A free world needs private money. Period. The entire financial system we have today is permission-based, censorable, and has many single points of failure. In other words, it is built upon trust (which can be betrayed). Bitcoin provides a permission-less parallel system for any individual to build on top of, and Bitcoiners are making privacy in the digital age a reality. Cashu (currently being built on top of the Bitcoin blockchain, and inter-operable with the Bitcoin Lightning network) is one of the most consequential technological developments of my lifetime. The revolution that is currently taking place thanks to Bitcoin is only possible because of over 40 years of brave individuals that believed in building freedom tools without permission even in the face of adversity. David Chaum is often celebrated as a pioneer in the realm of digital privacy, particularly through his invention of "blind signatures" in the 1980s. His work laid the groundwork for digital cash systems that could offer the privacy of physical currency. Chaum's concept of Chaumian mints was designed to allow for anonymous transactions where the identity of the payer is concealed from the issuer of the digital currency. This idea materialized into the eCash system through his company DigiCash, although it struggled with market adoption due to its centralized nature and the technological limitations of the time. In the 1990s, David Chaum's vision of Chaumian e-cash came close to becoming a widespread reality, particularly through his company DigiCash, which introduced eCash. The system was designed to mimic physical cash's privacy and security features, using cryptographic protocols like blind signatures to ensure anonymity in transactions. One of the most promising opportunities for eCash was a potential partnership with Microsoft. Bill Gates expressed interest in integrating eCash into every copy of Windows 95, which could have dramatically increased its adoption. Microsoft reportedly offered around $100 million for the technology, an offer that, if accepted, could have made eCash a standard digital payment method across a vast user base. However, the deal fell through because Chaum demanded $1 or $2 per sold copy of Windows 95, a condition Microsoft found too costly. This negotiation breakdown was a significant blow to eCash's prospects, as integration with Windows 95 could have provided the infrastructure and user base necessary for mainstream acceptance. Despite this and other potential partnerships with banks and companies like Visa and Netscape, DigiCash failed to secure the necessary traction. The absence of widespread merchant adoption and consumer usage, combined with Chaum's insistence on maintaining high privacy standards which might have limited commercial appeal, led to DigiCash's eventual bankruptcy in 1998. While Chaumian e-cash was previously on the brink of becoming a reality, the Microsoft partnership's failure was a critical juncture that significantly impacted its potential success in the 1990s. Today, Chaum's vision is being revitalized within the Bitcoin ecosystem through innovative projects like Cashu and Fedi. Cashu implements Chaumian e-cash on top of Bitcoin, using the Lightning Network for transactions. It enables users to transact with digital tokens that are backed by Bitcoin but maintain user privacy through blind signatures. Unlike traditional banking, where transactions can be traced, Cashu allows for mints to be run by anyone, ensuring no single entity controls the flow of money, thus preserving the privacy and immediacy of physical cash in a digital form. Meanwhile, Fedi leverages the Fedimint protocol to create a federated system of Chaumian mints, where a group of "Guardians" collectively manage the mint. This approach offers a community-based custody solution for Bitcoin, blending privacy with a form of decentralized governance. By using multi-signature wallets controlled by a federation, Fedimint reduces reliance on a single authority, enhancing security and privacy. Both Cashu and Fedi/Fedimint are bringing Chaum's dream of private, scalable digital cash into the modern era, integrating it with Bitcoin's blockchain technology to offer users the control, privacy, and accessibility akin to handling physical cash. Big thanks to @calle `and @Marty Bent for all the work they're doing to make anonymous digital cash a reality.