Most of your critique would be handled by proper input sanitation and allowing the user to review and confirm the best / default action. For a modern QR code I

Most of your critique would be handled by proper input sanitation and allowing the user to review and confirm the best / default action. For a modern QR code I'd prefer something that allows more data and which also mandates support for some compression algorithms and data filters. Old QR codes are optimized for shrinking serial numbers, barcodes, and the like to a very small size on a product. That's a good use case and I feel they've sufficiently solved that problem domain. A modern QR might include more like a very tiny web-page, with a subset of allowed entities for security. An icon, or a link to an icon, image (links, maybe bitstream embed?), and simple links. I would ideally love to be able to hand out small files as blob patches on a business card, printed on a standard laser printer (300 DPI max resolution, assume 100 to 150ish DPI). Maybe two files on the back half. One a reasonable resume and the other a pack of public key data. Edit, back of napkin math: In the US that would be about 3.5in by 2in and in the dot density about 1.5 in square for each of two squares. At 300 that'd be 450 by 450 dots, or 150 by 150 in the minimum. 22500 to about 200000 bits, not including ECC. The upper density I'd like only offers about 25K of data. This might be enough for a compressed mostly text document or some well-packed PQC safe keys and en EC crypto key or two for current use. https://en.wikipedia.org/wiki/Post-quantum_cryptography#Comparison https://en.wikipedia.org/wiki/Post-quantum_cryptography#Comp...