For the 8th session of Proof is in the Pudding, we teamed up with Archetype to explore the fascinating world of privacy in payment networks.

There's no single best approach to privacy, but there's no shortage of interesting techniques that have been developed over the years to break linkability, hide addresses, and obscure transaction data. In this session, we take a comprehensive tour through the evolution of private payment systems.

We covered:

• E-Cash: The first private digital money system and how David Chaum's pioneering work laid the foundation for privacy-preserving digital payments
• Blind signatures: The cryptographic primitive that enables unlinkable transactions by allowing a bank to sign a message without seeing its contents
• Bitcoin privacy: The privacy limitations of Bitcoin and why pseudonymity isn't the same as anonymity
• Confidential transactions and Pedersen commitments: How to hide transaction amounts while still allowing verification that no money was created out of thin air
• Mimblewimble: A novel approach that combines confidential transactions with transaction cut-through to minimize blockchain bloat
• Monero and updatable public keys: How Monero achieves privacy through a combination of techniques
• Stealth addresses: One-time addresses that prevent linking payments to a recipient's public address
• Ring signatures: How to sign a message on behalf of a group without revealing which member signed
• MobileCoin and TEEs: Combining privacy-preserving cryptography with Trusted Execution Environments
• Zcash: The shielded pool and how zero-knowledge proofs enable fully private transactions
• Zether: Privacy for smart contract platforms using homomorphic encryption and zero-knowledge proofs

This session provides a comprehensive look at the rich history and diverse approaches to achieving privacy in digital payment systems.

If you enjoy this video, check out our previous episodes:

• Session 01: Arithmetization - Introduction to converting logical statements into arithmetic circuits
• Session 02: zkTLS - Exploring zero-knowledge TLS and secure oracles
• Session 03: How to Prove False Statements - Fiat-Shamir security and the GKR protocol
• Session 04: Proofs On A Leash - Introduction to post-quantum lattice-based SNARKs with Greyhound
• Session 05: Trust, But Measure - Introduction to Trusted Execution Environments with Intel TDX
• Session 06: Introduction to Data Availability Sampling - How rollups and Ethereum's DA system work
• Session 07: The Other Dark Forest - Offchain public keys with zkLogin, ZK Email, and ZKPassport