Zero delay mask for galois LFSR

A masked Galois linear feedback shift register, comprising:

• a series of binary registers in a circuit loop with a value input of each subsequent register connected to an output of a previous register in the loop;
• one or more modulo-2 adders inserted between pairs of adjacent registers in the connections between the outputs of previous registers and respective value inputs of subsequent registers of the register series, each adder having a first input connected to the previous respective register and an output connected to the subsequent respective register of the register pair, and each adder having a second input connected to the output of a last register and to the input of a first register of the register series to form the loop;
• a clock signal line connected to a clock input of each register of the register series so that when a clock signal is transmitted through the clock signal line, each register begins to output a value being received at that time at the register's value input and continues to output that value regardless of any subsequent change in the input value until the next clock signal;
• means for initializing the value of each register to provide an initial value at least at the start-up of the Galois linear feedback shift register;
• a series of modulo-2 adders with a first input of each subsequent adder in the adder series connected to an output of a previous adder in the adder series;
• a multitude of mask switches including a first mask switch with an output connected to a first input of a first adder of the adder series and subsequent mask switches with outputs connected to respective second inputs of adders in the adder series;
• an mask value input line for each mask switch to set the value of the mask switches depending on a selected mask value;
• connection networks between the inputs or outputs of the registers and each respective mask switch, each network selected from:
• a connection between the input or output of the register and the input of the respective mask switch;
• and connections between the inputs or outputs of multiple registers and the inputs of a modulo-2 adder and a connection between the output of the adder and the respective mask switch;
• and
• an output terminal connected to the output of a last modulo-2 adder in the adder series.

A transmitter comprising:

• an input for an information signal;
• a power supply;
• a microcontroller connected to the power supply;
• a loop series of binary registers with a value input of each subsequent register connected to an output of a previous register;
• one or more modulo-2 adders selectively connected between respective pairs of subsequent registers of the register series, each adder having a first input connected to a previous register and an output connected to a subsequent register of the register pair and having a second input connected between a last register and a first register of the register series;
• a clock signal line connected to a clock input of each register of the register series so that when a clock signal is transmitted through the clock signal line each of the registers begins to output a value being received at that time at the register's value input;
• means for initializing the value of each register to provide an initial value at the start-up of a Galois linear feedback shift register;
• a series of modulo-2 adders with a first input of each subsequent adder in the adder series connected to an output of a previous adder in the adder series;
• a multitude of mask switches including a first mask switch with an output connected to a first input of a first adder of the adder series and subsequent mask switches with outputs connected to respective second inputs of adders in the adder series;
• a respective mask value input line for each mask switch to set the value of the mask switches depending on mask value automatically selected by the microcontroller;
• connection networks between the inputs or outputs of the registers and each respective mask switch, each network selected from:
• a connection between the input or output of the register and the input of the respective mask switch;
• and connections between the inputs or outputs of multiple registers and the inputs of a modulo-2 adder and a connection between the output of the adder and the respective mask switch;
• a spreader to spread the information signal depending on the output of a last modulo-2 adder of the adder series;
• and
• transmitter apparatus for transmitting the spread information signal into a medium.

A transmitter comprising:

• receiver means for receiving a spread information signal from a medium;
• a power supply;
• a microcontroller connected to the power supply;
• a loop series of binary registers with a value input of each subsequent register connected to an output of a previous register;
• one or more modulo-2 adders selectively connected between respective pairs of subsequent registers of the register series, each adder having a first input connected to a previous register and an output connected to a subsequent register of the register pair and having a second input connected between a last register and a first register of the register series;
• a clock signal line connected to a clock input of each register of the register series so that when a clock signal is transmitted through the clock signal line each of the registers begins to output a value being received at that time at the register's value input;
• means for initializing the value of each register to provide an initial value at the start-up of a Galois linear feedback shift register;
• a series of modulo-2 adders with a first input of each subsequent adder in the adder series connected to an output of a previous adder in the adder series;
• a multitude of mask switches including a first mask switch with an output connected to a first input of a first adder of the adder series and subsequent mask switches with outputs connected to respective second inputs of adders in the adder series;
• an mask value input line for each mask switch to set the value of the mask switches depending on mask value automatically selected by the microcontroller;
• connection networks between the inputs or outputs of the registers and each respective mask switch, each network selected from:
• a connection between the input or output of the register and the input of the respective mask switch;
• and connections between the inputs or outputs of multiple registers and the inputs of a modulo-2 adder and a connection between the output of the adder and the respective mask switch;
• a de-spreader to de-spread the spread information signal depending on the output of a last modulo-2 adder of the adder series to produce a recovered information signal;
• and
• an output for the recovered information signal.

A method of operating a recursive system, with an output depending on a plurality of previous outputs:

• processing a plurality of previous outputs to obtain processed values;
• storing the processed values;
• determining new outputs depending on the processed values by placing a connection to processed values stored in the step of storing, the connection providing the processed values as an input to at least one adder;
• and
• reverse processing the processed values to obtain the previous outputs, the step of reverse processing further comprising supplying an output from the adder to at least one switch.