Brief Cryptography history: Sending secret messages

Cryptography, from the Greek words for “hidden writing,” encrypts data so only the intended recipient can read it. Most major civilizations have sent secret messages since antiquity. Cryptography history is essential to cybersecurity today. Cryptography protects personal messages, digital signatures, online shopping payment information, and top-secret government data and communications. 

Despite its thousands-year history, cryptography and cryptanalysis have advanced greatly in the last 100 years. Along with modern computing in the 19th century, the digital age brought modern cryptography. Mathematicians, computer scientists, and cryptographers developed modern cryptographic techniques and cryptosystems to protect critical user data from hackers, cybercriminals, and prying eyes to establish digital trust.

Most cryptosystems start with plaintext, which is encrypted into ciphertext using one or more encryption keys. The recipient receives this ciphertext. If the ciphertext is intercepted and the encryption algorithm is strong, unauthorized eavesdroppers cannot break the code. The intended recipient can easily decipher the text with the correct decryption key. 

Cryptography history and evolution are covered in this article.

Early cryptography dates back to 1900 BC, when non-standard hieroglyphs were carved into a tomb wall in the Old Kingdom of Egypt.

1500 BC: Mesopotamian clay tablets contained enciphered ceramic glaze recipes, or trade secrets.

Spartans used an early transposition cipher to scramble letter orders in military communications in 650 BC. The process involves writing a message on leather wrapped around a hexagonal wooden scytale. When the strip is wound around a correctly sized scytale, the letters form a coherent message; when unwound, it becomes ciphertext. A private key in the scytale system is its size.

100-44 BC: Julius Caesar is credited with using the Caesar Cipher, a substitution cipher that replaces each letter of the plaintext with a different letter by moving a set number of letters forward or backward in the Latin alphabet, to secure Roman army communications. The private key in this symmetric key cryptosystem is the letter transposition steps and direction.

In 800, Arab mathematician Al-Kindi introduced the frequency analysis technique for cipher breaking, a significant advancement in cryptanalysis. Frequency analysis reverse engineer’s private decryption keys using linguistic data like letter frequencies, letter pairings, parts of speech, and sentence construction.

Brute-force attacks, in which codebreakers try many keys to decrypt messages, can be accelerated by frequency analysis. Single-alphabet substitution ciphers are vulnerable to frequency analysis, especially if the private key is short and weak. Al-Kandi also wrote about polyalphabetic cipher cryptanalysis, which replace plaintext with ciphertext from multiple alphabets for security that is less susceptible to frequency analysis.

1467: Leon Battista Alberti, the father of modern cryptography, most clearly explored polyphonic cryptosystems, the middle age’s strongest encryption.

1500: The Vigenère Cipher, published by Giovan Battista Bellaso but misattributed to French cryptologist Blaise de Vigenère, is the 16th century’s most famous polyphonic cipher. Vigenère invented a stronger autokey cipher in 1586, but not the Vigenère Cipher.

In 1913, World War I accelerated the use of cryptography for military communications and cryptanalysis for codebreaking. The Royal Navy won crucial battles after English cryptologists deciphered German telegram codes.

1917: American Edward Hebern invented the first cryptography rotor machine, which automatically scrambled messages using electrical circuitry and typewriter parts. Simply typing a plaintext message into a typewriter would automatically generate a substitution cipher, replacing each letter with a randomized new letter to produce ciphertext. To decipher the ciphertext, manually reverse the circuit rotor and type it back into the Hebern Rotor Machine to produce the plaintext.

1918: German cryptologist Arthur Scherbius invented the Enigma Machine, an advanced version of Hebern’s rotor machine that used rotor circuits to encode and decode plaintext. Before and during WWII, the Germans used the Enigma Machine for top-secret cryptography. Like Hebern’s Rotor Machine, decoding an Enigma message required advanced sharing of machine calibration settings and private keys, which were vulnerable to espionage and led to the Enigma’s downfall.

1939–45: Polish codebreakers fled Poland and joined many famous British mathematicians, including Alan Turing, to crack the German Enigma cryptosystem, a crucial victory for the Allies. Turing founded much of algorithmic computation theory.

1975: IBM block cipher researchers created the Data Encryption Standard (DES), the first cryptosystem certified by the National Institute for Standards and Technology (then the National Bureau of Standards) for US government use. The DES was strong enough to defeat even the strongest 1970s computers, but its short key length makes it insecure for modern applications. Its architecture advanced cryptography.

1976: Whitfield Hellman and Martin Diffie invented the Diffie-Hellman key exchange method for cryptographic key sharing. This enabled asymmetric key encryption. By eliminating the need for a shared private key, public key cryptography algorithms provide even greater privacy. Each user in public key cryptosystems has a private secret key that works with a shared public for security.

1977: Ron Rivest, Adi Shamir, and Leonard Adleman introduce the RSA public key cryptosystem, one of the oldest data encryption methods still used today. RSA public keys are created by multiplying large prime numbers, which even the most powerful computers cannot factor without knowing the private key.

2001: The DES was replaced by the more powerful AES encryption algorithm due to computing power improvements. AES is a symmetric cryptosystem like DES, but it uses a longer encryption key that modern hardware cannot crack.

Quantum, post-quantum, and future encryption

Cryptography evolves with technology and more sophisticated cyberattacks. Quantum cryptography, also known as quantum encryption, uses quantum mechanics’ naturally occurring and immutable laws to securely encrypt and transmit data for cybersecurity. Quantum encryption, though still developing, could be unhackable and more secure than previous cryptographic algorithms.

Post-quantum cryptographic (PQC) algorithms use mathematical cryptography to create quantum computer-proof encryption, unlike quantum cryptography, which uses natural laws of physics.

Post-quantum cryptography (also called quantum-resistant or quantum-safe) aims to “develop cryptographic systems that are secure against both quantum and classical computers, and can interoperate with existing communications protocols and networks,” according to NIST.

IBM cryptography helps businesses protect critical data

IBM cryptography solutions ensure crypto agility, quantum safety, governance, and risk compliance with technologies, consulting, systems integration, and managed security services. Asymmetric and symmetric cryptography, hash functions, and more ensure data and mainframe security with end-to-end encryption tailored to your business needs.