I think the most interesting part of my research into french trains in the early 90s has been the random references you find about the state of tech back then.
TIL you could buy train tickets "online" in France in 1990. Using a Minitel (France's alternative internet) with its LECAM addon, which features a smartcard reader. Online payment actually involved a challenge/response with the credit card's chip! And now in 2023 we just type card numbers/expiration/CVC into random websites...
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In case you didn't already, I recommend reading Chaum's papers on digital cash from early 90s. They provide a delightfully simple approach to preventing double-spending.
