Encoding/decoding circuit
AssigneeRenesas Electronics Corporation
InventorsShigenori Miyauchi, Atsuo Yamaguchi
Life of this patent
Estimating the term…
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;
- a decoding operation portion for decoding input data which is to be subject to decoding to obtain a second key for decoding an encoded data coded by using a first key received from outside thereof and stores said second key into said key storage portion;
- and
- a key validity judgment circuit,
- wherein said key validity judgment circuit activates a key valid signal indicating said second key is valid if said first key is used after said decoding operation portion obtains said second key, and
- said key validity judgment circuit inactivates said key valid signal and discards a result of the decoding operation if said first key has already changed after said second key was obtained.
Dependencies are inferred from the claim text.