Abstract: A cryptographic system creates a key table from a single key such that the relationship between the keys in the key table cannot be determined even if the system implementation is known. The system uses variable functions in which the determinants are changed by the variable function chosen by the determinant. Thus, the functions used in creating the key table do not have to be one-to-one functions. From the key table, four blocks of bytes of additional key based determinants are formed which are called masks. The original key does not exist in either the key table or the mask table. The system preferably uses the key table in a multiple round encryption process. The keys chosen from the table for a key addition operation are a function of the plaintext, the current state of the ciphertext, and the mask values. Therefore, the order in which the keys are chosen is not predetermined or patterned.