I recently installed Qubes OS; this is my experience. In general it’s fantastic and easily facilitates the workflow I had evolved previously using Xubuntu, but effortlessly expands the security and privacy afforded by the qubes architecture.

The things I like most from my first impressions are:

• Easy management of domains. This is genius, a bit like chromium ‘users’ which I used heavily.
• The cross-domain clipboard implementation is really elegant, as is the USB isolation.
• Template VMs are great and the Qubes VM Manager is very useful.

Background

The laptop I installed on is a Kirabook with an i7-4500U CPU, 8 GB RAM, 256 GB SSD.

Installation

General Overview

Installation was extremely simple and clear. I found it easier than installing ubuntu, which is very impressive indeed.

Keyboard Layout

Having a keyboard layout indicator at all steps was fantastic, but was displayed...

Some info about cross-compiling libsodium and safe_vault from x64 (ubuntu 16.04 64 bit) to aarch64 (pine64 soc running debian 64 bit)

Install dependencies

$ sudo apt-get install gcc-aarch64-linux-gnu

Compile libsodium (v1.0.9)

No longer required since commit 56fca57. Also see the forum post about this.

$ cd ~/Downloads
$ wget https://github.com/jedisct1/libsodium/releases/download/1.0.9/libsodium-1.0.9.tar.gz
$ tar xfz libsodium-1.0.9.tar.gz
$ rm libsodium-1.0.9.tar.gz
$ cd libsodium-1.0.9
$ export CFLAGS='-Os'
$ CC=aarch64-linux-gnu-gcc ./configure --enable-shared=no --host=aarch64-unknown-linux-gnu
$ make clean
$ make
$ sudo make install

Configure rust for aarch64

ensure ~/.cargo/config has these two lines

[target.aarch64-unknown-linux-gnu]
linker = "aarch64-linux-gnu-gcc"

Then run these commands to install the aarch64 environment for rust (must use rustup)

$ source

Using Xubuntu 16.04 with natural scrolling enabling in Settings > Mouse and Touchpad > Reverse scroll direction leaves some apps with natural scrolling and some not. It’s extremely confusing and frustrating and non-intuitive.

To get natural scrolling to work consistently across all apps, uncheck the box in the settings and instead enable natural scrolling in X11:

sudoedit /usr/share/X11/xorg.conf.d/50-synaptics.conf

add the lines in the Section “InputClass” Identifier “touchpad catchall”

Option "VertScrollDelta" "-111"
Option "HorizScrollDelta" "-111"

Reboot and natural scrolling will be applied consistently.

Sources:

https://askubuntu.com/questions/91426/reverse-two-finger-scroll-direction-natural-scrolling/278849278849

https://bugs.chromium.org/p/chromium/issues/detail?id=582547

Summary

128GB microSD cards work with the Raspeberry Pi 2.

The Card

The card in use is a 128GB Kingston SDC10G2/128GBFR

Check the file system ‘from factory’, which is exfat

ian@ian-laptop:~ $ blkid | grep mmcblk0p1
/dev/mmcblk0p1: UUID="0123-4567" TYPE="exfat"

Check the reported size, which is 118G

ian@ian-laptop:~ $ df -h | grep mmcblk
/dev/mmcblk0p1  118G   17M  117G   1%

ian@ian-laptop:~ $ df | grep mmcblk
/dev/mmcblk0p1 122691584     17024 122674560   1%

The Pi

Raspberry Pi 2 Model B V1.1

Raspbian Jessie with a fully expanded filesystem.

pi@raspberrypi:~ $ df | grep root
/dev/root      120715332 925232 114856388   1% /

pi@raspberrypi:~ $ df -h | grep root
/dev/root       116G  904M  110G   1% /

Fill it up to confirm the full size is available for use (ie check the microsd card is not fake)

pi@raspberrypi:~ $ date; cat /dev/zero > /tmp/zeros; date
Tue Jun 21

Engineers weigh different design choices on their merits and choose the solution that best matches the requirements.

The goals of the bitcoin project are outlined in the bitcoin whitepaper.

Trustless

The goal of being trustless is stated several times in the whitepaper, and can be summarized as:

Online payments can be sent directly between two parties without relying on a trusted third party.

Here’s the direct quotes from the whitepaper about the goal of trustlessness.

allow online payments to be sent directly from one party to another without going through a financial institution

an electronic payment system … allowing any two willing parties to transact directly with each other without the need for a trusted third party

a system for electronic transactions without relying on trust

Irreversible

Irreversibility is a key property of cash and bitcoin aims to achieve transactions...

Engineering

The crucial and unique task of the engineer is to identify, understand, and interpret the constraints on a design in order to produce a successful result.

Constraints

An engineer finds an acceptable solution within the given constraints of the problem.

For most problems solved by engineering, an upper limit on what may be achieved is set by budget, schedule and technological limitations; the lower limit is determined by the specific functional requirements of the project.

To engineer a useful bitcoin MAX_BLOCK_SIZE value, the constraints must be defined, or there can be no progress made.

Should max block size change?

Before addressing the constraints, an important question must be answered: should there even be any work undertaken?

The answer is maybe. The current value was chosen without any apparent engineering and may or may not be appropriate. Determining an...

Here’s a simple bash script to download the entire history of Satoshi’s posts on bitcointalk.org

!/bin/sh
 Fetch all posts by satoshi on bitcoin forum bitcointalk.org
PAGES=27
POSTS_PER_PAGE=20
LAST_PAGE=`expr $PAGES - 1`
for INDEX in `seq 0 $LAST_PAGE`; do
    START=$(($INDEX * $POSTS_PER_PAGE))
    PAGE=`expr $INDEX + 1`
    URL="https://bitcointalk.org/index.php?action=profile;u=3;sa=showPosts;start=$START"
     Fetch the page
    wget -O posts_$PAGE.html $URL
     Be a good citizen of the internet
    sleep 1
done

Now you can use standard operating system tools to search instead of the terrible web-based search which is rate limited and feature limited.

The bitcoin block size is 1MB. Why was this number chosen? The reasoning of the past may have application to the reasoning in the present and future.

Original Code

The block size is defined in code by MAX_BLOCK_SIZE and is 1000000 bytes.

MAX_BLOCK_SIZE first appears in commit a30b56ebe76ffff9f9cc8a6667186179413c6349 by s_nakamoto on Thu Jul 15 00:18:45 2010

You can verify this yourself:

git log -S MAX_BLOCK_SIZE --source --all

The line of code originally committed was (and still is)

static const unsigned int MAX_BLOCK_SIZE = 1000000;

Historical Context

Let’s get some context around bitcoin at this period of time.

The next release about a day after MAX_BLOCK_SIZE was introduced is version 0.3.1 rc1

Changelogs for bitcoin releases don’t go back to version 0.3.1, they start at v0.3.12. So the changelogs don’t contain any details about this change.

Coincidentally, there was a...

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