Encoding/decoding circuit
AssigneeRenesas Electronics Corporation
InventorsShigenori Miyauchi, Atsuo Yamaguchi
Life of this patent
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Abstract
An encoding/decoding operation portion includes an encoding/decoding operation circuit and an avoiding path for detouring the encoding decoding operation circuit and can select between encoding or decoding input data in the encoding/decoding operation circuit and detouring the encoding/decoding operation circuit to output the input data without change. Only one wire has to be provided from a selector to a key storage portion and an initialization-vector storage portion. With this construction, it is possible to realize an encoding/decoding circuit which can suppress an increase in the number of wires used to transmit a content of key data to the key storage portion and the initialization-vector storage portion and does not cause complication of circuit layout.
Claims3
An encoding/decoding circuit comprising:
- a key storage portion in which a first generation encoding key is stored;
- an encoding/decoding operation portion;
- and
- an encoding key/decoding key generation coincidence judgment circuit,
- wherein said encoding/decoding operation portion uses said first generation encoding key to generate a second generation encoding key for encoding input data, and updates said first generation encoding key and stores said second generation encoding key into said key storage portion,
- said encoding/decoding operation portion uses an n-th (n:
- natural number) generation encoding key to generate an (n+1)th generation encoding key for encoding said input data, and stores said (n+1)th generation encoding key into said key storage portion for updating the n-th generation encoding key,
- said encoding/decoding operation portion uses said first generation encoding key to generate a first generation decoding key for decoding said input data which is encoded by said first generation encoding key and stores said first generation decoding key into said key storage portion,
- said encoding/decoding operation portion uses the (n+1)th generation encoding keys to generate the (n+1)th generation decoding keys for decoding said input data, respectively, and stores said (n+1)th generation decoding key into said key storage portion for updating the n-th generation decoding key,
- said encoding key/decoding key generation coincidence judgment circuit activates an encoding key/decoding key generation coincidence signal indicating said n-th generation decoding key is valid if said encoding/decoding operation portion generates said n-th generation decoding key by using said corresponding n-th generation encoding key, and
- said encoding key/decoding key generation coincidence judgment circuit inactivates said encoding key/decoding key generation coincidence signal if said n-th generation decoding key is generated by using a key other than said corresponding n-th generation encoding key.
An encoding/decoding circuit comprising:
- a key storage portion in which a first generation encoding key is stored;
- an encoding/decoding operation portion;
- and
- an encoding key/decoding key generation permission circuit,
- wherein said encoding/decoding operation portion uses said first generation encoding key to generate a second generation encoding key for encoding input data, and updates said first generation encoding key and stores said second generation encoding key into said key storage portion,
- said encoding/decoding operation portion uses an n-th (n:
- natural number) generation encoding key to generate an (n+1)th generation encoding key for encoding said input data, and stores said (n+1)th generation encoding key into said key storage portion for updating the n-th generation encoding key,
- said encoding/decoding operation portion uses said first generation encoding key to generate a first generation decoding key for decoding said input data which is encoded by said first generation encoding key and stores said first generation decoding key into said key storage portion,
- said encoding/decoding operation portion uses the (n+1)th generation encoding keys to generate the (n+1)th generation decoding keys for decoding said input data, and stores said (n+1)th generation decoding key into said key storage portion for updating the n-th generation decoding key,
- said encoding key/decoding key generation permission circuit generates an encoding key/decoding key n-th generation permission signal indicating said all generation decoding keys until the n-th generation are generated every time when said n-th generation decoding key is generated whenever said encoding/decoding operation portion generates said n-th generation decoding key to be valid by using said corresponding n-th generation encoding key.
Dependencies are inferred from the claim text.