From 120c3bf72f46a125695b3f9104943a25492010e4 Mon Sep 17 00:00:00 2001
From: jvoisin <julien.voisin@dustri.org>
Date: Tue, 19 Jun 2018 23:39:06 +0200
Subject: [PATCH] Improve a bit our threat model
---
doc/threat_model.md | 40 +++++++++++++++++++++++-----------------
1 file changed, 23 insertions(+), 17 deletions(-)
diff --git a/doc/threat_model.md b/doc/threat_model.md
index 963a3ee..26e3741 100644
--- a/doc/threat_model.md
+++ b/doc/threat_model.md
@@ -1,5 +1,6 @@
Threat Model
============
+
The Metadata Anonymisation Toolkit 2 adversary has a number
of goals, capabilities, and counter-attack types that can be
used to guide us towards a set of requirements for the MAT2.
@@ -13,17 +14,18 @@ Mat only removes standard metadata from your files, it does _not_:
- anonymise their content (the substance and the form)
- handle watermarking
- - handle steganography
+ - handle steganography nor homoglyphs
- handle stylometry
- handle any non-standard metadata field/system
If you really want to be anonymous format that does not contain any
metadata, or better : use plain-text ASCII without trailing spaces.
-And as usual, think before clicking.
+
+And as usual, think twice before clicking.
Adversary
-------------
+---------
* Goals:
@@ -40,17 +42,18 @@ Adversary
to directly identify the author and/or source, his next
goal is to determine the source of the equipment used
to produce, copy, and transmit the document. This can
- include the model of camera used to take a photo, or
- which software was used to produce an office document.
+ include the model of camera used to take a photo or a film,
+ which software was used to produce an office document, …
* Adversary Capabilities - Positioning
+
- The adversary created the document specifically for this
user. This is the strongest position for the adversary to
have. In this case, the adversary is capable of inserting
arbitrary, custom watermarks specifically for tracking
- the user. In general, MAT cannot defend against this
- adversary, but we list it for completeness.
+ the user. In general, MAT2 cannot defend against this
+ adversary, but we list it for completeness' sake.
- The adversary created the document for a group of users.
In this case, the adversary knows that they attempted to
@@ -58,30 +61,33 @@ Adversary
or may not have watermarked the document for these
users, but they certainly know the format used.
- - The adversary did not create the document, the weakest
- position for the adversary to have. The file format is (most of the time)
- standard, nothing custom is added: MAT
- should be able to remove all meta-information from the
- file.
+ - The adversary did not create the document, the weakest
+ position for the adversary to have. The file format is
+ (most of the time) standard, nothing custom is added:
+ MAT2 must be able to remove all metadata from the file.
+
Requirements
----------------
+------------
* Processing
- - The MAT2 *should* avoid interactions with information.
+
+ - MAT2 *should* avoid interactions with information.
Its goal is to remove metadata, and the user is solely
responsible for the information of the file.
- - The MAT2 *must* warn when encountering an unknown
+ - MAT2 *must* warn when encountering an unknown
format. For example, in a zipfile, if MAT encounters an
unknown format, it should warn the user, and ask if the
file should be added to the anonymised archive that is
produced.
- - The MAT2 *must* not add metadata, since its purpose is to
+ - MAT2 *must* not add metadata, since its purpose is to
anonymise files: every added items of metadata decreases
anonymity.
- - The MAT2 *should* handle unknown/hidden metadata fields,
+ - MAT2 *should* handle unknown/hidden metadata fields,
like proprietary extensions of open formats.
+ - MAT2 *must not* fail silently. Upon failure,
+ MAT2 *must not* modify the file in any way.
--
GitLab