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Windows ships with a full volume encryption tool called BitLocker. The feature used to trust any SSD that claimed to offer its own hardware-based encryption, but that changed in the KB4516071 update to Windows 10 released on September 24, which now assumes that connected SSDs don't actually encrypt anything.

"SwiftOnSecurity" called attention to this change on September 26. The pseudonymous Twitter user then reminded everyone of a November 2018 report that revealed security flaws, such as the use of master passwords set by manufacturers, of self-encrypting drives. That meant people who purchased SSDs that were supposed to help keep their data secure might as well have purchased a drive that didn't handle its own encryption instead.

Those people were actually worse off than anticipated because Microsoft set up BitLocker to leave these self-encrypting drives to their own devices. This was supposed to help with performance--the drives could use their own hardware to encrypt their contents rather than using the CPU--without compromising the drive's security. Now it seems the company will no longer trust SSD manufacturers to keep their customers safe by themselves.

Here's the exact update Microsoft said it made in KB4516071: "Changes the default setting for BitLocker when encrypting a self-encrypting hard drive. Now, the default is to use software encryption for newly encrypted drives. For existing drives, the type of encryption will not change." People can also choose not to have BitLocker encrypt these drives, too, but the default setting assumes they don't want to take SSD manufacturers at their word.

We assume many people would prefer that self-encrypting drives would be as secure as they claim to having Microsoft update BitLocker. But at least now they won't be lulled into a false sense of security. If the drives work as advertised, BitLocker can be told to skip them when it's encrypting data. If they don't, however, at least Windows can now provide them a safety net rather than letting them fall because SSD companies messed up.