Imaging device including wear leveling for non-volatile memory and secure erase of data
View Patent ↗Methods and apparatus teach wear leveling non-volatile memory and secure erasure of data. A computing device receives data to be stored. The data is encrypted, including generation of encryption/decryption key(s). The key(s) are stored in either non-volatile or volatile memory according to a plurality of classification schemes. In a first scheme, key(s) are stored in non-volatile memory and will be retained in the event of a power cycle of the computing device. Otherwise, key(s) stored in volatile memory will be lost upon a power cycle. Upon issuance of a key destruction command, key(s) in the non-volatile memory are sanitized or erased, but the underlying encrypted data need not be erased since no key(s) exist that can recover original content. These techniques limit erasure commands to the non-volatile memory which prolongs its service life. Further embodiments note techniques in imaging devices conducting imaging operations, such as printing or scanning.
1. A method for wear leveling non-volatile memory and securely erasing data in an imaging device having volatile and non-volatile memory, comprising:
receiving for processing an imaging job having data to be stored;
identifying whether the imaging job needs to persist or not over a power cycle of the imaging device;
encrypting the data, including generating one or more keys;
storing the encrypted data in a memory of choice; and
storing the one or more keys in non-volatile memory if the imaging job has been identified as needing to persist over the power cycle of the imaging device, otherwise storing the one or more keys in volatile memory.
2. The method of claim 1 , further including sanitizing the stored one or more keys.
3. The method of claim 2 , further including writing zeros to all memory locations storing the stored one or more keys.
4. The method of claim 2 , wherein the sanitizing further includes issuing a sanitize command according to a type of storage medium storing the key(s).
5. The method of claim 4 , wherein the sanitize command is a function of a manufacturer of the storage medium.
6. The method of claim 1 , further including storing the encrypted data in said non-volatile memory.
7. The method of claim 1 , further including creating files to store the data of the print job.
8. The method of claim 7 , further including removing all the files upon destruction of the one or more keys stored in the volatile memory.
9. The method of claim 1 , further including receiving a secure erasure command for destroying the one or more keys.
10. The method of claim 9 , further including leaving the encrypted data in the memory of choice upon destroying the one or more keys.
11. An imaging device, comprising:
a volatile memory;
a non-volatile memory; and
a controller to receive imaging jobs having data to be stored in memory, the controller including configuration to identify whether the imaging job requires persistence over a power cycle of the imaging device and to encrypt data in the imaging job, including generating one or more keys, wherein the controller is further configured to store the one or more keys in the non-volatile memory if the imaging job has been identified as needing to persist over the power off cycle of the imaging device, otherwise the controller is configured to store the one or more keys in the volatile memory.
12. The imaging device of claim 11 , wherein the non-volatile memory is an eMMC storage device.
13. The imaging device of claim 11 , wherein the volatile memory is a DRAM.
14. The imaging device of claim 11 , wherein the non-volatile memory is a hard disk drive.
15. The imaging device of claim 11 , further including more than one non-volatile memory.
16. The imaging device of claim 15 , wherein the controller is configured to store the encrypted data in a second non-volatile memory different than said non-volatile memory storing the one or more keys.
17. The imaging device of claim 11 , further including an application programming interface wherein applications creating the imaging job have file extensions to classify the imaging job according to whether the imaging job is required to persist over the power cycle of the imaging device.
18. The imaging device of claim 17 , wherein the files extensions are configured to cause the controller to store the encrypted data in one of two directory schemes in memory according to whether the imaging job needs to persist or not over the power cycle of the imaging device.
19. In an imaging device having volatile memory and more than one non-volatile memory, a method for prolonging the service life of the non-volatile memories and securely erasing stored data, comprising:
receiving an imaging job to be stored;
classifying the imaging job, including determining whether data in the imaging job requires persistence over a power cycle of the computing device;
encrypting the data for storage, including generating one or more keys;
storing the encrypted data in a first of the non-volatile memories; and
storing the one or more keys in a second of the non-volatile memories if the data requires persistence over the power cycle of the computing device, otherwise storing the one or more keys in the volatile memory.
20. The method of claim 19 , further including sanitizing the stored one or more keys but not sanitizing the stored encrypted data in the first of the non-volatile memories.