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Comment by rlpb | Hacker News Reader

Won't this format leave behind traces of what was in the file before? I'm not sure that this is something that we want in a standard interchange format. Users will assume what they are sending is only what they see in an application. This is reasonable. I am concerned that using this format will lead to data leaks.

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Not if you set "PRAGMA secure_delete=ON;" See http://www.sqlite.org/pragma.html#pragma_secure_delete for additional information.

It could be defined in the format spec that applications should VACUUM the database after every save.

That ship has pretty much sailed with EXIF and embedded metadata anyways, right?

This would seem to be more targeted at digital content creation (and toolchain application interop) than a normal-use file format.

It's up to your editor what metadata it chooses to save. It is not up to your editor what data was in the sqlite row that it just modified or deleted but may still be forensically available. There is a fundamental difference here.

It is possible to clean it up of course - perhaps by vacuuming, or definitely by copying to a new file at database level. But it seems dangerous to me to start with a native format with this behavior and attempt to clean it up later.

>But it seems dangerous to me to start with a native format with this behavior and attempt to clean it up later.

File formats don't have behaviors. Programs do.

Lots of binary formats, including PNG, will ignore any extra junk after the end of the file. So if a change makes a PNG file smaller, there's nothing stopping a program from leaving data from the old version at the end. But that's not normal behavior for programs that write PNG, so it's not an issue.

As long as programs adopted the behavior of VACUUMing the database, this wouldn't be an issue either.

How is that different from a psd or editable fireworks png file? I can have several groups with various visibility toggles that any normal user wouldn't see unless they dig into the layers.

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