# US 7,089,350 B2 · Methods of sanitizing a flash-based data storage device

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- Number: US 7,089,350 B2
- Document ID: US7089350B2
- Status: Granted
- Kind: B2
- Application number: 11/171,188
- Filed: 2005-07-01
- Published: 2005-11-17
- Granted: 2006-08-08
- Earliest claimed: 2003-03-25
- Assignees: Msystems Ltd.
- Inventors: Rami Koren; Eran Leibinger; Nimrod Wiesz; Eugen Zilberman; Ofer Tzur; Sagiv Aharonoff; Mordechai Teicher
- Web page: https://patentgrep.com/patent/US7089350B2

## CPC

- G06F 3/0619: {in relation to data integrity, e.g. data losses, bit errors}
- G06F 3/0659: {Command handling arrangements, e.g. command buffers, queues, command scheduling}
- G06F 3/0679: {Non-volatile semiconductor memory device, e.g. flash memory, one time programmable memory [OTP]}
- G11C 16/102: {External programming circuits, e.g. EPROM programmers; In-circuit programming or reprogramming; EPROM emulators}
- G11C 16/105: {Circuits or methods for updating contents of nonvolatile memory, especially with 'security' features to ensure reliable replacement, i.e. preventing that old data is lost before new data is reliably written}
- G11C 16/16: for erasing blocks, e.g. arrays, words, groups
- G06F 2221/2143: Clearing memory, e.g. to prevent the data from being stolen
- G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N)
- G11C: STATIC STORES (semiconductor memory devices H10B)

## Abstract

A data storage device includes one or more non-volatile, blockwise erasable data storage media and a mechanism for sanitizing the media in response to a single external stimulus or in response to a predetermined physical or logical condition. Optionally, only part of the media is sanitized, at a granularity finer than the blocks of the medium. Setting a flag in an auxiliary nonvolatile memory enables an interrupted sanitize to be detected and restarted. Optionally, a “death certificate” verifying the sanitizing is issued. Preferably, the media are configured in a manner that allows atomic operations of the sanitizing to be effected in parallel.

## Claims

### Claim 1

A method of cleaning a data storage medium, comprising the steps of:
(a) sanitizing the data storage medium;
(b) subsequent to said sanitizing, setting a medium-is-sanitized flag;
(c) verifying that said sanitizing has been effected; and
(d) if said verifying determines that said sanitizing has been effected, issuing a death certificate, for the data storage medium, that is based on a serial number of a device that includes the data storage medium.

### Claim 2 (depends on 1)

The method of claim 1, wherein said verifying is effected by steps including:
(i) checking that said medium-is-sanitized flag is set.

### Claim 3 (depends on 2)

The method of claim 2, wherein said verifying is effected by steps further including:
(ii) checking for a data pattern, stored in at least a portion of the data storage medium, that indicates that said sanitizing has been effected.

### Claim 4 (depends on 3)

The method of claim 3, wherein said checking for said data is effected for all of the data storage medium.