|Simple Substitution Ciphers (e.g. Caesar)
|These are the earliest types of ciphers, where characters in a message are shifted or substituted with other characters. This was used for secret military or political communication.
|Transposition and Advanced Substitution
|As societies needed more secure communication, letter shuffling (transposition) and advanced substitution (e.g. Vigenère) were introduced.
|Early Modern Period
|Mechanical Encryption Machines
|The evolution of technology saw the creation of mechanical machines for encryption. Notably the Enigma machine, which used rotating disks to scramble messages in complex ways.
|World War to Cold War
|Involves a combination of electrical and mechanical processes to encrypt information. A more complex level of cryptography, making it harder to decipher without the exact keys and settings.
|Late 20th Century
|Symmetric Key Algorithms (e.g. DES, AES)
|The key used to encrypt a message is the same key that decrypts it. This brought about the digital age of cryptography, enabling secure electronic communications.
|Late 20th Century to Present
|Asymmetric Key Algorithms (e.g. RSA, DH, ECC)
|A pair of keys are used: one public key to encrypt the message, and a corresponding private key to decrypt it. This has become the foundation for secure online transactions.
|With the dawn of quantum computing come both threats and possibilities. Quantum cryptography aims to use the principles of quantum mechanics to establish more secure cryptographic systems.