-all operate on variable length data. They all take an initialisation vector
-B<ivec> which must be initially filled with zeros, but then just need to be
-passed along into the next call of the same function for the same message.
-BF_cbc_encrypt() operates of data that is a multiple of 8 bytes long, while
+all operate on variable length data. They all take an initialization vector
+B<ivec> which needs to be passed along into the next call of the same function
+for the same message. B<ivec> may be initialized with anything, but the
+recipient needs to know what it was initialized with, or it won't be able
+to decrypt. Some programs and protocols simplify this, like SSH, where
+B<ivec> is simply initialized to zero.
+BF_cbc_encrypt() operates on data that is a multiple of 8 bytes long, while