Symmetric Key Cryptography: The XOR Cipher

This is the fourth in a series about cryptography; an extremely important aspect of computer science and cyber security. It covers the XOR logical operation, that is the exclusive OR operation, explaining how it can be used to encrypt and decrypt a sequence of binary digits. XOR is an important process that is employed by many modern day ciphers. Using a spreadsheet, this video demonstrates how the XOR logical operation can be applied to a single character ASCII code to encrypt and decrypt it using the same symmetric key, and the same method.

[@marshall02019]

coming from a professional procrastinator, this video was very well put together and easy to follow. thanks a lot!

[@ComputerScienceLessons]

You are very welcome. Thanks for getting around to commenting :)KD

[@s.garabet1677]

This was very well explained. Thank you. It amazes me how some modern textbooks are written by people who likely can't even explain the concepts in person.

[@ComputerScienceLessons]

Thank you. You're very kind :)KD

[@inarisound]

This channel is a goldmine, thank you so much for your extraordinary work!

[@weslaycock466]

First time I was able to put the XOR decryption process to practice, feels good thank you.

[@ComputerScienceLessons]

Delighted to help :)KD

[@joykou2233]

and you also explained the name of 'XOR' . shouldn't we know the nature of a thing and then learn how to use it.
it's really a good way to learn everything!

[@joykou2233]

it's really a wonderful video explaining xor and encryption. compared with all other ones i watched this one just makes everything simple and easy for understanding.
thank you!
and i'm looking forward to more videos from you!!

[@dieglhix]

Agree wonderful is the word I also typed. I was feeling like a moron for not understanding until I found this ! Mind blown!

[@estellamariegulles2483]

Your explanation is unquestionable and I like how clear your voice is, keep it up! I've subscribed :)

[@ComputerScienceLessons]

Welcome aboard. :)KD

[@TheRen0gade]

Simple and easy to understand. Thank you.

[@kayquer]

Thanks for the effort in making this video. It really clarify and thought us how to think about symmetric cryptography. 👏🏻

[@ComputerScienceLessons]

my pleasure :)KD

[@velezmusic4350]

Great explanation boss!

[@belatcradus6123]

Well done.
Thanks for sharing your knowledge with others.

[@ComputerScienceLessons]

My pleasure :)KD

[@latedeveloper7836]

2:38 Encryption using the XOR function
2:42 Break down into separate cells
2:50 Any random sequence of 8 bits for the secret key
3:20 Applying the key comparing pairs of bits using XOR operation
3:50 Write 1 if they are different, "1 or the other is a 1", or "exclusively a 1".
7:00 Binary to ASCII in Excel
7:12 ASCII to Letters in Excel.
7:30 Practice exercise

[@ComputerScienceLessons]

Thanks. If you don't mind, I will add these to the video description, so they become chapters? :)KD

[@luispagarcia]

So clear, thank you!

[@annanyaartworks8244]

Its really helpful 👌👍 thank you

[@billchen4923]

Beautiful explanation, thank you very much.

[@ComputerScienceLessons]

You're most welcome :)KD

[@itsmeayan1728]

Awesome video

[@hecker688]

well summarized and easy to understand, nice video!
Here's the answer (spoiler!)
decrypted binary -> 01111010 01101001 01110000
decrypted ascii -> zip

[@ComputerScienceLessons]

Thank you :)KD

[@marcosduran3091]

This is SOOOOO appreciated.

[@ComputerScienceLessons]

You're very welcome :)KD

[@Charlestonmike34]

excellent explanation! Thanks!

[@ComputerScienceLessons]

You are welcome ,and thank you :)KD

[@LeittWolff]

Very nice explained... THANK YOU

[@ComputerScienceLessons]

You are welcome. :)KD

[@1CoreGame]

perfect explanation thanks!

[@ComputerScienceLessons]

Thank you. You are most welcome :)KD

[@merlynsalomon9922]

To the point! Thank you

[@jheffmat3263]

good and easy explanation
:) thanks

[@ComputerScienceLessons]

Thanks for the comment. :) KD

[@jaithranotla3783]

❤️ed your explanation

[@ComputerScienceLessons]

Thank you :)KD

[@isbeb507]

this helped me!

[@ComputerScienceLessons]

YW :)KD

[@dieglhix]

Just wonderful wow

[@ComputerScienceLessons]

Thank you so much 😀KD

[@mohammadaljboury878]

Thanks.

[@ComputerScienceLessons]

You're welcome :)KD

[@raghupal.v9751]

Super

[@ComputerScienceLessons]

Thanks :)KD

[@semiileka9571]

encryption is achieved by the function Y= E(K, X). using this function and given the key 1010011001, encryption the message 0011011 using the AND principle.

[@sengi12]

btw you make excellent videos! Are you involved in cyber security or computer engineering in any way?

[@ComputerScienceLessons]

Just a computer science teacher.

[@ihabayoub688]

Computer Science JUST!! a computer science teacher, I think you're doing a great job

[@m.alaiady3627]

if you guys wondering what was the result of encrypt the letter 'z' it was '/'' :)

[@angrysunshinebandit5114]

what would happen in a situation in which there is an 8-bit symmetric binary encryption key, but a 16-bit binary value to encrypt using the XOR method.
For example with a credit card number, turning each of the individual digits into 4-bit binary values, then combining every 4 into 16-bit chunks then encrypting them.

[@ComputerScienceLessons]

Interesting question. Why not give it a try? :)KD

[@JohnSmith-eo5sp]

The Vernam Cipher introduced this concept when it was patented in 1919

[@xavierarana5109]

can you do this without using binary digits? Like just with the original ASCII code?

[@ComputerScienceLessons]

Original ASCII codes ARE in binary. Computers transmit them with pulses of electricity and store them with devices that can be on or off (such as transistors). We express ASCII codes in denary (base 10), and sometimes hexadecimal (base 16) because that makes it easier for computer scientists to talk about them. The XOR cipher only works with binary digits. You can't XOR base 10 numbers together. I'm not aware of a base 10 equivalent. Interesting question! :)KD

[@lordfresh]

Fucking good

[@lllreddy829]

what is the answer of this question

[@ComputerScienceLessons]

Not telling :)KD

[@criticalminds1028]

zip

[@sengi12]

zip spoiler alert

[@kw0505]

zip

[@ComputerScienceLessons]

Penny dropped?