Encryption algorithm management system

A terminal unit having a common cipher-key in common with a common cipher-key in a center unit, said terminal unit comprising:

• a transmitter configured to transmit a demand to said center unit for obtaining an encrypted data needed for decrypting a ciphered encryption algorithm,
• an encryption controller configured to renew said common cipher-key in every case of receiving said encrypted data from said center unit in response to said demand, decrypt a cipher-key for the ciphered encryption algorithm from the encrypted data with the renewed common cipher-key, and decrypt an encryption algorithm from the ciphered encryption algorithm with the cipher-key for the ciphered encryption algorithm;
• and
• an encryption unit configured to encrypt a message with the encryption algorithm and send the encrypted message to a second terminal.

An encryption algorithm management system, comprising:

• a terminal unit;
• and
• a center unit,
• the terminal unit and the center unit having a common cipher-key,
• said terminal unit comprising:
• a transmitter configured to transmit a demand to said center unit for obtaining a ciphered encryption algorithm,
• an encryption controller configured to renew said common cipher-key in every case of receiving said ciphered encryption algorithm from said center unit in response to said demand, and decrypt an encryption algorithm from the ciphered encryption algorithm with the renewed common cipher-key, and
• an encryption unit configured to encrypt a message with the encryption algorithm and send the encrypted message to a second terminal;
• said center unit comprising:
• a key controller configured to renew said common cipher-key so as to be identical with said renewed common cipher-key in case of receiving said demand from said transmitter, and
• an encoder configured to produce said ciphered encryption algorithm with said renewed common cipher-key and transmit said ciphered encrypted algorithm to said terminal unit.

An encryption algorithm management system having a terminal unit and a center unit that have a common cipher-key to a ciphered encryption algorithm,

• said terminal unit comprises:
• a transmitter configured to transmit a demand to said center unit for obtaining an encrypted data needed for decrypting said ciphered encryption algorithm when said ciphered encryption algorithm is decrypted;
• an encryption controller configured to renew said common cipher-key in every case of receiving said encrypted data from said center unit in response to said demand, and to produce an encryption algorithm by decrypting said encrypted data with the renewed common cipher-key,
• wherein said encryption controller has a counter for counting a number transmitted from a controller, and if said counter receives a number transmitted from said controller more than a prescribed number of times, said encryption controller does not produce an encryption algorithm by decrypting said encrypted data with said renewed common cipher-key, and
• an encryption unit configured to encrypt a message with the encryption algorithm and send the encrypted message to a second terminal;
• said center unit comprises:
• a key controller configured to renew said common cipher-key so as to be identical with said renewed common cipher-key in case of receiving said demand from said transmitter;
• and
• an encoder configured to produce said encrypted data by encrypting a cipher-key with said renewed common cipher-key and to transmit said encrypted data to said terminal unit.