Patent ID: 7433474

Claim:
A deciphering device comprising: a recording unit configured to record at least part of a p number of second keys, where p is an integer greater than or equal to two, in a secret area in the deciphering device; an input unit configured to input first information composed of enciphered data obtained by enciphering data with a first key and second information composed of a p number of enciphered first keys obtained by enciphering said first key with said p number of second keys, respectively; and a deciphering unit configured to decipher at least one of said p number of enciphered first keys of said second information inputted from said input unit using the recorded at least part of the p number of second keys in said recording unit, confirm by a specific method that the obtained first key is correct, and decipher said enciphered data of said first information using said first key after the confirmation to obtain said data.