Why Encryption is Needed
Encryption is essential for protecting sensitive information from unauthorized access. It ensures privacy, secures data during transmission, and safeguards against cyber threats.
History of Applications
Encryption has been used for centuries to protect secrets. From ancient Roman ciphers to modern digital encryption, it has evolved to meet secure communication needs.
Ancient Rome
- Caesar Cipher: Named after Julius Caesar, who used it to protect military messages.
World War II
- Enigma Machine: Used by the Germans for secure communication, famously deciphered by Alan Turing and his team.
Basic Methods
Caesar Cipher
The Caesar Cipher shifts each letter in the plaintext a fixed number of places down the alphabet. For example, a shift of 3 would change:
- A -> D
- B -> E
- C -> F
To decrypt, shift the letters back by the same number.
Substitution Cipher
In a Substitution Cipher, each letter in the plaintext replaces another letter. The key is a mapping of each letter to its substitute.
Definitions
- Plaintext: The original, readable message or data; the input for an encryption algorithm.
- Ciphertext: The encoded message or data that results from an encryption algorithm. The ciphertext is only readable with decryption.