From the pages of history, there are stories of ciphers that have changed the course of wars and influenced the practice of diplomacy. One of the most well-known and oldest encryption methods is the Caesar cipher, named after Julius Caesar's use of a simple yet revolutionary encryption technique. This encryption method, which seems childishly simple in the light of current knowledge, once protected sensitive messages of the Roman Empire. Quite remarkable, isn't it?

Caesar cipher is based on shifting letters by a certain number in the alphabet. For example, by shifting each letter three steps forward, A becomes D, B becomes E, and so on. This method makes it difficult for outsiders to identify the original message without the key - in this case, information on how many steps the letters have been shifted.

Caesar moved letters in the alphabet by three. Nowadays we can talk about the fact that the encryption technique was called "Caesar cipher" and the encryption key was 3.

The same technique can of course be used with other encryption keys!

During Caesar's time, this encryption method was revolutionary. The messages sent by generals, diplomats, and Caesar himself often contained sensitive information, the disclosure of which could have led to disaster. Although breaking the Caesar encryption may seem quite simple with today's knowledge and technology, at that time it offered a significant level of security.

Lucky time traveler, you have managed to capture one of Julius Caesar's secret messages! This message contains important information that could turn the tide of war and change the course of history. However, the message is encrypted using the Caesar cipher, and your task is to decrypt this encryption, reveal the content of the message, and uncover the secrets it holds.

TIP: Take a pen and paper and shift the letters 3 backwards. Alternatively, you can use 

## What was the Caesar cipher?

From the pages of history, there are stories of ciphers that have changed the course of wars and influenced the practice of diplomacy. One of the most well-known and oldest encryption methods is the Caesar cipher, named after Julius Caesar's use of a simple yet revolutionary encryption technique. This encryption method, which seems childishly simple in the light of current knowledge, once protected sensitive messages of the Roman Empire. Quite remarkable, isn't it?

---

## Operation principle of Caesar cipher

Caesar cipher is based on shifting letters by a certain number in the alphabet. For example, by shifting each letter three steps forward, A becomes D, B becomes E, and so on. This method makes it difficult for outsiders to identify the original message without the key - in this case, information on how many steps the letters have been shifted.

---

## Encryption Key

Caesar moved letters in the alphabet by three. Nowadays we can talk about the fact that the encryption technique was called "Caesar cipher" and the encryption key was 3.

The same technique can of course be used with other encryption keys!

---

## Was this really used?

During Caesar's time, this encryption method was revolutionary. The messages sent by generals, diplomats, and Caesar himself often contained sensitive information, the disclosure of which could have led to disaster. Although breaking the Caesar encryption may seem quite simple with today's knowledge and technology, at that time it offered a significant level of security.

---

## Exercise

Lucky time traveler, you have managed to capture one of Julius Caesar's secret messages! This message contains important information that could turn the tide of war and change the course of history. However, the message is encrypted using the Caesar cipher, and your task is to decrypt this encryption, reveal the content of the message, and uncover the secrets it holds.

Message: **kdndwhpld uxohv**

TIP: Take a pen and paper and shift the letters 3 backwards. Alternatively, you can use [CyberChef's ROT13 module](https://gchq.github.io/CyberChef/#recipe=ROT13(true,true,false,-3)) as a key for -3.

@exercise 9f9d43e1c233


Caesar Cipher: The Ancient Code That Changed Communication

From the history of cryptography to current use, the basics of encryption, technologies, applications and their impact on security.

Welcome to Hakatemia's cryptography course!

In this course, we will go through the basics of cryptography, the most important encryption algorithms, and their modern applications. The course is beginner-friendly and practical.

The goal is that after the course you will know what cryptography is, what it is used for, and how to choose the right encryption techniques and settings for different purposes.

What is cryptography? Basic concepts and uses

Introduction to Cryptography

The Enigma Machine: How WWII Codebreakers Unlocked the Greatest Mystery of the War

Historical encryption techniques

Checksums

What are hash functions and what are they used for?

Cracking Hashes: How Does It Work?

MD5 hash - a broken classic

PBKDF2, BCrypt, SCrypt and Argon2

SHA2 vs SHA3 vs PBKDF2 vs bcrypt vs SCrypt vs Argon2: Which to choose for password storage?

Diversion functions

What is MAC and why is it needed?

Different MAC algorithms

MAC algorithms

Random numbers in cryptography

Random numbers

What is symmetric cryptography?

Block Ciphers

DES, 3DES and AES

Stream Ciphers

Initialization vector (IV) and its vulnerabilities in cryptography

Symmetric cryptography

What is asymmetric cryptography?

Digital signatures

Key exchange algorithms

Asymmetric cryptography

Encoding methods

Encoding Methods (Encoding Methods)

 TLS (Transport Layer Security): The foundation of Internet security

Certificates: Building blocks of digital trust

Public Key Infrastructure (PKI): The Foundation of Digital Trust

TLS Building Blocks: Cipher Suites

SSL/TLS threats

SSL/TLS and PKI

What is key management and why is it important?

Key management in cloud services: AWS, GCP and Azure

On-Premise Key Management with HashiCorp Vault

CertBot and automatic renewal of certificates

HSM modules

TPM modules

Key management

Auditing SSL/TLS settings with Qualys' SSL Labs scanner

Auditing SSH settings with Nmap

CyberChef - A browser-based cryptographic Swiss army knife

Useful Crypto Tools

Cryptography - Learned Practice

Crypto - Final Exercise

Cryptography

Caesar Cipher: The Ancient Code That Changed Communication

What was the Caesar cipher?

Learn to hack — start here