For most of its history, cryptography moved at the speed of ink, paper, and human calculation. Even mechanical devices such as rotor machines relied on physical motion. The arrival of electronic computing did not merely accelerate existing methods. It altered the scale, the actors, and the political stakes of secrecy.
Cryptography left the desk of the diplomat and entered the circuitry of machines.
The automation of secrecy
Early computers were built to calculate, simulate, and process data at speeds no human could match. It was inevitable that cryptography would migrate into this environment. Encryption, after all, is a structured transformation. Computers are built for structured transformation.
During the Cold War, state agencies began integrating encryption directly into communication systems. Algorithms were implemented in hardware and later in software, allowing large volumes of information to be secured quickly and consistently. The speed of transmission, especially over radio and satellite links, demanded automation.
But something subtle changed in this transition. When cryptography becomes automated, it becomes scalable. It is no longer tied to the limitations of trained clerks or specialized bureaux. It can be embedded into devices, standardized, and replicated.
The implications extended beyond the military.
Standardization and control
In the 1970s, cryptography crossed into civilian infrastructure in a visible way. Financial institutions, multinational corporations, and emerging computer networks required secure electronic transactions. Encryption could no longer remain exclusively classified.
The United States government played a central role in this shift through the development of the Data Encryption Standard, or DES. Adopted in 1977, DES was designed for commercial use but influenced heavily by the National Security Agency.
DES marked a turning point. It was publicly documented, widely distributed, and intended for implementation in both hardware and software. At the same time, its design raised questions. Critics argued that its key length was too short, potentially leaving it vulnerable to well-resourced adversaries.
For the first time, civilian cryptography was entangled with suspicion about state influence. The question was no longer whether encryption should exist outside government circles. It was whether it could be trusted.
Export control
As encryption spread, governments faced a dilemma. Strong cryptography protected commerce and infrastructure. It also limited surveillance and intelligence capabilities.
In response, encryption was treated as a munition under export regulations in the United States. Software with strong cryptographic functions could not be freely exported. Companies that wished to sell internationally were often required to weaken their products.
This created a split reality. Domestic systems could be stronger than those shipped abroad. Security was calibrated according to geopolitical boundaries.
The tension revealed something fundamental. Cryptography had become a strategic resource. Its strength was no longer only a technical matter. It was a policy decision.
The rise of software cryptography
As personal computers became widespread in the 1980s and 1990s, encryption began to appear in everyday tools. Email encryption, secure file storage, and encrypted network connections gradually entered public awareness.
Unlike mechanical or hardware-bound systems, software cryptography could be copied, modified, and distributed at negligible cost. Once an algorithm was published, it could not realistically be contained. Source code moved across borders faster than regulators could respond.
This marked the beginning of a decentralisation process. Cryptographic capability was no longer monopolised by states. It could be implemented by independent programmers, academics, and eventually open-source communities.
The shift from paper to silicon thus had two parallel effects. It strengthened the ability of governments to process and protect massive volumes of data. It also empowered individuals and private organizations with tools that were once restricted.
New threat models
Computers did not just speed up encryption: they changed the nature of the attack. Brute-force methods that would have been impractical by hand became feasible with sufficient computing power. Algorithms once considered safe were re-evaluated in light of exponential hardware improvements. Security margins had to account for machines, not humans.
This dynamic introduced a race condition. Cryptographic strength had to anticipate future computing advances. What was secure today might be vulnerable tomorrow.
The transition to silicon also introduced implementation risk. Programming errors, flawed random number generation, and insecure system configurations became common failure points. Security was no longer only about mathematical soundness. It depended on correct integration into complex software ecosystems.
Cryptography as infrastructure
By the end of the twentieth century, cryptography had become embedded in financial systems, telecommunications, and early internet protocols. It was no longer visible as a specialised activity. It functioned quietly beneath user interfaces.
This invisibility created a paradox. Society became dependent on cryptography without necessarily understanding it. Trust shifted from identifiable cipher offices to abstract standards, libraries, and algorithms.
The computer age transformed cryptography from a tool used by elites into infrastructure that underpins global communication. It also ensured that the contest between concealment and discovery would operate at machine speed.
From this point onward, cryptography would not merely protect messages. It would define how digital systems are built.