This will be a series on Encryption.
This will be split up into several posts. This first one is just an introduction on the topic.
Scrambling a message so that only the people who should read a message can read a message.
Or if you want the Google definition:
the process of converting information or data into a code, especially to prevent unauthorized access.
"I use encryption to protect sensitive information transmitted online"
That's about it.
The first known use of encryption was during Roman times. It's claimed that Julius Caesar used a shift cipher (now known as a Caesar Cipher) with a shift of 3 to encode significant military messages.
All we do is shift the letters the number of the encryption key. So if our shift was 4, each letter on the top row of the chart of your message would get replaced by the letter on the bottom.
The message "i like python" would get encrypted to "M PMOI TCXLSR". It's even easier to do with a printable encryption wheel.
There are TONS of tutorials on how to write a Caesar Cipher in various languages on Dev, so I don't feel a need to do it. We'll get into code in Part 2.
Is a Caesar Cipher secure?
Don't use it unless you're just passing notes in class (even then it may not be a good idea. A Caesar Cipher can be cracked by a basic linguistic statistical analysis. Meaning look for the letters in the encrypted message that are used the most and they most likely correspond to the letters that are most commonly used in a given language ("a" and "e" in English).
Another way is to just do a brute force attack. You could write a program that tries all 26 shifts and see which one isn't gibberish.
A Caesar Cipher is known as a symmetric cipher because the key to unlocking it is the same as the key to unlocking it. Also, both parties need to know the key before using it. There are plenty of other examples of Symmetric Ciphers-- the most famous (infamous?) of which was the enigma machine that the Germans used during WWII and was cracked by Alan Turing.
Asymmetric ciphers are a whole 'nother can of worms. Look out for part 2!