aes: Clarify IV requirements for OFB mode
Combine the two "must be unique" phrases into one for clarity. An IV
that is universally unique is also unique for each encryption operation.
diff --git a/include/mbedtls/aes.h b/include/mbedtls/aes.h
index de5ffad..e48981a 100644
--- a/include/mbedtls/aes.h
+++ b/include/mbedtls/aes.h
@@ -324,9 +324,9 @@
* you must either save it manually or use the cipher module
* instead.
*
- * \warning For the OFB mode, the initiallisation vector must be unique and
- * must be unique for every encryption operation. Reuse of an
- * initialisation vector will compromise security.
+ * \warning For the OFB mode, the initialisation vector must be unique
+ * every encryption operation. Reuse of an initialisation vector
+ * will compromise security.
*
* \param ctx The AES context to use for encryption or decryption.
* \param length The length of the input data.
