Explanation: data recovery is not possible because the controller is internally damaged
This example is only for SSDs and flash drives
To understand this, first, if you see the below-mentioned picture then it will be more clear.
So every SSD has a controller to control the data on NAND chips. Every company makes its own controller. Like in this picture there is a Western Digital controller and 8 NAND chips for data storage. So it is up to the controller algorithm how it will store data on these chips and what kind of XOR it will use.
XOR: is a kind of method that Scramble the data with a key. Look in the below-mentioned picture in middle, it mentioned encrypt, so plan-text is the text (data, like doc, xlsx, pictures) that we store on operating system level that we can see as data …but it doesn’t store on SSDs as it is, it goes through the controller that has the secret key (that we also mention as XOR key)….so controller change this simple data (doc; xls; etc) into encrypted content and store on NAND chips …
So if the controller is damaged then we don’t have this KEY (Secret Key)… for some controllers, we have that key in our program or sometimes we can design that by using reference controller XORs … but for some controllers, if we don’t have that key then we close the case as “controller algorithm is unknown”
Example if you want to store text “Stellar Data Recovery” on SSDs…then it will store like that
Forward way ( while storing data on SSD)
Stellar Data Recovery ( that your OS will show you) —–>> SATA interface —->> SSD Controller ( there it will XOR this content will key file= ” Stellar data Recovery XOR “Key File””) ——>> XOR scrambled content on NAND chips (dhwhhay fbwa ofbugstv)
Reverse way while reading data from SSD ( data recovery)
XOR scrambled content on NAND chips (dhwhhay fbwa ofbugstv) —-> SSD Controller ( there it will XOR this content will key file= ” Stellar data Recovery XOR “Key File”) —> SATA interface —-> Stellar data Recovery ( that your OS will show you)
So, you understand if the KEY file is missing then we cannot get the correct content. And the reason for recovery not possible is “controller algorithm is unknown”
I hope it is clear :-)