Pseudorandom number generators | Computer Science | Khan Academy

Random vs. Pseudorandom Number Generators
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[@DipperSlipper]

Great Video! I got here from Angela's Course.

[@WaterQube]

Same

[@BItencure]

Me too! Nice to see some fellow students around!

[@ajinkyadeshpande3992]

Same..... !

[@senzontsele8953]

Me 2

[@kaustubhgarg9662]

same

[@ThandaTaco4505]

this video is trippy af.

[@varunchelikani7891]

agreeded Man!!

[@TVVDINAKARAN]

Damn this shit was taking me to the 90's vibe, it was wa more than a tutorial...

[@sadijdhakal]

I felt like I watched those 1960s tutorial video. lol

[@swapnilchaturvedi821]

Great video,Got its link from Angela's course

[@mr.penguin2454]

Same

[@khansufyan3222]

Dr. Angela!

[@sumabich721]

same

[@oatscurry]

I just realized that since this video is in a series, it's probable that Khan Academy defined "shifts" in an earlier video. I remember watching these last year and believe that this may be the case.

[@Gersberms]

Came here to ask the same thing, "why is he talking about shifts?"

[@Athenas_Realm_System]

in cryptographically secure pseudo-random number generators such as the /dev/random and /dev/urandom on Unix machines, it constantly takes up new seeds to prevent anyone known the state of the generator at any one time fully. It usually uses stuff like block ciphers and hashes to take essentially random input like keystrokes, and hardware interrupt timing to continually shuffle the output to keep it as secure as possible for generating keys and stuff for encryption such as using a https connection. For CSPRNGs it is required to pass tests for statistical randomness as you wouldn't want to use a encryption key even for a one time pad that was a very simple number that wasn't random at all.

[@kebekbutcher]

Don't think you are safe behind cryptography, but the more bits involved, the more secure exponentially... but with super computer that government can use, 1024bits encryptions is pretty safe probably 512bits is enough for the effort needed for what you are hiding, if you don't know how computer encryption works, I invite you to look for basic encryption videos about it. This video is only about RNG in computing... It has nothing to do with RNG in encryptions...

[@SuperJosba]

me too :)!

[@ramakrishnakadiyala3014]

The background music felt like a thriller movie 😰

[@Nico-ny2om]

Quantum computers are coming, we're damned

[@yalongli3993]

Great to know the magic of random number generation!

[@shagunprasad4592]

this video literally reduces william stalling's entire sub section on PRNGs and TRNGs to a 6 minute video. absolutely mind blowing !!

[@agstechnicalsupport]

Great video explaining random and pseudo random number generation.

[@indiansoftwareengineer4899]

Nice video, truly educational. Love you Khan academy.

[@yuyhero]

This is good stuff. Not even being taught about this on my CS class

[@pankajthapaliya2336]

Thank you khan academy ! got here while learning random module in python

[@user-dz7ez2hn9z]

what does the word "shift" mean in this video? "if Alice generates a truly random sequence of 20 shifts, it's equivalent to a uniform selection from the stack of all possible sequences of shifts."

[@abdullahAboelkhair]

Mindblowing!

[@michaelmueller5211]

so much clearer! ty! 😇

[@francisdeleon4672]

great production!

[@prashoonbhattacharjee8211]

Good tutorial👍!!

[@mkerm3875]

whats with the song in the background bro its just math math itn't scary ... well it is but still

[@xXsniperleoXx]

we call things random because we don't see any links, that doesn't mean there necessarily aren't. maybe randomness is subjective

[@patricial.321]

You guys just saved my presentation due in 4 days

[@mrrakeshmohansinghnegi248]

I like the cosmic horror vibes

[@openroomxyz]

Love it

[@halimaa213]

This video was uncomfortable. But I had to watch as it was recommended by a javascript course I'm taking. Thanks!

[@oatscurry]

lol Dr. Angela Yu, perchance?

[@mertcankose5079]

@@oatscurry yeees :)

[@MrPicklepod]

I didn't think this video was going to be what it is

[@thanasisthanasistha]

Great video! Ι 've got this link from Angela's course!

[@TheEgg185]

4:12 what??? Shift? Pages? This part of the video made absolutely no sense.

[@baatar]

Yeah, I was lost too.

[@hugobarrazavizcarra482]

@@baatar Explanation please.

[@baatar]

@@hugobarrazavizcarra482 "If Alice generates a truly random sequence of 20 (shifts?)" No idea what he's saying here. 4:05

[@seras.gulser6962]

I think "shift" means the number times she throws the dice to make her sequence. Dice here is a dice-26 dice, hence 26 to the power of 20.

[@PvblivsAelivs]

It makes more sense if you have seen some of the other videos. He is talking about a stream cipher where each letter is shifted a number of places in the alphabet to produce the encrypted message. The pages refer to a stack in which each page refers to a possible sequence of shifts for each of 20 letters in a message. Admittedly, the videos don't stand very well independently.

[@shahryarhabibi7187]

thanks

[@skropp9339]

While word size dependence is true for linear congruential generators, there are plenty of random number generators whose period is independent of the word size; as an example, the mersenne generator or R250. What you are saying is accurate but it comes across as if you are saying that LCG is the only algorithm.

[@ishaanbhalla396]

damn I feel like doing shrooms and watching this again

[@raycipher]

same

[@SHaKoB0_0]

holy shit never knew that I needed this video that much

[@ThakurCoder77]

This video is educational and trippy at the same time😵‍💫

[@pradyumnakubear5366]

Nice

[@ryzenofficial4700]

I'm here because of Dr. Angela Yu's web development course on udemy.

[@nerfking1761]

Amazing video! Really helped me to understand random number generators. Got reference from Angela Yu’s course on udemy

[@tapiiee7776]

I always wondered how Minecraft seeds worked, this was really interesting

[@serious6037]

Why is this so mystical lmao

[@MotoMoto-ym3cp]

The examples for true randomness given in the beginning of the video are not rally randomness, but chaotic distributions. Waves, pepples at the beach, white noice are not indeterministic. As part of the macroscopic world they are deterministic albeit not computable. All true randomness comes only from quantum effects like nuclear decay. Only the quantum space provides randomness. The rest is either pseurdorandom or chaotic but deterministic

[@Obliviouse27]

So from what I understand by using the 3 middle numbers after doing 2 /3 actions and repeating we are saving ourselves some time to find matching sequence. While multiplying these gets you around 10000 unites of numbers which is not as big as million it some how saves time and I suppose makes the probability of matching the numbers fairly moderated.

[@lucacommonjay7894]

I like this video as much as Kanye loves Kanye

[@Mecharnie_Dobbs]

Very pretty

[@ShuAbLe]

Wow, that is a cliff hanger ending!

[@ponyatnoeit169]

Интересно😵

[@jonrutherford6852]

Very nice exposition. I did, though, get a chuckle from the bike-lock analogy. As thousands of cyclists know by now, a lock such as the one shown is not safe even for eight seconds, let alone eight hours. (Hint: chain cutter.)

[@JeffPittman]

DNA @ 3:04

[@kritisingh3194]

The end scared me, jeez. But hey, great video! :)

[@zacharysun01]

Joe Grand has a video where he uses the logic of Pseudorandom number generators to crack open a 3 million dollar crypto wallet.

[@user-mx6gi8fy6j]

why was this video so scary

[@mathlead956]

What if you make random numbers from nonrepeating things like Penrose tilings

[@AiSings163]

Well We are Living in a world where all the possibilities of guessing a pseudorandom is no more securty with quantam computing its now possible...⭐⭐

[@TheNetflixGamer]

Okay okay sick

[@codervipersan4321]

I also from angela yu course

[@sunanpatel6732]

Even me!

[@hotmandead1]

I got here from a book on C programming

[@anwarulbashirshuaib5673]

which book?

[@alexhichamk6630]

D.Angela is the reason

[@atikshaikh3121]

Got here from Angela's Course

[@mr.penguin2454]

Same

[@atikshaikh3121]

@@mr.penguin2454 yes

[@manikandand4439]

👐👐me

[@novanoskillz4151]

Angela sent me here!

[@mr.penguin2454]

Same

[@GFD_VIDEOS]

All casinos both online and land based use PRNG’s to insure profitability at the expense of gamblers being fooled to believe that they are actually playing !

[@pkpcmu]

that dong noise in last two minutes of this ruined it for me - sheer noise!

[@majorramsey3k]

I used 41 and got 4116814624384470560250062538447056025006253844etc Although I ended up with a repeating sequence, I did not encounter the seed of 41 repeating itself. Did I do something wrong?

[@lucianbicsi1636]

No. It doesn't have to start repeating at the initial seed.

[@majorramsey3k]

Thanks!

[@sbhtkapps364]

All it takes for the sequence to repeate itself is that one seed that has already been used show up again and then the sequence will start to repeat itself, that's why he said that for 2 digit it can go at most to 100 and not always

[@noorameera26]

@@lucianbicsi1636 thank you too!

[@will-se7wj]

the music is so creepy lol

[@yungtripoli]

i was high watching this and it gave me so much anxiety

[@luls9000]

What happens at 2:28 ??? The second output is 529, not 587... Wtf???

[@bengalbaby6118]

Isn't Bitcoin Blockchain set up something like this? Where to find a key, or a matching key, numbers must be ran, and ran, and ran, to get what the miner is looking for? Or they have to keep running numbers for the permission to claim that posting? Just curious.

[@samfield4114]

No

[@seckomatikreloaded5283]

This video is creepy, like one of those Dharma Initiative orientation videos from LOST

[@followrajah7743]

Dr Angela Yu brought me here

[@shreyasahu481]

Got scared and closed the tab.

[@youtubeshortsmix2356]

from udemy

[@blackhole1617]

I'm here from Angel's course

[@sumabich721]

Angela brought me here

[@watchmeexplode]

This video is creepy 😶

[@chandanchandu4914]

Nan Anthu obirayan kalaa kee hogidhee 🥴

[@ludwig8384]

Angela Yu brought me here.

[@pineapplewhatever5906]

1:12 I don't think machines are deterministic. I was running a program that backed up to a file each minute. I loaded the most recent backup into it. Power went off. Tried loading the backup again. It was BLANK. Inspected the backup with a hex editor: It was all zeroes. Inspected the code of the program: The program could not have written the zero byte into the file. Clearly, if the machine were deterministic, this could not have happened.

[@santaclaus008]

lol

[@pineapplewhatever5906]

@@santaclaus008 Ok then. You explain it.

[@mdraihan1067]

plzz stop the background sound

[@TheEgg185]

For every, I don't know, 10,000 calculations, why don't we start taking MORE than just the middle 3 digits and make THAT be the new seed??? Problem solved, no?

[@subhamrai4908]

Who is here from Angela's course? 😂

[@manikandand4439]

Me 👐

[@uzairali7420]

@@manikandand4439 i download this course from random website this course is old for me but its free there is no bootstrap 5 or flexbox

[@jsc3417]

I dump plenty seeds into the toilet each day.

[@HumbleTrader852]

I cant understand anything, am i dumb?

[@shubham_srt]

prolly

[@singerbabe82]

i hate the background music

[@neriyacohen7805]

Are you nuts? Worst video of khan. The noise drived me crazy. Why do it for knowledge seekers( ADHD aside?) If you dont remove the noise at the very least add scratching noises,screams and breaking glass