Cryptography

Encryption, decryption, and cracking

Caesar Cipher

is an encryption technique, invented by Julius Caesar two thousand years ago for the purpose of communicating messages to his allies.

is a simple substitution cipher which replaces each original letter with a different letter in the alphabet by shifting the alphabet by a certain amount.

Decrypting a message is usually done by de-coding the encrypted message, following a certain agreed on pattern.

Cracking the cipher

A message/code can be cracked/de-coded using multiple techniques:

• Frequency analysis (detecting the letters that are used freqeuntly)
• Known plaintext (in case of knowing some parts of the plaintext –> the original unencrypted message)
• Brute force

uncovering the original data without knowing the secret, by using a variety of clever techniques.

Example

Plaintext: THE QUICK BROWN FOX JUMPS OVER THE LAZY DOG Ciphertext: QEB NRFZH YOLTK CLU GRJMP LSBO QEB IXWV ALD