Module 14 of 22 · Operator · 90 min
The unpredictable number and pre‑play
Tag 9F37 is the terminal's only contribution of freshness, and some terminals supplied a counter. What that made possible, why it is neither a replay nor a clone, and how to measure a terminal for yourself.
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Open the free workbench →What this module covers
- 01What the field is supposed to do
- 02Where 9F37 actually travels
- 03Inside the cryptogram, and inside the signature
- 04The number that was not unpredictable
- 05Pre-play, and why it is not replay
- 06The variant a good generator does not fix
- 07A replay in the corpus, and what gave it away
- 08What catches it, and what does not
- 09Measuring a terminal for yourself
- 10What changed, and what did not