Cryptography Lab – Caesar, Vigenère, RSA & Poker Test

Author: Umme Farva

Overview

This project demonstrates several foundational cryptographic techniques using CrypTool 1.4.42.
The lab covers classical ciphers, modern public-key cryptography, and randomness testing used in security analysis.

Techniques Covered

• Caesar Cipher – classical substitution cipher
• Vigenère Cipher – polyalphabetic encryption
• RSA (1024-bit) – modern public/private key cryptography
• Poker Test – statistical randomness evaluation of ciphertext

What This Lab Shows

• How classical encryption works
• How decryption and brute-force attacks succeed
• How RSA keys are generated, used, and validated
• How randomness tests reveal weaknesses in classical ciphers
• How to document cybersecurity work clearly with screenshots

All screenshots used in this project are stored in the Screenshots/ folder.

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1. Caesar Cipher

1.1 Encryption (Key = 3)

Plaintext: THIS IS MY CRYPTOGRAPHY LAB

Encryption Window:

Ciphertext Output:

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1.2 Decryption

Recovered original plaintext.

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1.3 Brute-Force Attack

CrypTool tested all 25 shifts.

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2. Vigenère Cipher

2.1 Encryption (Key = SECURITY)

Plaintext:
CRYPTOGRAPHY PROJECT USING VIGENERE

Vigenère Encryption Window:

Ciphertext Output:

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2.2 Decryption

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2.3 Vigenère Key Analysis

CrypTool identifies:

• possible key length
• repeating patterns
• correlation peaks

Analysis Window:

Key Found:

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3. RSA Public-Key Cryptography

3.1 RSA Key Generation (1024-bit)

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3.2 RSA Encryption

Plaintext: HELLO RSA

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3.3 RSA Decryption

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4. Poker Test – Randomness Evaluation

Performed on Vigenère ciphertext.

Graph Output:

Summary (Score):

Result: FAILED — expected because classical ciphers are not random.

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Core Competencies

• Classical encryption methods (Caesar, Vigenère)
• Public-key cryptography using RSA (1024-bit)
• Cryptanalysis techniques and key-recovery concepts
• Statistical randomness evaluation using the Poker Test
• Documentation, reporting, and reproducible cybersecurity lab work

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Final Overview

• This cryptography lab provides hands-on experience with both classical and modern encryption techniques using CrypTool.

• It covers end-to-end workflow steps including encryption, decryption, key generation, ciphertext analysis, and randomness testing — all supported with screenshots stored in the Screenshots/ folder.

• The project is formatted for cybersecurity portfolios and academic submissions, demonstrating foundational cryptography skills relevant to SOC analysis, threat intelligence, and secure system design.

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Author

Umme Farva
Cybersecurity Analyst