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Can entropy being used as data removal verification in data wiping ? How we can implement the entropy calculation in a data wiping tool? The wiping tool will used overwriting method using single pass.

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  • $\begingroup$ Based on what I have found, there is an entropy based data wiping tool but the entropy is being used to detect and identify sensitive data blocks in the target area to be sanitized, and overwrites only those blocks that contain data within a specified sensitive entropy range $\endgroup$ – samihah kashfi Dec 2 '17 at 7:21
  • $\begingroup$ That sounds completely ridiculous to me. The chance that, e.g., AES-128 - which uses a 16 byte key - contains just printable ASCII is still pretty high. You don't want those kind of occurrences to be skipped. Or what about an RSA key present as digital digits, or zipped? $\endgroup$ – Maarten Bodewes Dec 3 '17 at 11:36
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Your wording is rather off, "entropy" is not a verification algorithm, so it is impossible to use it as "data removal verification tool".

To test the (pseudo-)randomness it is possible to use any random data testing tool, such as the testing framework of NIST described in FIPS 140-2. It should be used at least on data filled with zero and the data after the wipe; in that case the original data cannot influence the result.

Note that the tool won't be able to distinguish between random data and data that was designed to look random. You will also need a rather large amount of data - so you cannot use this for single, relatively small file for instance.


Generally single pass overwrites are OK for modern storage devices, but the problem is that the data may be copied somewhere else before it gets overwritten. This is why you should e.g. use the secure erase function on modern SSD's and HDD's to be sure to get rid of the data. Or you can throw away the key of encrypted files so that the data becomes inaccessible rather than destroyed altogether.

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