One of the most important elements that make modern cryptocurrency and blockchains possible is cryptography, the science of coding and ciphering. In fact, the cryptographic techniques we use today are the product of thousands of years of development. The use of cryptography dates back to ancient times when information was transmitted in a secure manner. Cryptography has a fascinating history, leading up to the advanced and sophisticated methods of digital encryption we use today.
The Ancient Roots of Cryptography
It is known that primitive cryptographic techniques existed in ancient times, and most early civilizations employed cryptography in some form. Symbol replacement is the most basic form of cryptography found in ancient Egyptian and Mesopotamian texts. The earliest known example of this type of cryptography was discovered in the tomb of Khnumhotep II, an Egyptian noble who lived around 3,900 years ago.
The goal of symbol replacement in the Knhumhotep inscription was to improve its linguistic appeal, not to conceal information. The first known use of cryptography to protect sensitive information was around 3,500 years ago when a Mesopotamian scribe used cryptography to conceal a formula for pottery glaze, which was used on clay tablets.
Cryptography was widely used to protect important military information in later periods of antiquity, and it still serves that purpose today. Messages were encrypted in the Greek city-state of Sparta by being written on parchment and laid over a cylinder of a specific size, rendering the message indecipherable until the recipient wrapped it around a similar cylinder. Similarly, coded messages were used by spies in ancient India as early as the 2nd century BC.
Developments in the Middle Ages and Renaissance
Throughout the Middle Ages, cryptography grew in importance, but substitution cyphers, such as the Caesar cypher, remained the standard. Cryptanalysis, the science of cracking codes and cyphers, began to catch up to cryptography, which was still a relatively primitive science. Around 800 AD, Al-Kindi, a well-known Arab mathematician, developed a technique known as frequency analysis, which rendered substitution cyphers vulnerable to decryption. For the first time, people attempting to decipher encrypted messages had access to a systematic method for doing so, necessitating further advancements in cryptography in order to remain useful.
Advances in More Recent Centuries
Throughout the centuries, the science of cryptography advanced gradually. In the 1790s, Thomas Jefferson described a significant breakthrough in cryptography that was possibly never built. His cypher wheel invention consisted of 36 rings of letters on moving wheels that could be used to achieve complex encoding. This concept was so advanced that it would serve as the foundation for American military cryptography until the end of World War II. The Enigma machine, a perfect example of analogue cryptography, would also be used in World War II. This Axis device, like the wheel cypher, used rotating wheels to encode a message, making it nearly impossible to read without another Enigma.
Cryptography in the Computer Age
With the advent of computers, cryptography advanced far beyond what it was in the analogue era. Many sensitive devices and computer systems now use 128-bit mathematical encryption, which is far stronger than any ancient or mediaeval cypher. Beginning in 1990, computer scientists were working on an entirely new type of cryptography known as quantum cryptography in the hopes of increasing the level of security provided by modern encryption. Cryptographic techniques have recently been used to make cryptocurrencies possible.