DK175426B1 - Procedure for deleting data on an electronic storage medium - Google Patents

Description

DK 175426 B1

BACKGROUND OF THE INVENTION This invention relates to a method for deleting data on an electronic storage medium. This means a hard disk, floppy disk, data tape or systems which are systematically used to store or systematically store data so that they can later be loaded from the storage medium / system to one: 5 computer, network or system of networks The storage media typically uses electromagnetic signal technology in a way that enables the reuse method. can therefore not be used, for example, on hole cards where the individual bits cannot be changed and where instead a new hole card must be used every time a change is made 10 The method can be used to systematically delete all data on a given device, for example a hard drive, or a given system of hard drives, for example a raid system The method can be used at the same time to delete certain segments, for example stored documents on a disk

Typically, the overwriting occurs for each byte at a time in the system in that a randomization program determines how many times between two and a maximum freely chosen by the user, the byte in question must be overwritten with a randomly selected character, but can be also carried out by sequential overwriting 20 In the known cutting techniques, data is overwritten the same number of times, selected by the program. In this context, a de facto standard from the US Department of Defense can be referred to, after which the unit is deleted at least three times. the title DOD 5220 22-M where it is described as or V 25

It states in section 8 306 e "Overwrite all addressable loyalties with a single character, its complementary 30 opposites, then a random character"

By repeatedly overwriting the storage medium, the tracking of previously loaded signals makes it difficult to see each bit position as a flat, box-shaped unit,. 35 over which the read / skew head is positioned above the intersection of the diagonallmiem, the direct magnetization will occur around the center When traces of previously loaded signals can be found at all, it is because the magnetized regions themselves re-magnetize their surroundings with weaker signals than those, the reading heads even magnetizes directly with This creates layers of previously 40 weak, weak signals Searching for previously loaded signals must be possible by searching further down and out to the pages Have you thus obtained a signal from a previously written file in a byte and hence its constituents of bits, the probability that a very large part of the data segment's input signals is located at the same position at the corresponding locations in the upper 45 bits as the found, rather high signal can thus be read with developed equipment previously loaded data overwritten in accordance with it so far prior art, the recording of the previously loaded and since I DK 175426 B1

In overwritten data be facilitated by repetition of knowledge of where the signals can be

You will read that will be possible in cases where bytes on the storage medium have passed through I

In the same historical course

I 5 There is concern among professionals that rediscovery of data is made more difficult by I

In multiple headings if these are made with different patterns Rediscovery 'I

is made more difficult so that the more transcripts, the more difficult it is to rediscover

In practice, in practice, the number of headings mentioned at a given point is mentioned

currently considered sufficient to achieve an acceptable high degree of I

I 10 protection I

I By minimum is meant the minimum number of times, the overwriting of the selected I

In area should be done with Minimum can theoretically be set to 0, but will in practice beg you

Significantly higher The selected expression for the minimum must be an integer I

I 15 Maximum is the largest number of overwrites that the process uses

You are talking about an integer that determines how many overwrites, a byte of I

In the unit maximum you can use I

In the invention, the parallel historical paths are broken which allow you to

In 20, data is retrieved using the above-mentioned repeat of reading I

of signals on the assumption that one must look for signals with the same I

In offset from the center of the surface for each bit position to find earlier I

loaded data

This is achieved according to the invention by varying the number of overwrites for each I

In single bytes, the number of layers from previous overwrites varies from byte to byte, I

I from a minimum of 2 and a maximum of a number of overwrites between 3 and infinity, selected I

by the user himself

I 30 I

In a given embodiment, a random generator is used to select it

In number of cuts to be performed for each byte to be cut

This method can be further elaborated through the choice of a case

In density generator with a very low degree of predictability in selection I

In the pattern I

In a given embodiment, a random generator is used for output

the choice of the characters to be used in each overwriting of each one

In cold bytes This method can also be further developed through the choice of a mate

In 40 random random generator leaving a very small degree of predictability I

In the selection pattern among all the characters used by the computer character set

Hereby, an overall higher degree of unpredictability is achieved and thereby a lower gene

Because of the pattern that a reconstructor of overwritten data had to use

I of I

45 I

I 2 I

Claims (4)

1 Procedure for deleting previously stored data on electronic data storage media or data storage systems by repeatedly writing S new characters on top of the previously stored characters characterized by the number of overwriting behaviors from byte to byte between a minimum (= 1) and a 'maximum (= infinite) A method for deleting previously stored data on electronic data storage media according to claim 1, characterized in that the number of times each byte is overwritten is selected by a randomization program Method for deleting data stored so far on electronic data storage media according to claim 1 and claim 2, characterized in that the administrator of the program 15 selects the number of switches Method for deleting previously stored data on electronic data storage media or data storage systems by repeatedly cutting new characters on top of the previously stored characters according to claim 1, characterized in that a random repetition program is used to select the characters selected by each overwriting method. is applied to any of the character sets used by that computer system 25 in 4