Internet Security

Perfect internet security is unachievable.

Security requires a cost benefit analysis. Understand that more security is not always better. A security expert will want to sell you more security, but you have to know if the cost is worth the benefit.

Your online value is determined by the benefits you have online, less the cost of protecting those benefits. Therefore, a cost-benefit analysis is always a good idea before you invest resources into internet security, as well as knowing what you stand to lose in a worst case hacking scenario.


Confidentiality is how we prevent unauthorized viewing of private information.

Integrity is knowing the information comes from a source you know, and that the information was not modified in transit.

Confidentiality spawns the terms encryption and decryption. Plaintext is the information we want to transmit, but first it has to be encrypted. Ciphertext is the encrypted message that must be decrypted back to the plaintext message.

Always Assume Someone is Spying

By the nature of how the internet works, you have to assume that ciphertext will be seen by other people, besides its intended recipient. You have to hope the encryption is challenging enough so that the message is not intelligible to unintended viewers.

A cryptosystem is a way of encrypting and decrypting messages. A secret-key cryptosystem was most commonly used in ancient Rome up through World War II. A secret-key is symmetric because the same key is required for both encryption and decryption. The challenge is devising a method to securely distribute the secret-key.

The Caesar Cipher Cryptosystem

The Caesar cipher is one of the simplest and oldest encryption techniques. It is a type of shift pattern where a character in the plaintext is shifted a fixed number of positions in the alphabet. For example, with a shift of two positions, ‘a’ becomes ‘c’, ‘b’ becomes ‘d’, etc. Given that it’s completely hackable, it’s surprising that this cryptosystem was widely used for a very long period of time.

Rot13 lets you play with an example of the Caesar cipher. You can enter in text, and it gets shifted thirteen positions. Apparently, this shift pattern was commonly used when the first internet users wanted to share dirty jokes. The story goes, these early adopters got so used to seeing the ciphertext, that they could understand the jokes without decryption back to plaintext.

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