Bruno Schaatsbergen

Signing TLS handshakes inside a TPM

Fri, 21 Aug 2026 00:00:00 +0000

I’ve been doing remote attestation work on confidential VMs. This post is one piece of that: whatever the attestation ends up looking like, the machine still needs an identity it can hold and use afterwards, and in my case that means authenticating to other services with mutual TLS.

An application that does mutual TLS authenticates with a client certificate, and on disk that is almost always two files. client.crt is the one you show: it carries a public key and a CA’s signature over that key, and it isn’t a secret. client.key is the one you sign the handshake with, and the server checks that signature against the public key in the certificate you just showed it.

Migrating out of GDC air-gapped in an emergency

Fri, 21 Aug 2026 00:00:00 +0200

Disclaimer. This is a personal thought exercise, written from public documentation on my own time. It is not affiliated with, endorsed by, or done on behalf of my employer, and nothing here represents my employer’s work, views, or internal systems.

Google Distributed Cloud (GDC) air-gapped is Google Cloud you run yourself, on your own premises, with no connection to Google or the internet. It is meant for workloads that cannot use a public network: classified systems, defense, or data that a regulator says must stay in the building. You get the Google Cloud APIs, running on hardware you control.

Blocking VoidLink with Tetragon

Thu, 20 Aug 2026 00:00:00 +0000

VoidLink is Linux malware written in Zig. Check Point Research found it in December 2025. It is modular and cloud-native: it goes after containers in a Kubernetes cluster and the VMs those clusters run on, and it is built to persist there quietly, for a long time.

I take no credit for finding this. I dug into it and figured it was worth writing up. Shoutout to Isovalent and Check Point Research for sharing their VoidLink research.

A TPM has a clock, but it does not have the time

Sun, 26 Jul 2026 00:00:00 +0000

I have a confidential VM running for some attestation work. It has a virtual TPM, which reports its manufacturer as GOOG. I was poking at it and ran tpm2_readclock, expecting a timestamp somewhere in there.

$ sudo tpm2_readclock
time: 964062646
clock_info:
 clock: 964065681
 reset_count: 15
 restart_count: 0
 safe: yes

No date. I went looking for why, assuming I’d missed a command.

what a TPM is

A TPM is a small, slow processor that holds keys and won’t give them back. You can ask it to sign something. You can’t ask it for the key.

cek (Container Exploration Kit)

Sat, 16 May 2026 00:00:00 +0000

cek is a small CLI I built to read and explore OCI container images without running them, and without needing a container daemon. It talks directly to any registry that implements the OCI Distribution Spec, pulls the manifest and layer blobs that make up an image, and walks them in memory.

$ cek cat nginx:latest /etc/nginx/nginx.conf

Under the tooling, an OCI image is a JSON manifest pointing at a stack of gzipped tar layers. What a running container sees is those layers merged top-down. cek reads from that same stack, just without the container.

Terraform, Google Cloud, and Secrets

Sat, 26 Jul 2025 00:00:00 +0000

In Google Cloud, Secret Manager is great for storing sensitive data—but keeping secrets out of Terraform state, logs, and version control is a challenge. Terraform 1.11 introduced ephemeral resources and write-only arguments to fix that. Here’s how.

Ephemerality

Ephemerality in computing refers to the ability to create something that is short-lived or temporary — a piece of data that exists only for a brief period and is discarded once its purpose is fulfilled. In Terraform, this concept was introduced to manage sensitive data or open a connection in a way that ensures it doesn’t persist beyond its immediate use. In Terraform 1.11, HashiCorp implemented new language constructs that track values only at runtime, making them transient and, therefore, ephemeral by design.

S3-native state locking

Sun, 22 Dec 2024 00:00:00 +0000

State locking is an important feature in Terraform that protects your Terraform state. Terraform produces “state”, a snapshot of your deployed configuration, stored in a file that tracks resource attributes, their relationships and more. State locking ensures only one operation can modify this file at a time, preventing conflicts and potential data corruption.

Terraform uses (remote state¹) backends to store the state file on a storage system. Each backend represents a specific storage system and manages its own approach to reading, writing, and locking the state file. For a backend to support state locking, it must adhere to a simple contract²: it needs to be able to Lock and Unlock a specific state. When Terraform starts an operation, it first acquires the lock (Lock), and once the operation is complete, it releases the lock (Unlock).

Why there isn't a generic HCL formatter

Wed, 18 Dec 2024 00:00:00 +0000

Sometimes, people ask why there isn’t a generic formatter for HCL (HashiCorp Configuration Language). The short answer is that HCL was designed as a framework for building languages, not as a standalone language, so it’s up to each application to define how formatting should work. Tools like Terraform and Packer include their own formatters, which extend basic HCL conventions with domain-specific rules. This ensures formatting aligns not only with general HCL syntax but also with the specific idiomatic patterns and best practices of the application.

Behind the Scenes Lambda

Fri, 12 Jun 2020 00:00:00 +0000

Lambda is split into a control plane and data plane. Each plane is responsible for a specific set of activities in the service. The Control Plane provides management APIs and manages integrations with all AWS services. Whilst the Data Plane is Lambda’s Invoke API that triggers Lambda function invocations, this explanation is still very abstract but things will become clearer over time.

Deployment Interoperability

When deploying your Lambda function, you can either define a container image which is stored in Amazon ECR registry or deploy the code through a .zip file. You can specificy the location of an object in Amazon S3 by defining this in a CloudFormation template or through the CLI. If you’re uploading the .zip through the console, it will be stored in an inaccessible S3 bucket.

about

Mon, 01 Jan 0001 00:00:00 +0000

Engineer from the Netherlands. Currently building systems for a national defence organisation, mostly Kubernetes and Go, with a focus on security. Open source maintainer across the Terraform and Kubernetes ecosystems, and Tech Lead in CNCF TAG Infrastructure.