Damn. I watched CS50 with younger David when I began Bachelor in Cybesecurity. Now I am writing my masters and still watching CS50. This quality of teaching will never bore me!
@avadhpatel8100
11 ай бұрын
They are changing the game with the high quality and easy to understand courses
@bidyashankarojha_5105
11 ай бұрын
Being Harvard student , i can assure u all that quality and purity of knowledge is fabulous both online and offline
@Alice8000
6 ай бұрын
fake
@leksandradubovik6291
4 ай бұрын
Explaining Quantum Cryptography in just 3 Minutes, what a genius! Even my non-IT friendly friends were really intrestet to listen to this
@abstraction6266
11 ай бұрын
Wow! What a great lecture full of details. With CS50 , I am starting or already started to love computer science more than ever. Thanks alot for the CS50 team. Much appreciation!
@cn1doblast
Ай бұрын
"Alllright...THIS is CS50!..." always makes me goosebumps.
@Fatima-Aria
19 күн бұрын
same bro
@victorcousin8059
11 ай бұрын
This CS50 is just the best
@aliben123
11 ай бұрын
I love CS50
@jeimohwash-ke1rn
10 ай бұрын
Wow,i started cyber security with lesson 0 of this and i was able to decode the statement OR FHER...using a simple C program to be sure to drink.....I mean,,its actually of great help,,,i mostly lve the teacher.
@jeimohwash-ke1rn
10 ай бұрын
i actually did it myself before he ask us to do so😚😚
@leocrypto976
11 ай бұрын
How good are these courses to provide you the basis of a subject in an understandable way. Thank you!
@SA_GAMER1515
4 ай бұрын
Thanks for giving free access on youtube and edex platform
@Justin.254
11 ай бұрын
My dream is to know what makes me active, and cs50 is one
@MahmoodHasand3
11 ай бұрын
Amazing it’s what I have been waiting for
@EsquireR
Ай бұрын
Cryptography is actually the trickiest thing to wrap my mind around, like multiple keys for locking/unlocking publicity/privacy...
@MOKAZIQ
Ай бұрын
realllll 😭
@VazzyCow
Ай бұрын
Did I just get rick-rolled?
@MOKAZIQ
Ай бұрын
big fan
@MOKAZIQ
Ай бұрын
I JUST REALIZED WHILE WATCHING AGAIN FOR TAKING NOTES LMFAO
@UniHab
4 ай бұрын
Thank you @David
@_..Deepanshu.Singh_
10 ай бұрын
Thank you
@Ewakaa
3 ай бұрын
I thought the salt will preferably be the row number Love how he respects Hackers
@yiannisserpico2646
6 ай бұрын
A. If salt value is chosen by moment on time, is there still a possibility any salting value be same as another one? Since any time moment is never same as another one. I believe if hashing function has in it a moment time variable, then it is impossible two or more salting values be the same. But, again, my assumption is based on the fact that hashing function has time variable (is base on time moments). B. 37:20 Are you refered to hash tables? Thank you professor.
@AlessandraHudson
2 ай бұрын
Yes, there salt values are not meant to be unique.
@ChristopherBruns-o7o
Ай бұрын
31:31 WHAT if it uses auto completions and cache to check for autocompletion and if true enumerates this? Also sso and a sys admin resetting the pass and with permission has a prefered pass set could send from here; Especially with prompted to change passwd. Probably more of an IntraNet feature perhaps but i don't think makes the company poorly. 38:38 this means that if the adversary can go through bucket would know how many sets of hashes each bucket has and from 100 out of 10 groups only has 8 unique hashes? 55:46 is this why chatgpt hallucinates and how image generations are trained? 58:19 cant you just make the password filter and user account control to alarm when censored. 59:13 but do the mathematician discuss the salt and matching pairs variable? 1:02:03 but with ai now human longevity could be a declaration. Especially touch @1:08:@22 if RSA is secure. 1:11:59 26 might throw zerodivision error? since ///// mod is false ** mod != mod / True 1:15:23 But rotational ciphr would be the correct choice since at this layer you either decrypted the hash thus far or have abstraction scoped. 1:15:30 You mean that there are ascii and hex2dec similar that nuance salt:hashing pair values. 1:18:19 an unescaped, escaped reference to string literal symbol || ```PS2 1:51:59 dude is there a coarse for reversing Ransomware:@CS50:?
@yiannisserpico2646
7 ай бұрын
On salting method, why do the output characters include salting value? Why is it necessary? b. If hashing function takes for two password+salting (same password but two different salting), the output will normally be different without being necessary to have on beginning of two outputs the salting value, unless on software code it is fixed, but I do not find a reason why. Thank you!
@TheMediinaa
6 ай бұрын
I think he did that in order to ilustrate the concept... in a real world scenario salting is usually implemented by concatenating a random salt to the string BEFORE being hashed, which does make a bit more sense right.
@yiannisserpico2646
6 ай бұрын
@@TheMediinaa Thanks for rep!y. After the investigation I made all these days, I found that salting value is placed there because server needs it in order to complete hashing. Server must find somewhere salting value, and waiting user to enter password, then server hash both salt+password to complete hashing. Salting value may be placed anywhere. At the beginning (as illustated), maybe at the end of hashing, or even as a separate record in hashing database. But somewhere, because server needs it in order to complete hashing after password is entered by user. It's what student asks, and teacher answers/analyses with the example after this question.
@TheMediinaa
6 ай бұрын
@@yiannisserpico2646 interesting, i think that makes sense. Would be nice to hear from professor David himself though haha
@dreamleaf6784
5 ай бұрын
Ok. Thanks, i have upgraded my cyber security game.
@sreesysadm
12 күн бұрын
Is the hash function same for both customer(us) and the adversary??
@MohammedArab-f6i
8 күн бұрын
hash functions are publicly available. So yes
@yigitturedi3511
11 ай бұрын
yes, finaly
@yiannisserpico2646
6 ай бұрын
Sir, where is the hashing function been stored? I guess somewhere on the server. Isn't there a possibility/danger for a hacker to find it there? Unless it is not stored on servers. But if not, where? Thank you!
@AlessandraHudson
2 ай бұрын
The hashing functions are actually basically public, because typically companies use well-established hashing functions that are known to be very well implemented. But the hashing process is not easily reversible. Just because you know how to get from "password" to "hash value" (because you have the hashing function), it doesn't mean you'll know how to get from "hash value" to "password". It's crucial for these hashing functions to be a one-way street.
@aleksandardimov897
8 ай бұрын
In regards to the salting technique, given that a username on a website must me unique, isn’t it better to use that as salt, in order to guarantee that there will be no two equal hash values stored in the database? With the addition that to really guarantee uniqueness of the hash value its fixed-length must be of the same length as the max allowed length of the username and password combined.
@davidjmalan
8 ай бұрын
A good question! See security.stackexchange.com/a/69456 !
@aleksandardimov897
8 ай бұрын
Thanks for sharing! Helped me to find some really insightful discussions on the topic. Using usernames as salt indeed introduces some vulnerabilities, such as the creation of rainbow tables for the most commonly used usernames.
@AlessandraHudson
2 ай бұрын
@@aleksandardimov897thanks for summarizing the answer!
@Archliked
8 күн бұрын
1. SA ✅
@moltyfoam4168
10 ай бұрын
If my public key can decrypt the message or value i send on the server and since the key is available to almost everyone doesn't that make me vulnerable to an attack?? I dont get it
@tyro7428
9 ай бұрын
That’s kinda the whole thing. It’s only a matter of time and risk. Cryptography 101 no? I haven’t even watched this yet, debating if it’s worth it
@AlessandraHudson
2 ай бұрын
No, the public key is only used for encryption, not decryption. If you (A) send B a message encrypted using B's public key, then B will use their own private key to decrypt the encrypted message you sent. In case you were instead talking about digital signatures: in that context, yes, the public key *is* used to decrypt. But in that context, the message (called "challenge" here) is not supposed to be kept secret. In that context, the goal is simply to verify that you possess a private key that has a mathematical relationship to your public key such as that when decrypting (through your public key) the encrypted challenge that was sent to you (encrypted by you using your private key), the result will be the original unecrypted challenge.
@saiadwith4693
6 ай бұрын
i didnt understand rainbow tables,can anyone explain?
@s.s.haswanthselvan7064
5 ай бұрын
To be simple, it's a table that the hacker uses as a dictionary for smaller hash values, but they're quite expensive to create them for longer hash strings
@rafsan229
11 ай бұрын
rockstar is such a big company with obvious sheer cyber security..then how an adversary succeeded in obtaining crucial data from gta 6
@majlindhoxha4713
10 ай бұрын
did he just rick roll us at 1:41:43
@bambimbambas
10 ай бұрын
He did indeed) That makes it so funny that this "binary" rick-roll's face is there for so long
@forheuristiclifeksh7836
8 ай бұрын
12:00
@tonyhany2021
3 ай бұрын
i think i can gess private key if i get public key, this right?
@AlessandraHudson
2 ай бұрын
You can't.
@CafeAlCognac
Ай бұрын
47:43
@ZAVENBBRYN-v9h
21 сағат бұрын
Please have the students submit their questions in writing, it is painful to witness their awful efforts to ask something.
@TheMediinaa
11 ай бұрын
Any tips on the cheeky cipher in the second assessment? Hahah it was too hard for me, but the curiosity is killing me
@matiasjaeger
10 ай бұрын
I'm so lost with that one hahahaha
@napukapu
11 ай бұрын
You pulled out a glass and water prop skit to explain variables in CS50, but no metaphor to explain RSA or DHE? Really? DHE was the perfect opportunity to pull out water colors or paints or something.
@knowislamproject
11 ай бұрын
October 1, 2023
@atius866
6 ай бұрын
1:41:34 Rick Roll again
@yt_brij
9 ай бұрын
W
@anmolgurung8901
2 ай бұрын
We got rick rossed just saying
@banana_marley
3 ай бұрын
Part of deletion has a rick roll
@iihhyu77
3 ай бұрын
did we get rick rolled ?
@kalei91
11 ай бұрын
Man, the questions asked are so absurd, it's like they aren't even listening, I'm half way in and there's been the third consecutive question about reversing hashes. It's been explained over and over that it's irreversible, but they are unable to understand it. It's actually quite fascinating.
@blutube9916
11 ай бұрын
This is a beginner level course, with people from all kind of backgrounds/ with different technical levels. For some, these ideas are very new, and might be hard to understand. The idea is to bring everyone up to speed, even if it seems overly simple/repetitive to some.
@kalei91
11 ай бұрын
@@blutube9916 sure, but the same question was asked over and over. He already explained that hashes cannot be reversed, there's no way to do that, and what does the next person ask? "But if I know the algorithm then I can reverse it, right?". This is an intelligence problem, they cannot learn, they are incapable.
@会供価
11 ай бұрын
@@kalei91hmm maybe you should be at Harvard instead 😂
@longbranch4493
11 ай бұрын
@@kalei91 maybe exactly these questions were shown to make us, the viewers, feel smarter than we actually are? And make us more self confident. Haha. If serious, maybe they asked the same questions but in different forms because they doubted or didn't believe what they heard. Since hash functions don't require keys but only an input value it feels like you have everything you need to reverse the process by doing all operations in reverse order. On the other hand, Mr. Malan provided a good example when your hash function returns only the first letter of a word so lots of words will have the same hash. But I think irreversibility becomes really clear when you learn that the modulus operator is used in hashing. UPD: Actually, I thinked about it again after posting the comment and I think that Mr. Malan's example with a single letter is right on point. Since probably not every hash function uses the modulus operator, his example expresses the same idea, but more genereally.
@mimi-jm1yc
11 ай бұрын
They are unable to understand it because it hasn’t been explained to them. They merely gotten information that that is the way it is and curious minds question things and apply their current knowledge with what they are being told. To someone that is new to cryptography it is counter intuitive that there are mathematical processes that are not reversible, when what you’ve been taught at school clearly would be reversible. To the go out of your way and claim that this is some sort of intelligence problem is not just disrespectful but also wrong. They have the courage to ask a professor infront of a large audience instead of just nodding along even though they didn’t understand. I don’t understand what is so „fascinating“ about that…
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