Hacker News Reader

Comment by karka91 | Hacker News Reader

On this note, maybe someone want's to program an application that would select random unused portions of hdd and write random data to them? Something like a daemon/windows service that would take care of the data that hasn't been fully purged by os delete. I would do it myself, but I lack knowledge in low level api's

View on HN

This application fits your needs on the Windows platform:

"Eraser is an advanced security tool for Windows which allows you to completely remove sensitive data from your hard drive by overwriting it several times with carefully selected patterns. Eraser is currently supported under Windows XP (with Service Pack 3), Windows Server 2003 (with Service Pack 2), Windows Vista, Windows Server 2008, Windows 7 and Windows Server 2008 R2."

http://eraser.heidi.ie

Overwriting data to safely delete it is usually enough, most of the recommended additional overwriting is snake oil. Unfortunately, overwriting data still takes a lot of time.

Using system encryption is therefore easier: You delete the key and your data is as good as overwritten a million times … all modern operation systems offer system encryption by default.

Disk encryption wouldn't defeat an attacker that had access to your keys (either by compromising a running system or through a cold-boot attack[1]). If the keys are available, the contents of the disk are accessible. Overwriting deleted files would still have value in these cases.

[1] https://jhalderm.com/pub/papers/coldboot-sec08.pdf

Does this properly work on a modern journal-ed filesystem? My impression of the equivalent linux utilities is that while they appear to work on modern linux filesystems, they no longer provide as much security as you might think.

Sorry, I don't understand the underlying principles enough to answer that question. How would journalling interfere with the behaviour of a tool like Eraser?

(I do know that SSDs change the nature of the problem dramatically, as their internal storage allocation techniques tend to be opaque to the operating system. One cannot guarantee that an instruction to overwrite block X will be interpreted in the desired manner.)

Reply on news.ycombinator.com