3Blue1Brown

8,510,000 subscribers

⏱ 👁 3,623,053 views

How secure is 256 bit security?

Video Overview & Insights

How hard is it to find a 256-bit hash just by guessing and checking?

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lol, do it again

— @aoumn

Help fund future projects: https://www.patreon.com/3blue1brown

An equally valuable form of support is to simply share some of the videos.

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It passed 2^23 subscribers!

— @TakenUsername42

Home page: https://www.3blue1brown.com/

Several people have commented about how 2^256 would be the maximum number of attempts, not the average. This depends on the thing being attempted. If it's guessing a private key, you are correct, but for something like guessing which input to a hash function gives the desired output (as in bitcoin mining, for example), which is the kind of thing I had in mind here, 2^256 would indeed be the average number of attempts needed, at least for a true cryptographic hash function. Think of rolling a die until you get a 6, how many rolls do you need to make, on average?

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Thanks!

— @davidkim4819

Music by Vince Rubinetti:

https://vincerubinetti.bandcamp.com/album/the-music-of-3blue1brown

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Fantastic explanation. You have a true gift for visualization and analogy, and your mathematical range is most impressive.

— @davidkim4819

Thanks to these viewers for their contributions to translations

Dutch: @bvdeijzen

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What about Quantum Computer?

— @muhammadkausar2842

Hebrew: Omer Tuchfeld

Italian: retr00h

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كأنما يريد يكول "لو تطلع نخله براسك ما" تنفتح

— @alsaderi

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3blue1brown is a channel about animating math, in all senses of the word animate. And you know the drill with YouTube, if you want to stay posted on new videos, subscribe, and click the bell to receive notifications (if you're into that).

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So, you're saying there's a chance to guess it in first take? 😁

— @mareksaltberg1484

If you are new to this channel and want to see more, a good place to start is this playlist: http://3b1b.co/recommended

Various social media stuffs:

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Ended up calculating 2^256 on a sheet of A4 paper. Took me like 6 hours.

— @Smartalex234

Website: https://www.3blue1brown.com

Twitter: https://twitter.com/3Blue1Brown

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Damn, he had only 262144 subs 8 years ago? Time flies.

— @hamzamotara4304

Patreon: https://patreon.com/3blue1brown

Facebook: https://www.facebook.com/3blue1brown

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You are at 2^23 subscribers now :)

— @shin_dakira

Reddit: https://www.reddit.com/r/3Blue1Brown

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This is how secure bitcoin is and more. Try again you stupif slow dumb fuckijg tbeiving mentally retarded November's. Naned it??? No, wrote the white paper you stupid pedophile retard

— @whatabunchofcowards

More User Perspectives

It's time to start turning on strangers devices

@vrajinuniversity27

Oh no :P

@sagiyoav

I built a computer in Geometry Dash for computing sha256 hashes out of a 256bit input, I knew it was secure but jeez.

@blitzycat

no 256 bit RSA can break in 10 min using p4

@unbreakablehost

Wow its in original hindi dubbed not ai

@arifali009

“that if thou shalt confess with thy mouth the Lord Jesus, and shalt believe in thine heart that God hath raised him from the dead, thou shalt be saved.”
‭‭Romans‬ ‭10‬:‭9‬ ‭KJV‬‬

@johndalessio4218

When my lecturer told this story about how hard it's to brute force decrypting things I told him that this require the computers not to evolve any more.
I guess 256-bit encryption will be beaten on a home computer within 256 years.

@HanMoP

в любом случае шанс найти кошелёк с битками есть

@aleksey767

lets say i already to the words where can iput them

@arturochavez2679

Quantum computer has entered the chat

@henri.isometsa

You had me at Kilo Google 🤣

@missionpupa

Mindblowing

@heinz_l_mann-j3q

I got recommanded this randomly before, and now again... NO ONE CAN REMEMBER MY PASSWORD EVEN IF I TOLD THEM!

@kaguraonlyreno

faixa de áudio em português portfavor

@Kcireh

Why i am always getting such video suggestions after my exams ends(Cryptographyand Network Security)? By the hindi dubbing is among the best i have seen so far

@greatgamer1

it doesnt require 2 to the power of 256 guesses on average tho. Thats just the number of possibilities

@yt___0_0___yt

The content with such animation before the existence of AI deserves appreciation.
Regards,

@uaziraslam29

Now, you have reached nearly 2²³ subscribers, congrats.

@alessandro22fox51

Quantum computer can do this in a second

@Voltnovolt

Imagine bigint security💔💔💔

@guriraphinha

erm....you don't need 2^265 guesses, you need about a third of it to have a good enough probability to guess the right message. Doesn't kill your whole video, but should be mentioned

@bluesparrow175

2:15 2026 UPDATE: 8.2 Billion

@OptiNihle

Is that Q&A still open?

@TotallyNotSusBob

wow

@JounhunKim

When you made this video you had 2^18 subscribers, now it's nearer 2*2^32, well done and keep up the good work

@DaveH3009

so like, a basic hacker could probably guess your password in like 3 or 4 days

@greenbanana36142

SHAW!

@stickwarGD

2025 year force rtx 5090 19 Gh/sec. Low entropy 2^100 cracked 😂😂😂

@an5droid1984

try to implement culture and moral, ethical values also

@vchess_playing

Feed giving this to me after i mentioned how the invention of quantum computers will put current cybersecurity at risk

@Nikko____

when i ask bro to talk to a girl
him:

@rishabhsinghicse8429

Anyone here in 2025 again

@Snabb9

thanks to ASICs: 4 billion galaxies of 4 billion planets, of 4 billion people each with a KiloGoogle of ASICS will CERTAINLY be able to guess a hash in a span of time that is 37 times the age of the universe. This makes me very uneasy for some reason.

@vai-d8m

Bold of you to assume I can comprehend 4 billion.

@LoremIpsum74

Social engineering bypasses all math

@byteafterlife

But it's still possible to get it first time?

@zvezda6545

Guys name any whole number from 0 to 255

@Greaty68official

хуйня
!

@EkaterinaAksenko

I enjoyed watching this video.

@SimrinLubaba-g5f