Sander

Code Verify has warned about validation failures for WhatsApp in Chrome ever since I first installed it. Bug at Meta?

blog.trailofbits.comSAML: A fractal of bad designSAML, the XML-based authentication protocol that birthed the SSO industry, is fundamentally flawed due to XML complexity, canonicalization issues, enveloped signatures, and design ossification, making...

How SAML got big and broken, why and how to replace it, and three excellent @sockpuppet.org quotes: blog.trailofbits.com/2026/09/21/s...

datatracker.ietf.orgHierarchical Deterministic KeysUsing a distinct holder-binding key for each Credential improves unlinkability, but generating and storing many keys in a Wallet secure area can be expensive or impossible. This document defines a way...

29 Aug

Just published a simplified Internet-Draft on Hierarchical Deterministic Keys (HDK). For the #EUDIW, HDK could help wallets bind multiple credentials to the same protected key material without relying party linkability. Feedback very welcome! datatracker.ietf.org/doc/draft-di...

29 Aug

In #EUDI, this makes it possible to batch-issue electronic attestations of attributes (EAA) to the same wallet that just presented its person identification data (PID), without making the resulting credentials linkable.

25 Aug

Interesting: I thought only ECDH-MAC could provide simple plausible deniability in digital credential presentation protocols, but it comes with deployment challenges. These lightweight OR-proofs may reduce the need for it.

ePrint Updates@eprint.ing.bot

Deniability for Signed Credentials: Revisiting the Authenticated Channel vs. Signed Data Debate in the EUDI Wallet (Magdalena Bertram, Anja Lehmann) ia.cr/2026/1648

25 Aug

Not sure whether an EUDI Wallet relying party can reuse its access certificate’s private key as skV for the Schnorr proof of knowledge. But it could easily generate an ephemeral skV and sign the corresponding pkV as part of its request.

preludes.euOn hybrid signatures | Digital Preludes

22 Aug

I enjoyed @sophieschmieg.infosec.exchange.ap.brid.gy’s rant on hybrid signatures. preludes.eu/2026/hybrid-...

Sophie Schmieg@sophieschmieg.infosec.exchange.ap.brid.gy

I had this one sitting in my draft queue before I went on vacation, and forgot to hit publish. I hope nobody starved. So please enjoy my rant on hybrid signatures. https://keymaterial.net/2026/06/18/on-hybrid-signatures/

salar-de-uyuni.wav

Attestation proves facts about records. Registration proves facts about data transmission. Time to replace data-sharing APIs. preludes.eu/op/2026/ii/

preludes.euTwo patterns to share data | Digital Preludes

24 May

The most confusing abbreviation under #eIDAS and #EUDIW regulation and standardisation is SCD. (Close second: SCA.) Here are the meanings I’ve found so far.

linkedin.com#eidas #domaindrivendesign | Sander DijkhuisThe most confusing abbreviation under #eIDAS and EU Digital Identity Wallet regulation and standardisation is SCD. (Close second: SCA.) Here are the meanings I’ve found so far. Just to illustrate: u...

24 May

Original discussion at www.linkedin.com/posts/sander...

After @writer.ia.net and @presenter.ia.net, I can’t wait to install iA Computer.

support.microsoft.comDefine and use names in formulas - Microsoft SupportAssign a descriptive name to a range of cells (a “named range”), that can be used in formulas.

16 Mar

There is still a vacancy open for the first iPad spreadsheet app to support [names](support.microsoft.com/en-us/office...) 😏

preludes.euPortable documents host new file formats | Digital Preludes

10 Nov 2025

How to introduce new formats to exchange structured data? Wrap them in PDF. An interactive demo: preludes.eu/op/2025/ii/

preludes.euIntroducing Areal, Are.na’s New Typeface | Digital Preludes

25 Sept 2025

Renaissance attitude in software preludes.eu/2025/areal-t...

preludes.euJava Card++ ? | Digital Preludes

This year’s eSIM hack demonstrates how threat models need to evolve. The vulnerability was well known for decades, but it took time to become relevant. preludes.eu/2025/bytecod...

preludes.euFree access to cryptographic module requirements | Digital Preludes

Understanding #DigitalIdentity standards is not easy, but even harder if the originals are expensive to obtain. Especially the ISO/IEC ones. This is getting better preludes.eu/2025/free-hs...

preludes.euIt’s Not About Credentials, It’s About Records | Digital Preludes

I’m intrigued by the @trbouma.bsky.social newsletter series on verifiable, portable digital accounts preludes.eu/2025/verify-...

24 Aug 2025

Credential is my new favourite polyseme in #DigitalIdentity. Sometimes it means data to present yourself as a digital entity, other times the document to exchange identity attributes between those digital entities. Reflect in preludes.eu/op/2025/i/ on different treatments in standards and systems.

preludes.euDigital Preludes

23 Aug 2025

Starting a blog on designing for digital identity: preludes.eu – would love your feedback and prompts.

certification.enisa.europa.euEUCC Guidelines on CryptographyEUCC Guidelines Cryptography

7 May 2025

New EU agreed cryptography: certification.enisa.europa.eu/publications... Replaces the SOG-IS docs. Still no Edwards curves, but we can now build and certify with PQC.

2 May 2025

Most APIs complect message delivery with business domain semantics. It’s an easy way to connect internal business applications mutually and to contracted infrastructure platforms. But to connect many-to-many people and organisations, we need something simpler.

atproto.comDocs | AT ProtocolA social networking technology created by Bluesky.

1 Aug 2023

Time to dive into the AT Protocol. Curious how Decentralized Identifiers complement human-readable Handles, and how this compares to Mastodon’s federation design. https://atproto.com/docs