eli5: How was the authenticity of a foreign passport ensured, before cryptographic signatures there a thing?

Question

eli5: How was the authenticity of a foreign passport ensured, before cryptographic signatures there a thing?

In: Other

Answer 1

Security evolved over time, just like with currency. Things started off simple, like having the official wax seal or notary imprint, rubber stamps, etc that could only be had if the document was official. Forgers got more sophisticated and started duplicating these features, so governments had to add more security features. Watermarks, iridescent inks, holograms, etc.