diff options
Diffstat (limited to 'web/blog')
| -rw-r--r-- | web/blog/.skip-subtree | 1 | ||||
| -rw-r--r-- | web/blog/default.nix | 59 | ||||
| -rw-r--r-- | web/blog/fragments.nix | 96 | ||||
| -rw-r--r-- | web/blog/posts.nix | 57 | ||||
| -rw-r--r-- | web/blog/posts/best-tools.md | 160 | ||||
| -rw-r--r-- | web/blog/posts/emacs-is-underrated.md | 233 | ||||
| -rw-r--r-- | web/blog/posts/make-object-t-again.md | 98 | ||||
| -rw-r--r-- | web/blog/posts/nixery-layers.md | 272 | ||||
| -rw-r--r-- | web/blog/posts/nsa-zettabytes.md | 93 | ||||
| -rw-r--r-- | web/blog/posts/reversing-watchguard-vpn.md | 158 | ||||
| -rw-r--r-- | web/blog/posts/sick-in-sweden.md | 26 | ||||
| -rw-r--r-- | web/blog/posts/the-smu-problem.md | 151 |
12 files changed, 0 insertions, 1404 deletions
diff --git a/web/blog/.skip-subtree b/web/blog/.skip-subtree deleted file mode 100644 index e7fa50d49bdd..000000000000 --- a/web/blog/.skip-subtree +++ /dev/null @@ -1 +0,0 @@ -Subdirectories contain blog posts and static assets only diff --git a/web/blog/default.nix b/web/blog/default.nix deleted file mode 100644 index d2f04aaea574..000000000000 --- a/web/blog/default.nix +++ /dev/null @@ -1,59 +0,0 @@ -# This creates the static files that make up my blog from the Markdown -# files in this repository. -# -# All blog posts are rendered from Markdown by cheddar. -{ depot, lib, ... }@args: - -with depot.nix.yants; - -let - inherit (builtins) filter hasAttr map; - - # Type definition for a single blog post. - post = struct "blog-post" { - key = string; # - title = string; - date = int; - - # Path to the Markdown file containing the post content. - content = path; - - # Should this post be included in the index? (defaults to true) - listed = option bool; - - # Is this a draft? (adds a banner indicating that the link should - # not be shared) - draft = option bool; - - # Previously each post title had a numeric ID. For these numeric - # IDs, redirects are generated so that old URLs stay compatible. - oldKey = option string; - }; - - posts = list post (import ./posts.nix); - fragments = import ./fragments.nix args; - - rendered = depot.third_party.runCommandNoCC "tazjins-blog" {} '' - mkdir -p $out - - ${lib.concatStringsSep "\n" (map (post: - "cp ${fragments.renderPost post} $out/${post.key}.html" - ) posts)} - ''; - - includePost = post: !(fragments.isDraft post) && !(fragments.isUnlisted post); -in { - inherit post rendered; - static = ./static; - - # Only include listed posts - posts = filter includePost posts; - - # Generate embeddable nginx configuration for redirects from old post URLs - oldRedirects = lib.concatStringsSep "\n" (map (post: '' - location ~* ^(/en)?/${post.oldKey} { - # TODO(tazjin): 301 once this works - return 302 https://tazj.in/blog/${post.key}; - } - '') (filter (hasAttr "oldKey") posts)); -} diff --git a/web/blog/fragments.nix b/web/blog/fragments.nix deleted file mode 100644 index 18416e4c4d29..000000000000 --- a/web/blog/fragments.nix +++ /dev/null @@ -1,96 +0,0 @@ -# This file defines various fragments of the blog, such as the header -# and footer, as functions that receive arguments to be templated into -# them. -# -# An entire post is rendered by `renderPost`, which assembles the -# fragments together in a runCommand execution. -# -# The post index is generated by //web/homepage, not by this code. -{ depot, lib, ... }: - -let - inherit (builtins) filter map hasAttr replaceStrings toFile; - inherit (depot.third_party) runCommandNoCC writeText; - - # Generate a post list for all listed, non-draft posts. - isDraft = post: (hasAttr "draft" post) && post.draft; - isUnlisted = post: (hasAttr "listed" post) && !post.listed; - - escape = replaceStrings [ "<" ">" "&" "'" ] [ "<" ">" "&" "'" ]; - - header = title: '' - <!DOCTYPE html> - <head> - <meta charset="utf-8"> - <meta name="viewport" content="width=device-width, initial-scale=1"> - <meta name="description" content="tazjin's blog"> - <link rel="stylesheet" type="text/css" href="/static/tazjin.css" media="all"> - <link rel="icon" type="image/webp" href="/static/favicon.webp"> - <link rel="alternate" type="application/rss+xml" title="RSS-Feed" href="/rss.xml"> - <title>tazjin's blog: ${escape title}</title> - </head> - <body class="light"> - <header> - <h1><a class="blog-title" href="/">tazjin's interblag</a> </h1> - <hr> - </header> - ''; - - footer = '' - <hr> - <footer> - <p class="footer"> - <a class="uncoloured-link" href="https://tazj.in">homepage</a> - | - <a class="uncoloured-link" href="https://git.tazj.in/about">code</a> - | - <a class="uncoloured-link" href="https://twitter.com/tazjin">twitter</a> - </p> - <p class="lod">ಠ_ಠ</p> - </footer> - </body> - ''; - - draftWarning = toFile "draft.html" '' - <p class="cheddar-callout cheddar-warning"> - <b>Note:</b> This post is a <b>draft</b>! Please do not share - the link to it without asking me first. - </p> - <hr> - ''; - - unlistedWarning = toFile "unlisted.html" '' - <p class="cheddar-callout cheddar-warning"> - <b>Note:</b> This post is <b>unlisted</b>! Please do not share - the link to it without asking me first. - </p> - <hr> - ''; - - renderPost = post: runCommandNoCC "${post.key}.html" {} '' - cat ${toFile "header.html" (header post.title)} > $out - - # Write the post title & date - echo '<article><h2 class="inline">${escape post.title}</h2>' >> $out - echo '<aside class="date">' >> $out - date --date="@${toString post.date}" '+%Y-%m-%d' >> $out - echo '</aside>' >> $out - - ${ - # Add a warning to draft/unlisted posts to make it clear that - # people should not share the post. - - if (isDraft post) then "cat ${draftWarning} >> $out" - else if (isUnlisted post) then "cat ${unlistedWarning} >> $out" - else "# Your ads could be here?" - } - - # Write the actual post through cheddar's about-filter mechanism - cat ${post.content} | ${depot.tools.cheddar}/bin/cheddar --about-filter ${post.content} >> $out - echo '</article>' >> $out - - cat ${toFile "footer.html" footer} >> $out - ''; -in { - inherit renderPost isDraft isUnlisted; -} diff --git a/web/blog/posts.nix b/web/blog/posts.nix deleted file mode 100644 index b43598d01358..000000000000 --- a/web/blog/posts.nix +++ /dev/null @@ -1,57 +0,0 @@ -# This file defines all the blog posts. -[ - { - key = "emacs-is-underrated"; - title = "Emacs is the most underrated tool"; - date = 1581286656; - content = ./posts/emacs-is-underrated.md; - draft = true; - } - { - key = "best-tools"; - title = "tazjin's best tools"; - date = 1576800001; - content = ./posts/best-tools.md; - } - { - key = "nixery-layers"; - title = "Nixery: Improved Layering Design"; - date = 1565391600; - content = ./posts/nixery-layers.md; - } - { - key = "reversing-watchguard-vpn"; - title = "Reverse-engineering WatchGuard Mobile VPN"; - date = 1486830338; - content = ./posts/reversing-watchguard-vpn.md; - oldKey = "1486830338"; - } - { - key = "make-object-t-again"; - title = "Make Object <T> Again!"; - date = 1476807384; - content = ./posts/make-object-t-again.md; - oldKey = "1476807384"; - } - { - key = "the-smu-problem"; - title = "The SMU-problem of messaging apps"; - date = 1450354078; - content =./posts/the-smu-problem.md; - oldKey = "1450354078"; - } - { - key = "sick-in-sweden"; - title = "Being sick in Sweden"; - date = 1423995834; - content = ./posts/sick-in-sweden.md; - oldKey = "1423995834"; - } - { - key = "nsa-zettabytes"; - title = "The NSA's 5 zettabytes of data"; - date = 1375310627; - content = ./posts/nsa-zettabytes.md; - oldKey = "1375310627"; - } -] diff --git a/web/blog/posts/best-tools.md b/web/blog/posts/best-tools.md deleted file mode 100644 index e4bad8f4cd07..000000000000 --- a/web/blog/posts/best-tools.md +++ /dev/null @@ -1,160 +0,0 @@ -In the spirit of various other "Which X do you use?"-pages I thought it would be -fun to have a little post here that describes which tools I've found to work -well for myself. - -When I say "tools" here, it's not about software - it's about real, physical -tools! - -If something goes on this list that's because I think it's seriously a -best-in-class type of product. - -<!-- markdown-toc start - Don't edit this section. Run M-x markdown-toc-refresh-toc --> -- [Media & Tech](#media--tech) - - [Keyboard](#keyboard) - - [Speakers](#speakers) - - [Headphones](#headphones) - - [Earphones](#earphones) - - [Phone](#phone) -- [Other stuff](#other-stuff) - - [Toothbrush](#toothbrush) - - [Shavers](#shavers) - - [Shoulder bag](#shoulder-bag) - - [Wallet](#wallet) -<!-- markdown-toc end --> - ---------- - -# Media & Tech - -## Keyboard - -The best keyboard that money will buy you at the moment is the [Kinesis -Advantage][advantage]. There's a variety of contoured & similarly shaped -keyboards on the market, but the Kinesis is the only one I've tried that has -properly implemented the keywell concept. - -I struggle with RSI issues and the Kinesis actually makes it possible for me to -type for longer periods of time, which always leads to extra discomfort on -laptop keyboards and such. - -Honestly, the Kinesis is probably the best piece of equipment on this entire -list. I own several of them and there will probably be more in the future. They -last forever and your wrists will thank you in the future, even if you do not -suffer from RSI yet. - -[advantage]: https://kinesis-ergo.com/shop/advantage2/ - -## Speakers - -The speakers that I've hooked up to my audio setup (including both record player -& Chromecast / TV) are the [Teufel Motiv 2][motiv-2]. I've had these for over a -decade and they're incredibly good, but unfortunately Teufel no longer makes -them. - -It's possible to grab a pair on eBay occasionally, so keep an eye out if you're -interested! - -[motiv-2]: https://www.teufelaudio.com/uk/pc/motiv-2-p167.html - -## Headphones - -I use the [Bose QC35][qc35] (note: link goes to a newer generation than the one -I own) for their outstanding noise cancelling functionality and decent sound. - -When I first bought them I didn't expect them to end up on this list as the -firmware had issues that made them only barely usable, but Bose has managed to -iron these problems out over time. - -I avoid using Bluetooth when outside and fortunately the QC35 come with an -optional cable that you can plug into any good old 3.5mm jack. - -[qc35]: https://www.bose.co.uk/en_gb/products/headphones/over_ear_headphones/quietcomfort-35-wireless-ii.html - -### Earphones - -Actually, to follow up on the above - most of the time I'm not using (over-ear) -headphones, but (in-ear) earphones - specifically the (**wired!!!**) [Apple -EarPods][earpods]. - -Apple will probably stop selling these soon because they've gotten into the -habit of cancelling all of their good products, so I have a stash of these -around. You will usually find no fewer than 3-4 of them lying around in my -flat. - -[earpods]: https://www.apple.com/uk/shop/product/MNHF2ZM/A/earpods-with-35mm-headphone-plug - -## Phone - -The best phone I have used in recent years is the [iPhone SE][se]. It was the -*last* phone that had a reasonable size (up to 4") *and* a 3.5mm headphone jack. - -Unfortunately, it runs iOS. Despite owning a whole bunch of SEs, I have finally -moved on to an Android phone that is only moderately larger (still by an -annoying amount), but does at least have a headphone jack: The [Samsung Galaxy -S10e][s10e]. - -It has pretty good hardware and I can almost reach 70% of the screen, which is -better than other phones out there right now. Unfortunately it runs Samsung's -impossible-to-remove bloatware on top of Android, but that is still less -annoying to use than iOS. - -QUESTION: This is the only item on this list for which I am actively seeking a -replacement, so if you have any tips about new phones that might fit these -criteria that I've missed please let me know! - -[se]: https://en.wikipedia.org/wiki/IPhone_SE -[s10e]: https://www.phonearena.com/phones/Samsung-Galaxy-S10e_id11114 - -# Other stuff - -## Toothbrush - -The [Philips Sonicare][sonicare] (note: link goes to a newer generation than -mine) is excellent and well worth its money. - -I've had it for a few years and whereas I occasionally had minor teeth issues -before, they seem to be mostly gone now. According to my dentist the state of my -teeth is now usually pretty good and I draw a direct correlation back to this -thing. - -The newer generations come with flashy features like apps and probably more -LEDs, but I suspect that those can just be ignored. - -[sonicare]: https://www.philips.co.uk/c-m-pe/electric-toothbrushes - -## Shavers - -The [Philipps SensoTouch 3D][sensotouch] is excellent. Super-comfortable close -face shave in no time and leaves absolutely no mess around, as far as I can -tell! I've had this for ~5 years and it's not showing any signs of aging yet. - -Another bonus is that its battery time is effectively infinite. I've never had -to worry when bringing it on a longer trip! - -[sensotouch]: https://www.philips.co.uk/c-p/1250X_40/norelco-sensotouch-3d-wet-and-dry-electric-razor-with-precision-trimmer - -## Shoulder bag - -When I moved to London I wanted to stop using backpacks most of the time, as -those are just annoying to deal with when commuting on the tube. - -To work around this I wanted a good shoulder bag with a vertical format (to save -space), but it turned out that there's very few of those around that reach any -kind of quality standard. - -The one I settled on is the [Waterfield Muzetto][muzetto] leather bag. It's one -of those things that comes with a bit of a price tag attached, but it's well -worth it! - -[muzetto]: https://www.sfbags.com/collections/shoulder-messenger-bags/products/muzetto-leather-bag - -## Wallet - -My wallet is the [Bellroy Slim Sleeve][slim-sleeve]. I don't carry cash unless -I'm attending an event in Germany and this wallet fits that lifestyle perfectly. - -It's near indestructible, looks great, is very slim and fits a ton of cards, -business cards, receipts and whatever else you want to be lugging around with -you! - -[slim-sleeve]: https://bellroy.com/products/slim-sleeve-wallet/default/charcoal diff --git a/web/blog/posts/emacs-is-underrated.md b/web/blog/posts/emacs-is-underrated.md deleted file mode 100644 index afb8dc889e53..000000000000 --- a/web/blog/posts/emacs-is-underrated.md +++ /dev/null @@ -1,233 +0,0 @@ -TIP: Hello, and thanks for offering to review my draft! This post -intends to convey to people what the point of Emacs is. Not to convert -them to use it, but at least with opening their minds to the -possibility that it might contain valuable things. I don't know if I'm -on track in the right direction, and your input will help me figure it -out. Thanks! - -TODO(tazjin): Restructure sections: Intro -> Introspectability (and -story) -> text-based UIs (which lead to fluidity, muscle memory across -programs and "translatability" of workflows) -> Outro. It needs more -flow! - -TODO(tazjin): Highlight more that it's not about editing: People can -derive useful things from Emacs by just using magit/org/notmuch/etc.! - -TODO(tazjin): Note that there's value in trying Emacs even if people -don't end up using it, similar to how learning languages like Lisp or -Haskell helps grow as a programmer even without using them day-to-day. - -*Real post starts below!* - ---------- - -There are two kinds of people: Those who use Emacs, and those who -think it is a text editor. This post is aimed at those in the second -category. - -Emacs is the most critical piece of software I run. My [Emacs -configuration][emacs-config] has steadily evolved for almost a decade. -Emacs is my window manager, mail client, terminal, git client, -information management system and - perhaps unsurprisingly - text -editor. - -Before going into why I chose to invest so much into this program, -follow me along on a little thought experiment: - ----------- - -Lets say you use a proprietary spreadsheet program. You find that -there are features in it that *almost, but not quite* do what you -want. - -What can you do? You can file a feature request to the company that -makes it and hope they listen, but for the likes of Apple and -Microsoft chances are they won't and there is nothing you can do. - -Let's say you are also running an open-source program for image -manipulation. You again find that some of its features are subtly -different from what you would want them to do. - -Things look a bit different this time - after all, the program is -open-source! You can go and fetch its source code, figure out its -internal structure and wrangle various layers of code into submission -until you find the piece that implements the functionality you want to -change. If you know the language it is written in; you can modify the -feature. - -Now all that's left is figuring out its build system[^1], building and -installing it and moving over to the new version. - -Realistically you are not going to do this much in the real world. The -friction to contributing to projects, especially complex ones, is -often quite high. For minor inconveniences, you might often find -yourself just shrugging and working around them. - -What if it didn't have to be this way? - -------------- - -One of the core properties of Emacs is that it is *introspective* and -*self-documenting*. - -For example: A few years ago, I had just switched over to using -[EXWM][], the Emacs X Window Manager. To launch applications I was -using an Emacs program called Helm that let me select installed -programs interactively and press <kbd>RET</kbd> to execute them. - -This was very useful - until I discovered that if I tried to open a -second terminal window, it would display an error: - - Error: urxvt is already running - -Had this been dmenu, I might have had to go through the whole process -described above to fix the issue. But it wasn't dmenu - it was an -Emacs program, and I did the following things: - -1. I pressed <kbd>C-h k</kbd>[^2] (which means "please tell me what - the following key does"), followed by <kbd>s-d</kbd> (which was my - keybinding for launching programs). - -2. Emacs displayed a new buffer saying, roughly: - - ``` - s-d runs the command helm-run-external-command (found in global-map), - which is an interactive autoloaded compiled Lisp function in - ‘.../helm-external.el’. - - It is bound to s-d. - ``` - - I clicked on the filename. - -3. Emacs opened the file and jumped to the definition of - `helm-run-external-command`. After a few seconds of reading through - the code, I found this snippet: - - ```lisp - (if (get-process proc) - (if helm-raise-command - (shell-command (format helm-raise-command real-com)) - (error "Error: %s is already running" real-com)) - ;; ... the actual code to launch programs followed below ... - ) - ``` - -4. I deleted the outer if-expression which implemented the behaviour I - didn't want, pressed <kbd>C-M-x</kbd> to reload the code and saved - the file. - -The whole process took maybe a minute, and the problem was now gone. - -Emacs isn't just "open-source", it actively encourages the user to -modify it, discover what to modify and experiment while it is running. - -In some sense it is like the experience of the old Lisp machines, a -paradigm that we have completely forgotten. - ---------------- - -Circling back to my opening statement: If Emacs is not a text editor, -then what *is* it? - -The Emacs website says this: - -> [Emacs] is an interpreter for Emacs Lisp, a dialect of the Lisp -> programming language with extensions to support text editing - -The core of Emacs implements the language and the functionality needed -to evaluate and run it, as well as various primitives for user -interface construction such as buffers, windows and frames. - -Every other feature of Emacs is implemented *in Emacs Lisp*. - -The Emacs distribution ships with rudimentary text editing -functionality (and some language-specific support for the most popular -languages), but it also brings with it two IRC clients, a Tetris -implementation, a text-mode web browser, [org-mode][] and many other -tools. - -Outside of the core distribution there is a myriad of available -programs for Emacs: [magit][] (the famous git porcelain), text-based -[HTTP clients][], even interactive [Kubernetes frontends][k8s]. - -What all of these tools have in common is that they use text-based -user interfaces (UI elements like images are used only sparingly in -Emacs), and that they can be introspected and composed like everything -else in Emacs. - -If magit does not expose a git flag I need, it's trivial to add. If I -want a keybinding to jump from a buffer showing me a Kubernetes pod to -a magit buffer for the source code of the container, it only takes a -few lines of Emacs Lisp to implement. - -As proficiency with Emacs Lisp ramps up, the environment becomes -malleable like clay and evolves along with the user's taste and needs. -Muscle memory learned for one program translates seamlessly to others, -and the overall effect is an improvement in *workflow fluidity* that -is difficult to overstate. - -Also, workflows based on Emacs are *stable*. Moving my window -management to Emacs has meant that I'm not subject to the whim of some -third-party developer changing my window layouting features (as they -often do on MacOS). - -To illustrate this: Emacs has development history back to the 1970s, -continuous git history that survived multiple VCS migrations [since -1985][first-commit] (that's 22 years before git itself was released!) -and there is code[^3] implementing interactive functionality that has -survived unmodified in Emacs *since then*. - ---------------- - -Now, what is the point of this post? - -I decided to write this after a recent [tweet][] by @IanColdwater (in -the context of todo-management apps): - -> The fact that it's 2020 and the most viable answer to this appears -> to be Emacs might be the saddest thing I've ever heard - -What bothers me is that people see this as *sad*. Emacs being around -for this long and still being unparalleled for many of the UX -paradigms implemented by its programs is, in my book, incredible - and -not sad. - -How many other paradigms have survived this long? How many other tools -still have fervent followers, amazing [developer tooling][] and a -[vibrant ecosystem][] at this age? - -Steve Yegge [said it best][babel][^5]: Emacs has the Quality Without a -Name. - -What I wish you, the reader, should take away from this post is the -following: - -TODO(tazjin): Figure out what people should take away from this post. -I need to sleep on it. It's something about not dismissing tools just -because of their age, urging them to explore paradigms that might seem -unfamiliar and so on. Ideas welcome. - ---------------- - -[^1]: Wouldn't it be a joy if every project just used Nix? I digress ... -[^2]: These are keyboard shortcuts written in [Emacs Key Notation][ekn]. -[^3]: For example, [functionality for online memes][studly] that - wouldn't be invented for decades to come! -[^4]: ... and some things wrong, but that is an issue for a separate post! -[^5]: And I really *do* urge you to read that post's section on Emacs. - -[emacs-config]: https://git.tazj.in/tree/tools/emacs -[EXWM]: https://github.com/ch11ng/exwm -[helm]: https://github.com/emacs-helm/helm -[ekn]: https://www.gnu.org/software/emacs/manual/html_node/efaq/Basic-keys.html -[org-mode]: https://orgmode.org/ -[magit]: https://magit.vc -[HTTP clients]: https://github.com/pashky/restclient.el -[k8s]: https://github.com/jypma/kubectl -[first-commit]: http://git.savannah.gnu.org/cgit/emacs.git/commit/?id=ce5584125c44a1a2fbb46e810459c50b227a95e2 -[studly]: http://git.savannah.gnu.org/cgit/emacs.git/commit/?id=47bdd84a0a9d20aab934482a64b84d0db63e7532 -[tweet]: https://twitter.com/IanColdwater/status/1220824466525229056 -[developer tooling]: https://github.com/alphapapa/emacs-package-dev-handbook -[vibrant ecosystem]: https://github.com/emacs-tw/awesome-emacs -[babel]: https://sites.google.com/site/steveyegge2/tour-de-babel#TOC-Lisp diff --git a/web/blog/posts/make-object-t-again.md b/web/blog/posts/make-object-t-again.md deleted file mode 100644 index 420b57c0fde9..000000000000 --- a/web/blog/posts/make-object-t-again.md +++ /dev/null @@ -1,98 +0,0 @@ -A few minutes ago I found myself debugging a strange Java issue related -to Jackson, one of the most common Java JSON serialization libraries. - -The gist of the issue was that a short wrapper using some types from -[Javaslang](http://www.javaslang.io/) was causing unexpected problems: - -```java -public <T> Try<T> readValue(String json, TypeReference type) { - return Try.of(() -> objectMapper.readValue(json, type)); -} -``` - -The signature of this function was based on the original Jackson -`readValue` type signature: - -```java -public <T> T readValue(String content, TypeReference valueTypeRef) -``` - -While happily using my wrapper function I suddenly got an unexpected -error telling me that `Object` is incompatible with the type I was -asking Jackson to de-serialize, which got me to re-evaluate the above -type signature again. - -Lets look for a second at some code that will *happily compile* if you -are using Jackson\'s own `readValue`: - -```java -// This shouldn't compile! -Long l = objectMapper.readValue("\"foo\"", new TypeReference<String>(){}); -``` - -As you can see there we ask Jackson to decode the JSON into a `String` -as enclosed in the `TypeReference`, but assign the result to a `Long`. -And it compiles. And it failes at runtime with -`java.lang.ClassCastException: java.lang.String cannot be cast to java.lang.Long`. -Huh? - -Looking at the Jackson `readValue` implementation it becomes clear -what\'s going on here: - -```java -@SuppressWarnings({ "unchecked", "rawtypes" }) -public <T> T readValue(String content, TypeReference valueTypeRef) - throws IOException, JsonParseException, JsonMappingException -{ - return (T) _readMapAndClose(/* whatever */); -} -``` - -The function is parameterised over the type `T`, however the only place -where `T` occurs in the signature is in the parameter declaration and -the function return type. Java will happily let you use generic -functions and types without specifying type parameters: - -```java -// Compiles fine! -final List myList = List.of(1,2,3); - -// Type is now myList : List<Object> -``` - -Meaning that those parameters default to `Object`. Now in the code above -Jackson also explicitly casts the return value of its inner function -call to `T`. - -What ends up happening is that Java infers the expected return type from -the context of the `readValue` and then happily uses the unchecked cast -to fit that return type. If the type hints of the context aren\'t strong -enough we simply get `Object` back. - -So what\'s the fix for this? It\'s quite simple: - -```java -public <T> T readValue(String content, TypeReference<T> valueTypeRef) -``` - -By also making the parameter appear in the `TypeReference` we \"bind\" -`T` to the type enclosed in the type reference. The cast can then also -safely be removed. - -The cherries on top of this are: - -1. `@SuppressWarnings({ "rawtypes" })` explicitly disables a - warning that would\'ve caught this - -2. the `readValue` implementation using the less powerful `Class` - class to carry the type parameter does this correctly: `public <T> - T readValue(String content, Class<T> valueType)` - -The big question I have about this is *why* does Jackson do it this way? -Obviously the warning did not just appear there by chance, so somebody -must have thought about this? - -If anyone knows what the reason is, I\'d be happy to hear from you. - -PS: Shoutout to David & Lucia for helping me not lose my sanity over -this. diff --git a/web/blog/posts/nixery-layers.md b/web/blog/posts/nixery-layers.md deleted file mode 100644 index 3f25ceadce7b..000000000000 --- a/web/blog/posts/nixery-layers.md +++ /dev/null @@ -1,272 +0,0 @@ -TIP: This blog post was originally published as a design document for -[Nixery][] and is not written in the same style -as other blog posts. - -Thanks to my colleagues at Google and various people from the Nix community for -reviewing this. - ------- - -# Nixery: Improved Layering - -**Authors**: tazjin@ - -**Reviewers**: so...@, en...@, pe...@ - -**Status**: Implemented - -**Last Updated**: 2019-08-10 - -## Introduction - -This document describes a design for an improved image layering method for use -in Nixery. The algorithm [currently used][grhmc] is designed for a slightly -different use-case and we can improve upon it by making use of more of the -available data. - -## Background / Motivation - -Nixery is a service that uses the [Nix package manager][nix] to build container -images (for runtimes such as Docker), that are served on-demand via the -container [registry protocols][]. A demo instance is available at -[nixery.dev][]. - -In practice this means users can simply issue a command such as `docker pull -nixery.dev/shell/git` and receive an image that was built ad-hoc containing a -shell environment and git. - -One of the major advantages of building container images via Nix (as described -for `buildLayeredImage` in [this blog post][grhmc]) is that the -content-addressable nature of container image layers can be used to provide more -efficient caching characteristics (caching based on layer content) than what is -common with Dockerfiles and other image creation methods (caching based on layer -creation method). - -However, this is constrained by the maximum number of layers supported in an -image (125). A naive approach such as putting each included package (any -library, binary, etc.) in its own layer quickly runs into this limitation due to -the large number of dependencies more complex systems tend to have. In addition, -users wanting to extend images created by Nixery (e.g. via `FROM nixery.dev/…`) -share this layer maximum with the created image - limiting extensibility if all -layers are used up by Nixery. - -In theory the layering strategy of `buildLayeredImage` should already provide -good caching characteristics, but in practice we are seeing many images with -significantly more packages than the number of layers configured, leading to -more frequent cache-misses than desired. - -The current implementation of `buildLayeredImage` inspects a graph of image -dependencies and determines the total number of references (direct & indirect) -to any node in the graph. It then sorts all dependencies by this popularity -metric and puts the first `n - 2` (for `n` being the maximum number of layers) -packages in their own layers, all remaining packages in one layer and the image -configuration in the final layer. - -## Design / Proposal - -## (Close-to) ideal layer-layout using more data - -We start out by considering what a close to ideal layout of layers would look -like for a simple use-case. - - - -In this example, counting the total number of references to each node in the -graph yields the following result: - -| pkg | refs | -|-------|------| -| E | 3 | -| D | 2 | -| F | 2 | -| A,B,C | 1 | - -Assuming we are constrained to 4 layers, the current algorithm would yield these layers: - -``` -L1: E -L2: D -L3: F -L4: A, B, C -``` - -The initial proposal for this design is that additional data should be -considered in addition to the total number of references, in particular a -distinction should be made between direct and indirect references. Packages that -are only referenced indirectly should be merged with their parents. - -This yields the following table: - -| pkg | direct | indirect | -|-------|--------|----------| -| E | 3 | 3 | -| D | 2 | 2 | -| F | *1* | 2 | -| A,B,C | 1 | 1 | - -Despite having two indirect references, F is in fact only being referred to -once. Assuming that we have no other data available outside of this graph, we -have no reason to assume that F has any popularity outside of the scope of D. -This might yield the following layers: - -``` -L1: E -L2: D, F -L3: A -L4: B, C -``` - -D and F were grouped, while the top-level references (i.e. the packages -explicitly requested by the user) were split up. - -An assumption is introduced here to justify this split: The top-level packages -is what the user is modifying directly, and those groupings are likely -unpredictable. Thus it is opportune to not group top-level packages in the same -layer. - -This raises a new question: Can we make better decisions about where to split -the top-level? - -## (Even closer to) ideal layering using (even) more data - -So far when deciding layer layouts, only information immediately available in -the build graph of the image has been considered. We do however have much more -information available, as we have both the entire nixpkgs-tree and potentially -other information (such as download statistics). - -We can calculate the total number of references to any derivation in nixpkgs and -use that to rank the popularity of each package. Packages within some percentile -can then be singled out as good candidates for a separate layer. - -When faced with a splitting decision such as in the last section, this data can -aid the decision. Assume for example that package B in the above is actually -`openssl`, which is a very popular package. Taking this into account would -instead yield the following layers: - -``` -L1: E, -L2: D, F -L3: B, -L4: A, C -``` - -## Layer budgets and download size considerations - -As described in the introduction, there is a finite amount of layers available -for each image (the “layer budget”). When calculating the layer distribution, we -might end up with the “ideal” list of layers that we would like to create. Using -our previous example: - -``` -L1: E, -L2: D, F -L3: A -L4: B -L5: C -``` - -If we only have a layer budget of 4 available, something needs to be merged into -the same layer. To make a decision here we could consider only the package -popularity, but there is in fact another piece of information that has not come -up yet: The actual size of the package. - -Presumably a user would not mind downloading a library that is a few kilobytes -in size repeatedly, but they would if it was a 200 megabyte binary instead. - -Conversely if a large binary was successfully cached, but an extremely popular -small library is not, the total download size might also grow to irritating -levels. - -To avoid this we can calculate a merge rating: - - merge_rating(pkg) = popularity_percentile(pkg) × size(pkg.subtree) - -Packages with a low merge rating would be merged together before packages with -higher merge ratings. - -## Implementation - -There are two primary components of the implementation: - -1. The layering component which, given an image specification, decides the image - layers. - -2. The popularity component which, given the entire nixpkgs-tree, calculates the - popularity of packages. - -## Layering component - -It turns out that graph theory’s concept of [dominator trees][] maps reasonably -well onto the proposed idea of separating direct and indirect dependencies. This -becomes visible when creating the dominator tree of a simple example: - - - -Before calculating the dominator tree, we inspect each node and insert extra -edges from the root for packages that match a certain popularity or size -threshold. In this example, G is popular and an extra edge is inserted: - - - -Calculating the dominator tree of this graph now yields our ideal layer -distribution: - - - -The nodes immediately dominated by the root node can now be “harvested” as image -layers, and merging can be performed as described above until the result fits -into the layer budget. - -To implement this, the layering component uses the [gonum/graph][] library which -supports calculating dominator trees. The program is fed with Nix’s -`exportReferencesGraph` (which contains the runtime dependency graph and runtime -closure size) as well as the popularity data and layer budget. It returns a list -of layers, each specifying the paths it should contain. - -Nix invokes this program and uses the output to create a derivation for each -layer, which is then built and returned to Nixery as usual. - -TIP: This is implemented in [`layers.go`][layers.go] in Nixery. The file starts -with an explanatory comment that talks through the process in detail. - -## Popularity component - -The primary issue in calculating the popularity of each package in the tree is -that we are interested in the runtime dependencies of a derivation, not its -build dependencies. - -To access information about the runtime dependency, the derivation actually -needs to be built by Nix - it can not be inferred because Nix does not know -which store paths will still be referenced by the build output. - -However for packages that are cached in the NixOS cache, we can simply inspect -the `narinfo`-files and use those to determine popularity. - -Not every package in nixpkgs is cached, but we can expect all *popular* packages -to be cached. Relying on the cache should therefore be reasonable and avoids us -having to rebuild/download all packages. - -The implementation will read the `narinfo` for each store path in the cache at a -given commit and create a JSON-file containing the total reference count per -package. - -For the public Nixery instance, these popularity files will be distributed via a -GCS bucket. - -TIP: This is implemented in [popcount][] in Nixery. - --------- - -Hopefully this detailed design review was useful to you. You can also watch [my -NixCon talk][talk] about Nixery for a review of some of this, and some demos. - -[Nixery]: https://github.com/google/nixery -[grhmc]: https://grahamc.com/blog/nix-and-layered-docker-images -[Nix]: https://nixos.org/nix -[registry protocols]: https://github.com/opencontainers/distribution-spec/blob/master/spec.md -[nixery.dev]: https://nixery.dev -[dominator trees]: https://en.wikipedia.org/wiki/Dominator_(graph_theory) -[gonum/graph]: https://godoc.org/gonum.org/v1/gonum/graph -[layers.go]: https://github.com/google/nixery/blob/master/builder/layers.go -[popcount]: https://github.com/google/nixery/tree/master/popcount -[talk]: https://www.youtube.com/watch?v=pOI9H4oeXqA diff --git a/web/blog/posts/nsa-zettabytes.md b/web/blog/posts/nsa-zettabytes.md deleted file mode 100644 index f8b326f2fb42..000000000000 --- a/web/blog/posts/nsa-zettabytes.md +++ /dev/null @@ -1,93 +0,0 @@ -I've been reading a few discussions on Reddit about the new NSA data -centre that is being built and stumbled upon [this -post](http://www.reddit.com/r/restorethefourth/comments/1jf6cx/the_guardian_releases_another_leaked_document_nsa/cbe5hnc), -putting its alleged storage capacity at *5 zettabytes*. - -That seems to be a bit much which I tried to explain to that guy, but I -was quickly blocked by the common conspiracy argument that government -technology is somehow far beyond the wildest dreams of us mere mortals - -thus I wrote a very long reply that will most likely never be seen by -anybody. Therefore I've decided to repost it here. - ------------------------------------------------------------------------- - -I feel like I've entered /r/conspiracy. Please have some facts (and do -read them!) - -A one terabyte SSD (I assume that\'s what you meant by flash-drive) -would require 5000000000 of those. That is *five billion* of those flash -drives. Can you visualise how much five billion flash-drives are? - -A single SSD is roughly 2cm\*13cm\*13cm with an approximate weight of -80g. That would make 400 000 metric tons of SSDs, a weight equivalent to -*over one thousand Boeing 747 airplanes*. Even if we assume that they -solder the flash chips directly onto some kind of controller (which also -weighs something), the raw material for that would be completely insane. - -Another visualization: If you stacked 5 billion SSDs on top of each -other you would get an SSD tower that is a hundred thousand kilometres -high, that is equivalent to 2,5 x the equatorial circumference of -*Earth* or 62000 miles. - -The volume of those SSDs would be clocking in at 1690000000 cubic -metres, more than the Empire State building. Are you still with me? - -Lets speak cost. The Samsung SSD that I assume you are referring to will -clock in at \$600, lets assume that the NSA gets a discount when buying -*five billion* of those and gets them at the cheap price of \$250. That -makes 1.25 trillion dollars. That would be a significant chunk of the -current US national debt. - -And all of this is just SSDs to stick into servers and storage units, -which need a whole bunch of other equipment as well to support them - -the cost would probably shoot up to something like 8 trillion dollars if -they were to build this. It would with very high certainty be more than -the annual production of SSDs (I can\'t find numbers on that -unfortunately) and take up *slightly* more space than they have in the -Utah data centre (assuming you\'re not going to tell me that it is in -fact attached to an underground base that goes down to the core of the -Earth). - -Lets look at the \"But the government has better technologies!\" idea. - -Putting aside the fact that the military *most likely* does not have a -secret base on Mars that deals with advanced science that the rest of us -can only dream of, and doing this under the assumption that they do have -this base, lets assume that they build a storage chip that stores 100TB. -This reduces the amount of needed chips to \"just\" 50 million, lets say -they get 10 of those into a server / some kind of specialized storage -unit and we only need 5 million of those specially engineered servers, -with custom connectors, software, chips, storage, most likely also power -sources and whatever - 10 million completely custom units built with -technology that is not available to the market. Google is estimated to -have about a million servers in total, I don\'t know exactly in how many -data centres those are placed but numbers I heard recently said that -it\'s about 40. When Apple assembles a new iPhone model they need -massive factories with thousands of workers and supplies from many -different countries, over several months, to assemble just a few million -units for their launch month. - -You are seriously proposing that the NSA is better than Google and Apple -and the rest of the tech industry, world-wide, combined at designing -*everything* in tech, manufacturing *everything* in tech, without *any* -information about that leaking and without *any* of the science behind -it being known? That\'s not just insane, that\'s outright impossible. - -And we haven\'t even touched upon how they would route the necessary -amounts of bandwidth (crazy insane) to save *the entire internet* into -that data center. - ------------------------------------------------------------------------- - -I\'m not saying that the NSA is not building a data center to store -surveillance information, to have more capacity to spy on people and all -that - I\'m merely making the point that the extent in which conspiracy -sites say they do this vastly overestimates their actual abilities. They -don\'t have magic available to them! Instead of making up insane figures -like that you should focus on what we actually know about their -operations, because using those figures in a debate with somebody who is -responsible for this (and knows what they\'re talking about) will end -with you being destroyed - nobody will listen to the rest of what -you\'re saying when that happens. - -\"Stick to the facts\" is valid for our side as well. diff --git a/web/blog/posts/reversing-watchguard-vpn.md b/web/blog/posts/reversing-watchguard-vpn.md deleted file mode 100644 index f1b779d8d993..000000000000 --- a/web/blog/posts/reversing-watchguard-vpn.md +++ /dev/null @@ -1,158 +0,0 @@ -TIP: WatchGuard has -[responded](https://www.reddit.com/r/netsec/comments/5tg0f9/reverseengineering_watchguard_mobile_vpn/dds6knx/) -to this post on Reddit. If you haven\'t read the post yet I\'d recommend -doing that first before reading the response to have the proper context. - ------------------------------------------------------------------------- - -One of my current client makes use of -[WatchGuard](http://www.watchguard.com/help/docs/fireware/11/en-US/Content/en-US/mvpn/ssl/mvpn_ssl_client-install_c.html) -Mobile VPN software to provide access to the internal network. - -Currently WatchGuard only provides clients for OS X and Windows, neither -of which I am very fond of. In addition an OpenVPN configuration file is -provided, but it quickly turned out that this was only a piece of the -puzzle. - -The problem is that this VPN setup is secured using 2-factor -authentication (good!), but it does not use OpenVPN\'s default -[challenge/response](https://openvpn.net/index.php/open-source/documentation/miscellaneous/79-management-interface.html) -functionality to negotiate the credentials. - -Connecting with the OpenVPN config that the website supplied caused the -VPN server to send me a token to my phone, but I simply couldn\'t figure -out how to supply it back to the server. In a normal challenge/response -setting the token would be supplied as the password on the second -authentication round, but the VPN server kept rejecting that. - -Other possibilities were various combinations of username&password -(I\'ve seen a lot of those around) so I tried a whole bunch, for example -`$password:$token` or even a `sha1(password, token)` - to no avail. - -At this point it was time to crank out -[Hopper](https://www.hopperapp.com/) and see what\'s actually going on -in the official OS X client - which uses OpenVPN under the hood! - -Diving into the client ----------------------- - -The first surprise came up right after opening the executable: It had -debug symbols in it - and was written in Objective-C! - - - -A good first step when looking at an application binary is going through -the strings that are included in it, and the WatchGuard client had a lot -to offer. Among the most interesting were a bunch of URIs that looked -important: - - - -I started with the first one - - %@?action=sslvpn_download&filename=%@&fw_password=%@&fw_username=%@ - -and just curled it on the VPN host, replacing the username and -password fields with bogus data and the filename field with -`client.wgssl` - another string in the executable that looked like a -filename. - -To my surprise this endpoint immediately responded with a GZIPed file -containing the OpenVPN config, CA certificate, and the client -*certificate and key*, which I previously thought was only accessible -after logging in to the web UI - oh well. - -The next endpoint I tried ended up being a bit more interesting still: - - /?action=sslvpn_logon&fw_username=%@&fw_password=%@&style=fw_logon_progress.xsl&fw_logon_type=logon&fw_domain=Firebox-DB - -Inserting the correct username and password into the query parameters -actually triggered the process that sent a token to my phone. The -response was a simple XML blob: - -```xml -<?xml version="1.0" encoding="UTF-8"?> -<resp> - <action>sslvpn_logon</action> - <logon_status>4</logon_status> - <auth-domain-list> - <auth-domain> - <name>RADIUS</name> - </auth-domain> - </auth-domain-list> - <logon_id>441</logon_id> - <chaStr>Enter Your 6 Digit Passcode </chaStr> -</resp> -``` - -Somewhat unsurprisingly that `chaStr` field is actually the challenge -string displayed in the client when logging in. - -This was obviously going in the right direction so I proceeded to the -procedures making use of this string. The first step was a relatively -uninteresting function called `-[VPNController sslvpnLogon]` which -formatted the URL, opened it and checked whether the `logon_status` was -`4` before proceeding with the `logon_id` and `chaStr` contained in the -response. - -*(Code snippets from here on are Hopper\'s pseudo-Objective-C)* - - - -It proceeded to the function `-[VPNController processTokenPrompt]` which -showed the dialog window into which the user enters the token, sent it -off to the next URL and checked the `logon_status` again: - -(`r12` is the reference to the `VPNController` instance, i.e. `self`). - - - -If the `logon_status` was `1` (apparently \"success\" here) it proceeded -to do something quite interesting: - - - -The user\'s password was overwritten with the (verified) OTP token - -before OpenVPN had even been started! - -Reading a bit more of the code in the subsequent -`-[VPNController doLogin]` method revealed that it shelled out to -`openvpn` and enabled the management socket, which makes it possible to -remotely control an `openvpn` process by sending it commands over TCP. - -It then simply sent the username and the OTP token as the credentials -after configuring OpenVPN with the correct config file: - - - -... and the OpenVPN connection then succeeds. - -TL;DR ------ - -Rather than using OpenVPN\'s built-in challenge/response mechanism, the -WatchGuard client validates user credentials *outside* of the VPN -connection protocol and then passes on the OTP token, which seems to be -temporarily in a \'blessed\' state after verification, as the user\'s -password. - -I didn\'t check to see how much verification of this token is performed -(does it check the source IP against the IP that performed the challenge -validation?), but this certainly seems like a bit of a security issue - -considering that an attacker on the same network would, if they time the -attack right, only need your username and 6-digit OTP token to -authenticate. - -Don\'t roll your own security, folks! - -Bonus ------ - -The whole reason why I set out to do this is so I could connect to this -VPN from Linux, so this blog post wouldn\'t be complete without a -solution for that. - -To make this process really easy I\'ve written a [little -tool](https://github.com/tazjin/watchblob) that performs the steps -mentioned above from the CLI and lets users know when they can -authenticate using their OTP token. diff --git a/web/blog/posts/sick-in-sweden.md b/web/blog/posts/sick-in-sweden.md deleted file mode 100644 index 0c43c5832d73..000000000000 --- a/web/blog/posts/sick-in-sweden.md +++ /dev/null @@ -1,26 +0,0 @@ -I\'ve been sick more in the two years in Sweden than in the ten years -before that. - -Why? I have a theory about it and after briefly discussing it with one -of my roommates (who is experiencing the same thing) I\'d like to share -it with you: - -Normally when people get sick, are coughing, have a fever and so on they -take a few days off from work and stay at home. The reasons are twofold: -You want to rest a bit in order to get rid of the disease and you want -to *avoid infecting your co-workers*. - -In Sweden people will drag themselves into work anyways, because of a -concept called the -[karensdag](https://www.forsakringskassan.se/wps/portal/sjukvard/sjukskrivning_och_sjukpenning/karensdag_och_forstadagsintyg). -The TL;DR of this is \'if you take days off sick you won\'t get paid for -the first day, and only 80% of your salary on the remaining days\'. - -Many people are not willing to take that financial hit. In combination -with Sweden\'s rather mediocre healthcare system you end up constantly -being surrounded by sick people, not just in your own office but also on -public transport and basically all other public places. - -Oh and the best thing about this? Swedish politicians [often ignore -this](https://www.aftonbladet.se/nyheter/article10506886.ab) rule and -just don\'t report their sick days. Nice. diff --git a/web/blog/posts/the-smu-problem.md b/web/blog/posts/the-smu-problem.md deleted file mode 100644 index f411e3116046..000000000000 --- a/web/blog/posts/the-smu-problem.md +++ /dev/null @@ -1,151 +0,0 @@ -After having tested countless messaging apps over the years, being -unsatisfied with most of them and finally getting stuck with -[Telegram](https://telegram.org/) I have developed a little theory about -messaging apps. - -SMU stands for *Security*, *Multi-Device* and *Usability*. Quite like -the [CAP-theorem](https://en.wikipedia.org/wiki/CAP_theorem) I believe -that you can - using current models - only solve two out of three things -on this list. Let me elaborate what I mean by the individual points: - -**Security**: This is mainly about encryption of messages, not so much -about hiding identities to third-parties. Commonly some kind of -asymmetric encryption scheme. Verification of keys used must be possible -for the user. - -**Multi-Device**: Messaging-app clients for multiple devices, with -devices being linked to the same identifier, receiving the same messages -and being independent of each other. A nice bonus is also an open -protocol (like Telegram\'s) that would let people write new clients. - -**Usability**: Usability is a bit of a broad term, but what I mean by it -here is handling contacts and identities. It should be easy to create -accounts, give contact information to people and have everything just -work in a somewhat automated fashion. - -Some categorisation of popular messaging apps: - -**SU**: Threema - -**MU**: Telegram, Google Hangouts, iMessage, Facebook Messenger - -**SM**: -[Signal](https://gist.github.com/TheBlueMatt/d2fcfb78d29faca117f5) - -*Side note: The most popular messaging app - WhatsApp - only scores a -single letter (U). This makes it completely uninteresting to me.* - -Let\'s talk about **SM** - which might contain the key to solving SMU. -Two approaches are interesting here. - -The single key model --------------------- - -In Signal there is a single identity key which can be used to register a -device on the server. There exists a process for sharing this identity -key from a primary device to a secondary one, so that the secondary -device can register itself (see the link above for a description). - -This *almost* breaks M because there is still a dependence on a primary -device and newly onboarded devices can not be used to onboard further -devices. However, for lack of a better SM example I\'ll give it a pass. - -The other thing it obviously breaks is U as the process for setting it -up is annoying and having to rely on the primary device is a SPOF (there -might be a way to recover from a lost primary device, but I didn\'t find -any information so far). - -The multiple key model ----------------------- - -In iMessage every device that a user logs into creates a new key pair -and submits its public key to a per-account key pool. Senders fetch all -available public keys for a recipient and encrypt to all of the keys. - -Devices that join can catch up on history by receiving it from other -devices that use its public key. - -This *almost* solves all of SMU, but its compliance with S breaks due to -the fact that the key pool is not auditable, and controlled by a -third-party (Apple). How can you verify that they don\'t go and add -another key to your pool? - -A possible solution -------------------- - -Out of these two approaches I believe the multiple key one looks more -promising. If there was a third-party handling the key pool but in a way -that is verifiable, transparent and auditable that model could be used -to solve SMU. - -The technology I have been thinking about for this is some kind of -blockchain model and here\'s how I think it could work: - -1. Bob installs the app and begins onboarding. The first device - generates its keypair, submits the public key and an account - creation request. - -2. Bob\'s account is created on the messaging apps\' servers and a - unique identifier plus the fingerprint of the first device\'s public - key is written to the chain. - -3. Alice sends a message to Bob, her device asks the messaging service - for Bob\'s account\'s identity and public keys. Her device verifies - the public key fingerprint against the one in the blockchain before - encrypting to it and sending the message. - -4. Bob receives Alice\'s message on his first device. - -5. Bob logs in to his account on a second device. The device generates - a key pair and sends the public key to the service, the service - writes it to the blockchain using its identifier. - -6. The messaging service requests that Bob\'s first device signs the - second device\'s key and triggers a simple confirmation popup. - -7. Bob confirms the second device on his first device. It signs the key - and writes the signature to the chain. - -8. Alice sends another message, her device requests Bob\'s current keys - and receives the new key. It verifies that both the messaging - service and one of Bob\'s older devices have confirmed this key in - the chain. It encrypts the message to both keys and sends it on. - -9. Bob receives Alice\'s message on both devices. - -After this the second device can request conversation history from the -first one to synchronise old messages. - -Further devices added to an account can be confirmed by any of the -devices already in the account. - -The messaging service could not add new keys for an account on its own -because it does not control any of the private keys confirmed by the -chain. - -In case all devices were lost, the messaging service could associate the -account with a fresh identity in the block chain. Message history -synchronisation would of course be impossible. - -Feedback welcome ----------------- - -I would love to hear some input on this idea, especially if anyone knows -of an attempt to implement a similar model already. Possible attack -vectors would also be really interesting. - -Until something like this comes to fruition, I\'ll continue using -Telegram with GPG as the security layer when needed. - -**Update:** WhatsApp has launched an integration with the Signal guys -and added their protocol to the official WhatsApp app. This means -WhatsApp now firmly sits in the SU-category, but it still does not solve -this problem. - -**Update 2:** Facebook Messenger has also integrated with Signal, but -their secret chats do not support multi-device well (it is Signal -afterall). This means it scores either SU or MU depending on which mode -you use it in. - -An interesting service I have not yet evaluated properly is -[Matrix](http://matrix.org/). |