In 1991, Philip R. Zimmermann released Pretty Good Privacy (PGP), a free encryption tool designed to secure digital communications. Zimmermann developed PGP in response to proposed legislation that would have mandated backdoors in encryption software, enabling government access to private messages. The timing coincided with the Senate's consideration of S. 266, an anticrime bill containing a provision urging manufacturers to build surveillance capabilities into communication systems. Though the bill stalled, Zimmermann published PGP publicly to ensure encryption remained accessible without restrictions.

The initiative emerged amid broader anxieties about digital privacy erosion. Technologies like telephone wiretapping and email interception had shifted surveillance from labor-intensive, case-specific efforts to scalable, automated monitoring. Zimmermann argued that if privacy tools were criminalized, only malicious actors would possess them, undermining civil liberties. He framed widespread encryption adoption as a collective safeguard, noting that societal norms protect privacy through collective action—such as using envelopes for physical mail—rather than individual suspicion.

Government proposals intensified over subsequent years. The 1994 Communications Assistance for Law Enforcement Act (CALEA) required telecom companies to integrate surveillance infrastructure into digital switches, enabling centralized wiretapping. The FBI later proposed scaling this capability to monitor 1% of all U.S. phone calls simultaneously, a plan that relied on automated voice recognition to parse vast data streams. Though defeated, the proposal underscored growing ambitions to expand surveillance reach. Simultaneously, the Clipper Chip initiative—a government-backed encryption standard with built-in escrow keys—sparked industry backlash. Officials like FBI Director Louis Freeh later advocated for restricting public cryptography after events like the Oklahoma City bombing, despite no evidence linking encryption to the attack.

Zimmermann rejected the notion that encryption was solely for illicit use. He highlighted risks from corporate espionage, foreign intelligence operations, and unauthorized access by third parties. U.S. export restrictions on cryptography during the 1990s, he argued, weakened domestic businesses' defenses against such threats. The Clinton administration's 1993 encryption policy, centered on the Clipper Chip, sought to balance law enforcement access with privacy claims, but faced widespread resistance. Zimmermann contended that voluntary adoption of strong encryption was essential to prevent its criminalization, stating that privacy erosion could normalize surveillance under the guise of security.

By 1999, export controls on cryptographic software were lifted, allowing broader dissemination of strong encryption tools. Zimmermann viewed this as a hard-won victory for digital rights but emphasized ongoing efforts to protect domestic privacy rights against institutional resistance. He concluded that PGP's enduring relevance lay in its role as a practical tool for individuals to reclaim control over their communications, asserting that privacy is not inherently suspicious but a foundational aspect of personal autonomy.

The historical context of PGP's creation reflects a pivotal tension between technological progress and civil liberties. Zimmermann's actions underscored how policy decisions about encryption could shape the balance between state power and individual privacy in the digital age.