Quiz Entry - updated: 2026.07.14
Who is David Chaum, and why does he keep appearing in privacy-cryptography history?
David Chaum is the cryptographer who invented blind signatures (1982), DigiCash (1990), and mix networks (1981). Almost every modern privacy-preserving protocol traces back to one of his ideas.
| Year | Contribution | Modern descendants |
|---|---|---|
| 1981 | Mix networks ("untraceable electronic mail") | Tor, Mixmaster, modern anonymous comms |
| 1982 | Blind signatures | Anonymous credentials, e-voting, e-cash |
| 1985 | Anonymous credentials ("Security without Identification") | Idemix, IRMA, EU eIDAS-2 wallets |
| 1990 | DigiCash / ecash | Bitcoin's design draws on this lineage |
| 2017 | Elixxir / xx network | Quantum-resistant mixnet platform |
Chaum's recurring theme: cryptographic mechanisms that let authorities prove things about users (eligibility, payment, identity) without learning who the user is. The opposite of "log everything, audit later."
Why he matters now:
- All modern privacy coins (Zcash, Monero) and anonymous-credential systems (e.g. the EU's eIDAS-2 wallets) sit on protocols he or his students pioneered.
- His 2017 IEEE Spectrum article "Privacy by Design" reads as a manifesto for the post-Snowden era.
Tip: When you encounter a "surprisingly clever" privacy mechanism — like signing a message without seeing it — there is a very high prior that Chaum invented it or directly inspired its inventor.