Hey there,

Sorry it has been a while, I have been really busy at University.
Today I want to talk about security basics which often get confused.

There are basically:

> Integrity, Confidentiality, Authenticity & Availability.

Now, sure, that would be only half the fun if I wouldn’t ask Fritz for help.

![](https://i.imgur.com/TekP1cO.png)

Now sure, that would be only half the fun if I wouldn’t ask Fritz for help.



Now, Fritz is older now and got his first girlfriend, Adelheit.
Both are so mature and are sending each other super sweet love letters.

![](https://i.imgur.com/S3nkjgU.png)


But, there is one little problem.

Little Ursula is Jealous of all the attention Adelheit is getting and started intercepting the messages.

![](https://i.imgur.com/eMaCLYz.png)


Now, in the act of intercepting messages, she did not yet hurt any of our security concerns.
But the moment she reads the mature messages both are exchanging she for sure is violating the:

> Confidentiality of the message

But, after reading this message Ursula is getting really furious.

So she throws the message in the trash.

![](https://i.imgur.com/FubHZoX.png)


And in that act she now even violated the:

> availability of the communication

 between those two lovebirds.

But Ursula is not finished yet!

![](https://i.imgur.com/qKMsMJB.png)


She writes her own messages and gives that to her brother and tells him that Adelheit sent it.
She now really has a run and violated directly the.

> Authenticity

Now, Fritz and Adelheid meat and Fritz finds out that it really was his sister that has written this message. Therefore, both decide to now authenticate all their letters with their signatures so nothing like that can happen anymore.

Fritz immediately sends a new message:

![](https://i.imgur.com/pSjuHhN.png)


But little Ursula isn’t that easy to come by, she gets a hold of that message again and has a final idea.

![](https://i.imgur.com/CD1Zp7o.png)


With which she now finally violated the final principal of:

> Integrity of the message

![](https://i.imgur.com/vo2XzQ8.png)


A short recap:

> Integrity: Message arrives without changes
> Confidentiality: No one else is able to read the message
> Authenticity: The sender of the message is clear
> Availability: The message arrives at all


I hope that helped you guys understanding those basic principles a bit better. The next time I will talk about the possibilities of guaranteeing the above.