Petronas Interuniversity CTF 2023 CTF Writeup

Harmonic Secrets

My objective in the Harmonic Secrets challenge was to decrypt a given ciphertext using the provided key, which I suspected to be a Vigenère cipher. My task was to apply the key and reveal the hidden flag.

Harmonic Secrets - CTF Challenge Writeup

Challenge: Harmonic Secrets
Points: 100
Category: Cryptography

Objective

My objective in the Harmonic Secrets challenge was to decrypt a given ciphertext using the provided key, which I suspected to be a Vigenère cipher. My task was to apply the key and reveal the hidden flag.

Solution

To successfully complete the Harmonic Secrets challenge, I followed these steps:

  1. Key Analysis:

    • I began by examining the provided key. Based on the challenge information, I suspected that it was a Vigenère cipher key.

  2. Vigenère Cipher Decryption:

    • I applied the Vigenère decryption process using the provided key to decipher the given ciphertext.

  3. Flag Discovery:

    • After successfully decrypting the ciphertext with the Vigenère key, I revealed the hidden flag.

By following these steps and applying the Vigenère cipher decryption, I uncovered the flag.

Flag

The flag for this challenge is in the format: petgrad2023{XXXXXXXXXX}.

In the Harmonic Secrets challenge, my cryptography skills came into play as I decrypted the Vigenère-encrypted message using the provided key to unveil the flag. It was a satisfying experience. Best of luck!