Advent of Code: Libraries
The libraries I built for Advent of Code
~elly/blog
Latest posts
Advent of Code: 500 Stars
My experiences solving every Advent of Code challenge released so far
Reservoir sampling
How to choose a random subset of a large set efficiently
X.509 Certificates
How do X.509 certificates actually work, and what's actually inside them?
Fossil
An introduction to the fossil vcs, and some comparison to git
Macaroon MAC Chaining
A cryptographic technique to create constrainable auth tokens
Parser Combinators
A neat technique for building parsers out of smaller parsers
Rogue Source Tour
A quick tour through the source of rogue(1), one of the classic Unix games
Binary Transparency
A technique for shipping binaries which are provably derived from specific source trees
Fennel for Advent
Experiences doing Advent of Code 2022 in Fennel, a tiny Lisp that compiles to Lua
Packaging for Alpine
My experiences creating and publishing my first package for Alpine Linux
Alpine on Framework
My experiences using Alpine Linux on an 11th gen Framework laptop
Lambda Calculus
An introduction to the lambda calculus, given as a Scheme program
Struct Member Naming History
Why do some libc structs have prefixes on all their names?
General Purpose Macrogenerator
A rewrite of the historic GPM in C, slightly touching on differences between C and CPL
Hare First Impressions
Trying out the Hare programming language
Doing It Right: Passwords, Keys, and Backups
Some thoughts on protecting your most important data, and how I do it
Just-In-Time Compilation
A worked example of how some types of JIT compilation work, in C
IRC Client Design Thoughts
Some design notes on how to structure an IRC client with an eye towards persistent presence
Cipherpunks, Mixmaster, and Mixminion: Anonymous Email
An overview of email anonymization tools and attacks against them
Book Review: A Psalm For The Wild-Built
A review of "A Psalm For The Wild-Built" by Becky Chambers
The ChaCha20 Cipher Core
An amd64 assembly of the core of the chacha20 stream cipher
The PPM Image Format
The world's simplest image format!
Backups
How I make backups of my systems, 2022 edition
Shellballs and self-extractors
How self-extracting shell tarballs work and why they exist
m4
A historical overview of the m4(1) macro language
Tarballs
History and design of the tar(1) file format
Whence Autotools?
Where exactly did autotools come from, and what were the people who created it thinking?
Constant-Time Operations
In cryptography, what are constant-time operations and why do they matter?
The Shunting-Yard Algorithm
An algorithm for doing precedence-aware parsing of mathematical expressions into a sequence of stack ops in a single pass
The Boyer-Moore String Search Algorithm
A fast algorithm for finding substring matches, implemented in C
Virtual Machines, Part 1: Instruction Encoding
How instruction encoding and decoding works in hardware and software
Length Extension Attacks
How length-extension attacks work against Merkle-Damgard hash functions
Virtual Machines, Part 0
What virtual machines are, how they work, and a worked example of one in C.
My Homedir Layout
How the subdirectories in my home directory are laid out and why
Pinebook
Some notes from getting my Pinebook Pro set up
Merkle Trees
A data structure (a tree of hashes) to allow for efficient validation of parts of a huge data set.
Lamport Signatures
A way to use trees of hashes to produce a simple, post-quantum signature scheme
Broadcast Buffers
A data structure for handling buffered messages being fanned out to many clients
Boring Protocols
What makes protocols "boring", and why is boring-ness desirable?
The C++ static constructor registration trick
A way to register members of a set (modules, etc) at program startup time in C++ without needing to fill out a big table at compile time
Linda Tuple Spaces
A cool data structure for distributed programming
Using The ed(1) Text Editor
How to use /bin/ed!
Rules For Getting Along With Others
Just a bit of life advice stolen from Ann Landers.
Writing a Unix Userland
What the main components of a rudimentary Unix userland are and how to write them in C.