Device authentication system

1. An authenticating device for authenticating a device to be authenticated, comprising:

means for generating authentication base data having N bytes, where N denotes a predetermined natural number;

means for generating verification data having M bytes, where M denotes a predetermined natural number smaller than the predetermined natural number N;

means for embedding the generated verification data in the generated authentication base data according to a first prescribed embedding pattern to generate authentication data;

means for sending the generated authentication data toward the device to be authenticated;

means for receiving authentication reply data from the device to be authenticated, the authentication reply data having L bytes, where L denotes a predetermined natural number greater than the predetermined natural number M;

means for extracting verification reply data from the received authentication reply data according to a second prescribed embedding pattern, the extracted verification reply data having M bytes;

means for dividing the extracted verification data into first data segments;

means for dividing the verification data into second data segments which correspond to the first data segments respectively;

means for adding different values to each of the second data segments to obtain different addition results for each of the second data segments;

means for deciding whether or not one of the obtained different addition results for each of the second data segments is equal to corresponding one of the first data segments;

means for concluding that the device to be authenticated is genuine in cases where one of the obtained different addition results for each of the second data segments is equal to corresponding one of the first data segments; and

means for concluding that the device to be authenticated is not genuine in cases where none of the obtained different addition results for at least one of the second data segments are equal to corresponding one of the first data segments.

2. The authenticating device as recited in claim 1 , wherein the first and second prescribed embedding patterns are equal to each other.

3. The authenticating device as recited in claim 1 , wherein the first and second prescribed embedding patterns are different from each other.

4. A device to be authenticated by an authenticating device, comprising:

means for receiving authentication data from the authenticating device, the received authentication data having N bytes, where N denotes a predetermined natural number;

means for extracting verification data from the received authentication data according to a first prescribed embedding pattern, the extracted verification data having M bytes, where M denotes a predetermined natural number smaller than the predetermined natural number N;

means for dividing the extracted verification data into first data segments;

means for generating random numbers each in a prescribed range;

means for adding the generated random numbers to the first data segments to generate second data segments respectively;

means for combining the generated second data segments to generate verification reply data;

means for generating reply base data having L bytes, where L denotes a predetermined natural number greater than the predetermined natural number M;

means for embedding the generated verification reply data in the generated reply base data according to a second prescribed embedding pattern to generate authentication reply data; and

means for sending the generated authentication reply data toward the authenticating device.

5. A device authentication system including an authenticating device and a device to be authenticated, wherein the authenticating device comprises:

means for generating authentication base data having N bytes, where N denotes a predetermined natural number;

means for generating verification data having M bytes, where M denotes a predetermined natural number smaller than the predetermined natural number N;

means for embedding the generated verification data in the generated authentication base data according to a first prescribed embedding pattern to generate authentication data;

means for sending the generated authentication data toward the device to be authenticated;

means for receiving authentication reply data from the device to be authenticated, the authentication reply data having L bytes, where L denotes a predetermined natural number greater than the predetermined natural number M;

means for extracting verification reply data from the received authentication reply data according to a second prescribed embedding pattern, the extracted verification reply data having M bytes;

means for dividing the extracted verification data into first data segments;

means for dividing the verification data into second data segments which correspond to the first data segments respectively;

means for adding different values to each of the second data segments to obtain different addition results for each of the second data segments;

means for deciding whether or not one of the obtained different addition results for each of the second data segments is equal to corresponding one of the first data segments;

means for concluding that the device to be authenticated is genuine in cases where one of the obtained different addition results for each of the second data segments is equal to corresponding one of the first data segments; and

means for concluding that the device to be authenticated is not genuine in cases where none of the obtained different addition results for at least one of the second data segments are equal to corresponding one of the first data segments;

wherein the device to be authenticated comprises:

means for receiving the authentication data from the authenticating device;

means for extracting the verification data from the received authentication data according to the first prescribed embedding pattern;

means for dividing the extracted verification data into third data segments;

means for generating random numbers each in a prescribed range;

means for adding the generated random numbers to the third data segments to generate fourth data segments respectively;

means for combining the generated fourth data segments to generate the verification reply data;

means for generating reply base data having L bytes;

means for embedding the generated verification reply data in the generated reply base data according to the second prescribed embedding pattern to generate the authentication reply data; and

means for sending the generated authentication reply data toward the authenticating device.