cryptography Archives - Michael Altfield's Tech Blog

Nightmare on Lemmy Street (A Fediverse GDPR Horror Story)

By Michael Altfield, on March 4th, 2024

Nightmare on Lemmy "A Fediverse GDPR Horror Story"

This article will describe how lemmy instance admins can purge images from pict-rs (click here if you just want to know how).

This is (also) a horror story about accidentally uploading very sensitive data to Lemmy, and the (surprisingly) difficult task of deleting it.

Intro

tl;dr I (accidentally) uploaded a photo of my State-issued ID to Lemmy, and I couldn't delete it.

Friends don't let friends compose jerboa comments in bed before coffee (@theyshane)

A few weeks ago I woke up to my 06:00 AM alarm, snoozed my phone, rubbed my eyes, and started reading /c/worldnews (on Lemmy).

Still half-asleep, I was typing a comment when my thumb accidentally hit the "upload media" button. Up popped a gallery of images. I tried to click the back button, but I missed. I tapped on a photo. The photo that I tapped-on was a KYC selfie image (that I took the previous day for a service that has no business having such PII anyway).

That was all it took -- two consecutive mis-taps while half-asleep in bed, and my dumb-ass just inadvertently uploaded a KYC selfie onto the public internet. And thanks to archaic State authentication systems, anyone with
. . . → Read More: Nightmare on Lemmy Street (A Fediverse GDPR Horror Story)

Extend GPG Key Expiration

By Michael Altfield, on September 25th, 2010

I came back from my "cross-country bicycle trip":http://1guy2biketrips.michaelaltfield.net to discover I could no longer send signed email because my key expired! I've also changed colleges from "SPSU":http://www.spsu.edu/ to "UCF":http://www.ucf.edu, and my old college is expiring my email address, so here's what I need to do:

# Extend my key's expiration another year # Add new email address to subkey # Save updates to key # Export a new public key

Background Information GPG

"GPG (GNU Privacy Guard)":http://www.gnupg.org/ (used here) is a popular, cross-platform implementation of "OpenPGP (Pretty Good Privacy)":http://en.wikipedia.org/wiki/Pretty_Good_Privacy defined in "RFC 4880":http://tools.ietf.org/html/rfc4880. OpenPGP outlines a standard, open message format for maintaining the "confidentiality":http://en.wikipedia.org/wiki/Information_security#Confidentiality and "integrity":http://en.wikipedia.org/wiki/Information_security#Integrity of electronic messages.

Why Subkeys?

"Public Key Cryptography":http://en.wikipedia.org/wiki/Public-key_cryptography is long, complicated, and well outside the scope of this post. However, one thing I never fully understood was the functional purpose of subkeys. Thankfully, "the GPG documentation":http://www.gnupg.org/gph/en/manual.html is excellent.

So, there's 2 major things I want to accomplish by using GPG with my email

# Confidentiality through encryption # Integrity through signatures

The designers of PGP viewed the signature role as indefinitely important while the encryption role as dynamic overtime. Therefore, when we first generate a keypair, 2 keys are created: 1 primary key for
. . . → Read More: Extend GPG Key Expiration