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CU-dgpgu9 Added markdownlint and fixed markdown

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Bastian de Byl
2020-10-09 20:37:26 -04:00
parent 858875a95e
commit 245111cbb9
17 changed files with 356 additions and 161 deletions
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16
.drone.yml
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@@ -3,11 +3,25 @@ kind: pipeline
name: default
steps:
- name: lint
image: peterdavehello/markdownlint
commands:
- markdownlint content/
trigger:
event:
exclude:
- promote
- name: build
image: bdebyl/hugo
commands:
- git clone https://github.com/bdebyl/hugo-theme-even.git themes/even
- hugo
when:
event:
- promote
target:
- production
- name: deploy
image: bdebyl/awscli
@@ -29,6 +43,6 @@ steps:
- production
---
kind: signature
hmac: 3109d79e76507ab2e9a820522c68b429007ca6f25e0ca16b1b46ed0aba66d23e
hmac: 7f15ec618d95cce36ecf999e018b38c056d52538fd6b5c81bdf5c6ce46e0fd21
...

8
.markdownlint.json Normal file
View File

@@ -0,0 +1,8 @@
{
"default": true,
"MD025": false,
"MD013": false,
"MD033": {
"allowed_elements": ["center", "sub", "i"]
}
}

62
config.yaml
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@@ -1,31 +1,45 @@
# core
baseURL: "https://bdebyl.net/"
title: "A random assortment of my personal projects."
title: "Collection of useful, and useless information"
theme: "even"
# settings
paginate: 5
defaultContentLanguage: "en"
languageCode: "en"
paginate: 5
copyright: "Bastian de Byl" # default: author.name
preserveTaxonomyNames: true
enableRobotsTXT: true
buildDrafts: false
canonifyURLs: true
enableRobotsTXT: true
preserveTaxonomyNames: true
markup:
goldmark:
renderer:
unsafe: true
googleVerification: "" # Google Verification
googleAnalytics: "UA-163975086-1" # UA-XXXXXXXX-X
# google analytics
googleAnalytics: "UA-163975086-1"
googleVerification: ""
# See https://gohugo.io/about/hugo-and-gdpr/
privacy:
googleAnalytics:
anonymizeIP: true
youtube:
privacyEnhanced: true
# https://gohugo.io/content-management/syntax-highlighting/
pygmentsOptions: ""
pygmentsCodefences: true
pygmentsUseClasses: true
pygmentsCodefencesGuessSyntax: true
pygmentsOptions: ""
pygmentsUseClasses: true
author:
name: "Bastian de Byl"
sitemap:
changefreq: "weekly"
priority: 0.5
filename: "sitemap.xml"
priority: 0.5
menu:
main:
@@ -56,16 +70,12 @@ params:
# paginate of archives, tags and categories
archivePaginate: 20
# show 'xx Posts In Total' in archive page ?
showArchiveCount: true
# The date format to use; for a list of valid formats, see https://gohugo.io/functions/format/
dateFormatToUse: "2006-01-02"
# show word count and read time ?
moreMeta: false
postMetaInFooter: true # contain author, lastMod, markdown link, license
linkToMarkDown: true # Only effective when hugo will output .md files.
contentCopyright: '<a rel="license" href="http://creativecommons.org/licenses/by-nc/4.0/"><img alt="Creative Commons License" style="border-width:0" src="https://i.creativecommons.org/l/by-nc/4.0/80x15.png" /></a>'
@@ -75,27 +85,3 @@ params:
g-github: "https://github.com/bdebyl"
m-instagram: "https://instagram.com/bastian.remi"
n-gitlab: "https://gitlab.com/bdebyl"
# See https://gohugo.io/about/hugo-and-gdpr/
privacy:
googleAnalytics:
anonymizeIP: true
youtube:
privacyEnhanced: true
# Uncomment these options to make hugo output .md files.
#[mediaTypes]
# [mediaTypes."text/plain"]
# suffixes: ["md"]
#
#[outputFormats.MarkDown]
# mediaType: "text/plain"
# isPlainText: true
# isHTML: false
#
#[outputs]
# home: ["HTML", "RSS"]
# page: ["HTML", "MarkDown"]
# section: ["HTML", "RSS"]
# taxonomy: ["HTML", "RSS"]
# taxonomyTerm: ["HTML"]

9
content/about.md
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@@ -2,6 +2,7 @@
title: "About"
---
# About
I created this site as a way of showcasing my projects, or other general
ideas. It's a sort of _engineering_ portfolio, if you will.
@@ -17,10 +18,12 @@ Git repositories[^1], or ways to contact me such as
[email](mailto:bastian@bdebyl.net).
# GPG Fingerprint
The image at the **top-left** of this site (_on desktop_) is my OpenPGP v4 key
fingerprint QR-code. Feel free to scan it using the
[OpenKeychain](https://www.openkeychain.org/) app! I'll provide it here in-case
you are on a mobile device, and my full public key:
<center>
![OpenPGP v4 Fingerprint](/static/img/pubfpr-lrg.png)
@@ -28,7 +31,8 @@ you are on a mobile device, and my full public key:
</center>
{{< admonition info "Public Key" true >}}
```
```text
-----BEGIN PGP PUBLIC KEY BLOCK-----
mQINBFoTpoMBEADDIjRewOTvJBQF4ZxK/LS7yBL0TuU7VbZzEH3s5YKj63P/Rmvx
8/jMm0iop+uiPNo+0imIGYsdfW77bt95I9+kBm27eVf8mDMldMiS/LBCCmnuQ19u
@@ -146,11 +150,12 @@ teulWQZ/WMzUvU9IR6q3RcYbHm3yzbXVGzHXeLGUDWjvbKsDezUmn2desfexh+U7
KpNnEkXDMtMCsNkEMzM+3/BkuxLO52zYpDe5tV7Igx0=
=N6h6
-----END PGP PUBLIC KEY BLOCK-----
```
{{< /admonition >}}
# Resume
I do not currently keep an up-to-date version of my resume. In the past, I have
written up my resume using [LaTeX](https://www.latex-project.org/) as a PDF. I
may explore other solutions such as simply keeping it on this website.. _we'll

27
content/post/aperture-study.md
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@@ -17,28 +17,30 @@ setting for a specific lens.
<!--more-->
# The Setup
I started out using a tripod, with the same ISO and exposure compensation using
a [**Minolta 50mm f1/7**](https://en.wikipedia.org/wiki/Minolta_AF_50mm_f/1.7)
lens. Starting at *f/1.7* I worked my way up at reasonable steps to *f/4.0*. My
aim was to compare the differences. See the shots below. The target couch
cushion was set up roughly a meter from the bottom center of the tripod.
# Depth-of-Field
There may be something to be said about maintaining the best DoF
(*Depth-of-field*). However, using [PhotoPills DoF Calculator]
(https://www.photopills.com/calculators/dof) proves just how **wild**, using a
50mm lens, an aperture of *f/1.7* is. Shooting a target of *2 meters* results in
a depth-of-field of **16 centimeters** -- that's a very narrow range! Bumping up
the aperture value to *f/2.8* provides a much more reasonable *27 centimeters*,
though still a bit narrow. Either way this allays any fears I had of losing out
on that sweet, *sweet* [bokeh](https://en.wikipedia.org/wiki/Bokeh), though the
photos themselves illustrate that not a significant amount of Depth-of-Field is
lost at that target distance of 1 meter.
There may be something to be said about maintaining the best DoF
(*Depth-of-field*). However, using [PhotoPills DoF Calculator](https://www.photopills.com/calculators/dof)
proves just how **wild**, using a 50mm lens, an aperture of *f/1.7* is.
Shooting a target of *2 meters* results in a depth-of-field of **16
centimeters** -- that's a very narrow range! Bumping up the aperture value to
*f/2.8* provides a much more reasonable *27 centimeters*, though still a bit
narrow. Either way this allays any fears I had of losing out on that sweet,
*sweet* [bokeh](https://en.wikipedia.org/wiki/Bokeh), though the photos
themselves illustrate that not a significant amount of Depth-of-Field is lost
at that target distance of 1 meter.
# Comparison
## *f/1.7*--*f/4.0*
The biggest difference can be seen between the *f/1.7* and *f/4.0* shots. Note
the increase in clarity on the pillows fabric.
@@ -49,6 +51,7 @@ the increase in clarity on the pillows fabric.
---
## *f/1.7*--*f/2.8*
At *f/2.8* and above I started noticing less increase in perceived sharpness of
the image, though the difference in comparison to *f/1.7* was still fairly
noticeable
@@ -60,6 +63,7 @@ noticeable
---
## *f/2.8*--*f/4.0*
Aside from the perceived exposure difference from what is most likely a
difference in shutter speed, the overall difference does not seem as dramatic
from *f/2.8* to *f/4.0*. Personally, I'd say that *f/2.8* is the clear winner in
@@ -72,6 +76,7 @@ finding the best middle-ground between maximum aperture and image quality.
---
# Individual Photos
Below is the entire collection of all the photos taken of the subject at
increasing aperture steps.

133
content/post/archinstall.md
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@@ -16,6 +16,7 @@ better understanding of the tools and methods used.
---
# Partitioning
1. Create a partition scheme using partitioner of choice (e.g. `gdisk`, `fdisk`,
`cgdisk`).
- First partition should be EFI/boot partition at around 256MB+ (type:
@@ -25,93 +26,116 @@ better understanding of the tools and methods used.
1. Make the the EFI/boot partition FAT32 via `mkfs.fat -F32`
# Encryption
1. Format the Linux LVM partition:
```
# cryptsetup luksFormat /dev/sdaN
```bash
cryptsetup luksFormat /dev/sdaN
Enter passphrase:
```
**Note:** _Remember your passphrase! You will need this every time you boot
your computer_
1. Create a mapping for your Linux LVM (LUKS):
```bash
cryptsetup open --type luks /dev/sdaN <map_name>
```
# cryptsetup open --type luks /dev/sdaN <map_name>
```
_Use whatever name you want. Ex. `lvm`, `volume`, etc._
1. Create the physical volume, volume group, and logical volumes for
`<map_name>` specified in the previous step:
```bash
pvcreate /dev/mapper/<map_name>
vgcreate <volume_name> /dev/mapper/<map_name>
```
# pvcreate /dev/mapper/<map_name>
# vgcreate <volume_name> /dev/mapper/<map_name>
```
_Use whatever volume name you want. Ex. `volume`, `main`, `linux`, etc._
```bash
lvcreate -L2G <volume_name> -n swap
```
# lvcreate -L2G <volume_name> -n swap
```
_Select size for swap, if desired. Here we use `2G` for 2Gb._
```bash
lvcreate -L16G <volume_name> -n root
lvcreate -l 100%FREE <volume_name> -n home
```
# lvcreate -L16G <volume_name> -n root
# lvcreate -l 100%FREE <volume_name> -n home
```
1. Specify and write the desired filesystems:
```
# mkfs.ext4 /dev/mapper/<volume_name>-root
# mkfs.ext4 /dev/mapper/<volume_name>-home
# mkswap /dev/mapper/<volume_name>-swap
```bash
mkfs.ext4 /dev/mapper/<volume_name>-root
mkfs.ext4 /dev/mapper/<volume_name>-home
mkswap /dev/mapper/<volume_name>-swap
```
# Install Linux
1. Mount the boot partition and logical volumes for installation:
```
# mount /dev/mapper/<volume_name>-root /mnt
# mkdir /mnt/home
# mkdir /mnt/boot
# mount /dev/mapper/<volume_name>-home /mnt/home
# mount /dev/sdaN /mnt/boot
# swapon /dev/mapper/<volume_name>-swap
```bash
mount /dev/mapper/<volume_name>-root /mnt
mkdir /mnt/home
mkdir /mnt/boot
mount /dev/mapper/<volume_name>-home /mnt/home
mount /dev/sdaN /mnt/boot
swapon /dev/mapper/<volume_name>-swap
```
1. Install the base system (_Assuming you have internet connectivity. Use
`wifi-menu`, or other, to connect to the internet at this point._):
```
# pacstrap /mnt base base-devel
```bash
pacstrap /mnt base base-devel
```
# Set-up Linux Installation
1. Generate the `fstab`:
```
# genfstab -p /mnt >> /mnt/etc/fstab
```bash
genfstab -p /mnt >> /mnt/etc/fstab
```
1. Move into the installation:
```
# arch-chroot /mnt
```bash
arch-chroot /mnt
```
1. Configure `initramfs`:
1. Edit `HOOKS` in `/etc/mkinitcpio.conf` using text editor of your choice
(e.g. `vi`, `nano`, etc.). Move the `keyboard` hook before `filesystems`,
and add `encrypt` and `lvm2` hooks **before** `filesystems`:
```
# egrep '^HOOKS' /etc/mkinitcpio.conf
```bash
$ egrep '^HOOKS' /etc/mkinitcpio.conf
HOOKS=(base udev autodetect modconf block keyboard encrypt lvm2 filesystems fsck)
```
_Read the comment documentation on `HOOKS` in the document to find out
more._
1. Generate `initramfs`:
```
# mkinitcpio -p linux
```bash
mkinitcpio -p linux
```
1. Install a bootloader (e.g. `systemd-boot`, `grub`, `syslinux`, etc.):
1. I will be using `systemd-boot`
```
# bootctl --path=/boot/ install
```bash
bootctl --path=/boot/ install
```
1. Edit the loader configuration using a text editor of your choice:
```apacheconf
# cat /boot/loader/loader.conf
```bash
$ cat /boot/loader/loader.conf
default arch
timeout 3
editor 0
@@ -121,8 +145,9 @@ better understanding of the tools and methods used.
can edit this name if desired._). Use `blkid /dev/sdaN` to find the UUID
of your crypt device, and recall the volume name you gave your device
above (_`main` in example below_):
```apacheconf
# cat /boot/loader/entries/arch.conf
```bash
$ cat /boot/loader/entries/arch.conf
title Arch Linux
linux /vmlinuz-linux.img
initrd /initramfs-linux.img
@@ -131,26 +156,30 @@ better understanding of the tools and methods used.
1. Create a root password using `passwd`.
1. Set a hostname:
```
# echo "<your_hostname>" > /etc/hostname
```bash
echo "<your_hostname>" > /etc/hostname
```
1. Set up the time:
```
# ln -fs /usr/share/zoneinfo/<continent>/<city/place> /etc/localtime
# hwclock --systohc --utc
```bash
ln -fs /usr/share/zoneinfo/<continent>/<city/place> /etc/localtime
hwclock --systohc --utc
```
1. Set the locale to `en_US`:
```
# sed -i 's/^\#en_US/en_US/' /etc/locale.gen
# locale-gen
# locale > /etc/locale.conf
```bash
sed -i 's/^\#en_US/en_US/' /etc/locale.gen
locale-gen
locale > /etc/locale.conf
```
1. Done!
```
# exit
# unmount -R /mnt
# reboot
```bash
exit
unmount -R /mnt
reboot
```

22
content/post/emacs_clang_libopencm3.md
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@@ -20,6 +20,7 @@ Emacs workflow to include IntelliSense-like auto-completion!
# Dependencies
## System
Assuming you're running Linux, you'll need to have the following packages
installed:
@@ -29,21 +30,25 @@ installed:
## Emacs
### ELPA
If you already have ELPA/MELPA, feel free to skip this first part
To be able to easily fetch the packages, it's highly recommended you use the
**Emacs Lisp Package Archive** (ELPA). To do this, all that's required is to
simply add the following to your `init.el`/`.emacs`[^1] file:
```lisp
(require 'package)
(add-to-list 'package-archives
'("melpa" . "https://melpa.org/packages/"))
(package-initialize)
```
<sub>Emacs will need to be restarted or reloaded to load the package
repository.</sub>
### Packages
Install the following packages in Emacs (`M-x package-install`):
- `irony`
@@ -51,14 +56,15 @@ Install the following packages in Emacs (`M-x package-install`):
- `company-irony`
- `company-irony-c-headers` <sub>(_Required if you want header auto-completion_)</sub>
# Configuration
## Company
Company ([company-mode](http://company-mode.github.io/)) needs to be required,
added to the `after-init-hook` (_or similar / manually called_), and the back ends
to be added to it's list of usable back ends. This is done in the initialization
file[^1]:
```lisp
(require 'company)
(add-hook 'after-init-hook 'global-company-mode)
@@ -66,11 +72,13 @@ file[^1]:
```
## Irony
Initial setup of `irony` **requires** `M-x irony-install-server` to be run. If
errors are encountered, please ensure that you have the necessary [system
dependencies](https://github.com/Sarcasm/irony-mode#dependencies) installed.
Irony's `irony-mode` should be added to the relevant C/C++ mode hooks:
```lisp
(add-hook 'c++-mode-hook 'irony-mode)
(add-hook 'c-mode-hook 'irony-mode)
@@ -79,21 +87,25 @@ Irony's `irony-mode` should be added to the relevant C/C++ mode hooks:
Additionally, it's a good idea to add the compile options auto setup helper
command to the `irony-mode` hook:
```
```lisp
(add-hook 'irony-mode-hook 'irony-cdb-autosetup-compile-options)
```
# Usage
There are several ways to make `irony-mode` aware of what it should look for in
it's completion. My preferred method, though not the only one, is to simply add
my compile flags in the special `.clang_complete` file as part of the working
directory of the project.
For an STM32F0 project, the context of the `.clang_complete` file would be:
```
```text
-I./libopencm3/include
-DSTM32F0
```
<sub>The above assumes that `libopencm3` is also places within the project
directory</sub>
@@ -106,9 +118,9 @@ fairly uninvolved workaround.
{{< /admonition >}}
## Example
{{< img src="/static/img/emacs-clang-libopencm3/completion.png"
sub="Completion"
alt= "Screenshot showing auto completion for C functions in emacs">}}
[^1]: [Emacs Initialization File]
(https://www.gnu.org/software/emacs/manual/html_node/emacs/Init-File.html)
[^1]: [Emacs Initialization File](https://www.gnu.org/software/emacs/manual/html_node/emacs/Init-File.html)

39
content/post/gpg_best_practices_and_git.md
View File

@@ -21,16 +21,18 @@ git config --global commit.gpgSign true
For reference, I am directly referencing the subkey ID I use for **signing only**
denoted by `[S]`:
```
```text
pub rsa4096/ADAA54FC 2017-11-21 [SC] [expires: 2020-02-23]
uid Bastian de Byl <bastiandebyl@gmail.com>
sub rsa4096/A72FC2F1 2017-11-21 [E] [expires: 2020-02-23]
sub rsa4096/875953A2 2019-02-23 [S] [expires: 2020-02-23]
```
<sub>Note: _I am using git version `2.20.1` in the above example._</sub>
# Getting Started with OpenPGP
It is recommended to read through the
[Getting Started](https://www.gnupg.org/gph/en/manual/c14.html) page on the
official GnuPG website. It is also **strongly** recommend to use the
@@ -40,6 +42,7 @@ create a separate subkey for **signing only** -- read more about that
[here](https://wiki.debian.org/Subkeys).
# OpenPGP Keyserver Pool
As of GnuPG version
[2.1.11](https://github.com/riseupnet/riseup_help/issues/294#issuecomment-192913705),
the `hpks.pool.sks-keyservers.net` CA certificate is installed and made use by
@@ -51,13 +54,16 @@ signature. Instructions can be found on the
reading further below.
## Verification
To verify and retrieve the necessary keys to do so (automatically, if possible):
```bash
gpg --auto-key-retrieve --verify sks-keyservers.netCA.pem.asc sks-keyservers.netCA.pem
```
The expected output:
```
```text
gpg: Signature made Wed 30 Mar 2016 11:06:29 AM EDT
gpg: using RSA key 250B7AFED6379D85
gpg: key 0B7F8B60E3EDFAE3: 1214 signatures not checked due to missing keys
@@ -76,57 +82,66 @@ Primary key fingerprint: 94CB AFDD 3034 5109 5618 35AA 0B7F 8B60 E3ED FAE3
```
## Adding the HKPS Pool CA
Once the signature has been verified, the CA can be moved over to
`/usr/share/ca-certificates` to update the list of trusted CA certificates. Do
this via:
+ **ArchLinux:** `sudo update-ca-trust`
+ **Debian/Ubuntu, RHEL:** `sudo update-ca-certificates`
- **ArchLinux:** `sudo update-ca-trust`
- **Debian/Ubuntu, RHEL:** `sudo update-ca-certificates`
{{< admonition tip "CA Path" >}}
On my system the full path to the CA certs is:
- `/etc/ca-certificates/extracted/cadir/sks-keyservers.net_CA.pem`
{{< /admonition >}}
Two following parameters should be added to your `~/.gnupg` configuration files:
### GnuPG Versions >2.1
{{< admonition note "gpg.conf" >}}
```
```text
keyserver hkps://hkps.pool.sks-keyservers.net
```
{{< /admonition >}}
{{< admonition note "dirmngr.conf" >}}
```
```text
hkp-cacert /etc/ca-certificates/path/to/CA.pem
```
{{< /admonition >}}
### GnuPG Versions <2.1
{{< admonition note "gpg.conf" >}}
```
```text
keyserver hkps://hkps.pool.sks-keyservers.net
keyserver-options ca-cert-file=/path/to/CA/sks-keyservers.netCA.pem
```
{{< /admonition >}}
## *Optional* - Ensure keys refreshed through keyserver
To ensure no keys are pulled from insecure sources, or that an attacked would
not be able to designate a keyserver they control, it is recommended to add the
following additional parameter to the above `gpg.conf` file:
```
```text
keyserver-options no-honor-keyserver-url
```
---
# More Information
The
[OpenPGP Best Practices](https://riseup.net/en/security/message-security/openpgp/best-practices)
page is a good resource for finding out more on best practices. A few points

24
content/post/hardened_linux.md
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@@ -20,31 +20,37 @@ enable more hardening features. By default, the `linux-hardened` kernel on Arch
Linux has security leaning defaults.
# Laying the Ground Work
On Arch Linux, it's as simple as:
```
```text
# pacman -S linux-hardened linux-hardened-headers
```
_Optionally (additionally) run `mkinitcpio -p linux-hardened` as root if
this wasn't already done automatically as part of the installation_
<sub><i>Optionally (additionally) run `mkinitcpio -p linux-hardened` as root if
this wasn't already done automatically as part of the installation</i></sub>
The steps to boot to the hardened kernel will change based on your boot
loader. Personally, I am using
[`systemd-boot`](https://wiki.archlinux.org/index.php/Systemd-boot) and will
therefore start with that.
## Boot Loader Configuration
### **`systemd-boot`**
Create a new loader config will need to be created on top of your existing one
in `/boot/loader/entries/`
**Example**
#### Example Systemd-boot Entry
```apacheconf
title Arch Linux (Hardened)
linux /vmlinuz-linux-hardened
initrd /initramfs-linux-hardened.img
options ...
```
_The `options` line above will be specific to your system. This can be copied
from existing, working loader configurations or such as the one described in
[Installing Arch Linux](/post/archinstall/#set-up-linux-installation)_
@@ -53,14 +59,17 @@ Change the default **or** enable `auto-entries` to selectively boot from it in
`/boot/loader/loader.conf`
### **`grub`**
For grub, it should be as simple as running `grub-mkconfig -o
/boot/grub/grub.cfg` (_as root_)
### **`syslinux`**
Similar to `systemd-boot`, `syslinux` requires an additional entry in it's
configuration file, found at `/boot/syslinux/syslinux.conf`
**Example**
#### Example Syslinux Config
```apacheconf
PROMPT 1
TIMEOUT 50
@@ -73,10 +82,12 @@ LABEL archhardened
...
```
<sub>Note that the `APPEND` may differ from the example, same with `options`
for `systemd-boot`</sub>
# Finish Line
It's that simple! There are additional system hardening steps one may opt to
take such as:
@@ -90,6 +101,7 @@ On top of that, there are other tools one could leverage in addition to a
hardened kernel, though that's out-of-scope for this post. One example would be
something as simple as **disabling SSH password authentication**
(`/etc/ssh/sshd_config`):
```apacheconf
..
PasswordAuthentication no

10
content/post/headphone-fix.md
View File

@@ -13,7 +13,8 @@ with the catch being: _I had to fix them_
alt="Photo of Bern brand headphones under magnifying glass" >}}
<!--more-->
# Don't Turn It On, Take It Apart!
# Don't Turn It On, Take It Apart
Past mistakes have taught me to be gentle and patient when it comes to taking
things apart. This was no exception either. After looking over the unit on each
side, I figured the only way *in* was lifting the mesh cover off. So I went at
@@ -21,6 +22,7 @@ it, carefully, with a pair of tweezers. I worked my way around the edge and
wedged the mesh upwards.
# Okay, Maybe Turn It On
Now that the problematic speaker side was successfully opened without any
damage, it was time to investigate what was wrong.
@@ -41,8 +43,8 @@ problematic, speaker. The result was much different, indicating either noise or
an open circuit. It may be worth mentioning that the right speaker was
disconnected at this point in time to ease the troubleshooting process.
# Where Did It All Go Wrong
# Where Did It All Go Wrong?
Lucky for me the PCB pads were labeled -- even better `SPKL+` (_left_) and
`SPKR+` (_right_) were easy to find.
@@ -70,8 +72,8 @@ bother desoldering the left speaker connections to make removal easier. So, with
a bit of gentle back and forth I was able to get it the PCB out and inspect
traces on the bottom side.
# Something's Not Quite Right
# Something's Not Quite Right...
Continuity from `SPKL+` to the QFN pin was good, yet `SPKR+` to the op-amp
showed open circuit. Visibly, everything on the PCB looked fine. There were no
apparent signs of damaged or lifted traces, nor bad soldered wires or
@@ -90,8 +92,8 @@ bodge wire was in order_..
{{< thumb src="/static/img/headphone-fix/IMG_7515.jpg" sub="Note the bodge wire"
alt="Photo of close-up magnified view with soldered fix wire in right speaker PCB" >}}
# All's Well That Ends Well
Again, using my trusty Fluke 115, I verified continuity from the chip's `OUTR`
pin to `SPKR+`. Lo and behold it was now closed-circuit! I was very happy to see
the expected waveform from the known-good left channel now also appearing on the

9
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@@ -13,6 +13,7 @@ from WordPress)
<!--more-->
# Disclaimer
{{< admonition warning "Out of Date" >}}
The information in this article is **out-of-date**. I am, and have been, using my
own fork of the [hugo-even-theme](https://gitlab.com/bdebyl/hugo-theme-even) on
@@ -26,8 +27,8 @@ relevant
[commit](https://github.com/bdebyl/hugo-tracks-theme/commit/86ca4963c4d0a67ddb1560197c91617e7d3e3754) on
my GitHub fork of the **Tracks** theme.
# Rough Start
Right off the bat I noticed the navigation bar seemed a bit off, to say the least:
<center>![Problem Navbar](/static/img/humble-beginnings/header-problem.png)</center>
@@ -40,7 +41,7 @@ page header.
> **.Site.Sections**
>
> top-level directories of the site.
> top-level directories of the site.
\- [Source](https://gohugo.io/variables/site/#site-variables-list)
@@ -53,8 +54,8 @@ fully understanding where the `0` and `1` "sections" even originated from. In
any case, I decided the only course of action was to use something other than
sections for the behavior I wanted.
# The Fix
Looking at other template files in the theme's layout, I stumbled on a chunk of
code in `layouts/partials/headers.html` that defined the behavior of the
aforementioned "navbar" problem:
@@ -91,8 +92,8 @@ appears to be used*) to include the nav links and get my desired behavior:
</div>
```
# But Wait, There's More
# But Wait, There's More!
After getting more comfortable with how themes are written for Hugo, I found a
slew of other problems with the ported **Tracks** theme:

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@@ -22,9 +22,9 @@ with a custom recovery to utilize for this purpose!
alt="Screenshot showing the LineageOS Trust feature" >}}
{{< /thumbgallery >}}
<!--more-->
# Thank You
Before going on any further, I'd like to take a moment to give my sincere thanks
to InvisibleK (Dan Pasanen). Having to set up the entire custom build for Pixel
3a of LineageOS myself would add far more overhead in the overall simple task in
@@ -33,6 +33,7 @@ trying to get LineageOS to work on a Pixel 3a!
[**tl;dr**](#flash-custom-recovery)
# Preface
There are plenty of guides out there on how to install and set up ADB and
Fastboot on your host machine. For me, on Arch Linux, this was as simple as
running `pacman -S android-tools`. However, should you be on MacOS or Windows
@@ -43,11 +44,14 @@ Additionally, this _guide_ also assumes the reader has some familiarity with ADB
and/or Fastboot.
# Source Files
If you, the reader, know what you're doing and simply just require the files
for your Pixel 3a they can be found here:
- https://updater.invisiblek.org/sargo
- <https://updater.invisiblek.org/sargo>
# Installation
{{< admonition warning "Warning!" >}}
If it isn't abundantly clear by now, be aware that you **will be destroying all
the data currently on your Pixel 3a** in the process of installing LineageOS on
@@ -56,69 +60,88 @@ proceeding.
{{< /admonition >}}
## Note about TWRP
As of writing this, TWRP[^1] (_a custom recovery commonly used in custom OS
installation_) does not support Android 10. This would have been the preferred
for a custom recovery, though not strictly required. Since we will be installing
LineageOS 17.1 for Android 10 we cannot use TWRP.
## Flash to Stock
Google is kind enough to provide a variety of versions of the stock images for
the Pixel devices. In my process of installing LineageOS, as it will be on
Android 10, I made sure to flash to the latest stock version of Pixel 3a Android
10. Do note that the versions are listed in reverse order, with the latest being
found in the bottom-most row.
- https://developers.google.com/android/images
- <https://developers.google.com/android/images>
Additionally, Google provides a helper script `flash-all` that I highly
recommend running as-is to flash your Pixel 3a to stock. This can take a few
minutes to complete.
## Flash Custom Recovery
Using InvisibleK's build page, you'll find the required custom recovery image
for flashing found at the bottom of the list of zip files marked with a lone
"download" link.
Flash it via the following steps:
1. Reboot to recovery
```bash
$ adb reboot bootloader
adb reboot bootloader
```
1. Unlock the bootloader if the 'Status' is locked:
```bash
fastboot flashing unlock
```
$ fastboot flashing unlock
```
1. Flash the custom recovery (_make sure to replace `N` with the version you
downloaded, mine was '4'_)
```bash
$ fastboot flash boot sargo-recovery-eng-N.img
fastboot flash boot sargo-recovery-eng-N.img
```
1. Boot the custom recovery either by re-entering recovery mode or fastboot --
make sure to wait for it to enter Android Recovery after
```bash
$ fastboot boot sargo-recovery-eng-N.img
fastboot boot sargo-recovery-eng-N.img
```
## Install LineageOS
Now that the custom recovery is set up and booted into, we're ready to install LineageOS!
1. **Important!** Once in recovery, ensure to `Wipe data/factory reset` prior to
proceeding.
1. Select `Apply update from ADB`
1. ADB Sideload the version, if not latest, of LineageOS you want for your Pixel
3a
```bash
$ adb sideload lineage-17.1-2020517-UNOFFICIAL-sargo.zip
adb sideload lineage-17.1-2020517-UNOFFICIAL-sargo.zip
```
1. Wait for installation to complete then select 'Reboot system now' from the
recovery menu
1. **Enjoy LineageOS!**
## Verification
Once in LineageOS, you can browse the settings to verify the installation and
set up Trust the preferred way. Personally, I chose to leave the defaults.
# Bugs / Issues
I plan to keep this list of bugs and issues I discover up to date, but this is
what I have encountered so far:
- WiFi calling does not seem to work
[^1]: [Team Win Recovery Project](https://twrp.me/)

13
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@@ -16,6 +16,7 @@ script with the following goals:
<!--more-->
# Preface
The full **source code** for this script can be found in my public scripts
repository:
[scripts/bash/pass-check.sh](https://gitlab.com/bdebyl/scripts/blob/master/bash/pass-check.sh)
@@ -27,6 +28,7 @@ to generate, and manage my passwords. On mobile, this is done using the official
shared across my devices using Git[^2]
# Pump Your Brakes
Instead of jumping right into checking all my passwords, in plain-text, against
the `pwnedpasswords` API, it would be best to figure out how to safely transform
them to SHA-1[^3]. The API supports sending the first 5 characters of a SHA-1
@@ -34,9 +36,11 @@ hash, returning a list of all SHA-1s of exposed passwords (_with the exposed
count_) for the user to verify them on their end.
# Gathering Passwords
The easiest way to get a comprehensive list (_associative array_[^4]) of
passwords and their `pass` path was to use `find` to look for `*.gpg` files in
my `.password-store` directory:
```bash
# Fetches all passwords in $PASSDIR and checks for duplicates (base check)
getpws()
@@ -52,6 +56,7 @@ getpws()
done < <(find "$PASSDIR" -name "*.gpg" -type f -print0)
}
```
To note, `find` with `-print0` is used to avoid printing newline characters
(_unlikely, but good practice_), so that we can utilize the null terminator `''`
within `read -d ''`. Also, `read -r` simply prevents backslashes from being
@@ -71,10 +76,12 @@ That takes care of gathering our passwords, but we'll revisit this again in the
next part.
# Sharing is not Caring
The most efficient way of checking for duplicates was simply to iterate over the
array of passwords gathered, and check against the current one found in the
`getpws()` function's loop. The names of the duplicate passwords are stored in
_another_ associative array for printing later as part of the "report".
```bash
# Checks for duplicate sha1sums of passwords in the associative array
checkdupes()
@@ -88,6 +95,7 @@ checkdupes()
```
That being done, we just incorporate it into the above `getpws()` loop!
```bash
getpws()
{
@@ -102,6 +110,7 @@ This accomplishes our *first goal* of checking duplicate passwords --
**hooray!**
# Passwortstärke
The simplest method of password strength checking, with indications as to _why_
it's weak (_i.e. "Exists in attack dictionary", "Too short", etc._) was to use
[`cracklib`](https://github.com/cracklib/cracklib). Sadly, it's not the most
@@ -117,6 +126,7 @@ This addition was made in the following order:
1. First, we need to find the executable **and** create _yet another_ useful
associative array for us to store the outputs (_a.k.a. messages_):
```bash
CRACKLIB=$(command -v cracklib-check)
declare -A pwscracklib
@@ -124,6 +134,7 @@ This addition was made in the following order:
1. Then a convenient function to iterate over all found passwords, safely
"expose" them, and run the check storing all **relevant** "outputs":
```bash
# Run through the global pws associative array and check for suggestions
checkcracklib()
@@ -140,6 +151,7 @@ This addition was made in the following order:
Done! It's _that_ easy.
# Have you been Pwned
The last, but **most important**, step was to add the actual check against the
`pwnedpass` API check! This gets a bit fun as we use
[Shell Parameter Expansion](https://www.gnu.org/software/bash/manual/html_node/Shell-Parameter-Expansion.html)
@@ -152,6 +164,7 @@ exposed (_"pwned"_) password's SHA-1 hash, and the amount of times they have
been leaked as a response. The prefix of the first 5 characters is dropped in
this list, thus we check for a match of our password using everything after the
first 5 characters of the SHA-1 hash and we're done!
```bash
# Check passwords against the HIBP password API (requires internet)
checkpwnapi()

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@@ -30,6 +30,7 @@ For those that want to cut to the chase and save time, here is the full source
code with friendly names to get you started:
{{< admonition note "Source Code" true >}}
```C
#include <libopencm3/stm32/gpio.h>
#include <libopencm3/stm32/rcc.h>
@@ -47,9 +48,11 @@ int main(void) {
while (1);
}
```
{{< /admonition >}}
# Getting Started with libopencm3
[libopencm3](https://github.com/libopencm3/libopencm3) is a very powerful,
useful, open-source firmware library for use in writing programs for various
different ARM Cortex-M microcontrollers. It's read me contains plenty of
@@ -60,8 +63,8 @@ Additionally, there is a
[libopencm3-template](https://github.com/libopencm3/libopencm3-template)
repository to help in getting started.
## Dependencies
Prior to doing any ARM Cortex-M development, the necessary dependencies need to
be installed in order to successfully build/compile source code into a binary
capable of being flashed (written) onto the microcontroller:
@@ -74,6 +77,7 @@ capable of being flashed (written) onto the microcontroller:
- **Text Editor or IDE**: Anything, _really_.
## Flashing the STM32F0 Discovery Board
The discovery series boards provided by ST come with an on-board
[ST-LINK/V2](https://www.st.com/en/development-tools/st-link-v2.html)
programmer. There are several ways to flash your build programs using this,
@@ -86,6 +90,7 @@ not be overlooked for too long! For the sake of brevity, this guide will omit
diving into that until later.
## Makefile
The aforementioned `libopencm3-examples` repository provides a useful, yet
overly complex, Makefile. For the reader, this has been boiled down (_assuming
they are also using `stlink` mentioned above_) the following, simple Makefile[^2] on
@@ -95,6 +100,7 @@ To flash, it's as simple as `make flash` (_will also build the binary for your
convenience_).
## Linker Script
The loader (`.ld`) file is specific to the _flavor_ of ARM Cortex-M
microcontroller being used. The authors of `libopencm3` provide example
loader files that can be used for most projects (_e.g. located in
@@ -104,12 +110,13 @@ for proper use. There are several articles online that go into detail about
linker scripts
## Project Structure
The Makefile, as of writing this, assumes your project directory structure has
`libopencm3` either cloned, copied, or initialized as a git submodule within the
same directory of your `main.c`. It is advised that you look through the
Makefile's variables of things you may want to change:
```
```text
.
├── libopencm3
├── main.c
@@ -139,16 +146,19 @@ The Discovery board comes with two LEDs for use by the user, tied to Port C pins
8 (blue LED), and 9 (green LED).
## Reset and Clock Control (RCC)
The **RCC**, and it's registers, are an important part in _using_ the STM32
microcontroller's peripherals. Luckily, utilizing `libopencm3` we can forego
bit-banging our way through each register's bits found in the reference
manual[^5] and simply utilize the GPIO port that we need -- in this case
`GPIOC`:
```C
rcc_periph_clock_enable(RCC_GPIOC);
```
## GPIO Setup
Next, we need to define what mode we want the GPIO pins on their respective port
to be along with the internal pull-up or pull-down resistor mode:
@@ -169,20 +179,22 @@ to be along with the internal pull-up or pull-down resistor mode:
authors, along with the function definition can be found
[**here**](https://libopencm3.org/docs/latest/html/)</i></sub></center>
Having clarified that, as we want to **drive** the LEDs, we will need to
configure the pins as outputs with no internal pull-up or pull-down resistor:
```C
gpio_mode_setup(GPIOC, GPIO_MODE_OUTPUT, GPIO_PUPD_NONE, GPIO8);
gpio_mode_setup(GPIOC, GPIO_MODE_OUTPUT, GPIO_PUPD_NONE, GPIO9);
```
_Simplified using bitwise[^6] OR:_
```C
gpio_mode_setup(GPIOC, GPIO_MODE_OUTPUT, GPIO_PUPD_NONE, GPIO8 | GPIO9);
```
## GPIO Output Options Setup
Now that the GPIO mode has been set up, the GPIO output options need to be
defined as well. This will encompass the output type, and output speed:
@@ -216,11 +228,13 @@ gpio_set_output_options(GPIOC, GPIO_OTYPE_PP, GPIO_OSPEED_LOW, GPIO9);
```
_Simplified[^6]:_
```C
gpio_set_output_options(GPIOC, GPIO_OTYPE_PP, GPIO_OSPEED_LOW, GPIO8 | GPIO9);
```
## Turn it on!
## Turn it On
There are no additional options required for the user to be able to now set, or
clear, the desired GPIO pins. Thus, we set it _and forget it_:
@@ -230,12 +244,14 @@ gpio_set(GPIOC, GPIO9);
```
_Simplified[^6]:_
```C
gpio_set(GPIOC, GPIO8 | GPIO9);
```
Lastly, we need to make sure our program never **exits** and does something
_undesirable_ by keeping it inside a loop:
```C
while(1);
```
@@ -256,7 +272,7 @@ Explained](http://www.learningaboutelectronics.com/Articles/While-(1)-embedded-C
[^1]: [GNU Arm Embedded Toolchain](https://developer.arm.com/tools-and-software/open-source-software/developer-tools/gnu-toolchain/gnu-rm)
[^2]: [Makefile](https://gitlab.com/bdebyl/stm32f0-example-project/blob/b858d5e38026bcce3b8aad4085ffb665ddf63eef/Makefile) as of writing this post
[^3]: https://gitlab.com/bdebyl
[^3]: <https://gitlab.com/bdebyl>
[^4]: [STM32F0 Discovery User Manual](https://www.st.com/content/ccc/resource/technical/document/user_manual/30/ae/6e/54/d3/b6/46/17/DM00050135.pdf/files/DM00050135.pdf/jcr:content/translations/en.DM00050135.pdf)
[^5]: [STM32F0 Reference Manual](https://www.st.com/content/ccc/resource/technical/document/reference_manual/c2/f8/8a/f2/18/e6/43/96/DM00031936.pdf/files/DM00031936.pdf/jcr:content/translations/en.DM00031936.pdf)
[^6]: [Bitwise Operators in C](https://en.wikipedia.org/wiki/Bitwise_operations_in_C)

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@@ -26,6 +26,7 @@ For those that want to cut to the chase and save time, here is the full source
code with friendly names to get you started:
{{< admonition note "Source Code" true >}}
```C
#include <libopencm3/stm32/gpio.h>
#include <libopencm3/stm32/rcc.h>
@@ -76,20 +77,23 @@ int main(void) {
return 0;
}
```
{{< /admonition >}}
# Set up the GPIO
Assuming the reader is either familiar with GPIO setup for the STM32F0, or has
reviewed [**Part 0**](/post/stm32-part0) of this series we will set up the GPIO
pins tied to the LEDs (_port C, pins 8 and 9_) in the Alternate Function mode.
Knowing that we'll be using `GPIOC`, we should enable this peripheral:
```C
rcc_periph_clock_enable(RCC_GPIOC);
```
## Alternate Functions
The STM32 microcontroller's GPIO has a hardware feature allowing you to tie
certain port's pins to a different register as part of the output or input
control:
@@ -107,8 +111,8 @@ Review the datasheet for the specific **STM32Fx** microcontroller being
programmed, as the Alternate Function mappings may be *significantly* different!
{{< /admonition >}}
## GPIO Alternate Function Setup
For the STM32F0 we are using in this series, the Alternate Function selection
number desired is `GPIO_AF0` for use with `TIM3_CH3` (_timer 3, channel 3_) and
`TIM3_CH4` (_timer 3, channel 4_):
@@ -116,8 +120,8 @@ number desired is `GPIO_AF0` for use with `TIM3_CH3` (_timer 3, channel 3_) and
sub="STM32F051 Alternate Function Mapping"
alt="Screenshot of alternate function pin definition table for STM32F0" >}}
Ultimately, the code with `libopencm3` becomes the following for our use case:
```C
gpio_mode_setup(GPIOC, GPIO_MODE_AF, GPIO_PUPD_NONE, GPIO8 | GPIO9);
gpio_set_output_options(GPIOC, GPIO_OTYPE_PP, GPIO_OSPEED_HIGH, GPIO8 | GPIO9);
@@ -125,16 +129,19 @@ gpio_set_af(GPIOC, GPIO_AF0, GPIO8 | GPIO9);
```
# Set up the General Purpose Timer
From the previous section we chose the two on-board LEDs on the STM32F0
Discovery board tied to `PC8` and `PC9`. From the Alternate Function GPIO
mapping, we know these will be Timer 3 (_channels 3, and 4_).
Knowing that we'll be using `TIM3`, we should enable this peripheral:
```C
rcc_periph_clock_enable(RCC_TIM3);
```
## Timer Mode
The first step in setting up the timer, similar to GPIO, is setting the timer
mode. The encompass the divider amount (_dividing the peripheral clock_),
alignment for capture/compare, and up or down counting:
@@ -165,6 +172,7 @@ timer_set_mode(TIM3, TIM_CR1_CKD_CK_INT, TIM_CR1_CMS_EDGE, TIM_CR1_DIR_UP);
```
## Timer Prescaler
In addition to the timer clock, set by the peripheral clock (internal), each
timer has a perscaler value. This determines the counter clock frequency and is
equal to `Frequency/(Prescaler + 1)`. This is the value the timer will count to prior
@@ -175,6 +183,7 @@ integer value_).
For the sake of simplicity in dividing the clock into easy decimal values, we
will utilize setting up the High Speed Internal clock to 48MHz and dividing by
48,000:
```C
rcc_clock_setup_in_hsi_out_48mhz(); // Place at the beginning of your int 'main(void)'
...
@@ -184,18 +193,20 @@ timer_set_prescaler(TIM3, (rcc_apb1_frequency/48000)/2*SECONDS));
```
## Timer Period
Having set the prescaler to determine the maximum count of the timer, there is
an additional period we need to set. For our purposes, this will simply be the
same value of the prescaler:
```C
timer_set_period(TIM3, 48000);
```
## Timer Additional Configuration
There are two minor settings we want to configure for the timer:
<div style="display: none;">[^1]</div>
1. Disable preloading the ARR<sup id="fnref:1" class="footnote-ref"><a href="#fn:1">1</a></sup> (auto-reload register) when the timer is reset
There are two minor settings we want to configure for the timer:
1. Disable preloading the ARR[^1] (auto-reload register) when the timer is reset
1. Run the timer in continuous mode (never stop counting, clear the status
register automatically)
@@ -205,6 +216,7 @@ timer_continuous_mode(TIM3);
```
## Timer Channel Output Compare Mode
Since we are utilizing Timer 3's channel 3 (`GPIOC8`), and channel 4 (`GPIOC9`)
we need to determine the output compare mode we want to use for each channel. By
default the mode for each channel is frozen (unaffected by the comparison of the
@@ -232,6 +244,7 @@ timer_set_oc_mode(TIM3, TIM_OC4, TIM_OCM_PWM2);
In layman's terms: _only one LED will be on at a time, alternating._
## Timer Channel Output Compare Value
Lastly, we need to set the values that the output compare looks to for it's
comparison. For this example, we want a 50%-on/50%-off time for ease of timing
the duration of LEDs on-time determined by the frequency and period of the
@@ -244,6 +257,7 @@ timer_set_oc_value(TIM3, TIM_OC4, 24000);
```
### Exercise for the Reader
A fun exercise in C to reduce repetition would be by creating an array of timer
output compare address values and looping through them to set them to the same
value.
@@ -254,6 +268,7 @@ microcontroller. That being said, there is still some fun to have.
The following snippet will be provided as a note and exercise for the reader in
exploring memory allocation and garbage collection:
```C
int tim_oc_ids[2] = { TIM_OC3, TIM_OC4 };
@@ -261,10 +276,12 @@ for (i = 0; i < (sizeof(tim_oc_ids)/sizeof(tim_oc_ids[0])); ++i) {
timer_set_oc_value(TIM3, tim_oc_ids[i], 24000);
}
```
<center><sub>_Determining the 'length' of an array in C is different than in
other languages.[^2]_</sub></center>
## Enable the Timer
Lastly, to kick everything off we need to enable both the timer and the relevant
output-compare outputs.
@@ -277,6 +294,7 @@ timer_enable_counter(TIM3);
```
### Another Exercise for the Reader
The same for loop for `timer_set_oc_value()` can be appended to
for `timer_enable_oc_output()` as discussed previously:
@@ -290,8 +308,10 @@ for (i = 0; i < (sizeof(tim_oc_ids)/sizeof(tim_oc_ids[0])); ++i) {
```
# Fin
Lastly, as always, we should not forget to place the microcontroller in an
infinite loop:
```C
while (1);
```

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@@ -17,6 +17,7 @@ to say this required fixing.
<!--more-->
# Damage Assessment
The first step was to look at the PCB to assess how this could be, if at all,
replaced. From the outside you could see the damage done. Note the single
pin left and lack of the inner pad (_bolster?_).
@@ -25,8 +26,8 @@ pin left and lack of the inner pad (_bolster?_).
sub="One pin remains"
alt="Photo showing one pin remaining on a damaged USB receptacle ">}}
# Measure Twice
Next on the list: measurements. To find a suitable replacement receptacle, I
needed to have the relevant dimensions in comparing to receptacle part drawings
of those available for sale.
@@ -50,13 +51,14 @@ Using generic, non-branded digital calipers I was able to get the following
| Pad Width | _1.9mm_ |
<center><sub>Fig. 1</sub></center>
# Shopping with Purpose
Using the value above, I was able to track down a USB receptacle[^1] on
Digi-Key[^2] that matched my requirements very, _very_
closely.
## Resounding Comparison
Keep in mind the measured values were an eyeball approximation with a low cost,
unbranded digital caliper. Those values are nearly spot-on.
@@ -76,6 +78,7 @@ other the two receptacles matched up just as I had hoped.. **Fantastic!**
alt="Photo showing new USB receptacle on top of damaged one for comparison" >}}
# It's not over yet
Initial attempts at desoldering the existing (_broken_) receptacle proved
futile. Even with liberal application of flux, high soldering iron temperatures
well beyond typical soldering temperatures[^3], the solder would not flow and
@@ -92,6 +95,7 @@ having spent about half an hour on it with tweezers, solder wick, a solder
sucker (_desoldering pump_), and flush cutters, I gave up.
# Throwing in the Towel
It turned out the only way to attach the replacement was to modify the new part
to fit -- _luckily I had ordered two replacements as I broke the first one in
the modification "process"_. Cutting and bending the pins, I was able to get it
@@ -108,6 +112,7 @@ been able to bend the flat pads towards the entry of the receptacle down to
attempt to solder them to the surface mount pads.
# All the King's horses, all the King's men
Alas, it was time to put the laptop back together. To my dismay there were
further problems. Due to the modification and forced fitment of the replacement,
the USB receptacle was sticking out too far off of the PCB preventing the

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@@ -19,18 +19,22 @@ write-up on this blog: [**OpenPGP Best Practices (and Git)**](/post/gpg_best_pra
{{< /admonition >}}
# Importing Secret Keys
Personally, my secret (primary) key is not kept on any device. It's stored, and
backed up in encrypted external media devices (_USB, etc._) only to be imported
when keys require editing.
## Mounting Secure Device (LUKS)
This is done using `cryptsetup` and Linux Unified Key Setup[^1] (LUKS) for
encryption. Plugging in my USB device and mounting it requires only _one_
additional step. Instead of initially running `mount /dev/sdXN` we first must
"open" the encrypted drive via:
```bash
cryptsetup --type luks open /dev/sdXN encryptedusb
```
{{< sub >}}
The `encryptedusb` name is a user-specified friendly name that has
no relevance to accessing the drive
@@ -39,47 +43,58 @@ no relevance to accessing the drive
**Now** the device can be mounted to a directory, but not via the `/dev/sdXN` device
-- rather the `/dev/mapper/encryptedusb` device (_or whatever friendly name you
gave it_).
```bash
mount /dev/mapper/encryptedusb /mnt/media
```
## Backing up the Keys
Once the device has been securely mounted, it's a good idea to either export
the keys currently in the keyring **or** back-up the entire `~/.gnupg`
directory. The backup created will be stored on the previously mounted external
media device.
### GPG Key Export Backup
It's as simple as exporting the secret key, which will also contain your public
key:
```bash
gpg --armor --export-secret-key your@email.address > /mnt/media/some/dir/secretkey.gpg.bak
```
### GPG Directory Backup (optional)
This isn't entirely necessary, though it's never a bad idea to create a hard
back-up of the directory -- _just don't forget to remove it after!_
```bash
cp ~/.gnupg /mnt/media/some/backup/dir/.gnupg.bak
```
{{< sub >}}
Note: If the `~/.gnupg.bak` directory already exists, the above command will
copy it to `~/gnupg.bak/.gnupg`!
{{< /sub >}}
## Import and Update Expiration
Now that back-ups have been taken care of, the current keyring can either be
emptied, deleted, or simply worked with. That's up to the user.
### Import
In any event, the next step ultimately becomes importing the secret (primary)
key:
```bash
gpg --import /mnt/media/some/backup/dir/secretprimarykey.gpg
```
Verify the presence of the primary secret key, noting no presence of `sec#` in
the output indicating only a partially stripped secret key, via:
```bash
gpg --list-secret-keys
@@ -89,9 +104,11 @@ sec rsa4096 2017-11-21 [SC] [expires: 2021-02-16]
```
### Update
Updating the primary secret key and all it's sub keys is done via `gpg` in the
following manner:
```
```text
gpg --edit-key your@email.address
gpg> key 0
@@ -114,6 +131,7 @@ gpg> save
```
At this point, it's a good idea to send the key to the key server:
```bash
gpg --send-keys your@email.address
# or
@@ -121,8 +139,10 @@ gpg --keyserver pgp.mit.edu --send-keys your@email.address
```
## Cleanup
Now it's time to export the primary key and it's sub keys to the encrypted
external media device:
```bash
gpg --armor --export-secret-key your@email.address > /mnt/media/some/dir/secretkey.gpg
gpg --armor --export-secret-subkeys your@email.address > /mnt/media/some/dir/secretsubkey.gpg
@@ -130,6 +150,7 @@ gpg --armor --export-secret-subkeys your@email.address > /mnt/media/some/dir/sec
Then, delete the primary secret key from your keyring and import **only** the
secret sub-key:
```bash
gpg --delete-secret-keys your@email.address
# reply 'yes' to the prompts as needed
@@ -138,29 +159,33 @@ gpg --import /mnt/media/some/dir/secretsubkey.gpg
```
### Verification
Once **only** the secret sub-key has been imported from the previous step, it
should be verified that the primary secret key is **not** in your keyring
(partial stripped key designated via `sec#` in the following):
```
```text
gpg --list-secret-keys
--------------------------------
sec# rsa4096 2017-11-21 [SC] [expires: 2021-02-16]
...
```
{{< sub >}}
Note: `sec#` is what we are looking for. If it is indicated as only `sec` then
the primary secret key is **still** in the keyring! Repeat the prior steps to
attempt this again should you have to, but do so carefully.
{{< /sub >}}
## Unmounting
Lastly, remember to remove any local back-ups of the keyring or keys you stored
on the host! These should _only_ exist on the encrypted external device.
To un-mount the LUKS[^1] encrypted device, it's just one additional step to the
usual `umount`:
```bash
umount /mnt/media
cryptsetup --type luks close encryptedusb
@@ -169,13 +194,16 @@ cryptsetup --type luks close encryptedusb
That being done, it is safe to remove the external device!
# OpenKeychain Export & Import
Provided the reader is on an Android device, it can be mounted onto the local
host using `simple-mtpfs`.
## Mounting Android Device
First, plug in the Android device via a suitable USB cable to the local host and
set the USB managed option to "File Transfer" on the Android device. After this
the device should be mountable:
```bash
simple-mtpfs -l
1: Google IncNexus/Pixel (MTP)
@@ -184,10 +212,12 @@ simple-mtpfs --device 1 /mnt/android
```
## Export Secret Key
Once the device is mounted, we want to export the _partially_ stripped key (_not
the primary key_) to be imported using OpenKeychain on the Android device. The
next steps quote from the [OpenKeychain
FAQ](https://www.openkeychain.org/faq/#how-to-import-an-openkeychain-backup-with-gpg):
```bash
# generate a strong random password
gpg --armor --gen-random 1 20
@@ -199,5 +229,4 @@ gpg --armor --export-secret-keys YOUREMAILADDRESS | gpg --armor --symmetric --ou
Import it in OpenKeychain (_may require deletion in OpenKeychain first -- make
sure **not to revoke and delete!**_) and we're done!
[^1]: https://guardianproject.info/archive/luks/