A MATHEMATICAL WORD BLOCK CIPHER
Mike Barlow · Cryptologia · 1988
A cipher based on word block lengths interpreted as base N numbers, and converted to base M numbers is described. The advantage is that the ciphertext length can be chosen to be greater or less than the plaintext length, even though word divisions are maintained. This gives a very high resistance to Probable Word searches. In its simplest form, however, the number of possible keys is limited, reducing the security of the cipher once the basis is guessed.