Inside SecurityNet

A personal look inside SecurityNet—how it evolved, why it works the way it does, and the thinking behind its privacy and engineering decisions.

Every piece of software has a story.

SecurityNet is no different.

These essays explore how years of working with complex systems, designing secure solutions and solving practical problems gradually shaped SecurityNet.

They aren't marketing articles.

They're a record of the thinking behind the software—the architecture, the engineering decisions, the mistakes, compromises and lessons learned while building it.

Some tell the story of how SecurityNet evolved. Others look more closely at a particular design decision or explain why something works the way it does.

Read them in order, or simply begin wherever your curiosity takes you.

29 short essays • Read in order or dip into any topic

Act 1 – The Journey

How years working in banking and building SecurityBlanket gradually evolved into the ideas that eventually became SecurityNet.

Episode 1 – From Banking Systems to SecurityNet
How a career in banking unexpectedly led to building privacy software
Episode 2 – SecurityBlanket: When an Idea Became a Product
Looking for something that didn't exist
Episode 3 – From Security Blanket to SecurityNet
SecurityBlanket required a bank's IT department; SecurityNet is plug-and-play for everyone

Act 2 – The Philosophy

The principles that guided the design of SecurityNet and the reasons some popular features were deliberately left out.

Episode 4 – The Difference Between Security and Privacy
Encryption protects content. Privacy is much broader than that
Episode 5 – Privacy Isn't About Hiding
It's about choosing what we reveal
Episode 6 – Why I Chose Not to Build a Mobile App
Does a mobile app reveal more information than it needs to?
Episode 7 – Every Feature Has a Privacy Cost
In privacy-focused software, those costs matter

Act 3 – Show Me

Seeing SecurityNet through practical examples rather than technical specifications.

Episode 8 – Why There Are No Phone Numbers
Once an application knows your phone number, it often knows far more than just a number
Episode 9 – Why There Is No Cloud Archive
Data that is never stored cannot be stolen later
Episode 10 – Why Messages Travel Like Files
SecurityNet was built around the idea of moving information directly between authorised computers
Episode 11 – Why Group Chat Is Different
This feature genuinely required a different solution
Episode 12 – Why I Recommend a VPN
SecurityNet protects your data; VPNs protect your connection; together they solve different privacy problems.

Act 4 – The Judgements

The difficult design decisions, compromises and lessons that shaped the finished product.

Episode 13 – Who Is Responsible for Your Data
YOU get to decide where your own information lives - NOT the software
Episode 14 – Should Software Remember Everything
SecurityNet doesn't need to become a permanent record of everything you've ever done
Episode 15 – When Testing Changed My Mind
I found that testing the software wasn't teaching me about code. It was teaching me about people
Episode 16 – Why Simplicity Is Harder to Build Than Complexity
Complexity belonged to me, the developer; simplicity belongs to the person using the software

Act 5 – Inside SecurityNet

A guided tour of the architecture and the engineering decisions behind SecurityNet.

Episode 17 – How Two Computers Find Each Other
Something has to introduce them. That "something" in SecurityNet is called the Mediator
Episode 18 – The Journey of a File
A lot happens between pressing Send and the data appearing safely on someone else's computer
Episode 19 – Every Fifteen Seconds
While you're reading a document or making a cup of tea, SecurityNet is quietly looking after itself
Episode 20 – One Application. A Small Team.
Behind the scenes several small specialist programs are quietly working together
Episode 21 – A Shared Folder Without a Shared Server
How SecurityNet supports the ability for a group of people to work with the same collection of files
Episode 22 – Why Group Chat Uses Temporary Server Storage
User chats travel directly between authorised users; Group chats are synchronised across members
Episode 23 – Why One-to-One Chat Doesn't Use the Same Architecture
A private conversation involves only two people; Group Chat is a different kettle of fish
Episode 24 – SecurityNet Evolved One Decision at a Time
How SecurityNet evolved from an idea to a project to a finished working product

Act 6 – Evidence, Not Assumptions

How questioning the assumptions about privacy led to the search for explicit eveidnce.

Episode 25 — Why I Started Looking for Evidence
Privacy claims are easy to make. Verifying them is much harder.
Episode 26 — The Day I Logged Into an Icelandic VPS
The answers weren't on my website. They were on the server itself.
Episode 27 — Finding Logs Where I Didn't Expect Them
The software wasn't storing messages, but that didn't mean information wasn't being recorded elsewhere.
Episode 28 — Removing the Logs Was the Easy Part
Changing a configuration file took minutes. Understanding the consequences took much longer.
Episode 29 — Privacy Shouldn't Depend on Trust
Evidence isn't perfect, but it's better than assumptions.