Method for using a CAPTCHA challenge to protect a removable mobile flash memory storage device
The embodiments described herein generally use a challenge to protect a removable mobile flash memory storage device, where the challenge may be in the form of a “Completely Automated Public Turing Test to Tell Computers and Humans Apart” (“CAPTCHA”). In one embodiment, a method is provided in which a removable mobile flash memory storage device receives a command from a host device, generates a CAPTCHA challenge, provides the CAPTCHA challenge to the host device, receives a response to the CAPTCHA challenge from the host device, determines if the response satisfies the CAPTCHA challenge, and performs the command only if the response satisfies the CAPTCHA challenge. In another embodiment, a removable mobile flash memory storage device is provided for performing these acts.
1. A method for using a “Completely Automated Public Turing Test to Tell Computers and Humans Apart” (“CAPTCHA”) challenge to protect a removable mobile flash memory storage device, the method comprising:
performing by a removable mobile flash memory storage device in communication with a host device, wherein the removable mobile flash memory storage device lacks a physical write-protect switch movable by a user between a first position that allows writes to the removable mobile flash memory storage device and a second position that prevents writes to the removable mobile flash memory storage device:
receiving a command from the host device;
determining if the command is a restricted command, wherein a restricted command is a command that would not be performed if a write-protect switch were present on the removable mobile flash memory storage device and in the second position;
only if the command is a restricted command:
generating a CAPTCHA challenge;
providing the CAPTCHA challenge to the host device;
receiving a response to the CAPTCHA challenge from the host device;
determining if the response satisfies the CAPTCHA challenge; and
performing the command only if the response satisfies the CAPTCHA challenge;
wherein the CAPTCHA challenge is provided to the host device on a command-by-command basis only if it is determined that the command is a restricted command, and wherein the CAPTCHA challenge is a substitute for having a write-protect switch on the removable mobile flash memory storage device.
2. The method of claim 1 , wherein a restricted command is a command that, if performed, would cause a loss of data stored in the removable mobile flash memory storage device.
3. The method of claim 1 , wherein a restricted command comprises one or more of the following commands: a command to write data to the removable mobile flash memory storage device, a command to read data from the removable mobile flash memory storage device, a command to reformat the removable mobile flash memory storage device, a command to erase data from the removable mobile flash memory storage device, a command to update firmware on the removable mobile flash memory storage device, a command to obtain diagnostic data from the removable mobile flash memory storage device, a command to partition the removable mobile flash memory storage device, and a command relating to cryptographic capabilities of the removable mobile flash memory storage device.
4. The method of claim 1 , wherein the CAPTCHA challenge requires a user to identify at least one distorted image.
5. The method of claim 1 , wherein generating the CAPTCHA challenge comprises:
generating a random string;
rendering the random string as a graphic image; and
distorting and adding visual noise to the graphic image.
6. The method of claim 1 , wherein the removable mobile flash memory storage device comprises a universal serial bus (USB) device.
7. The method of claim 1 , wherein the removable mobile flash memory storage device comprises a memory card.
8. A removable mobile flash memory storage device lacking a physical write-protect switch movable by a user between a first position that allows writes to the removable mobile flash memory storage device and a second position that prevents writes to the removable mobile flash memory storage device, the removable mobile flash memory storage device comprising:
an input/output port configured to connect the removable mobile flash memory storage device with a host device;
a memory; and
circuitry in communication with the input/output port and the memory, wherein the circuitry is operative to:
receive a command from the host device;
determine if the command is a restricted command, wherein a restricted command is a command that would not be performed if a write-protect switch were present on the removable mobile flash memory storage device and in the second position;
only if the command is a restricted command:
generate a CAPTCHA challenge;
provide the CAPTCHA challenge to the host device;
receive a response to the CAPTCHA challenge from the host device;
determine if the response satisfies the CAPTCHA challenge; and
performing the command only if the response satisfies the CAPTCHA challenge;
wherein the CAPTCHA challenge is provided to the host device on a command-by-command basis only if it is determined that the command is a restricted command, and wherein the CAPTCHA challenge is a substitute for having a write-protect switch on the removable mobile flash memory storage device.
9. The removable mobile flash memory storage device of claim 8 , wherein a restricted command is a command that, if performed, would cause a loss of data stored in the removable mobile flash memory storage device.
10. The removable mobile flash memory storage device of claim 8 , wherein a restricted command comprises one or more of the following commands: a command to write data to the removable mobile flash memory storage device, a command to read data from the removable mobile flash memory storage device, a command to reformat the removable mobile flash memory storage device, a command to erase data from the removable mobile flash memory storage device, a command to update firmware on the removable mobile flash memory storage device, a command to obtain diagnostic data from the removable mobile flash memory storage device, a command to partition the removable mobile flash memory storage device, and a command relating to cryptographic capabilities of the removable mobile flash memory storage device.
11. The removable mobile flash memory storage device of claim 8 , wherein the CAPTCHA challenge requires a user to identify at least one distorted image.
12. The removable mobile flash memory storage device of claim 8 , wherein the circuitry is operative to generate the CAPTCHA challenge by:
generating a random string;
rendering the random string as a graphic image; and
distorting and adding visual noise to the graphic image.
13. The removable mobile flash memory storage device of claim 8 , wherein the removable mobile flash memory storage device comprises a universal serial bus (USB) device.
14. The removable mobile flash memory storage device of claim 8 , wherein the removable mobile flash memory storage device comprises a memory card.