los21dalmatas: First Deadline

3rd Term - First Deadline

Juan Lucas Verschoor and Giuliano Menini

Hello everyone!

Since 2 weeks we are working with a new topic in Khan Academy. This new topic is called “Cryptography”, you can see the topic in more detail with “Cryptography challenge 101”. Cryptography is an art or technique that was mostly used over the years in wars to carry messages in code without the enemy to discover and understand them, that’s why today we will be telling you that almost every cipher code in the whole world can be decoded just by you, obviously if the pattern is known. So now you just need to read this to understand the first Cipher codes and how to solve them. One of the most known was the Caesar Cipher, which was published 800 years later , by Al-Kindi. This secret message can be decoded by finding the “key’’ , in other words it means that you have to find the correct shift of letters. Therefore you need a clue based on the language the message is written in. If it is written in English, firstly you have to count which letter mostly appears in the message which you have to decode (in this case the letter that is mostly used in English is the“e”). Depending on the language yuo can count the frequency of the letters. That is why you have to see how far the fingerprint has shifted. This is called frequency analysis.

However finding the key is not to easy. To find the key, it is important to remember one thing:

This was an issue that we had to solve. However this woudn't be easy, because all the cleu's that we found are encrypted in different ways.

That´s why for solving this encrypted messages we have to use the Caesar Cipher an the Polyalphabetic/Vigenére Cipher.

In this examples you can see the "Key" (the most used letter), in the first one with red and in the other one with blue. This Cipher code is in english, that's why in this case this marked letters are an "E".