A method for encryption and decryption of data items is provided by
defining a cipher key based on variables in a Chaotic Equation. The
method includes selecting a Chaotic Equation from a set of Chaotic
Equations, defining starting conditions of the variables of the equation,
and applying the equation to each data item. The real and imaginary parts
of the result of the iteration of the Chaotic Equation are combined with
the data item by an arithmetic operation, for example, an XOR operation.
Data items in a continuous stream with a rate dependency can be encrypted
and decrypted on an item by item basis. The input or cipher key changes
for each byte of the data encryption. Blocks of data can be encrypted
using the method with an identifier of the order of the blocks in the
data stream. If blocks are received out of sequence, the identifiers can
be used to maintain the correct decryption order. The method of
encryption and decryption can be used in devices to avoid the need for a
session key. The continuously updating input or cipher key enables
fraudulent use of devices to be identified.