Patent ID: 8155320
Filing Date: 2012-04-10
Classification: G06F,H04L,H04N,H04W

Abstract:
1. A data storage apparatus connected to a management server, comprising: a data storage unit configured to store data wherein Pn is an n'th serial number for data P and n≧1; an integrated circuit coupled to said data storage unit, wherein said integrated circuit comprises: a key generation information storage unit configured to store first generation information and second generation information for generating key information; a key generation unit configured to generate key information from said first generation information and second generation information; and an update unit configured to update said data and said first generation information and second generation information, wherein: first generation information stored in said key generation information storage unit is X(n,A) resulting from performing irreversible calculation X n times using first secret information A as a starting parameter of the irreversible calculation X, and second generation information stored in said key generation information storage unit is Y(M−n,B) resulting from performing irreversible calculation Y M−n times (where M−n≧1) on second secret information B; and when receiving from the management server encrypted update information for updating data Pn to updated data Pk (where M≧k≧1), where the encrypted update information used by a plurality of data storage apparatuses and each of the plurality of the data storage apparatuses has installed data that is one of (n−i)'th serial number through data of (n+j)'th serial number (where M≧n+j≧n≧n−i≧1), the data Pn being among data of (n−i)'th serial number through data of (n+j)'th serial number (where M≧n+j≧n≧n−i≧1): said key generation unit configured to generate X(n+j,A) by performing irreversible calculation X j times using first generation information as a starting parameter of the irreversible calculation X, generates Y(M−n+i,B) by performing irreversible calculation Y i times using second generation information as a starting parameter of the irreversible calculation Y, and furthermore generates key information G (X(n+j,A),Y(M−n+i,B)) (where G is an arbitrary function) from said X(n+j,A) and Y(M−n+i,B); and said update unit configured to decrypt encryption of said encrypted update information using said generated key information G(X(n+j,A),Y(M−n+i,B)), acquires said data Pk, said first updated generation information X(k,A) and said second updated generation information Y(M−k,B) from said encrypted update information, updates data Pn stored in said data storage unit to said data Pk acquired from said encrypted update information, and updates said first generation information X(n,A) and said second generation information Y(M−n,B) stored in said key generation information storage unit to said first updated generation information X(k,A) acquired from said encrypted update information and said second updated generation information Y(M−k,B) acquired from said encrypted update information, respectively.