hands-on lab

Cryptanalysis of Substitution Ciphers

Up to 2h
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Monoalphabetic ciphers are simple substitution ciphers where only one alphabet is used to substitute the characters from the plaintext and replace them one-for-one, where each character in the plaintext is always substituted with the same character in the ciphertext. This means that these ciphertexts are susceptible to frequency analysis.

Frequency analysis is a technique where a sample text is analysed to find out how often each character appears, which is used to build a histogram. This becomes the reference guide.

In this lab you will explore this by decrypting a classical cipher, the Caesar cipher.

This lab is part of a series on cyber network security.

Learning Objectives

Upon completion of this lab you will be able to:

  • Show how monoalphabetic ciphers are susceptible to frequency analysis

Intended Audience

This lab is intended for:

  • Cyber and network security specialists


You should possess:

  • A basic understanding of Windows operating system environments

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Covered topics

Lab steps

Starting the Cyber Network Security Lab Exercise