SSD: What does hardware encryption actually do, and a few other questions!

[OrangeLike]

Hi all!

Just got my first machine with an SSD, and like a lot of people new to SSDs, I had all kinda of panic-responses about wear leveling, slow down, etc.

But, between the articles on the main page and Zap's excellent sticky post (thank you Zap) most of my concerns about moving around temp files and directories and other freaking out have been utterly alleviated.

The take away that I'm working with is given that I'm running Windows 7, with an Intel drive (320) I just don't need to worry about it. And that is a huge relief.

But, I did have a few questions that I haven't been able to wrap my head around properly, and was hoping you folks could help me with.

1) What does the hardware encryption on the Intel 320 actually do? How is it used (by bitlocker? automatically?)

2) Does a secure erase require having set up the hardware encryption first?

3) I had traditionally been used to using CCleaner to toss accumulated cruft. I'm assuming that I can continue to use it (see: Zap's "don't panic" instructions). Is this correct? Should I not use the "secure" delete (because it's extraneous, or for any other reasons?)

Thanks much all!

 

[Coup27]

I'm not an expert but I can help a bit.

1) The hardware encryption is built into the controller and has nothing to do with software at all. I presume you'll set a hard drive password in BIOS or UEFI which you'll have to enter when you boot the system. The data on the SSD is encrypted at NAND level and only with that password can you access it. This will also prevent you accessing the data on any other machine.

2) Secure erase will work fine on an SSD with no encryption. Remember that more SSDs don't support encryption than do. Whether it works on one with encryption enabled without the password I don't know.

3) Yes. Windows and usual operations are totally normal as its all done at the SSD controller level.

 

[Mark R]

1. SATA drives have the facility to set a password for the drive. If you program a password into a SATA drive (using the manufacturer's tool), then when the drive will lock-up next time it is powered on. The drive will not be detectable by the PC, unless the BIOS (or some other tool) transmits the correct password to the drive.

The hardware encryption ensures that all the data stored on the flash memory chips is encrypted, so that data can only be accessed via SATA (and not by a hacker connecting probes to the flash chips).

How the HD password acts depends on the BIOS. Most allow the HD password to be programmed in on the BIOS config page. The BIOS will then automatically unlock the HD on every boot. This is convenient, but essentially locks the HD to that motherboard (so, the HD cannot be moved to a new computer or used in a USB dock). For example, take an employee who has a company laptop with confidential files, where the OS is locked down to prevent copying the files. If the HD is password protected, the employee can't move the HDD to his home PC and copy the data off.

3. Yes. The drive will work exactly like any traditional HD does.

The "secure" delete function in programs like CClaner works by deleting file data that may remain on a HD after a file is deleted in a normal way.

Whe an OS deletes (e.g. emptying the recycle bin in Windows) a file from a HD, what the OS actually does is delete the filename from the directory index. It leaves the actual file contents on the drive, and marks the sectors used by the file data as available for reuse. This means that the actual data in the file is still there, until the space it once occupied is actually needed for new files. Confidential data can leak out this way, as there are "undelete" and file recovery tools available that can retrieve data.

The "secure" delete function in programs like CCleaner, first replace the actual file data on the drive with garbage, then they delete the filename in the normal way. This way, if you have temporarily stored a confidential file on your computer, you can be more confident that it will be destroyed than with a normal OS delete.

Things get a bit more complicated with SSDs. Because of the way that SSDs work, they work better (faster and longer lived) if they can dispose of old data. With a modern OS (like Win 7) when you delete a file, the deletion occurs in the normal way. Then, if the OS detects an SSD, it sends a command called "TRIM" to the drive which tells the drive that the sectors corresponding to that file can be destroyed. The result is that a normal delete works very much like a "secure" delete from a tool like CCleaner.

 

[OrangeLike]

Thanks guys.

If I understand correctly, it sounds like the security provided by the HD encryption is really limited to concerns about removal of the hard drive at the cost of drive flexibility (for example, yanking the drive and connecting it externally in order to retrieve data). I think, given my needs, that it's probably extraneous.

As to CCleaner, it would seem that given the nature of TRIM, the "secure" erase feature is redundant.

Is my understanding correct?

Thanks again!

 

[Mark R]

1. Pretty much.

2. Secure file deletion programs are designed to ensure that all traces of that file are destroyed, at the time the file is deleted.

With TRIM, it's up to the drive when, or how much, if any, of the data gets destroyed.
TRIM merely tells the drive that the data is unwanted; the drive may not actually destroy the data until it wants to do something with the space. Also, drives may ignore TRIM for small requests (e.g. <1 MB) as flash memory can usually only be erased in 1 MB chunks - so it may not be worth the effort for a drive to handle smaller requests.

 

[OrangeLike]

Ah, makes sense. So a secure delete would make TRIM more likely, because it's requesting use of the "deleted" areas?


Sent from my generic electronic device using some lines of code and waves and stuff.

 

[Topweasel]

Ah, makes sense. So a secure delete would make TRIM more likely, because it's requesting use of the "deleted" areas?


Sent from my generic electronic device using some lines of code and waves and stuff.

Secure Delete would work through all three stages. It would Delete the file in windows, a trim command would be sent no matter what, and then it would clear out the data in NAND like a GC would do. Most GC's would eventually get to the file an clear it out, It just wouldn't be instantaneous like a secure delete would be. Most Garbage collectors wait till idle time and enough information to make it worth while.

As for the encryption. Its not just about removing the drive. You still have to enter a password to get past that. Meaning that as long as you powered down the system, then there is little way people can get your info without that password.