Cryptographic Services

This section covers the key topics of cryptography. You should understand these principles before studying VPN technologies.


Cryptology is the science of making and breaking secret codes. A cipher is an algorithm for performing encryption and decryption. The Vigenère cipher is a polyalphabetic cipher that encrypts text by using a series of different Caesar ciphers based on the letters of a keyword.

Cryptanalysis is the practice of breaking codes to obtain the meaning of encrypted data. Here are examples of attacks:

Image Brute-force attack: The attacker tries every possible key with the decryption algorithm.

A cipher-text-only ...

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