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Cryptography

Quick Start

  • Is the text relatively small? a few sentences?

    * Is the text 32 characters long? Most likely an md5 hash

    * 40 characters long? Most likely a SHA1 hash

    * Are there equal signs spread out through the text, often next to each other? Probably a base64 encoded string

    * Is the text only letters, without numbers or special characters?

      * Check if it is a [Caesar](./caesar-cipher/), [Vigenere](./vigenere-cipher/), or other type of cipher
    

    * Rarely, it may be a keyboard map as found in the Olympic CTF 2014

  • Any hints about keys? signing? most likely RSA

About

Cryptography is the practice and study of techniques for secure communication in the presence of third parties. - Wikipedia

In the case of CTFs, the goal is usually to crack or clone cryptographic objects or algorithms to reach the flag.

Example

If you look around the folders in this page you should be able to find a suitable way to solve this simple cipher:

Hint: Julius Caesar's favorite cipher

kxn iye lbedec

Sources/See More

Introduction to Cryptography