Portable information terminal and data protecting method

• US 20060190729A1
• Filed: 02/03/2006
• Published: 08/24/2006
• Est. Priority Date: 02/23/2005
• Status: Active Grant

• Current Assignee: NTT Docomo Incorporated (Nippon Telegraph and Telephone Corporation)
• Original Assignee: NTT Docomo Incorporated (Nippon Telegraph and Telephone Corporation)
• Inventors: Uchida, Motoyuki
• Granted Patent: US 7,921,305 B2
• Time in Patent Office: Days
• US Class Current: 713/168
• CPC Class Codes: G06F 21/88 Detecting or preventing theft or loss

Abstract

Even if a portable information terminal is lost or stolen, a third party is prevented from illegally browsing data stored in the portable information terminal. When a control signal is received through wireless communication part and when the received control signal is an instruction signal to execute an encryption process on plaintext data stored in data memory, the plaintext data is encrypted and encrypted data is stored in the data memory. Thereafter, erasing part erases the plaintext data stored in the data memory.

Claims

1. A portable information terminal comprising:

data storing means for storing plaintext data;

receiving means for receiving a control signal through wireless communication;

encrypting means for, when the control signal received by the receiving means is an instruction signal to execute an encryption process on the plaintext data stored in the data storing means, encrypting the plaintext data stored in the data storing means and storing encrypted data resulting from the encryption process, in the data storing means; and

erasing means for erasing the plaintext data from the data storing means after the encrypting means has encrypted the plaintext data.

2. A portable information terminal comprising:

data storing means for storing plaintext data or encrypted data;

acquiring means for acquiring right information necessary for an encryption process of the plaintext data stored in the data storing means, and for a decryption process of the encrypted data stored in the data storing means;

encrypting means for encrypting the plaintext data stored in the data storing means, using the right information acquired by the acquiring means, and for storing the encrypted data resulting from the encryption process, in the data storing means;

erasing means for erasing the plaintext data stored in the data storing means, after the encrypting means has stored the encrypted data in the data storing means;

right information storing means for, when the acquiring means acquires the right information, validating and storing the acquired right information; and

decrypting means for enabling the decryption process of the encrypted data using the right information when the right information stored in the right information storing means is validated, with reception of a reproduction instruction to reproduce the encrypted data obtained by the encrypting means.

3. A portable information terminal comprising:

data storing means for storing encrypted data,

right information storing means for storing right information necessary for a decryption process of the encrypted data stored in the data storing means;

decrypting means for, when the right information stored in the right information storing means is valid, with issuance of a reproduction instruction to reproduce the encrypted data stored in the data storing means, executing the decryption process on the encrypted data stored in the data storing means, using the right information and for, when the right information stored in the right information storing means is invalid, avoiding executing the decryption process on the encrypted data stored in the data storing means, using the right information; and

reproducing means for reproducing plaintext data resulting from the decryption process by the decrypting means.

4. The portable information terminal according to claim 3, wherein the right information storing means further stores as the right information, whether reproduction of the encrypted data is enabled, for each data type, and

wherein the decrypting means executes the decryption process if that the reproduction of data is enabled is stored for a data type of the encrypted data to be reproduced, and the decrypting means avoids the decryption process if that the reproduction of data is disabled is stored.

5. The portable information terminal according to claim 3, comprising authenticating means for performing an authentication process through communication with a server for performing authentication of the portable information terminal, with issuance of a reproduction instruction to reproduce data stored in the data storing means,

wherein the decrypting means executes the decryption process of decrypting the encrypted data stored in the data storing means, when the authenticating means determines that the authentication is successfully done.

6. The portable information terminal according to claim 3, comprising confirming means for, with issuance of a reproduction instruction to reproduce the encrypted data stored in the data storing means, communicating with a server storing for each data type, information for restricting a reproduction process of encrypted data in the portable information terminal, to confirm presence or absence of a restriction on the reproduction process,

wherein the decrypting means executes the decryption process of decrypting the encrypted data when the confirming means confirms the absence of the restriction on the reproduction process.

7. A portable information terminal comprising:

data storing means for storing encrypted data;

right information storing means for storing right information necessary for a decryption process of the encrypted data and for an encryption process of plaintext data;

acquiring means for, with reception of an instruction to update old right information stored in the right information storing means, acquiring new right information and storing the acquired new right information in the right information storing means;

decrypting means for decrypting the encrypted data stored in the data storing means, using the old right information stored in the right information storing means, to obtain plaintext data;

encrypting means for encrypting the plaintext data obtained through the decryption by the decrypting means, using the new right information acquired by the acquiring means, and for storing encrypted data in the data storing means; and

erasing means for erasing the old right information from the right information storing means after completion of the encryption process by the encrypting means and the decryption process by the decrypting means.

8. A data protecting method in a portable information terminal with data storing means for storing plaintext data, comprising:

a receiving step of receiving a control signal through wireless communication;

an encrypting step of, when the control signal received in the receiving step is an instruction signal to execute an encryption process on the plaintext data stored in the data storing means, encrypting the plaintext data stored in the data storing means and storing encrypted data resulting from the encryption process, in the data storing means; and

an erasing step of erasing the plaintext data from the data storing means after the plaintext data stored in the data storing means has been encrypted in the encrypting step.

9. A data protecting method in a portable information terminal with data storing means for storing plaintext data or encrypted data, and right information storing means for storing right information necessary for encrypting the plaintext data stored in the data storing means, or for decrypting the encrypted data, comprising:

an acquiring step of acquiring the right information necessary for an encryption process of the plaintext data stored in the data storing means, and for a decryption process of the encrypted data stored in the data storing means;

an encrypting step of encrypting the plaintext data stored in the data storing means, using the right information acquired in the acquiring step, and storing the encrypted data resulting from the encryption process, in the data storing means;

an erasing step of erasing the plaintext data stored in the data storing means, after the encrypted data has been stored in the data storing means in the encrypting step;

a storing step of, when the right information is acquired in the acquiring step, validating the acquired right information and storing the right information in the right information storing means; and

a decrypting step of enabling the decryption process of the encrypted data using the right information when the right information stored in the right information storing means is valid, with issuance of a reproduction instruction to reproduce the encrypted data resulting from the encryption in the encrypting step.

10. A data protecting method in a portable information terminal with data storing means for storing encrypted data, and right information storing means for storing right information necessary for a decryption process of the encrypted data stored in the data storing means, comprising:

a decrypting step of, when the right information stored in the right information storing means is valid, with issuance of a reproduction instruction to reproduce the encrypted data stored in the data storing means, executing the decryption process on the encrypted data stored in the data storing means, using the right information, and, when the right information stored in the right information storing means is invalid, avoiding executing the decryption process on the encrypted data stored in the data storing means, using the right information; and

a reproducing step of reproducing plaintext data resulting from the decryption process in the decrypting step.

11. A data protecting method in a portable information terminal with data storing means for storing encrypted data, and right information storing means for storing right information necessary for a decryption process of the encrypted data and for an encryption process of plaintext data, comprising:

an acquiring step of, with reception of an instruction to update old right information stored in the right information storing means, acquiring new right information and storing the acquired new right information in the right information storing means;

a decrypting step of decrypting the encrypted data stored in the data storing means, using the old right information stored in the right information storing means, to obtain plaintext data;

an encrypting step of encrypting the plaintext data obtained through the decryption in the decrypting step, using the new right information acquired in the acquiring step, and storing encrypted data in the data storing means; and

an erasing step of erasing the old right information from the right information storing means after completion of the encryption process in the encrypting step and the decryption process in the decrypting step.