.It Fa ad_size
length of the additional data.
.Sy That length is not authenticated.
-If the additional data is of variable length, the length should be appended to
+If the additional data is of variable length, the length should be
+appended to
.Fa ad
so it gets authenticated, and should be extracted from the end of the
message when decrypting.
Otherwise an attacker could provide a false length, effectively moving
-the boundary between the additional data and the ciphertext.
-This may cause buffer overflows in some programs.
+the boundary between the additional data and the ciphertext. This may
+cause buffer overflows in some programs.
.El
.Pp
An incremental interface is available; see