encryption - noun - the process of converting messages in ordinary language, or other information into a secret coded form that cannot be interpreted without knowing the secret method for interpretation, called the key.
decryption - noun - the activity of making clear or converting from code into plain text
Encryption Coding
Big Picture
Read CS Field Guide 8.1 When sending data from one location to another your data goes through a series of points. Much like a subway (picture on the right) your information stops at every point and then continues on. What is the problem? Well imagine that you are passing notes through the class about a class member. Consider this comic for a second |
The image on the right is what happens when I run the "tracert" command on my computer to find out how many locations my connection goes through to reach YouTube
You can see my router IP on 192.168.1.1 Discussion: How is it that we can do internet banking, online sales and send personal emails even though our data goes to different points? What stops people being able to steal the data and easily hack your accounts? |
Sally, Tom and Nancy
In the 80's no one had cell phones or computer technology.
Sally who sits at the back of the class has a big crush on Tom. Tom during one Physics lecture turned and smiled at Sally. Sally was so excited and she wanted to tell Nancy (her best friend) immediately. However, she didn't want Tom to be aware that she was talking about him. She wants to send this message to Nancy: "Tom is super cute, and he just smiled at me <3" The note has to be passed to Tom and then to Nancy. It could be thrown, however, the teacher could intercept it and read it out loud. Task: Figure out a way that Sally can send the message to Nancy without anyone intercepting it. |
Ciphers and Encryption
Computers use encryption to encrypt data so that if someone steals the message or your data they cannot access it unless they have a "key" or "cipher". This "cipher" is often linked to your password and email address.
Nancy send back this message: YXZH LCC EB FP JFKB 3 Task: Based on the cipher on the right what did Nancy send back to Sally? Tom is actually quite sneaky, Tom has been copying the notes and so far has 27 of them. Considering that Tom is actually quite good at physics and algorithms. Tom does not know what a Caesar Cipher is. Are the girls' messages in danger of being intercepted? |
Caesar Cipher
Nancy added the number 3 to the end to let Sally know to rotate the alphabet 3 positions A-> A no rotation A = B 1 rotation A = C 2 rotations A = D 3 Rotations This is known as a Caesar Cipher. The Key is the number 3. The key could be anywhere between 1-25. (26 would rotate back to the start). |
How is encryption actually used?
In the analogy with Nancy, Sally, and Tom we see that it is important to protect our information from the moment that it is sent to the moment that it is received. Distrustful individuals with malicious intent are always out there seeking to take advantage of others for various reasons, sometimes for personal gain, sometimes just for the fun of causing a bit of mischief. Because we are sadly unable to trust some people out there, the onus falls on us to ensure that we protect our interests in whatever ways necessary. Examples of areas that we use encryption to protect our information are: protecting personal information, banking, communication, transport & logistics, radio messaging, and even television. We will look into some of these below.
HTTPS
HTTPS stands for Hypertext Transfer Protocol Secure and has become the standard for transferring information over the Internet. HTTPS is an extension of HTTP, which you'll notice only lacks the 'S' for Secure. Information sent over HTTP is not encrypted and thus is highly unsecure (Note: when talking about the security - or lack thereof - in computer systems we tend to say "unsecure" instead of "insecure". Computers don't have emotional issues. Yet.), this means that any information that is intercepted can easily be understood and potentially used for nefarious purposes by malicious individuals. To avoid this we have added encryption to our HTTP through use of TLS (Transport Layer Security) which has superceded SSL (Secure Sockets Layer). This means that when we are sending personal information over the Internet we can be sure that nobody is able to use it even if they manage to intercept it.
When you are using banking websites or even social media you will see that there is an "https://" before the site's address, denoting that they are conforming to current Internet standards and that they are keeping your information safe. It is fine to use sites that only have HTTP, however, you must NEVER enter personal information on these sites, it's generally just a very bad idea.
HTTPS
HTTPS stands for Hypertext Transfer Protocol Secure and has become the standard for transferring information over the Internet. HTTPS is an extension of HTTP, which you'll notice only lacks the 'S' for Secure. Information sent over HTTP is not encrypted and thus is highly unsecure (Note: when talking about the security - or lack thereof - in computer systems we tend to say "unsecure" instead of "insecure". Computers don't have emotional issues. Yet.), this means that any information that is intercepted can easily be understood and potentially used for nefarious purposes by malicious individuals. To avoid this we have added encryption to our HTTP through use of TLS (Transport Layer Security) which has superceded SSL (Secure Sockets Layer). This means that when we are sending personal information over the Internet we can be sure that nobody is able to use it even if they manage to intercept it.
When you are using banking websites or even social media you will see that there is an "https://" before the site's address, denoting that they are conforming to current Internet standards and that they are keeping your information safe. It is fine to use sites that only have HTTP, however, you must NEVER enter personal information on these sites, it's generally just a very bad idea.
Police radio
Communications over radio will often need to be encrypted to ensure security. Ordinary AM/FM radio obviously does not need to be encrypted as it is just music and public talkback which is designed to be freely available for everyone. However, organisations like the police have a vested interest in keeping their communications private and secure from outside individuals. To do this, radio transmitters/receivers are all installed with a key, this key is used to take in ordinary communication and encrypt it. This encrypted information is then sent via radio waves and received by the other receivers that will then use their key to decrypt the information into clear speech. This means that even if someone managed to get on the police frequency to try and listen in, all that they would hear is the noises that you hear as you seek around for radio stations in your car. |
The Enigma Machine
In World War II, the Nazis developed a mechanical system in order to keep their Morse code communications a mystery from the Allied forces. Each day the cipher would change so that even if at the end of a day the Allies were able to start figuring out the messages, the next day the messages were being encrypted through a totally different code. Have a further read in this very good article this in a very good article by brilliant.org.
In World War II, the Nazis developed a mechanical system in order to keep their Morse code communications a mystery from the Allied forces. Each day the cipher would change so that even if at the end of a day the Allies were able to start figuring out the messages, the next day the messages were being encrypted through a totally different code. Have a further read in this very good article this in a very good article by brilliant.org.
Assessment Tasks
In One Note do the following:
1.) Briefly (3-4 Sentences) explain what encryption is and what it is used for.
2.) List some (at least 5) of the problems that would occur if there was no such thing as encryption.
3.) Create a Caesar Cipher, and encrypt a small sentence "Tom is quite good at physics" for example. Use a Number between 1-25 as an encryption key.
4.) Create a conversion table that shows how each letter in the sentence should be changed.
5.) Explain briefly what you have done through your example use the terms "plain text", "key, and "cipher text" in the relevant places.
6.) Describe what information a classmate would need to decrypt your message (assuming they were doing it properly rather then trying to hack it).
1.) Briefly (3-4 Sentences) explain what encryption is and what it is used for.
2.) List some (at least 5) of the problems that would occur if there was no such thing as encryption.
3.) Create a Caesar Cipher, and encrypt a small sentence "Tom is quite good at physics" for example. Use a Number between 1-25 as an encryption key.
4.) Create a conversion table that shows how each letter in the sentence should be changed.
5.) Explain briefly what you have done through your example use the terms "plain text", "key, and "cipher text" in the relevant places.
6.) Describe what information a classmate would need to decrypt your message (assuming they were doing it properly rather then trying to hack it).