Ciro Santilli (@cirosantilli) - undefined articles

 Home  Updated 2025-03-25  +Created 1970-01-01

Check out: OurBigBook.com, the best way to publish your scientific knowledge. It's an open source note taking system that can publish from lightweight markup files in your computer both to a multi-user mind melding dynamic website, or as a static website. It's like Wikipedia + GitHub + Stack Overflow + Obsidian mashed up. Source code: github.com/ourbigbook/ourbigbook.

Sponsor me to work on this project. For 200k USD I will quit my job or not get a new job and work on OurBigBook full time for a second year to try and kickstart The Higher Education Revolution. Status: ~44k / 200k USD. At 2M USD I retire and work on open STEM forever. How to donate: Section "Sponsor Ciro Santilli's work on OurBigBook.com".

I first quit my job 1st June 2024 to work on the project for 1 year after I reached my initial 100k goal mostly via a 1000 Monero donation. For a second follow up year, I increased my requirement to 200k USD to give me more peace of mind. So the total donation so far is 144k, and if I reach a total of 300k USD, then I'll work on the project for a second year. A second year greatly improve chances of success: year one I improved my tech, year two I come guns blazing to solve courses and expand further.

Mission: to live in a world where you can learn university-level mathematics, physics, chemistry, biology and engineering from perfect free open source books that anyone can write to get famous. More rationale: Section "OurBigBook.com"

Explaining things is my superpower, e.g. I was top user #39 on Stack Overflow in 2023^[ref]^[ref] and I have a few 1k+ star educational GitHub repositories^[ref]^[ref]^[ref]^[ref]. Now I want to bring that level of awesomeness to masters level Mathematics and Physics. But I can't do it alone! So I created OurBigBook.com to allow everyone to work together towards the perfect book of everything.

My life's goal is to bring hardcore university-level STEM open educational content to all ages. Sponsor me at github.com/sponsors/cirosantilli starting from 1$/month so I can work full time on it. Further information: Section "Sponsor Ciro Santilli's work on OurBigBook.com". Achieving what I call "free gifted education" is my Nirvana.

This website is written in OurBigBook Markup, and it is published on both cirosantilli.com (static website) and outbigbook.om/cirosantilli (multi-user OurBigBook Web instance). Its source code is located at: github.com/cirosantilli/cirosantilli.github.io and also at cirosantilli.com/_dir and it is licensed under CC BY-SA 4.0 unless otherwise noted.

To contact Ciro, see: Section "How to contact Ciro Santilli". He likes to talk with random people of the Internet.

https://raw.githubusercontent.com/cirosantilli/media/master/ID_photo_of_Ciro_Santilli_taken_in_2013.jpg

Besides that, I'm also a freedom of speech slacktivist and recreational cyclist. I like Chinese traditional music and classic Brazilian pop. Opinions are my own, but they could be yours too. Tax the rich.

Let's create an educational system with:

no distinction between university and high school, students just go as fast as they can to what they really want without stupid university entry exams
fully open source learning material
on-demand examinations that anyone can easily take without prerequisites
granular entry selection only for space in specific laboratories or participation in specific novel research projects

I offer:

online private tutoring for:
- any STEM university course
- passionate younger STEM students (any age) who want to learn university level material and beyond. Can your kid be the next Fields Medalist or Nobel Prize winner? I'm here to help, especially if you are filthy rich! I focus moving students forward as fast as they want on and on producing useful novel tutorials and results
Let your child be my Emile, and me be their Adolfo Amidei, and let's see how far they can go! I will help take your child:
- into the best universities
- into the best PhD programs
and achieve their ambitious STEM goals!
educational consulting for institutions looking to improve their STEM courses
- do you know that course or teacher that consistently gets bad reviews every year? I'll work with the teacher to turn the problem around!
- are you looking to create a consistent open educational resources offering to increase your institutions internationally visibility? I can help with that too.

My approach is to:

propose interesting research projects. The starting point is always deciding the end goal: Section "Backward design"
learn what is needed to do the project together with the student(s)
publish any novel results or tutorials/tools produced freely licensed online, and encourage the student to do the same (Section "Let students learn by teaching", digital garden)

For minors, parents are welcome to join video calls, and all interactions with the student will be recorded and made available to parents.

I have a proven track of explaining complex concepts in an interesting and useful way. I work for the learner. Teaching statement at: Section "How to teach". Pricing to be discussed. Contact details at: Section "How to contact Ciro Santilli".

I am particularly excited about pointing people to the potential next big things, my top picks these days are:

quantum computing
AGI research, in particular AI code generation, automated theorem proving and robotics
assorted molecular biology technologies

I am also generally interested in:

20th century physics, notably AMO and condensed matter
the history of science, and in particular trying to look at seminal papers of a field

Figure 1.

Ciro Santilli's amazing Stack Overflow profile

. Ciro contributes almost exclusively by answering question he Googles into out of his own need, and never by refreshing the newest question of big tags for low hanging fruit! More information at: Section "Ciro Santilli's Stack Overflow contributions".

Figure 2.
Ciro Santilli's Stack Overflow stats
. Further methodology details at: Figure "Ciro Santilli's Stack Overflow stats".

Video 1.

Introduction to the OurBigBook Project

. Source.

Video 2.

OurBigBook Web topics demo

. Source. The OurBigBook topic feature allows users to "merge their minds" in a "sort by upvote"-stack overflow-like manner for each subject. This is the killer feature of OurBigBook Web. More information at: docs.ourbigbook.com/ourbigbook-web-topics.

Video 3.

OurBigBook dynamic article tree demo

. Source. The OurBigBook dynamic tree feature allows any of your headers to be the toplevel h1 header of a page, while still displaying its descendants. SEO loves this, and it also allows users to always get their content on the correct granularity. More information at: docs.ourbigbook.com/ourbigbook-web-dynamic-article-tree.

Video 4.

OurBigBook local editing and publishing demo

. Source. With OurBigBook you can store your content as plaintext files in a Lightweight markup, and then publish that to either OurBigBook.com to get awesome multi-user features, or as a static website where you are in full control. More information at: docs.ourbigbook.com/publish-your-content.

Video 5.

Top Down 2D continuous game with Urho3D C++ SDL and Box2D for Reinforcement learning by Ciro Santilli (2018)

Source. More information: Section "Ciro's 2D reinforcement learning games". This is Ciro's underwhelming stab at the fundamental question: Can AGI be trained in simulations?. This project could be taken much further.

Video 6.

Water Margin tribute to Chinese dissidents by Ciro Santilli (2022)

Source. Part of Ciro Santilli's campaign for freedom of speech in China, see also: cirosantilli.com/china-dictatorship/water-margin.

Figure 3.
Lenovo ThinkPad T430 running a BIOS hello world
. Source code: github.com/cirosantilli/x86-bare-metal-examples. Ciro's Linux Kernel Module Cheat is a closely related and much more important project that covers the Linux kernel and assembly language.

Video 7.

My Bitcoin inscription museum by Ciro Santilli

. Source. Introductory video to Section "Cool data embedded in the Bitcoin blockchain".

 -------------------------------------
|  Force of Will               3 U U  |
|  ---------------------------------  |
| |                  ////////////   | |
| |                ////() ()\////\  | |
| |               ///_\ (--) \///\  | |
| |        )      ////  \_____///\\ | |
| |       ) \      /   /   /    /   | |
| |    ) /   \     |   |  /   _/    | |
| |   ) \  (  (   /   / /   / \     | |
| |  / ) ( )  / (    )/(    )  \    | |
| |  \(_)/(_)/  /UUUU \  \\\/   |   | |
| .---------------------------------. |
| Interrupt                           |
| ,---------------------------------, |
| | You may pay 1 life and remove a | |
| | blue card in your hand from the | |
| | game instead of paying Force of | |
| | Will's casting cost.  Effects   | |
| | that prevent or redirect damage | |
| | cannot be used to counter this  | |
| | loss of life.                   | |
| | Counter target spell.           | |
| `---------------------------------` |
|                                     l
| Illus.  Terese Nelsen               |
 -------------------------------------

Code 1.

ASCII art of a Force of Will Magic: The Gathering card inscribed in the Bitcoin blockchain

.

Artist unknown, uploaded December 2014. Part of Section "Cool data embedded in the Bitcoin blockchain" where Ciro Santilli maintains a curated list of such interesting inscriptions.

This was a small project done by Ciro for artistic purposes that received some attention due to the incredible hype surrounding cryptocurrencies at the time. Ciro Santilli's views on cryptocurrencies are summarized at: Section "Are cryptocurrencies useful?".

Figure 4.
`YellowRobot.jpg`
. Source.
JPG image fully embedded in the Bitcoin blockchain depicting some kind of cut material art depicting a yellow robot, inscribed on January 29, 2017.
Ciro Santilli found this image and others during his research for Section "Cool data embedded in the Bitcoin blockchain" by searching for image fingerprints on every transaction payload of the blockchain with a script.
The image was uploaded by EMBII, co-creator of the AtomSea & EMBII upload mechanism, which was responsible for a large part of the image inscriptions in the Bitcoin blockchain.
The associated message reads:
Chiharu [EMBII's Japanese wife] and I found this little yellow robot while exploring Chicago. It will be covered by tar or eventually removed but this tribute will remain. N 41.880778 E -87.629210
This is one of Ciro Santilli's favorite AtomSea & EMBII uploads, as it perfectly encapsules the "medium as an art form" approach to blockchain art, where even non-novel works can be recontextualized into something interesting, here depicting an opposition between the ephemeral and the immutable.
At twitter.com/EMBII4U/status/1615389973343268871 EMBII announced that he would be giving off shares of that image on Sup!?, a Bitcoin-backed NFT system he was; making. In December 2023, he gave some shares of the robot to Ciro Santilli.

Figure 5.
2010 Wayback Machine archive of starwarsweb.net
.
This website was used as one of the CIA 2010 covert communication websites, a covert system the CIA used to communicate with its assets. More details at: Section "CIA 2010 covert communication websites".
Ciro Santilli had some naughty OSINT fun finding some of the websites of this defunct network in 2023 after he heard about the 2022 Reuters report on the matter, which for the first time gave away 7 concrete websites out of a claimed 885 total found. As of November 2023, Ciro had found about 350 of them.

Figure 6.
2010 Wayback Machine archive of noticiasmusica.net
.
This is another website that was used as one of the CIA 2010 covert communication websites. This website is written in Brazilian Portuguese, and therefore suggests that the CIA had assets in Brazil at the time, and thus was spying on a "fellow democracy".
Although Snowden's revelations made it extremely obvious to the world that the USA spies upon everyone outside of the Five Eyes, including fellow democracies, it is rare to have such a direct a concrete proof of it visible live right on the Wayback Machine. Other targeted democracies include France, Germany, Italy and Spain. More details at: USA spying on its own allies.

Video 8.

How I found a Star Wars website made by the CIA by Ciro Santilli

. Source. Slightly edited VOD of the talk Aratu Week 2024 Talk by Ciro Santilli: My Best Random Projects about the CIA 2010 covert communication websites.

Figure 7.
Diagram of the fundamental theorem on homomorphisms by Ciro Santilli (2020)

Shows the relationship between group homomorphisms and normal subgroups.
Used in the Stack Exchange answer to What is the intuition behind normal subgroups? One of Section "The best articles by Ciro Santilli".

Figure 8.
Spacetime diagram illustrating how faster-than-light travel implies time travel by Ciro Santilli (2021)
Used in the Stack Exchange answer to Does faster than light travel imply travelling back in time?. One of Section "The best articles by Ciro Santilli".

Figure 9.
Average insertion time into heaps, binary search tree and hash maps of the C++ standard library by Ciro Santilli (2015)
Source. Used in the Stack Overflow answer to Heap vs Binary Search Tree (BST). One of Section "The best articles by Ciro Santilli".

Video 9.

Birch and Swinnerton-Dyer conjecture in two minutes by Ciro Santilli

. Source. Quick and direct explanation of the statement of the BSD conjecture for people who know basic university mathematics. This is one of the Millennium Prize Problems, and you will get a million dollars if you can solve it! This therefore falls in the Simple to state but hard to prove of Ciro Santilli's the beauty of mathematics aesthetics.

A quick 2D continuous AI game prototype for reinforcement learning written in Matter.js, you can view it on a separate page at cirosantilli.com/_raw/js/matterjs/examples.html#top-down-asdw-fixed-viewport. This is a for-fun-only prototype for Ciro's 2D reinforcement learning games, C++ or maybe Python (for the deep learning ecosystem) seems inevitable for a serious version of such a project. But it is cute how much you can do with a few lines of Matter.js!

HTML snippet:

<iframe src="_raw/js/matterjs/examples.html#top-down-asdw-fixed-viewport" width="1000" height="850"></iframe>

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The best articles by Ciro Santilli  Updated 2025-03-25  +Created 1970-01-01

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These are the best articles ever authored by Ciro Santilli, most of them in the format of Stack Overflow answers.

Ciro posts update about new articles on his Twitter accounts.

A chronological list of all articles is also kept at: Section "Updates".

Some random generally less technical in-tree essays will be present at: Section "Essays by Ciro Santilli".

Trended on Hacker News:
- CIA 2010 covert communication websites on 2023-06-11. 190 points, a mild success.
- x86 Bare Metal Examples on 2019-03-19. 513 points. The third time something related to that repo trends. Hacker news people really like that repo!
  - again 2020-06-27 (archive). 200 points, repository traffic jumped from 25 daily unique visitors to 4.6k unique visitors on the day
- How to run a program without an operating system? on 2018-11-26 (archive). 394 points. Covers x86 and ARM
- ELF Hello World Tutorial on 2017-05-17 (archive). 334 points.
- x86 Paging Tutorial on 2017-03-02. Number 1 Google search result for "x86 Paging" in 2017-08. 142 points.
  Figure 1.
  BIOS bare metal hello world running on a Lenovo ThinkPad T430
  . Source.
x86 assembly
- What does "multicore" assembly language look like?
- What is the function of the push / pop instructions used on registers in x86 assembly? Going down to memory spills, register allocation and graph coloring.
Linux kernel
QEMU
gcc and Binutils:
- How do linkers and address relocation works?
- What is incremental linking or partial linking?
- GOLD (-fuse-ld=gold) linker vs the traditional GNU ld and LLVM ldd
- What is the -fPIE option for position-independent executables in GCC and ld? Concrete examples by running program through GDB twice, and an assembly hello world with absolute vs PC relative load.
- How many GCC optimization levels are there?
- Why does GCC create a shared object instead of an executable binary according to file?
C/C++: almost all of those fall into "disassemble all the things" category. Ciro also does "standards dissection" and "a new version of the standard is out" answers, but those are boring:
- What does "static" mean in a C program?
- In C++ source, what is the effect of extern "C"?
- Char array vs Char Pointer in C
- How to compile glibc from source and use it?
- When should static_cast, dynamic_cast, const_cast and reinterpret_cast be used?
- What exactly is std::atomic in C++?. This answer was originally more appropriately entitled "Let's disassemble some stuff", and got three downvotes, so Ciro changed it to a more professional title, and it started getting upvotes. People judge books by their covers.
- notmain.o 0000000000000000 0000000000000017 W MyTemplate<int>::f(int) main.o 0000000000000000 0000000000000017 W MyTemplate<int>::f(int)
  Code 1.
  nm outputs showing that objects are redefined multiple times across files if you don't use template instantiation properly
  . From: What is explicit template instantiation in C++ and when to use it?

IEEE 754

What is difference between quiet NaN and signaling NaN?
In Java, what does NaN mean?

Without subnormals:

          +---+---+-------+---------------+-------------------------------+
exponent  | ? | 0 |   1   |       2       |               3               |
          +---+---+-------+---------------+-------------------------------+
          |   |   |       |               |                               |
          v   v   v       v               v                               v
          -----------------------------------------------------------------
floats    *    **** * * * *   *   *   *   *       *       *       *       *
          -----------------------------------------------------------------
          ^   ^   ^       ^               ^                               ^
          |   |   |       |               |                               |
          0   |   2^-126  2^-125          2^-124                          2^-123
              |
              2^-127

With subnormals:

          +-------+-------+---------------+-------------------------------+
exponent  |   0   |   1   |       2       |               3               |
          +-------+-------+---------------+-------------------------------+
          |       |       |               |                               |
          v       v       v               v                               v
          -----------------------------------------------------------------
floats    * * * * * * * * *   *   *   *   *       *       *       *       *
          -----------------------------------------------------------------
          ^   ^   ^       ^               ^                               ^
          |   |   |       |               |                               |
          0   |   2^-126  2^-125          2^-124                          2^-123
              |
              2^-127

Code 2.

Visualization of subnormal floating point numbers vs what IEEE 754 would look like without them

. From: What is a subnormal floating point number?

Computer science
- Algorithms
  - Figure 5.
    Average insertion time into heaps, binary search tree and hash maps of the C++ standard library
    . Source. From: Heap vs Binary Search Tree (BST)
- Is it necessary for NP problems to be decision problems?
- Polynomial time and exponential time. Answered focusing on the definition of "exponential time".
- What is the smallest Turing machine where it is unknown if it halts or not?. Answer focusing on "blank tape" initial condition only. Large parts of it are summarizing the Busy Beaver Challenge, but some additions were made.

Git

  | 0           | 4            | 8           | C              |
  |-------------|--------------|-------------|----------------|
0 | DIRC        | Version      | File count  | ctime       ...| 0
  | ...         | mtime                      | device         |
2 | inode       | mode         | UID         | GID            | 2
  | File size   | Entry SHA-1                              ...|
4 | ...                        | Flags       | Index SHA-1 ...| 4
  | ...                                                       |

Code 3.

ASCII art depicting the binary file format of the Git index file

. From: What does the git index contain EXACTLY?

tree {tree_sha}
{parents}
author {author_name} <{author_email}> {author_date_seconds} {author_date_timezone}
committer {committer_name} <{committer_email}> {committer_date_seconds} {committer_date_timezone}

{commit message}

Code 4.

Description of the Git commit object binary data structure

. From: What is the file format of a git commit object data structure?

How do I clone a subdirectory only of a Git repository?

Python
- What is the difference between old style and new style classes in Python?
- What is a mixin in Python, and why are they useful?
- What are the differences between threads and processes in Python?
  Figure 6.
  Python Threads vs Processes with 8 hyperthreads
  . Source.
Web technology
- What does enctype='multipart/form-data' mean?
- JavaScript
  - How does JavaScript .prototype work?
  - What is the difference between .prop() vs .attr() in JavaScript?
OpenGL
- Figure 7.
  OpenGL rendering output dumped to a GIF file
  . Source. From: How to use GLUT/OpenGL to render to a file?
- Figure 8.
  Example of a texture atlas containing glyphs
  . Source.
  Image by Nicolas P. Rougier, author of Freetype GL.
  Used on Ciro Santilli's answer: How to draw text using only OpenGL methods?
- Figure 9.
  OpenGL glFrustrum vs glOrtho
  . Source. From: How to use glOrtho() in OpenGL?
- What are shaders in OpenGL?
- Why do we use 4x4 matrices to transform things in 3D?
- Figure 10.
  Sinusoidal circular wave heatmap generated with an OpenGL shader at 60 FPS on SDL
  . Source.
  From: Is it possible to build a heatmap from point data at 60 times per second?
  Compared CPU vs GPU shaders.
- Image Processing with GLSL shaders? Compared the CPU and GPU for a simple blur algorithm.
  Figure 11. Source.
  Video 1.
  OpenGL GPU GLSL fragment shader real time v4l2 Linux webcam computer vision box blur vs CPU
  . Source.
Node.js
- What's the difference between dependencies, devDependencies and peerDependencies in npm package.json file?
Ruby on Rails
- What is the difference between +<%+, +<%=+, +<%#+ and +-%>+ in ERB in Rails?
POSIX
- What is POSIX? Huge classified overview of the most important things that POSIX specifies.

Systems programming

What do the terms "CPU bound" and "I/O bound" mean?
Figure 12.
Plot of "real", "user" and "sys" mean times of the output of time for CPU-bound workload with 8 threads
. Source. From: What do 'real', 'user' and 'sys' mean in the output of time?

+--------+                  +------------+       +------+
| device |>---------------->| function 0 |>----->| BAR0 |
|        |                  |            |       +------+
|        |>------------+    |            |
|        |             |    |            |       +------+
   ...        ...      |    |            |>----->| BAR1 |
|        |             |    |            |       +------+
|        |>--------+   |    |            |
+--------+         |   |         ...        ...    ...
                   |   |    |            |
                   |   |    |            |       +------+
                   |   |    |            |>----->| BAR5 |
                   |   |    +------------+       +------+
                   |   |
                   |   |
                   |   |    +------------+       +------+
                   |   +--->| function 1 |>----->| BAR0 |
                   |        |            |       +------+
                   |        |            |
                   |        |            |       +------+
                   |        |            |>----->| BAR1 |
                   |        |            |       +------+
                   |        |            |
                   |             ...        ...    ...
                   |        |            |
                   |        |            |       +------+
                   |        |            |>----->| BAR5 |
                   |        +------------+       +------+
                   |
                   |
                   |             ...
                   |
                   |
                   |        +------------+       +------+
                   +------->| function 7 |>----->| BAR0 |
                            |            |       +------+
                            |            |
                            |            |       +------+
                            |            |>----->| BAR1 |
                            |            |       +------+
                            |            |
                                 ...        ...    ...
                            |            |
                            |            |       +------+
                            |            |>----->| BAR5 |
                            +------------+       +------+

Code 5.

Logical struture PCIe device, functions and BARs

. From: What is the Base Address Register (BAR) in PCIe?

Electronics
- Raspberry Pi
  - Figure 13.
    Raspberry Pi 2 directly connected to a laptop with an Ethernet cable
    . Image from answer to: How to hook up a Raspberry Pi via Ethernet to a laptop without a router?
    Figure 14.
    Raspberry Pi 2 connected to a laptop with an USB UART adapter
    . Image from answer to: How to hook up a Raspberry Pi via Ethernet to a laptop without a router?
    Figure 15.
    Raspberry Pi OS being emulated on QEMU 2.5.0 on Ubuntu 16.04 with a modified kernel
    . Image from answer to: How to emulate the Raspberry Pi 2 on QEMU?
    Figure 16.
    Bare metal LED blinker program running on a Raspberry Pi 2
    . Image from answer to: How to run a C program with no OS on the Raspberry Pi?
Computer security
- Why is the same origin policy so important?
Media
- Video 2.
  Canon in D in C
  . Source.
  From: How is audio represented with numbers in computers?.
  The original question was deleted, lol...: How to programmatically synthesize music?
- How to resize a picture using ffmpeg's sws_scale()?
- Is there any decent speech recognition software for Linux? ran a few examples manually on vosk-api and compared to ground truth.
Eclipse
- How to set up the Eclipse for remote C debugging with gdbserver?
Computer hardware
- Are there good open source standard cell libraries to learn IC synthesis with EDA tools?
Scientific visualization software
- Figure 17.
  VisIt zoom in 10 million straight line plot with some manually marked points
  . Source. From: Section "Survey of open source interactive plotting software with a 10 million point scatter plot benchmark by Ciro Santilli"
Numerical analysis
- Video 3.
  Real-time heat equation OpenGL visualization with interactive mouse cursor using relaxation method by Ciro Santilli (2016)
  Source.
Computational physics
- Figure 18.
  gnuplot plot of the y position of a sphere bouncing on a plane simulated in Bullet Physics
  . Source. From: What is the simplest collision example possible in a Bullet Physics simulation?
Register transfer level languages like Verilog and VHDL
- Verilog:
  Figure 19.
  Interacgive ASDF-controlled demo with core logic written in Verilog using Verilator
  .
  From: Is it possible to do interactive user input and output simulation in VHDL or Verilog?
  See also: Section "Verilator interactive example"
Android
- Figure 20. Source. From: How to compile the Android AOSP kernel and test it with the Android Emulator?
- Video 4.
  Android screen showing live on an Ubuntu laptop through ADB
  . Source. From: How to see the Android screen live on an Ubuntu desktop through ADB?
Debugging
Program optimization
- What is tail call optimization?
- Figure 21.
  gprof2dot image generated from the gprof data of a simple test program
  . Source.
  From: How can I profile C++ code running on Linux?
  The answer compares gprof, valgrind callgrind, perf and gperftools on a single simple executable.
Data
- Figure 22.
  Mathematics dump of Wikipedia CatTree
  . Source. In this project, Ciro Santilli explored extracting the category and article tree out of the Wikipedia dumps.
Mathematics
- Figure 23.
  Diagram of the fundamental theorem on homomorphisms by Ciro Santilli (2020)
  
  Shows the relationship between group homomorphisms and normal subgroups.
  From: What is the intuition behind normal subgroups?
- Section "Formalization of mathematics": some early thoughts that could be expanded. Ciro almost had a stroke when he understood this stuff in his teens.
- Figure 24.
  Simple example of the Discrete Fourier transform
  . Source. That was missing from Wikipedia page: en.wikipedia.org/wiki/Discrete_Fourier_transform!
Network programming
- How to make an HTTP get request in C without libcurl?
Physics
- What is the difference between plutonium and uranium?
- Figure 25.
  Spacetime diagram illustrating how faster-than-light travel implies time travel
  . From: Does faster than light travel imply travelling back in time?
Biology
- Figure 26.
  Top view of an open Oxford Nanopore MinION
  . Source. From: Section "How to use an Oxford Nanopore MinION to extract DNA from river water and determine which bacteria live in it"
- Figure 27.
  Mass fractions in a minimal growth medium vs an amino acid cut in a simulation of the E. Coli Whole Cell Model by Covert Lab
  . Source. From: Section "E. Coli Whole Cell Model by Covert Lab"
Quantum computing
- Section "Quantum computing is just matrix multiplication"
- Figure 28.
  Visualization of the continuous deformation of states as we walk around the Bloch sphere represented as photon polarization arrows
  . From: Understanding the Bloch sphere.
Bitcoin
- Section "Cool data embedded in the Bitcoin blockchain"
GIMP
- Figure 29.
  GIMP screenshot part of how to combine two images side-by-side in GIMP?
  .
Home DIY
- Figure 30.
  Total_Blackout_Cassette_Roller_Blind_With_Curtains.
  Source. From: Section "How to blackout your window without drilling"
China
- What would happen if I walked around Beijing with a t-shirt that said "freedom of speech is pretty great"?

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Boitatech  Updated 2025-03-25  +Created 1970-01-01

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A misogenous Brazilian hacking group:

Just kidding.

Some people from them contacted Ciro Santilli after Ciro's initial publishing of CIA 2010 covert communication websites.

After a quick Discord chat with them, it was apparent that these people were really cool and knowledgeable.

Also many of them seem to think university is broken and just go hack straigh away.

A perfect example of a dojo learning model.

Also they don't seem to need sleep. Go figure!

With pepole like this, there's hope for Brazil: Section "What poor countries have to do to get richer".

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CIA usage of Domains by Proxy  Updated 2025-03-25  +Created 1970-01-01

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The CIA really likes this registrar, e.g.:

CIA 2010 covert communication websites
2014 www.newsweek.com/former-cia-officials-ready-defend-agency-after-torture-reports-release-290383
A group of former CIA officials are gearing up to defend the agency when the Senate releases its long-awaited report investigating "enhanced interrogation" tactics used on prisoners after 9/11. The highlight of their PR push will be a website, "CIASAVEDLIVES.COM," which is set to go live when the report is released on Tuesday, Foreign Policy reported.
The domain was registered on November 2 under a private registration name, through DomainsByProxy, a company that guards the identity of registrants.

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Reactions to cirosantilli.com  Updated 2025-03-25  +Created 1970-01-01

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Deep psychological analyses:

Hacker News user MichaelZuo comments on a post about CIA 2010 covert communication websites:
Yeah [the website] seems a bit odd, as if the author is intentionally trolling in some areas, or is easily susceptible to being trolled by random folks, and thus displaying some kind of compensation dynamic.
www.reddit.com/r/China_irl/comments/1bn47e5/comment/kwgkl88/ user Opening_Gazelle_1323 comments:
Can your kid be the next Fields Medalist or Nobel Prize winner? I'm here to help, especially if you are filthy rich!
三西猴老哥这一张嘴⏰味拉满，可以封为荣誉中国人
Brother Sanxihou’s mouth is so full of flavor that he can be named an honorary Chinese.
www.reddit.com/r/Monero/comments/1brryao/ciro_santilli_received_a_1000_xmr_donation_to/ from 1000 Monero donation user Inaeipathy:;
It reads like an ode to himself, very strange in my opinion. I don't really know what's up with the black-green text scheme, I can barely read any of it.
archive.is/W1ocv originally boards.4channel.org/g/thread/75097729/who-is-this-guy on 4chan:
a based retard
Is that his own personal site where he has just listed everything he has ever done? Based.
He refers to himself in the third person, because gender has non place in the Sciences. Based autismo.
Holy based. Keep up the good work my man.

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Reactions to cirosantilli.com's design  Updated 2025-03-25  +Created 1970-01-01

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People love green on black mostly.

news.ycombinator.com/item?id=38492304 about Section "CIA 2010 covert communication websites":

user thewildginger:
Nothing like finding a webpage you can read from Lynx.
user socketcluster:
Based on the choice of fonts and colors, you know this is a serious hacker website ;p

At www.reddit.com/r/numberstations/comments/14dexiu/comment/jordtjc Reddit user Short_Ad_7853:

Jesus that is an interesting choice of colors

www.reddit.com/r/Monero/comments/1brryao/ciro_santilli_received_a_1000_xmr_donation_to/ from 1000 Monero donation:

user -TrustyDwarf-:
Anyone mind to explain wtf this ugly piece of webpage reminding me of geocities from the 90s is about? I'd read it myself but I can't because it already gave me eye cancer.
user rbrunner7:
It's all quite strange. Never mind the 90s design, people built good websites already back then with the tools at hand, but even their "About" isn't very clear. If you need 5 minutes to be reasonably sure what it is all about they are still doing it wrong.
automobi1e
I'd rather take a look at the welding

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Anonymity of the donation  Updated 2025-03-25  +Created 1970-01-01

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44 new CIA websites  Updated 2025-03-25  +Created 2025-03-13  2025-03-25

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This is an update to the article: Section "CIA 2010 covert communication websites"

I found 44 new covert websites made by the CIA around 2010 bringing the total to 397!

Most websites were boring as usual, but one was slightly cooler: webofcheer.com is a comedy fansite featuring Johnny Carson, Charles Chaplin, Rowan Atkins (of Mr. Bean fame), The Three Stooges and some other Americans no one knows about anymore. There must have been a massive Johnny Carson amongst the contractors at that time, given that we previously also knew about alljohnny.com, a site dedicated fully to him! Both of these sites also serve as some of the earliest examples we've got so far, dating back to 2004 and 2005.

Figure 1.
2011 Wayback Machine archive of webofcheer.com
. Source.

Figure 2.
2011 Wayback Machine archive of webofcheer.com scrolled to show Johnny Carson
. Source.

Figure 3.
2004 Wayback Machine archive of alljohnny.com
. Source. This one was a previously known website featuring Johnny Carson.

Another cool discovery is that I found the Getty Images source of the Jedi boy on their Star Wars themed site starwarsweb.net: web.archive.org/web/20101230033220/http://starwarsweb.net/ The photo can still be licensed today as of 2025: www.gettyimages.co.uk/detail/photo/little-jedi-royalty-free-image/172984439. I found it by searching for "jedi boy" on gettyimages.co.uk. The photo is credited to username madisonwi, presumably an alias of a photographer from Madison, Wisconsin. Inspired by this I reverse image searched and found the source of many other stock images from other websites, and I pinged their authors whenever I could locate them e.g. x.com/cirosantilli/status/1899750172260806711.

Figure 4.
Stock photo of a Jedi boy from Getty Images used on starwarsweb.net
. Source.

Figure 5.
2010 Wayback Machine archive of starwarsweb.net
.

There were two small advances that led to the discovery of new domains:

while looking for a way to procrastinate I decided to scrape justdropped.com/drops/ for fun. That website lists expired domain names and see if it would yield any new results.
I had already scrapped other expired domain websites before and used that data, and I hoped that this one would provide some new domain hits, even though it had very large overlap with the other websites I had scraped domains from previously.
Such domain name lists tend to contain all SCAM domains in existence, since those inevitably expire once the scammers are caught.
even more importantly, I noticed by chance that I was being too strict on a small part of my fingerprinting which was excluding a few good domains, by removing any hits that had multiple archives of the Communication mechanism

With those two new developments, I then kicked off my pre-existing search pipelines searching for domain names with the word news on them, an amazingly efficient heuristic because many of the websites were disguised as news aggregators, and after a few hours theses new hits emerged. A few of those also led to the discovery of new IPs which then led to new domains.

One entirely new IP range was found around fastnews-online.com from 208.93.112.105 to 208.93.112.125. There were many domain names with very promising names in the range, but unfortunately for some reason most didn't have Wayback Machine Archives so I didn't count them as hits as per my guidelines.

Figure 6.
2009 Wayback Machine archive of fastnews-online.com
.

Also the newly found todaysengineering.com at 208.254.38.39 appears to form an IP range with the previously known nejadnews.com at 208.254.38.56, but I couldn't find any other domains in the region with our current data sources.

Figure 7.
2011 Wayback Machine archive of todaysengineering.com
.

All other domains either slot into previously known IP ranges, or more commonly don't currently have a known IP, though they would likely just slot in existing ranges if we had better data.

Thanks to Jack Rhysider from the Darknet Diaries podcast for pointing me to the existing of the 2022 Reuters article that kickstarted my research on the subject!

One outcome of this update is that I've increased my jq level to better automate the maintenance of the hits.json file were I store all the known websites in JSON format. I love that tool so much, I managed to merge two JSONs with it removing duplicates and then sort the JSON as desired. Beauty.

The full list of newly found websites is:

Announced at:

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CIA 2010 websites video  Updated 2025-03-25  +Created 2024-10-26

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I edited the VOD of the talk Aratu Week 2024 Talk by Ciro Santilli: My Best Random Projects about the CIA 2010 covert communication websites a bit and published it at: www.youtube.com/watch?v=TFfuzZC5Qpc.

Video 1.

How I found a Star Wars website made by the CIA by Ciro Santilli

. Source.

Announcements:

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Getting a list of all currencies from Wikidata with SPARQL  Updated 2025-03-25  +Created 2024-11-18

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opendata.stackexchange.com/questions/1560/how-can-i-get-a-list-of-currencies-from-wikidata/21839#21839

I've had a bit more fun with SPARQL and Wikidata.

This one was way harder than my previous fun with "find the oldest people who won a given prize" (Nobel Prize/Oscar) mastodon.social/@cirosantilli/112689376315990248 because unlike those prizes where all the decisions are centralized, countries are much more complicated beasts, with changing currencies and international recognition.

This was a good experience to see a few ways in which Wikidata is inconsistent, with the same concept being expressed in multiple different ways, e.g. "end time" property of the current vs the superior "end time" qualifier.

Particularly bad is the notion of a "deprecated rank", that should really not exist.

This is exactly the type of semi interactive data munching that I like to do, a bit in the same vein as CIA 2010 covert communication websites and Cool data embedded in the Bitcoin blockchain.

As you might imagine, the secret services use exactly this type of knowledge modelling to do their dirty business, e.g. Gaffer by the GCHQ.

If only I weren't such a rebel, I'd be a perfect fit for the intelligence agencies.

This is the best monstrosity I had the patience to come up with:

SELECT
  ?currency
  (GROUP_CONCAT(DISTINCT ?currencyIsoCode; SEPARATOR=", ") AS ?currencyIsoCodes)
  ?currencyLabel
  (GROUP_CONCAT(DISTINCT ?countryLabel; SEPARATOR=", ") AS ?countries)
WHERE {
  ?country wdt:P31/wdt:P279* wd:Q6256. # is country
  ?country p:P38 ?countryHasCurrency.
  ?countryHasCurrency ps:P38 ?currency.
  ?countryHasCurrency wikibase:rank ?countryHasCurrencyRank.
  OPTIONAL {
    ?currency p:P498 ?currencyHasIsoCode.
    ?currencyHasIsoCode ps:P498 ?currencyIsoCode.
  }
  FILTER NOT EXISTS {?country wdt:P576 ?countryAbolished}
  FILTER NOT EXISTS {?currency wdt:P576 ?currencyAbolished}
  FILTER NOT EXISTS {?currency wdt:P582 ?currencyEndTime}
  FILTER NOT EXISTS {?countryHasCurrency pq:P582 ?countryHasCurrencyEndtime}
  FILTER (?countryHasCurrencyRank != wikibase:DeprecatedRank)
  FILTER (!bound(?currencyHasIsoCode) || ?currencyHasIsoCode != wikibase:DeprecatedRank)
  # TODO makes query take timeout? Why? Needed to exclude PLZ.
  FILTER NOT EXISTS {?currencyHasIsoCode pq:P582 ?currencyHasIsoCodeEndtime}
  SERVICE wikibase:label {
    bd:serviceParam wikibase:language "[AUTO_LANGUAGE],en".
    ?currency rdfs:label ?currencyLabel .
    ?country rdfs:label ?countryLabel .
  }
}
GROUP BY ?currency ?currencyLabel
ORDER BY ?currencyIsoCodes ?currencyLabel

It got quite close to the ISO 4217 list.

I was drawn into this waste of time after I noticed that someone had managed to create the Wikipedia of PsiQuantum which I had tried earlier but got deleted: mastodon.social/@cirosantilli/113488891292906243, and then I made the mistake of having a look at the Wikidata page of PsiQuantum.

Figure 1.
500,000 Transnistrian ruble banknote 1997 series
. This is one of the most widely used currencies which does not have an ISO 4217 code.

Announcements:

I also had one more fun with: opendata.stackexchange.com/questions/15750/structured-data-for-nobel-prizes/21847#21847 getting some basic info about Nobel Prize winners, and noticed one, John Sulston, 2002 Nobel Prize in Physiology and Medicine laureate, who likely has the wrong place of birth on his Nobel Prize profile: www.nobelprize.org/prizes/medicine/2002/sulston/facts/ which is funny. I suggested the change now. Edit they fixed it after I pointed it out:

Another highlight was 1913 Nobel Prize in Chemistry laureate Alfred Werner who born either in Mulhouse in Alsace, France, or in "Yo no sé qué me pasó" ("I don't know what happened to me" in Spanish), a 1986 song by Mexican singer Juan Gabriel.

Announcements:

Also at opendata.stackexchange.com/questions/21849/how-to-get-a-list-of-all-nobel-prize-winners-who-never-had-a-doctorate-from-wiki/21850#21850 I tried to get the list of Nobel Prize laureates who don't have a PhD. I think the query was correct, but Wikidata data is just too incomplete. Related:

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viewdns.info  Updated 2025-03-25  +Created 2025-03-11

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viewdns.info

This is the most accessible DNS database online, as it does not require login or payment.

They have reasonable data. It's not fully complete as Ciro Santilli saw on CIA 2010 covert communication websites, but it is very valuable.

Tested as of 2025, they seem to have removed the pre-IP checks on web interface, and just instead use Cloudfare to check that you are human from time to time, which allows for a lot manual searching to be done! Awesome!

Previously, tou could only get about 250 queries on the web interface, then 250 queries per free account via API. They check your IP when you signup, and you can't sign in twice from the same IP. They also state that Tor addresses are blacklisted. They also normalize dots in gmail addresses, so you need more diverse email accounts. But they haven't covered the .gmail vs .googlemail trick.

Their data is also quite disjoint from the data of the 2013 DNS Census. There is some overlap, but clearly their methodology is very different. Some times they slot into one another almost perfectly.

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Ciro Santilli @cirosantilli 35

 Incoming links: CIA 2010 covert communication websites