ilen,
unsigned char *output, size_t *olen );