.TP
.B mac-tagsz
The length of the message authentication tag, in octets.
+.TP
+.B blkc
+The block cipher in use, e.g.,
+.BR blowfish .
+.TP
+.B blkc-keysz
+The length of key used by the block cipher, in octets.
+.TP
+.B blkc-blksz
+The block size of the block cipher.
.PP
The various sizes are useful, for example, when computing the MTU for a
tunnel interface. If