A full dump is just 1024 bytes of hex — until you know how to read it. Using a real public-transport card, here’s how to go from raw sectors to the MAD, an NDEF message, a digital signature, and the access bits that decide what you can touch.
While cleaning up I found a stack of old chipcards and got curious. Here’s the full, honest log of getting a Proxmark3 built, flashed, and reading/writing Mifare Classic cards — segfaults, all-zero dumps, and every gotcha in between.
Three photos of pencil sketches went in, a flat-pack style assembly manual for a nest box with a camera compartment came out. What Claude Code read, what it fixed, and how to build the images and a multi-page PDF from the plan.
One, two, three or four? The number of OIDC client registrations an MCP server for OAuth-enabled IMAP/SMTP needs depends on the architecture. Five scenarios compared: token passthrough, single-client broker, split broker, IdP as authorization server with token exchange, and hosted providers.
How a small PAdES signing tool grew into slim-pdf: smartcards and KeePass as key sources, a ribbon GUI, form filling, OCR with each system’s own engine, text search, and why the license ended up as GPL-3.0.
How a document scanner without eSCL/AirScan led to slim-scan: a pure-Python WSD client, a GTK 4 desktop app, image clean-up on the scanned pages, a SANE backend, and two upstream bugs in the epsonds driver.
Building an OAuth2-secured MCP mail server against a real Dovecot/Postfix mailbox surfaced four separate Keycloak client registrations, a Default-vs-Optional scope trap, and a genuinely counter-intuitive Audience-mapper gotcha behind a mysterious active: false.
I recently tried to migrate my database backup strategy to portabase. It has a (c)lean interface and can handle the most common database types (postgres, mysql/mariadb but also mongodb or redis). While setting up things looked promising (once you configured the agent it regularly checks connections using the provided credentials and shows the results). This […]
Categories
Debugging MCP servers
MCP communication MCP servers and clients can talk to each other in different technical ways: Type Description Transport URL stdio In/output using stdio stdio SSE Server-Sent Events Network (HTTP) /sse Streamable HTTP Streamable HTTP Network (HTTP) /mcp Classic MCP Alternative: mcpo (openapi.json) Tools like openwebui prefer to use open APIs (like openapi) to achieve the […]
Categories
eduMFA/privacyIdea - convert TOTP secrets
eduMFA (privacyIDEA) only accepts hex‑encoded TOTP secret keys; this post shows why, and how to convert between hex and Base32 with ready‑to‑use Python scripts.