Calculation device and calculation method

• US 20040162869A1
• Filed: 12/19/2003
• Published: 08/19/2004
• Est. Priority Date: 04/19/2002
• Status: Active Grant

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Tanaka, Masao, Matsuda, Hiromi, Morinaga, Eiichiro, Abe, Miki
• Granted Patent: US 7,392,272 B2
• Time in Patent Office: Days
• US Class Current: 708/490
• CPC Class Codes: H04L 2209/60 Digital content management, e.g. content distribution
• CPC Class Codes: H04L 9/0877 using additional device, e.g. trusted platform module [TPM], smartcard, USB or hardware security module [HSM]

Abstract

An arithmetic unit and an arithmetic method that output no information necessary for decryption or encryption to the outside and can perform a self-protecting function when an illegal attack is made. A command monitoring part (44) monitors input command sequences. In a first sequence, a process key in a first stage is calculated from a hardware key (Khd) and is then written to a key storing part (47). In each of the following sequences, a process key in a next stage is calculated from a process key stored in the key storing part (47). When commands of predetermined contents are inputted in predetermined order, a content key is calculated and then written to the key storing part (47). Encrypted data is decrypted with the content key, and the result is outputted from data output means (63). When an illegal attack is made, initialization is performed by selecting fixed value data (Kf) as key data (Ksl) and selecting fixed value data (Df) as input data (Ein).

Claims

1. An arithmetic unit comprising:

data input means for inputting data to be subjected to arithmetic processing;

command input means for inputting a command for specifying processing on said data;

arithmetic processing means for subjecting the data inputted by said data input means to arithmetic processing;

data output means for outputting the data processed by the arithmetic processing means;

output selecting means for selecting data to be outputted from the data output means; and

control means for controlling said output selecting means such that only data allowed to be outputted is outputted from said data output means on the basis of the command inputted by said command input means.

2. The arithmetic unit as claimed in claim 1,

wherein said control means includes determining means for determining input order of commands inputted by said command input means, and controls said output selecting means on the basis of a result of the determination.

3. The arithmetic unit as claimed in claim 1, further comprising storing means for storing at least one piece of data processed by said arithmetic processing means.

4. The arithmetic unit as claimed in claim 3,

wherein said arithmetic processing means uses the data stored in said storing means and the data inputted by said data input means for an operation.

5. The arithmetic unit as claimed in claim 1, further comprising data generating means for generating initial value data,

wherein said arithmetic processing means uses the initial value data generated by the data generating means and the data inputted by said data input means for an operation.

6. The arithmetic unit as claimed in claim 5, further comprising storing means for storing at least one piece of data processed by said arithmetic processing means.

7. The arithmetic unit as claimed in claim 6, further comprising data selecting means for selecting the data stored in said storing means and the initial value data generated by said data generating means and inputting the selected data to said arithmetic processing means,

wherein said control means controls said data selecting means to selectively input the data stored in said storing means and the initial value data generated by said data generating means into said arithmetic processing means on the basis of the command inputted by said command input means;

and

said arithmetic processing means subjects the data selected by said data selecting means and the data inputted by said data input means to an operation.

8. The arithmetic unit as claimed in claim 7,

wherein first fixed value data is further inputted to said data selecting means;

and

when said control means determines that commands are inputted in a different order from predetermined order, said control means controls said data selecting means such that said data selecting means selects said first fixed value data and inputs said first fixed value data to said arithmetic processing means.

9. The arithmetic unit as claimed in claim 2, further comprising input data selecting means for selecting the data inputted by said data input means and second fixed value data and outputting the selected data,

wherein when said control means determines that commands are inputted in a different order from predetermined order, said control means controls said input data selecting means such that said input data selecting means selects said second fixed value data and inputs said second fixed value data to said arithmetic processing means.

10. The arithmetic unit as claimed in claim 2, further comprising command storing means for storing a command inputted by said command input means,

wherein said control means determines command input order on the basis of the command stored in said command storing means and an input command.

11. An arithmetic method comprising the steps of:

performing arithmetic processing on input data on the basis of an input command;

determining whether the input command specifies output of a result of the arithmetic processing; and

outputting the result of the arithmetic processing on said input data when the input command specifies the output of the result of the arithmetic processing.

12. The arithmetic method as claimed in claim 11, further comprising the steps of:

storing the input command; and

determining that said result of the arithmetic processing is to be outputted on the basis of the stored command and a newly input command when input order of the commands is predetermined order.