Method of and an apparatus for generating internal crypto-keys

An apparatus for generating internal crypto-keys to be set as initial values in feedback registers of an pseudo-random-sequence generator of a stream cipher system from an external key;

• the apparatus comprising:
• a first cascade connection of m one-way-function circuits, a first one-way-function circuit of the first cascade connection outputting a conversion result by processing a first part of the external key with a first one-way-function and each i-th one-way-function circuit of the first cascade connection outputting a conversion result by processing an output of an (i−1)-th one-way-function circuit of the first cascade connection with the first one-way-function, m being a positive integer more than one, i being a positive integer more than one and not more than m, and the first one-way-function being a function wherein a variable giving a value of the function is substantially impossible to be estimated from the value of the function;
• a second cascade connection of m one-way-function circuits, a first one-way-function circuit of the second cascade connection outputting a conversion result by processing a second part of the external key with a second one-way-function and each i-th one-way-function circuit of the second cascade connection outputting a conversion result by processing an output of an (i−1)-th one-way-function circuit of the second cascade connection with the second one-way-function, the second one-way-function being a function wherein a variable giving a value of the function is substantially impossible to be estimated from the value of the function;
• and
• m combining functions, each j-th of the m combining function outputting j-th of m internal crypto-keys by combining outputs of a j-th one-way-function circuit of the first cascade connection and an (m−j+1)-th one-way-function circuit of the second cascade connection, j being a positive integer not more than m.

An apparatus for generating internal crypto-keys to be set as initial values in feedback registers of an pseudo-random-sequence generator of a stream cipher system from an external key;

• the apparatus comprising:
• a first one-way-function circuit for outputting a conversion result by processing an input bit sequence with a first one-way function, the first one-way-function being a function wherein a variable giving a value of the function is substantially impossible to be estimated from the value of the function;
• a first register for holding the conversion result outputted from the first one-way-function circuit and outputting the conversion result previously held in the first register in synchronization with a clock signal;
• a first selector for selecting either a first part of the external key or an output of the first register according to a selection signal as the input bit sequence to be processed by the first one-way-function circuit;
• a second one-way-function circuit for outputting a conversion result by processing an input bit sequence with a second one-way function, the second one-way-function being a function wherein a variable giving a value of the function is substantially impossible to be estimated from the value of the function;
• a second register for holding the conversion result outputted from the second one-way-function circuit and outputting the conversion result previously held in the second register in synchronization with the clock signal;
• a second selector for selecting either a second part of the external key or an output of the second register according to the selection signal as the input bit sequence to be processed by the second one-way-function circuit;
• a LIFO (Last-In-First-Out) buffer wherein conversion results outputted from the second one-way-function circuit are stacked in synchronization with the clock signal when the LIFO buffer is controlled in a writing mode, and the conversion results stacked in the LIFO buffer are popped up in synchronization with the clock signal when the LIFO buffer is controlled in a reading mode;
• and
• a combining circuit for outputting internal crypto-keys in synchronization with the clock signal by combining outputs of the LIFO buffer and the first one-way-function circuit.

An apparatus for generating internal crypto-keys to be set as initial values in feedback registers of an pseudo-random-sequence generator of a stream cipher system from an external key;

• the apparatus comprising:
• a one-way-function circuit for outputting a conversion result by processing an input bit sequence with a one-way function, the one-way-function being a function wherein a variable giving a value of the function is substantially impossible to be estimated from the value of the function;
• a register for holding the conversion result outputted from the one-way-function circuit and outputting the conversion result previously held in the register in synchronization with a clock signal;
• a selector for selecting either the external key or an output of the register according to a selection signal as the input bit sequence to be processed by the one-way-function circuit;
• a LIFO buffer wherein conversion results output from the one-way-function circuit are stacked in synchronization with the clock signal when the LIFO buffer is controlled in a writing mode, and the conversion results stacked in the LIFO buffer are popped up in synchronization with the clock signal when the LIFO buffer is controlled in a reading mode;
• and
• a combining circuit for outputting internal crypto-keys in synchronization with the clock signal by combining outputs of the LIFO buffer and the one-way-function circuit.