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How do you destroy an SSD?
First, let's focus on some "dont's." These are tried and true methods used to make sure that your data is unrecoverable from spinning hard disk drives. But these don't carry over to the SSD world.
Degaussing – applying a very strong magnet – has been an accepted method for erasing data off of magnetic media like spinning hard drives for decades. But it doesn't work on SSDs. SSDs don't store data magnetically, so applying a strong magnetic field won't do anything.
Spinning hard drives are also susceptible to physical damage, so some folks take a hammer and nail or even a drill to the hard drive and pound holes through the top. That's an almost surefire way to make sure your data won't be read by anyone else. But inside an SSD chassis that looks like a 2.5-inch hard disk drive is actually just a series of memory chips. Drilling holes into the case may not do much, or may only damage a few of the chips. So that's off the table too.
Erasing free space or reformatting a drive by rewriting it zeroes is an effective way to clear data off on a hard drive, but not so much on an SSD. In fact, in a recent update to its Mac Disk Utility, Apple removed the secure erase feature altogether because they say it isn't necessary. So what's the best way to make sure your data is unrecoverable?
(Score: 3, Informative) by VLM on Friday March 17 2017, @12:17PM
Everyone is giving you the long answer but the short answer is the world is analog and based on experience with magnetic media like cassette tapes and UV erased eproms, everything is analog fundamentally and its "easy" to mess with stuff at the analog level to apply your own ratio of signal to noise ratio and recover the data.
You never wrote a zero to that eprom cell. You injected a vaguely unclear number of electrons in that floating gate that you can hopefully measure later, by shoving a known current pulse which is caused by a known voltage pulse after you think you shorted than floating gate to ground by a transistor of unclear resistance and time is money so they cut the erase time as short as possible. And in electronics nobody pays for tolerances more than 1% or so and there is/was lots of good EE work done at the 20% and 10% tolerance level. And all this stuff scales with temperature and you have no idea if its -65C or 120C but you think it might work. And it all probably depends on clock speed and you don't know that either.
Most of the time it kinda works. There's an electric field on that floating gate corresponding to 100 electrons ideally meaning a zero. But in the real world 99 electrons means there was a 0 stored there last time and 101 means there was a 1 stored there last time and the usual reading algo says less than 110 means a 0, but if you work around that its all kinds of fun.
Its actually very similar to breaking XOR encryption so a series of eeprom cells with 99, 101, 99, 101 electrons is read as hex F aka 1111 but due to poor erasing (time is money and people want high performance...) you subtract the current value and the last value held in that eeprom was hex 5 aka 0101
In the old days UV erasable eproms were black magic and leaving them in weak UV fields like office lights or indirect sunlight led to truly weird bit patterns appearing. Also poor programmer burn timings could turn an eprom into a prom, essentially, plus or minus crazy 3 hour erase timings. Of course long erasure timings did weird things to chips too such as burn permanent zeros into them.
In summary in analog world a lot of stuff barely works and barely works in security speak is an attack vector to be exploited.