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Audio Signal Processing

Cryptosystem

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Cryptosystem

Details

Inventors: Takeda, Noriko; Shinoda, Seiichi; Haseyama, Toshio;
Assignee: Mitsubishi Denki Kabushiki Kaisha (Tokyo, JP)
Primary Examiner: Swann; Tod R.
Assistant Examiner: Jack; Todd
Attorney, Agent or Firm: Burns, Doane, Swecker & Mathis, LLP

In a cryptosystem, communication terminals and encryptors can be grouped physically and logically. The communication mode can be switched by the encryptor between ciphertext communication and plaintext communication. The encryptor includes the session key memorizing unit for memorizing the session key and the mode switch for switching the communication mode between ciphertext communication and plaintext communication. The key manager distributes the session key generated by the session key generating unit and the valid/invalid information set by the valid/invalid setting unit to each encryptor. The valid/invalid judging unit judges whether the communication data should be sent in ciphertext or plaintext using the mode switch and the valid/invalid information.

DETAILED DESCRIPTION What is claimed is: 1.
A cryptosystem comprising: a communication apparatus; an encryptor for encrypting/decrypting communication data sent/received by the communication apparatus using a session key; and a key manager for managing the session key, wherein the encryptor comprises a mode switch for setting a communication mode wherein the communication mode is one of a mode in which communication data is encrypted/decrypted by the session key and a mode in which communication data is not encrypted/decrypted by the session key, wherein the key manager includes a valid/invalid setting unit for setting valid/invalid information showing validity/invalidity of the mode switch of the encryptor and sending the valid/invalid information to the encryptor, and wherein the encryptor further comprises a validity/invalidity judging unit for judging that the communication data is to be encrypted/decrypted based on the mode switch and the valid/invalid information.
2.
The cryptosystem of claim 1, wherein the encryptor further comprising: a session key memorizing unit for memorizing at least one session key for encrypting/decrypting communication data sent/received by the communication apparatus; a cipher processing unit for encrypting/decrypting the communication data using the session key; and a data sending/receiving unit for sending/receiving the communication data processed by the cipher processing unit.
3.
The cryptosystem of claim 1 further comprising a group of communication apparatuses, wherein the key manager includes: a communication apparatus group memorizing unit for memorizing a group of communication apparatuses; and a session key generating unit for generating the session key to be used in the group of communication apparatuses and outputting the session key to the group of communication apparatuses memorized in the communication apparatus group memorizing unit.
4.
The cryptosystem of claim 3, wherein the key manager comprises a session key encrypting unit for encrypting the session key generated by the session key generating unit and a session key sending unit for sending the session key to the encryptor corresponding to the group memorized in the communication apparatus group memorizing unit, and wherein the encryptor further comprises a session key receiving unit for receiving the session key encrypted and sent by the session key sending unit of the key manager and a session key decrypting unit for decrypting the session key encrypted

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