oramfs - ORAM filesystem written in Rust

Travis Biehn tbiehn at gmail.com
Mon Jul 5 14:23:22 PDT 2021

On Mon, Jul 5, 2021 at 5:07 PM Karl Semich <0xloem at gmail.com> wrote:
>> >> Karl, pleasure writing to you, I hope you understand a bit better why
>> >> I'm asking about ORAM-FS's benefits.
>> >
>> >
>> > I hear you asking with an eye towards when a large business or government might find it efficient to use.
>> >
>> > I don't understand why you are asking this.  I observed you didn't share a threat model.
>> >
>> > Oramfs is actually completely pluggable under the hood.  What do you think about expanding it so it can do non-obfuscated encryption if desired?
>> >
>> > This would be incredibly easy to add.
>> Karl,
>> How do we know that your commentary isn't in bad faith? Textbook
>> disruption techniques. Please share your rationale for questioning my
>> rationale.
>> Just kidding,
>> -Travis
> Thanks for the joke, Travis.
> Yeah, don't trust me, I'm messed up in the head from my fears and experiences.  It's nice to read your quote that answered part of your question.
> I composed a couple emails that answered more as I saw them, but honestly I was scared to send them, I'm so sorry.
> We need to build, share, and use stuff like oramfs more.  I don't know what to say to cause that.

The development, open distribution, and use of tools like ORAM-FS is important.

Here's where I'm at;

A frame; just one example of the differences between windows' early
NTFS file encryption and 'TrueCrypt''s approach. In NTFS the structure
of the filesystem was not encrypted, so an adversary could see all the
filenames and metadata but no content. In a TrueCrypt volume an
adversary has an opaque blob.

An adversary can look at r/w access to a TC-like blob (a non-ORAM
encrypted FS) and determine what filesystem is in use, then the
attacker might guess at the boundaries of individual files, determine
the specific implementation of the filesystem (a specific version),
the Operating System writing to it, and when some typical files are
being written to or read from. If you don't hook any commodity
software up to the ORAM-FS then the attacker can probably at most
glean the filesystem type and the boundaries of individual files.
Depending on the filesystem they may also recover more structural

I don't see a clear benefit when the files being r/w'd are a variety
that your attacker can't predict (a mix of non-standardized mission
specific artifacts). But I see an advantage if they can.

It looks like access patterns are really useful when the domain of the
data is constrained (in structure and type, or perhaps the access
domain (e.g. search)); e.g. medical records and emails.

The ORAM topic is fresh to me, maybe it's time to do a deep dive on
the academic work. Happy for other examples or pointers to content
that might help.


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