Clearly, the VCF could be of any desired size. This value is needed to specify the length of the last data block, which is usually short by some unknown amount. This provides an automatic form of block chaining and randomization for the leftmost and rightmost column inputs. Those designs which use substitution tables step through an array of 64 such tables. These VSBC designs have a very similar structure for both enciphering and deciphering.
Data flows down for enciphering, and up for deciphering.
In the SBBM and OLs designs, the diffusion direction also changes. In the two designs which use substitution tables, the tables are numbered to remind us that each is generally different. Each table is separately shuffled by the cryptographic RNG and each table represents a potential 1648-bit key. Normally, the keyspace of this sort of cipher is limited by the size of the RNG used to key the tables or squares, and it is easy to have an efficient true keyspace of many thousands of bits. In marked contrast to other cipher designs, additional confusion and diffusion layers are easily and modularly added to produce a cipher of any desired working strength.