The Unbreakable Cipher: One-Time Pads (1 of 2: How do they improve on Caesar?)

[@user-em9mw9ch3y]

This teacher has more enthusiasm than all my lecturers combined ... in one whole year.

[@alexzanderellis547]

Sorry to be off topic but does anybody know a trick to log back into an instagram account? I was dumb forgot the account password. I love any help you can give me

[@dhruvRajput0579]

​@@alexzanderellis547you logged in now bud? or do you still need help 💀

[@Drirton]

I've been trying to understand how a One-Time Pad works for the past hour or two and finally, it makes sense. Great teacher! Love the enthusiasm as well! Accent helps too. =P

[@wes_btc]

Great explanation, I wish we had such a passionate teacher. Keep up the good work!

[@missghani8646]

your students are so lucky to have as a teacher. you always remind me of my teacher who had the same passion for his subject, God bless both of you

[@588158]

I must say the your explanation of how "On Time Pads" work was the clearest and simplest explanation I have seen on youtube. I might also add your that presentation performance was outstanding; you are a great teacher! Keeping the student's attention as well as encouraging and challenging them to think and be engaged and active participants in their training is the essence of what great teachers do. You were also energetic and entertaining. Having been a teacher and administrator for 36 years, I used to like to say that Teaching is salesmanship and Show Biz in the best senses of the words.

[@devangsolanki3356]

Videos is 6 years old, but still enjoyable in 2021. Great work Eddie Woo!

[@BeyondBreakthroughs]

man i would never miss your class, i attended class last week and my lecturer spoke about the one time pad but i didnt understand anything, you good man i would never miss class wit you

[@abhishekshah11]

This cleaned up my doubts.

[@marahfaron3565]

ABSOLUTELY BRILLIANT EXPLANATION! THANKS VERY MUCH

[@wattosacrim]

Thanks Eddie. I came here from reading about Seagruppe Wulf Nazi Submarines using T43 One Time Pad codes to escape to argentina!

[@karenolearyevans5447]

love this guy thank you, you explain it in such detail but so much easier to follow.

[@davros0007]

Nice! There used to be radio channels on short wave saying numbers that made no sense- was likely for this information.

[@nhiap6]

You are absolutely brilliant. Keep up the good work !

[@wannabkain4400]

I learned about the one time pad from Tom Clancy book so wanted to check out how it functions.

[@adamevans8187]

Thank you so much, I actually learned something today for my assignment today using this!.

[@s0rthak]

Wonderful storytelling skills :)

[@Chris_Hetherington]

This is somewhat correct... Generally a one time pad has 250 characters. That entire pad is used for a single message. Also, the plain text letters are converted to numbers using a chart that uses completely different numbers than are normally used, this chart also incorporates punctuation. Once a message has been converted into the numbers in accordance with the specialized chart, the pad is used to encrypt the message. The pad contains numbers 0 thru 9 and is grouped into 5 digit groups. Once the sender has encrypted the message, that entire pad is destroyed. The recipient receives the encrypted message and uses their pad to decrypt the message and converts the numbers back to letter format using the same specialized chart, then their pad is destroyed.

[@bephrem]

This guy is the model of great education. A teacher that cares. Huh. Rare. It is so simple. Just care and be competent. Have some life.

[@vicz98]

love your enthusiasm! i hope you can be my teacher at my college lol

[@sajithedu]

Eddie is gifted 💌

[@papazguy]

wow you're amazing.great explanation

[@charlesdeguzman3687]

why does he explain it better than my CS lecturer

[@weslaycock466]

God dam, give this man a raise stat!

[@yashshukla5686]

thank u sooooo muuuuchhhhhh sir

[@manifest12345678]

Guy, u are awesome! :D keep it up!

[@spiritusmundi8295]

You are a blessing

[@ZadenZane]

Was this a lesson at school? Wow maths has come a long way since I was at school. I got lost as soon as we hit algebra let alone this prime number kappa value random frequency of letters stuff!

[@ThamaraHessel]

Just amazing ❤️

[@xusmico187]

taught OTP in '84. only reason they are not still used i secure pad delivery to users. One can still here OWVL transmissions

[@Cat-With-3-Out-Of-9]

There was a machine they called enigma!

[@dw524451]

I want him as my teacher!

[@trytoo5167]

I like to imagine he doesnt have a class and hes just pretending he does for our sake.

[@guysaban1957]

Thank you!!!!

[@MCLooyverse]

At first, I really doubted that it was "literally unbreakable", since there's always brute-force, but that's not the case here. Sure, you can just make up keys (or pads) and try them, but there is *no* way to tell if you have the right one at all. The only things that I see as being attackable are the key generation, and transmission, which every encryption method has to deal with, which is why we have PRNGs, and people developing less-psudo-random number resources, and why we have things like the Diffie-Helman key exchange.

[@LFSPharaoh]

I understand for the sake of discussion, here, that the one-time pad is considered "unbreakable", but in the real world it's unrealistic to claim as you run into the byzantine problem (I think it's called). It's only unbreakable when you can assume, with absolute 100% certainty, that we both are working with the same one-time pad (or, more specifically, I know with 100% certainty that you were the one who gave it to me - like over a computer network).

[@salehaboutaama7370]

Aren't you supposed to use the numbers from 0-25? a = 0, b = 1, c = 2...z = 25??

[@MCLooyverse]

Yeah, but for some reason it seems that the general populace doesn't like counting from zero, so I guess he didn't just to not throw them off. You can do wonky modular arithmetic by taking not a % b, but (a - 1) % b + 1. Take mod 5 for example, (1 - 1) % 5 + 1 = 0 % 5 + 1 = 1; (2 - 1) % 5 + 1 = 2 ...; (5 - 1) % 5 + 1 = not 0, but 5.

[@Martijn9860]

I think he uses Z=0 to keep students from the "programmers count from 0" sidetrack

[@arnavbrawls9586]

what if i get the answer as zero after using modulus for example if i have "Y" as 25 and my random number is 53. I would add 25 and 53 = 78 78%26 (because 26 letters in the alphabet) =0 Now what does 0 refer back to? edit - I got it it goes back to Z

[@chromakeyblue]

The pad Are the numbers 1 to 26? How are they generated randomly?

[@jeffreyweaver9854]

Why not create random letter sequences and use something like either the Vigenere grid or the Diana Cryptosystem, instead of complicating this with extra steps?

[@toby9999]

Because this is a high school maths class discussing the one time pad method. It's not complicated.

[@northdevonpictures826]

Good presentation and easy to understand. Dislike for the constant scribbling on the board in illegible scrawl, which adds nothing to the tutorial and only detracts from it. Much better to have prepared hidden bullet points, revealed/stripped off one by one in large legible and logical text through the tutorial. I would have learned only half the material from this tutorial.

[@karenolearyevans5447]

Can someone direct me or explain does one-time pad always use Mod 26, or does it ever use Mod 25? When I try decrypt the following using Mod 25 it is not working for me. Could be me miscalculating.

[@karenolearyevans5447]

I Figured out where i was going wrong, if using A=0 I kept looking at letter D under the number 3 as opposed to counting C in 3rd place after counting from 25

[@reob12]

im wondering, is cryptography taught in high school or is this a discrete math course, or what?

[@formulaint]

It's not normally taught in school, it's just a high school teacher teaching cool things outside of the syllabus. My teacher did that a lot, we once had a lesson on the mandelbrot set and other cool stuff like p vs np

[@djgryffindor7686]

How do you know when they use mod 26?

[@toby9999]

You don't need to know.

[@largol33t1]

What is he teaching: history of cryptography or is this for computer science since there is a lot of correlation between ciphers and computer programming such as "fish" or "enigma"? 9:40 - This is the trick. A cipher is vulnerable to easy decryption if it cannot encode a letter as itself. If "happy" followed this rule, you would not be allowed to use a number that allowed it to encrypt the two p's as ct, you'd be in deep crap. The cryptologists working for the bad guys would exploit this weakness to find out why the two p's kept showing up as cc or tt for example. Then they can simply run a software program that looks for a repeat of those letters. From there, they can work out what the other letters might be. They'll probably never get it 99% accurate but that's not a minor concern because enough of the letters will be exposed to work out what the missing ones are. This is why the British broke the Enigma cipher. They knew it would not encipher "a" to come out as "a" again. However, I think the professor should have mentioned one thing earlier: some people do not take numbers off the top of their heads because of the danger of accidentally picking them in a pattern. They avoid this by using two or three dice. They roll them and pick the higher of the two numbers or sometimes add/subtract them. They do this every single time they need a new letter or number. This keeps the numbers random and will make the bad guys' lives miserable because they can't find a predictable pattern. Remember, they're trying to find patterns to match up with specific letters or numbers.' However, a former British spy once mentioned another weakness: a $2 hammer! If the spy was caught with the pads and tortured into giving out the numbers, it would compromise the entire code. The spy would have to have a plan worked out with the receiving party BEFORE he/she got caught so that they would know the cipher had been compromised. This happened during the Cold War when one-time pads were in such widespread use that, among some Soviet citizens, possession of a pad would result in the Komitet knocking on their doors the next morning! If possible, one should read the book Spy Catcher by the late Peter Wright. It has a chapter or two about this and it's fascinating although scary stuff to read.

[@largol33t1]

Does anyone know if using gibberish on OTP makes it more secure? I don't understand why it would help if at all. A website about OTPs stated that one should never just write down the newly encoded letters. It said add gibberish to the front and backs of the words. If you were to send this message: "the drop was made", BEFORE you even start the cipher, you add nonsense to the words such as ditktheoiu fdtdropeif axewasoyd limadeight. Then you can start encrypting them. Since the OTP is a secure system, isn't this method a waste of time? I can't think of a reason why adding gibberish will make it more secure.

[@davros0007]

largol33t1 it wouldn’t. You’re right

[@iosifpuha6114]

freakin hating the fact that this guy is so enthusiastic and I get teachers who read slides🥲🥲