Patent ID: 7058178

Claim:
An encryptor and/or decryptor station comprising: an input for receiving a stream of encrypted, respectively, decrypted data items in synchronization with a clock trigger; a data-stream generator for in response to the clock trigger generating a stream of generated data items; and means for combining the received stream of encrypted, respectively, decrypted data items with the stream of generated data items providing a stream of decrypted, respectively, encrypted data items; the data-stream generator comprising: a plurality of subgenerators M i , i≧1, each subgenerator M i comprising respective clock input and a respective output; each subgenerator M i being operative to generate a data item of at least one bit on the respective output in response to a trigger received via the respective clock input; means for combining a generated data item of each of the subgenerators Mi, forming the output data item of the data-stream generator; a control subgenerator C comprising an input for receiving the clock trigger and an output; the control subgenerator C being operative to generate a control data item of at least one bit on the output in response to the clock trigger; and control means operative to provide a trigger to at least one of the clock inputs of the subgenerators M i in dependence on the control data item of the control subgenerator C; characterised in that: the control means comprises for at least one subgenerator M i an associated number selector S i for, in dependence on the control data item of the control subgenerator C, selecting a number n i,j from a group H i of different integer numbers; at least two numbers of the group Hi being larger than zero; the group H i being associated with the number selector S i ; and in that the control means is operative to cause the associated subgenerator M i to provide at the output the selected n i,j -th data item successive to a last generated data item.