Trim on LUKS encrypted LVM root volumes

I noticed that fstrim wasn't working on my new Ubuntu 24.04 desktop installation, failing with "fstrim: /: the discard operation is not supported". In that setup, Ubuntu is installed into an LUKS encrypted LVM volume, so the ext4 file system, LVM and LUKS need to play nicely together for flash discard to work. That's how … Continue reading Trim on LUKS encrypted LVM root volumes →

Unlocking a password-protected hard disk

TL;DR: Recovering data from a password-protected SATA hard disk that was locked by a Thinkpad I wish this post would be as generally valid as the title suggests; at this hour I'm just unspeakably glad to have unlocked a hard disk I didn't even know I had locked and can finally go to bed. What … Continue reading Unlocking a password-protected hard disk →

Secure messaging in the browser

By observing news and public discussions I feel that there is a growing awareness of data privacy and an increasing demand for secure person-to-person communication. In order to address my communication needs, I plugged together a few Javascript libraries and started the Webencryption [1] project on Github. What is Webencryption? Webencryption is a rather crude … Continue reading Secure messaging in the browser →

RSA is partially cryptographically homomorphic

Homomorphic cryptography [1], should it ever become available as a product, will have an intriguing property: computers will be able to operate on encrypted data without either having to- or being able to decrypt it. Competitive or regulatory pressure leads many organisations to distrust public (or private) clouds with their data and algorithms, so they … Continue reading RSA is partially cryptographically homomorphic →

Stateless user sessions with encrypted session IDs

When trying to design for stateless services one finds it easy to reduce the information stored in an http session but for one piece: whether the client has authenticated against the server or not. Usually you would implement a proccess for authenticating like this: Client submits credentials (login / password) to the server Server checks … Continue reading Stateless user sessions with encrypted session IDs →