Safely wiping data from Android device: Gutmann or others?
<p>I've been reading a few articles on Gutmann method of securely wiping data. I understood that the method is designed for <strong>hard disks</strong>. I want to write my tiny app that securely wipes data (there are a few on Google Play, I know) from either phone memory or SD card.</p>

<p>My questions are</p>

<h3>Question 1: Gutmann or others?</h3>

<p>As for the above observation, is Gutmann algorithm both effective and efficient? I believe that it is indeed effective because it rewrites the data so many times that a technology like flash memory has no way to remember data 35-writes-older. I don't know if it's efficient: I mean, do I just need fewer random writes to achieve a result?</p>

<h3>Question 2: do I really overwrite sectors?</h3>

<p>A question that came into my mind is the following: if I <a href="http://www.java-forums.org/advanced-java/13328-file-overwrite-method.html" rel="nofollow">overwrite a file in Java</a>, does Linux kernel write new data on old sectors or does it allocate new sectors on physical media while deallocating the old ones? You know, this makes the difference...</p>
